zng_wgt_text/

text_properties.rs

use std::{fmt, num::NonZeroU32, time::Duration};

use zng_app::render::FontSynthesis;
use zng_color::COLOR_SCHEME_VAR;
use zng_ext_font::{font_features::*, *};
use zng_ext_l10n::{LANG_VAR, Langs};
use zng_view_api::config::FontAntiAliasing;
use zng_wgt::prelude::*;
use zng_wgt_layer::AnchorOffset;

use crate::node::TEXT;

/// Basic text font properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// See also [`FontFeaturesMix<P>`] for the other font properties.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct FontMix<P>(P);

context_var! {
    /// Font family of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_FAMILY_VAR: FontNames = FontNames::default();

    /// Font size of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_SIZE_VAR: FontSize = FontSize::Pt(11.0);

    /// Font weight of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_WEIGHT_VAR: FontWeight = FontWeight::NORMAL;

    /// Font style of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_STYLE_VAR: FontStyle = FontStyle::Normal;

    /// Font stretch of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_STRETCH_VAR: FontStretch = FontStretch::NORMAL;

    /// Font synthesis of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_SYNTHESIS_VAR: FontSynthesis = FontSynthesis::ENABLED;

    /// Font anti-aliasing of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_AA_VAR: FontAntiAliasing = FontAntiAliasing::Default;
}

impl FontMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&FONT_FAMILY_VAR);
        set.insert(&FONT_SIZE_VAR);
        set.insert(&FONT_WEIGHT_VAR);
        set.insert(&FONT_STYLE_VAR);
        set.insert(&FONT_STRETCH_VAR);
        set.insert(&FONT_SYNTHESIS_VAR);
        set.insert(&FONT_AA_VAR);
    }
}

/// Font family name or list of names for texts in this widget or descendants.
///
/// All fonts in the list are resolved according to the [`font_style`], [`font_weight`] and [`font_stretch`] config.
/// During text shaping the first font on the list is preferred, but if the font does not cover a character or word, that
/// character or word  to the second font in the list and so on.
///
/// Sets the [`FONT_FAMILY_VAR`].
///
/// [`font_style`]: fn@font_style
/// [`font_weight`]: fn@font_weight
/// [`font_stretch`]: fn@font_stretch
#[property(CONTEXT, default(FONT_FAMILY_VAR), widget_impl(FontMix<P>))]
pub fn font_family(child: impl IntoUiNode, names: impl IntoVar<FontNames>) -> UiNode {
    with_context_var(child, FONT_FAMILY_VAR, names)
}

/// Sets the font size for the widget and descendants.
///
/// This property affects all texts inside the widget and the [`Length::Em`] unit.
///
/// Sets the [`FONT_SIZE_VAR`] context var and the [`LayoutMetrics::font_size`].
///
/// [`LayoutMetrics::font_size`]: zng_wgt::prelude::LayoutMetrics::font_size
/// [`Length::Em`]: zng_wgt::prelude::Length::Em
#[property(CONTEXT, default(FONT_SIZE_VAR), widget_impl(FontMix<P>))]
pub fn font_size(child: impl IntoUiNode, size: impl IntoVar<FontSize>) -> UiNode {
    let child = match_node(child, |child, op| match op {
        UiNodeOp::Init => {
            WIDGET.sub_var_layout(&FONT_SIZE_VAR);
        }
        UiNodeOp::Measure { wm, desired_size } => {
            let font_size = FONT_SIZE_VAR.get();
            let font_size_px = font_size.layout_dft_x(LAYOUT.root_font_size());
            *desired_size = if font_size_px >= 0 {
                LAYOUT.with_font_size(font_size_px, || child.measure(wm))
            } else {
                tracing::error!("invalid font size {font_size:?} => {font_size_px:?}");
                child.measure(wm)
            };
        }
        UiNodeOp::Layout { wl, final_size } => {
            let font_size = FONT_SIZE_VAR.get();
            let font_size_px = font_size.layout_dft_x(LAYOUT.root_font_size());
            *final_size = if font_size_px >= 0 {
                LAYOUT.with_font_size(font_size_px, || child.layout(wl))
            } else {
                tracing::error!("invalid font size {font_size:?} => {font_size_px:?}");
                child.layout(wl)
            };
        }
        _ => {}
    });
    with_context_var(child, FONT_SIZE_VAR, size)
}

/// Defines the thickness or boldness the preferred font should have.
///
/// This value influences font resolution, the variant within the font family that is closest to this config will be selected.
///
/// Sets the [`FONT_WEIGHT_VAR`].
#[property(CONTEXT, default(FONT_WEIGHT_VAR), widget_impl(FontMix<P>))]
pub fn font_weight(child: impl IntoUiNode, weight: impl IntoVar<FontWeight>) -> UiNode {
    with_context_var(child, FONT_WEIGHT_VAR, weight)
}

/// Defines the skew style of the font glyphs.
///
/// This value influences font resolution, the variant within the font family that is closest to this config will be selected.
///
/// Sets the [`FONT_STYLE_VAR`].
#[property(CONTEXT, default(FONT_STYLE_VAR), widget_impl(FontMix<P>))]
pub fn font_style(child: impl IntoUiNode, style: impl IntoVar<FontStyle>) -> UiNode {
    with_context_var(child, FONT_STYLE_VAR, style)
}

/// Defines how condensed or expanded the preferred font should be.
///
/// This value influences font resolution, the variant within the font family that is closest to this config will be selected.
///
/// Sets the [`FONT_STRETCH_VAR`].
#[property(CONTEXT, default(FONT_STRETCH_VAR), widget_impl(FontMix<P>))]
pub fn font_stretch(child: impl IntoUiNode, stretch: impl IntoVar<FontStretch>) -> UiNode {
    with_context_var(child, FONT_STRETCH_VAR, stretch)
}

/// Configure if a synthetic font is generated for fonts that do not implement **bold** or *oblique* variants.
///
/// Not all fonts implement the requested [`font_weight`] and [`font_style`], this config allows the renderer
/// to try and generate the style and weight anyway, using transforms and the glyph outlines.
///
/// Sets the [`FONT_SYNTHESIS_VAR`].
///
/// [`font_weight`]: fn@font_weight
/// [`font_style`]: fn@font_style
#[property(CONTEXT, default(FONT_SYNTHESIS_VAR), widget_impl(FontMix<P>))]
pub fn font_synthesis(child: impl IntoUiNode, enabled: impl IntoVar<FontSynthesis>) -> UiNode {
    with_context_var(child, FONT_SYNTHESIS_VAR, enabled)
}

/// Configure the anti-aliasing used to render text glyphs inside the widget.
///
/// Uses the operating system configuration by default.
///
/// Sets the [`FONT_AA_VAR`].
#[property(CONTEXT, default(FONT_AA_VAR), widget_impl(FontMix<P>))]
pub fn font_aa(child: impl IntoUiNode, aa: impl IntoVar<FontAntiAliasing>) -> UiNode {
    with_context_var(child, FONT_AA_VAR, aa)
}

/// Text color properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextFillMix<P>(P);

context_var! {
    /// Color of [`Text!`] glyphs that are not colored by palette.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_COLOR_VAR: Rgba = COLOR_SCHEME_VAR.map(|s| match s {
        ColorScheme::Light => colors::BLACK,
        ColorScheme::Dark => colors::WHITE,
        _ => colors::BLACK,
    });

    /// Color of [`Text!`] glyphs that are colored by palette, mostly Emoji.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_PALETTE_VAR: FontColorPalette = COLOR_SCHEME_VAR.map_into();

    /// Overrides of specific colors in the selected colored glyph palette.
    pub static FONT_PALETTE_COLORS_VAR: Vec<(u16, Rgba)> = vec![];
}

impl TextFillMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&FONT_COLOR_VAR);
        set.insert(&FONT_PALETTE_VAR);
        set.insert(&FONT_PALETTE_COLORS_VAR);
    }
}

/// Defines the color the most text glyphs are filled with.
///
/// Colored glyphs (Emoji) are not affected by this, you can use [`font_palette`] to modify
/// Emoji colors.
///
/// Sets the [`FONT_COLOR_VAR`].
///
/// [`font_palette`]: fn@font_palette
#[property(CONTEXT, default(FONT_COLOR_VAR), widget_impl(TextFillMix<P>))]
pub fn font_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, FONT_COLOR_VAR, color)
}

/// Defines the palette used to render colored glyphs (Emoji).
///
/// This property only affects Emoji from fonts using COLR v0. You can use [`font_color`] to set
/// the base color, and [`font_palette_colors`] to change specific colors.
///
/// Sets the [`FONT_PALETTE_VAR`].
///
/// [`font_color`]: fn@font_color
/// [`font_palette_colors`]: fn@font_palette_colors
#[property(CONTEXT, default(FONT_PALETTE_VAR), widget_impl(TextFillMix<P>))]
pub fn font_palette(child: impl IntoUiNode, palette: impl IntoVar<FontColorPalette>) -> UiNode {
    with_context_var(child, FONT_PALETTE_VAR, palette)
}

/// Set the palette color in the font palette colors.
///
/// The `index` is pushed or replaced on the context [`FONT_PALETTE_COLORS_VAR`].
///
/// This function is a helper for declaring properties that configure the colors of a specific font, you
/// can use [`font_palette_colors`] to set all color overrides directly.
///
/// [`font_palette_colors`]: fn@font_palette_colors
pub fn with_font_palette_color(child: impl IntoUiNode, index: u16, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(
        child,
        FONT_PALETTE_COLORS_VAR,
        merge_var!(FONT_PALETTE_COLORS_VAR, color.into_var(), move |set, color| {
            let mut set = set.clone();
            if let Some(i) = set.iter().position(|(i, _)| *i == index) {
                set[i].1 = *color;
            } else {
                set.push((index, *color));
            }
            set
        }),
    )
}

/// Defines custom palette colors that affect Emoji colors.
///
/// The palette is selected by [`font_palette`] and then each valid index entry in this property replaces
/// the selected color.
///
/// Sets the [`FONT_PALETTE_COLORS_VAR`].
///
/// [`font_palette`]: fn@font_palette
#[property(CONTEXT, default(FONT_PALETTE_COLORS_VAR), widget_impl(TextFillMix<P>))]
pub fn font_palette_colors(child: impl IntoUiNode, colors: impl IntoVar<Vec<(u16, Rgba)>>) -> UiNode {
    with_context_var(child, FONT_PALETTE_COLORS_VAR, colors)
}

/// Text align, justify.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextAlignMix<P>(P);

context_var! {
    /// Text alignment inside the available space.
    pub static TEXT_ALIGN_VAR: Align = Align::START;

    /// Text alignment inside the available space when it overflows.
    pub static TEXT_OVERFLOW_ALIGN_VAR: Align = Align::TOP_START;

    /// Text justify mode when text align is fill.
    pub static JUSTIFY_MODE_VAR: Justify = Justify::Auto;
}

impl TextAlignMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&TEXT_ALIGN_VAR);
        set.insert(&TEXT_OVERFLOW_ALIGN_VAR);
        set.insert(&JUSTIFY_MODE_VAR);
    }
}

/// Alignment of text inside available space.
///
/// Horizontal alignment is applied for each line independently, vertical alignment is applied for the entire
/// text block together.
///
/// Note that the [`Text!`] widget only implements this for text inside each instance in isolation, multiple
/// text instances in an inline row will not all align together by the [`Text!`] layout implementation alone.
///
/// Sets the [`TEXT_ALIGN_VAR`].
///
/// See also [`txt_overflow_align`], used when the text overflows.
///
/// [`Text!`]: struct@crate::Text
/// [`txt_overflow_align`]: fn@txt_overflow_align
#[property(CONTEXT, default(TEXT_ALIGN_VAR), widget_impl(TextAlignMix<P>))]
pub fn txt_align(child: impl IntoUiNode, mode: impl IntoVar<Align>) -> UiNode {
    with_context_var(child, TEXT_ALIGN_VAR, mode)
}

/// Alignment of text inside available space when the text overflows.
///
/// Note that the [`Text!`] widget only implements this for text inside each instance in isolation, multiple
/// text instances in an inline row will not all align together. Also note that [`txt_overflow`] truncation
/// only applies to the end of the text after it is aligned, so unless this is [`Align::TOP_START`] (default) the
/// start of the text maybe still be clipped after truncation.
///
/// Sets the [`TEXT_OVERFLOW_ALIGN_VAR`].
///
/// [`Text!`]: struct@crate::Text
/// [`txt_overflow`]: fn@txt_overflow
/// [`Align::TOP_START`]: zng_wgt::prelude::Align::TOP_START
#[property(CONTEXT, default(TEXT_OVERFLOW_ALIGN_VAR), widget_impl(TextAlignMix<P>))]
pub fn txt_overflow_align(child: impl IntoUiNode, mode: impl IntoVar<Align>) -> UiNode {
    with_context_var(child, TEXT_OVERFLOW_ALIGN_VAR, mode)
}

/// Config the automatic spacing inserted between words and letters when text is aligned to fill.
///
/// Text alignment can be set to [`Align::FILL_X`], if that is the case this config is defines how
/// the glyphs are spaced to *fill* the text block.
///
/// Sets the [`JUSTIFY_MODE_VAR`].
///
/// [`Align::FILL_X`]: zng_wgt::prelude::Align::FILL_X
#[property(CONTEXT, default(JUSTIFY_MODE_VAR), widget_impl(TextAlignMix<P>))]
pub fn justify_mode(child: impl IntoUiNode, mode: impl IntoVar<Justify>) -> UiNode {
    with_context_var(child, JUSTIFY_MODE_VAR, mode)
}

/// Text wrap, hyphenation.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextWrapMix<P>(P);

context_var! {
    /// If line breaks are automatically inserted to fill the available space.
    ///
    /// The [`LINE_BREAK_VAR`], [`WORD_BREAK_VAR`] and [`HYPHENS_VAR`] configure how the text is split.
    ///
    /// Is `true` by default.
    pub static TEXT_WRAP_VAR: bool = true;

    /// Configuration of line breaks inside words during text wrap.
    pub static WORD_BREAK_VAR: WordBreak = WordBreak::Normal;

    /// Configuration of line breaks in Chinese, Japanese, or Korean text.
    pub static LINE_BREAK_VAR: LineBreak = LineBreak::Auto;

    /// Text hyphenation config.
    pub static HYPHENS_VAR: Hyphens = Hyphens::default();

    /// Hyphen text rendered when auto-hyphenating.
    pub static HYPHEN_CHAR_VAR: Txt = Txt::from_char('-');

    /// Text overflow handling.
    pub static TEXT_OVERFLOW_VAR: TextOverflow = TextOverflow::Ignore;
}

impl TextWrapMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&TEXT_WRAP_VAR);
        set.insert(&WORD_BREAK_VAR);
        set.insert(&LINE_BREAK_VAR);
        set.insert(&HYPHENS_VAR);
        set.insert(&HYPHEN_CHAR_VAR);
        set.insert(&TEXT_OVERFLOW_VAR);
    }
}

/// Defines how text overflow is handled by the text widgets.
#[derive(Clone, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
pub enum TextOverflow {
    /// Text is allowed to overflow.
    ///
    /// Note that the text widget can still [`clip_to_bounds`], and text widgets also clip any text
    /// that overflows over one line-height in any direction. Text overflow is tracked even if `Ignore`
    /// is set, so custom properties may also implement some form of overflow handling.
    ///
    /// [`clip_to_bounds`]: fn@zng_wgt::clip_to_bounds
    Ignore,
    /// Truncate the text so it will fit, the associated `Txt` is a suffix appended to the truncated text.
    ///
    /// Note that if the suffix is not empty the text will truncate more to reserve space for the suffix. If
    /// the suffix itself is too wide it will overflow.
    Truncate(Txt),
}
impl fmt::Debug for TextOverflow {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if f.alternate() {
            write!(f, "TextOverflow")?
        }
        match self {
            Self::Ignore => write!(f, "Ignore"),
            Self::Truncate(arg0) => f.debug_tuple("Truncate").field(arg0).finish(),
        }
    }
}
impl TextOverflow {
    /// Truncate without suffix.
    pub fn truncate() -> Self {
        Self::Truncate(Txt::from_static(""))
    }

    /// Truncate with the ellipses `'…'` char as suffix.
    pub fn ellipses() -> Self {
        Self::Truncate(Txt::from_char('…'))
    }
}
impl_from_and_into_var! {
    /// Truncate (no suffix), or ignore.
    fn from(truncate: bool) -> TextOverflow {
        if truncate { TextOverflow::truncate() } else { TextOverflow::Ignore }
    }

    fn from(truncate: Txt) -> TextOverflow {
        TextOverflow::Truncate(truncate)
    }
    fn from(s: &'static str) -> TextOverflow {
        Txt::from(s).into()
    }
    fn from(s: String) -> TextOverflow {
        Txt::from(s).into()
    }
    fn from(c: char) -> TextOverflow {
        Txt::from(c).into()
    }
}

/// Enables or disables text wrap.
///
/// If enabled, line-breaks and hyphens are automatically inserted to flow the text to fill the available width. Wrap
/// can be configured using the [`line_break`], [`word_break`] and [`hyphens`] properties.
///
/// Sets the [`TEXT_WRAP_VAR`].
///
/// [`line_break`]: fn@line_break
/// [`word_break`]: fn@word_break
/// [`hyphens`]: fn@hyphens
#[property(CONTEXT, default(TEXT_WRAP_VAR), widget_impl(TextWrapMix<P>))]
pub fn txt_wrap(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, TEXT_WRAP_VAR, enabled)
}

/// Configure line breaks inside words during text wrap.
///
/// This value is only considered if it is impossible to fit a full word to a line.
///
/// Hyphens can be inserted in word breaks using the [`hyphens`] configuration.
///
/// Sets the [`WORD_BREAK_VAR`].
///
/// [`hyphens`]: fn@hyphens
#[property(CONTEXT, default(WORD_BREAK_VAR), widget_impl(TextWrapMix<P>))]
pub fn word_break(child: impl IntoUiNode, mode: impl IntoVar<WordBreak>) -> UiNode {
    with_context_var(child, WORD_BREAK_VAR, mode)
}

/// Configuration of text wrapping for Chinese, Japanese, or Korean text.
///
/// Sets the [`LINE_BREAK_VAR`].
#[property(CONTEXT, default(LINE_BREAK_VAR), widget_impl(TextWrapMix<P>))]
pub fn line_break(child: impl IntoUiNode, mode: impl IntoVar<LineBreak>) -> UiNode {
    with_context_var(child, LINE_BREAK_VAR, mode)
}

/// Configure hyphenation.
///
/// Note that for automatic hyphenation to work the [`lang`] must also be set and the [`HYPHENATION`] service must support it.
///
/// The auto hyphenation char can be defined using [`hyphen_char`].
///
/// [`HYPHENATION`]: zng_ext_font::HYPHENATION
/// [`lang`]: fn@lang
/// [`hyphen_char`]: fn@hyphen_char
#[property(CONTEXT, default(HYPHENS_VAR), widget_impl(TextWrapMix<P>))]
pub fn hyphens(child: impl IntoUiNode, hyphens: impl IntoVar<Hyphens>) -> UiNode {
    with_context_var(child, HYPHENS_VAR, hyphens)
}

/// The char or small string that is rendered when text is auto-hyphenated.
///
/// Note that hyphenation is enabled by the [`hyphens`] property.
///
/// [`hyphens`]: fn@hyphens
#[property(CONTEXT, default(HYPHEN_CHAR_VAR), widget_impl(TextWrapMix<P>))]
pub fn hyphen_char(child: impl IntoUiNode, hyphen: impl IntoVar<Txt>) -> UiNode {
    with_context_var(child, HYPHEN_CHAR_VAR, hyphen)
}

/// Defines if text overflow is truncated, with optional suffix append.
///
/// When enabled overflow is truncated by character or by the wrap rules if [`txt_wrap`] is enabled (it is by default).
///
/// Overflow is always ignored when the text is editable.
///
/// [`txt_wrap`]: fn@txt_wrap
#[property(CONTEXT, default(TEXT_OVERFLOW_VAR), widget_impl(TextWrapMix<P>))]
pub fn txt_overflow(child: impl IntoUiNode, overflow: impl IntoVar<TextOverflow>) -> UiNode {
    with_context_var(child, TEXT_OVERFLOW_VAR, overflow)
}

/// Gets if the text is overflown.
#[property(CHILD_LAYOUT+100, widget_impl(TextWrapMix<P>))]
pub fn is_overflown(child: impl IntoUiNode, state: impl IntoVar<bool>) -> UiNode {
    let state = state.into_var();
    match_node(child, move |_, op| match op {
        UiNodeOp::Deinit => {
            state.set(false);
        }
        UiNodeOp::Layout { .. } => {
            let is_o = super::node::TEXT.laidout().overflow.is_some();
            if is_o != state.get() {
                state.set(is_o);
            }
        }
        _ => {}
    })
}

/// Gets if the text has an entire line overflown.
///
/// This is `true` when the text has multiple lines, either due to line-break or wrap, and at
/// least one line overflows the allowed height, partially or fully.
#[property(CHILD_LAYOUT+100, widget_impl(TextWrapMix<P>))]
pub fn is_line_overflown(child: impl IntoUiNode, state: impl IntoVar<bool>) -> UiNode {
    let state = state.into_var();
    match_node(child, move |_, op| match op {
        UiNodeOp::Deinit => {
            state.set(false);
        }
        UiNodeOp::Layout { .. } => {
            let txt = super::node::TEXT.laidout();
            let is_o = if let Some(info) = &txt.overflow {
                info.line < txt.shaped_text.lines_len().saturating_sub(1)
            } else {
                false
            };
            if is_o != state.get() {
                state.set(is_o);
            }
        }
        _ => {}
    })
}

/// Gets the overflow text, that is a clone of the text starting from the first overflow character.
///
/// Note that overflow is tracked even if [`txt_overflow`] is set to [`TextOverflow::Ignore`].
///
/// [`txt_overflow`]: fn@txt_overflow
#[property(CHILD_LAYOUT+100, widget_impl(TextWrapMix<P>))]
pub fn get_overflow(child: impl IntoUiNode, txt: impl IntoVar<Txt>) -> UiNode {
    let txt = txt.into_var();
    match_node(child, move |_, op| {
        if let UiNodeOp::Layout { .. } = op {
            let l_txt = super::node::TEXT.laidout();
            if let Some(info) = &l_txt.overflow {
                let r = super::node::TEXT.resolved();
                let tail = &r.segmented_text.text()[info.text_char..];
                if txt.with(|t| t != tail) {
                    txt.set(Txt::from_str(tail));
                }
            } else if txt.with(|t| !t.is_empty()) {
                txt.set(Txt::from_static(""));
            }
        }
    })
}

/// Text underline, overline and strikethrough lines.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextDecorationMix<P>(P);

bitflags! {
    /// Represents what parts of a text the underline must skip over.
    #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
    #[serde(transparent)]
    pub struct UnderlineSkip: u8 {
        /// Underline spans the entire text length.
        const NONE = 0;

        /// Skip white space.
        const SPACES = 0b0001;

        /// Skip over glyph descenders that intersect with the underline.
        const GLYPHS = 0b0010;

        /// Default value, skip glyphs.
        const DEFAULT = Self::GLYPHS.bits();
    }
}
impl Default for UnderlineSkip {
    fn default() -> Self {
        Self::DEFAULT
    }
}

/// Defines what line gets traced by the text underline decoration.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Default, serde::Serialize, serde::Deserialize)]
pub enum UnderlinePosition {
    /// Underline is positioned using the offset defined in the font file.
    #[default]
    Font,
    /// Underline is positioned after the text *descent*, avoiding crossover with all glyph descenders.
    Descent,
}

context_var! {
    /// Underline thickness.
    pub static UNDERLINE_THICKNESS_VAR: UnderlineThickness = 0;
    /// Underline style.
    pub static UNDERLINE_STYLE_VAR: LineStyle = LineStyle::Hidden;
    /// Underline color, inherits from [`FONT_COLOR_VAR`].
    pub static UNDERLINE_COLOR_VAR: Rgba = FONT_COLOR_VAR;
    /// Parts of text skipped by underline.
    pub static UNDERLINE_SKIP_VAR: UnderlineSkip = UnderlineSkip::DEFAULT;
    /// Position of the underline.
    pub static UNDERLINE_POSITION_VAR: UnderlinePosition = UnderlinePosition::Font;

    /// Overline thickness.
    pub static OVERLINE_THICKNESS_VAR: TextLineThickness = 0;
    /// Overline style.
    pub static OVERLINE_STYLE_VAR: LineStyle = LineStyle::Hidden;
    /// Overline color, inherits from [`FONT_COLOR_VAR`].
    pub static OVERLINE_COLOR_VAR: Rgba = FONT_COLOR_VAR;

    /// Strikethrough thickness.
    pub static STRIKETHROUGH_THICKNESS_VAR: TextLineThickness = 0;
    /// Strikethrough style.
    pub static STRIKETHROUGH_STYLE_VAR: LineStyle = LineStyle::Hidden;
    /// Strikethrough color, inherits from [`FONT_COLOR_VAR`].
    pub static STRIKETHROUGH_COLOR_VAR: Rgba = FONT_COLOR_VAR;

    /// Underline thickness for the IME preview underline.
    pub static IME_UNDERLINE_THICKNESS_VAR: UnderlineThickness = 1;
    /// Underline style for the IME preview underline.
    pub static IME_UNDERLINE_STYLE_VAR: LineStyle = LineStyle::Dotted;
}

impl TextDecorationMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&UNDERLINE_THICKNESS_VAR);
        set.insert(&UNDERLINE_STYLE_VAR);
        set.insert(&UNDERLINE_COLOR_VAR);
        set.insert(&UNDERLINE_SKIP_VAR);
        set.insert(&UNDERLINE_POSITION_VAR);
        set.insert(&OVERLINE_THICKNESS_VAR);
        set.insert(&OVERLINE_STYLE_VAR);
        set.insert(&OVERLINE_COLOR_VAR);
        set.insert(&STRIKETHROUGH_THICKNESS_VAR);
        set.insert(&STRIKETHROUGH_STYLE_VAR);
        set.insert(&STRIKETHROUGH_COLOR_VAR);
        set.insert(&IME_UNDERLINE_THICKNESS_VAR);
        set.insert(&IME_UNDERLINE_STYLE_VAR);
    }
}

/// Draw lines *under* each text line.
///
/// Sets the [`UNDERLINE_THICKNESS_VAR`] and [`UNDERLINE_STYLE_VAR`].
#[property(CONTEXT, default(UNDERLINE_THICKNESS_VAR, UNDERLINE_STYLE_VAR), widget_impl(TextDecorationMix<P>))]
pub fn underline(child: impl IntoUiNode, thickness: impl IntoVar<UnderlineThickness>, style: impl IntoVar<LineStyle>) -> UiNode {
    let child = with_context_var(child, UNDERLINE_THICKNESS_VAR, thickness);
    with_context_var(child, UNDERLINE_STYLE_VAR, style)
}
/// Custom [`underline`](fn@underline) color, if not set
/// the [`font_color`](fn@font_color) is used.
///
/// Sets the [`UNDERLINE_COLOR_VAR`].
#[property(CONTEXT, default(UNDERLINE_COLOR_VAR), widget_impl(TextDecorationMix<P>))]
pub fn underline_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, UNDERLINE_COLOR_VAR, color)
}
/// Defines what segments of each text line are skipped when tracing the [`underline`](fn@underline).
///
/// By default skips glyphs that intercept the underline.
///
/// Sets the [`UNDERLINE_SKIP_VAR`].
#[property(CONTEXT, default(UNDERLINE_SKIP_VAR), widget_impl(TextDecorationMix<P>))]
pub fn underline_skip(child: impl IntoUiNode, skip: impl IntoVar<UnderlineSkip>) -> UiNode {
    with_context_var(child, UNDERLINE_SKIP_VAR, skip)
}
/// Defines what font line gets traced by the underline.
///
/// By default uses the font configuration, but it usually crosses over glyph *descents* causing skips on
/// the line, you can set this [`UnderlinePosition::Descent`] to fully clear all glyph *descents*.
///
/// Sets the [`UNDERLINE_POSITION_VAR`].
#[property(CONTEXT, default(UNDERLINE_POSITION_VAR), widget_impl(TextDecorationMix<P>))]
pub fn underline_position(child: impl IntoUiNode, position: impl IntoVar<UnderlinePosition>) -> UiNode {
    with_context_var(child, UNDERLINE_POSITION_VAR, position)
}

/// Draw lines *above* each text line.
///
/// Sets the [`OVERLINE_THICKNESS_VAR`] and [`OVERLINE_STYLE_VAR`].
#[property(CONTEXT, default(OVERLINE_THICKNESS_VAR, OVERLINE_STYLE_VAR), widget_impl(TextDecorationMix<P>))]
pub fn overline(child: impl IntoUiNode, thickness: impl IntoVar<TextLineThickness>, style: impl IntoVar<LineStyle>) -> UiNode {
    let child = with_context_var(child, OVERLINE_THICKNESS_VAR, thickness);
    with_context_var(child, OVERLINE_STYLE_VAR, style)
}
/// Custom [`overline`](fn@overline) color, if not set
/// the [`font_color`](fn@font_color) is used.
///
/// Sets the [`OVERLINE_COLOR_VAR`].
#[property(CONTEXT, default(OVERLINE_COLOR_VAR), widget_impl(TextDecorationMix<P>))]
pub fn overline_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, OVERLINE_COLOR_VAR, color)
}

/// Draw lines across each text line.
///
/// Sets the [`STRIKETHROUGH_THICKNESS_VAR`] and [`STRIKETHROUGH_STYLE_VAR`].
#[property(CONTEXT, default(STRIKETHROUGH_THICKNESS_VAR, STRIKETHROUGH_STYLE_VAR), widget_impl(TextDecorationMix<P>))]
pub fn strikethrough(child: impl IntoUiNode, thickness: impl IntoVar<TextLineThickness>, style: impl IntoVar<LineStyle>) -> UiNode {
    let child = with_context_var(child, STRIKETHROUGH_THICKNESS_VAR, thickness);
    with_context_var(child, STRIKETHROUGH_STYLE_VAR, style)
}
/// Custom [`strikethrough`](fn@strikethrough) color, if not set
/// the [`font_color`](fn@font_color) is used.
///
/// Sets the [`STRIKETHROUGH_COLOR_VAR`].
#[property(CONTEXT, default(STRIKETHROUGH_COLOR_VAR), widget_impl(TextDecorationMix<P>))]
pub fn strikethrough_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, STRIKETHROUGH_COLOR_VAR, color)
}

/// Style and thickness of the line drawn *under* the IME preview text.
///
/// Sets the [`IME_UNDERLINE_THICKNESS_VAR`] and [`IME_UNDERLINE_STYLE_VAR`].
#[property(CONTEXT, default(IME_UNDERLINE_THICKNESS_VAR, IME_UNDERLINE_STYLE_VAR), widget_impl(TextDecorationMix<P>))]
pub fn ime_underline(child: impl IntoUiNode, thickness: impl IntoVar<UnderlineThickness>, style: impl IntoVar<LineStyle>) -> UiNode {
    let child = with_context_var(child, IME_UNDERLINE_THICKNESS_VAR, thickness);
    with_context_var(child, IME_UNDERLINE_STYLE_VAR, style)
}

/// Text spacing properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// See also [`ParagraphMix<P>`] for paragraph spacing.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextSpacingMix<P>(P);

context_var! {
    /// Text line height of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static LINE_HEIGHT_VAR: LineHeight = LineHeight::Default;

    /// Extra spacing in between lines of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static LINE_SPACING_VAR: LineSpacing = LineSpacing::Default;

    /// Extra letter spacing of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static LETTER_SPACING_VAR: LetterSpacing = LetterSpacing::Default;

    /// Extra word spacing of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static WORD_SPACING_VAR: WordSpacing = WordSpacing::Default;

    /// Length of the `TAB` space.
    pub static TAB_LENGTH_VAR: TabLength = 400.pct();
}

impl TextSpacingMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&LINE_HEIGHT_VAR);
        set.insert(&LINE_SPACING_VAR);
        set.insert(&LETTER_SPACING_VAR);
        set.insert(&WORD_SPACING_VAR);
        set.insert(&TAB_LENGTH_VAR);
        set.insert(&PARAGRAPH_INDENT_VAR);
    }
}

/// Height of each text line.
///
/// The [`Default`] value is computed from the font metrics, `ascent - descent + line_gap`, this is
/// usually similar to `1.2.em()`. Relative values are computed from the default value, so `200.pct()` is double
/// the default line height.
///
/// The text is vertically centered inside the height.
///
/// [`Default`]: Length::Default
///
/// Sets the [`LINE_HEIGHT_VAR`].
#[property(CONTEXT, default(LINE_HEIGHT_VAR), widget_impl(TextSpacingMix<P>))]
pub fn line_height(child: impl IntoUiNode, height: impl IntoVar<LineHeight>) -> UiNode {
    with_context_var(child, LINE_HEIGHT_VAR, height)
}

/// Extra spacing added in between text letters.
///
/// Letter spacing is computed using the font data, this unit represents
/// extra space added to the computed spacing.
///
/// A "letter" is a character glyph cluster, e.g.: `a`, `â`, `1`, `-`, `漢`.
///
/// The [`Default`] value signals that letter spacing can be tweaked when text *justification* is enabled, all other
/// values disable automatic adjustments for justification inside words.
///
/// Relative values are computed from the length of the space `' '` character.
///
/// [`Default`]: Length::Default
///
/// This property sets the [`LETTER_SPACING_VAR`] context var that affects all inner texts.
#[property(CONTEXT, default(LETTER_SPACING_VAR), widget_impl(TextSpacingMix<P>))]
pub fn letter_spacing(child: impl IntoUiNode, extra: impl IntoVar<LetterSpacing>) -> UiNode {
    with_context_var(child, LETTER_SPACING_VAR, extra)
}

/// Extra spacing in-between text lines.
///
/// The [`Default`] value is zero. Relative values are calculated from the [`LineHeight`], so `50.pct()` is half
/// the computed line height. If the text only has one line this property is not used.
///
/// [`Default`]: Length::Default
///
/// Sets the [`LINE_SPACING_VAR`].
///
/// [`LineHeight`]: zng_ext_font::LineHeight
#[property(CONTEXT, default(LINE_SPACING_VAR), widget_impl(TextSpacingMix<P>))]
pub fn line_spacing(child: impl IntoUiNode, extra: impl IntoVar<LineSpacing>) -> UiNode {
    with_context_var(child, LINE_SPACING_VAR, extra)
}

/// Extra spacing added to the Unicode `U+0020 SPACE` character.
///
/// Word spacing is done using the space character "advance" as defined in the font,
/// this unit represents extra spacing added to that default spacing.
///
/// A "word" is the sequence of characters in-between space characters. This extra
/// spacing is applied per space character not per word, if there are three spaces between words
/// the extra spacing is applied thrice. Usually the number of spaces between words is collapsed to one,
/// see [`WhiteSpace`], resulting in only one extra spacing.
///
/// The [`Default`] value signals that word spacing can be tweaked when text *justification* is enabled, all other
/// values disable automatic adjustments for justification. Relative values are computed from the length of the space `' '` character,
/// so a word spacing of `100.pct()` visually adds *another* space in between words.
///
/// [`Default`]: Length::Default
///
/// This property sets the [`WORD_SPACING_VAR`] context var that affects all inner widgets.
///
/// [`WhiteSpace`]: zng_ext_font::WhiteSpace
#[property(CONTEXT, default(WORD_SPACING_VAR), widget_impl(TextSpacingMix<P>))]
pub fn word_spacing(child: impl IntoUiNode, extra: impl IntoVar<WordSpacing>) -> UiNode {
    with_context_var(child, WORD_SPACING_VAR, extra)
}

/// Length of the TAB character space, relative to the normal space advance.
///
/// Is set to `400.pct()` by default, so 4 times a space.
///
/// Sets the [`TAB_LENGTH_VAR`].
#[property(CONTEXT, default(TAB_LENGTH_VAR), widget_impl(TextSpacingMix<P>))]
pub fn tab_length(child: impl IntoUiNode, length: impl IntoVar<TabLength>) -> UiNode {
    with_context_var(child, TAB_LENGTH_VAR, length)
}

/// Text transform properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextTransformMix<P>(P);

context_var! {
    /// Text white space transform of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static WHITE_SPACE_VAR: WhiteSpace = WhiteSpace::Preserve;

    /// Text transformation function applied to [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static TEXT_TRANSFORM_VAR: TextTransformFn = TextTransformFn::None;
}

impl TextTransformMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&WHITE_SPACE_VAR);
        set.insert(&TEXT_TRANSFORM_VAR);
    }
}

/// Text white space transform.
///
/// Can be used to collapse a sequence of spaces into a single one, or to ignore line-breaks.
/// Is [`WhiteSpace::Preserve`] by default.
///
/// This property is not applied when the text is [`txt_editable`].
///
/// Sets the [`WHITE_SPACE_VAR`].
///
/// [`txt_editable`]: fn@txt_editable
/// [`WhiteSpace::Preserve`]: zng_ext_font::WhiteSpace::Preserve
#[property(CONTEXT, default(WHITE_SPACE_VAR), widget_impl(TextTransformMix<P>))]
pub fn white_space(child: impl IntoUiNode, transform: impl IntoVar<WhiteSpace>) -> UiNode {
    with_context_var(child, WHITE_SPACE_VAR, transform)
}

/// Text transform, character replacement applied to the text before it is processed by the text widget.
///
/// This property is not applied when the text is [`txt_editable`].
///
/// Sets the [`TEXT_TRANSFORM_VAR`].
///  
/// [`txt_editable`]: fn@txt_editable
#[property(CONTEXT, default(TEXT_TRANSFORM_VAR), widget_impl(TextTransformMix<P>))]
pub fn txt_transform(child: impl IntoUiNode, transform: impl IntoVar<TextTransformFn>) -> UiNode {
    with_context_var(child, TEXT_TRANSFORM_VAR, transform)
}

/// Language and text direction properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct LangMix<P>(P);

/// Sets the text language and script for the widget and descendants.
///
/// This property affects all texts inside the widget and the layout direction.
///
/// Sets the [`LANG_VAR`] and [`DIRECTION_VAR`] context vars and the [`LayoutMetrics::direction`].
/// Also sets the [`access::lang`] when accessibility is enabled.
///
/// [`access::lang`]: fn@zng_wgt_access::lang
/// [`LANG_VAR`]: zng_ext_l10n::LANG_VAR
/// [`DIRECTION_VAR`]: zng_wgt::prelude::DIRECTION_VAR
/// [`LayoutMetrics::direction`]: zng_wgt::prelude::LayoutMetrics::direction
#[property(CONTEXT, default(LANG_VAR), widget_impl(LangMix<P>))]
pub fn lang(child: impl IntoUiNode, lang: impl IntoVar<Langs>) -> UiNode {
    let lang = lang.into_var();
    let child = direction(child, lang.map(|l| l.best().direction()));
    let child = zng_wgt_access::lang(child, lang.map(|l| l.best().clone()));
    with_context_var(child, LANG_VAR, lang)
}

/// Sets the layout direction used in the layout of the widget and descendants.
///
/// Note that the [`lang`] property already sets the direction, this property can be used to directly override the direction.
///
/// Sets the [`DIRECTION_VAR`] context var and the [`LayoutMetrics::direction`].
///
/// [`lang`]: fn@lang
///
/// [`DIRECTION_VAR`]: zng_wgt::prelude::DIRECTION_VAR
/// [`LayoutMetrics::direction`]: zng_wgt::prelude::LayoutMetrics::direction
#[property(CONTEXT+1, default(DIRECTION_VAR), widget_impl(LangMix<P>))]
pub fn direction(child: impl IntoUiNode, direction: impl IntoVar<LayoutDirection>) -> UiNode {
    let child = match_node(child, |child, op| match op {
        UiNodeOp::Init => {
            WIDGET.sub_var_layout(&DIRECTION_VAR);
        }
        UiNodeOp::Measure { wm, desired_size } => {
            *desired_size = LAYOUT.with_direction(DIRECTION_VAR.get(), || child.measure(wm));
        }
        UiNodeOp::Layout { wl, final_size } => *final_size = LAYOUT.with_direction(DIRECTION_VAR.get(), || child.layout(wl)),
        _ => {}
    });
    with_context_var(child, DIRECTION_VAR, direction)
}

impl LangMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&LANG_VAR);
        set.insert(&DIRECTION_VAR);
    }
}

/// Advanced font config, features, kerning, variations and more.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct FontFeaturesMix<P>(P);

context_var! {
    /// Font features of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_FEATURES_VAR: FontFeatures = FontFeatures::new();

    /// Font variations of [`Text!`] spans.
    ///
    /// [`Text!`]: struct@crate::Text
    pub static FONT_VARIATIONS_VAR: FontVariations = FontVariations::new();
}

impl FontFeaturesMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&FONT_FEATURES_VAR);
        set.insert(&FONT_VARIATIONS_VAR);
    }
}

/// Includes the font variation config in the widget context.
///
/// The variation `name` is set for the [`FONT_VARIATIONS_VAR`] in this context, variations already set in the parent
/// context that are not the same `name` are also included.
pub fn with_font_variation(child: impl IntoUiNode, name: FontVariationName, value: impl IntoVar<f32>) -> UiNode {
    with_context_var(
        child,
        FONT_VARIATIONS_VAR,
        merge_var!(FONT_VARIATIONS_VAR, value.into_var(), move |variations, value| {
            let mut variations = variations.clone();
            variations.insert(name, *value);
            variations
        }),
    )
}

/// Include the font feature config in the widget context.
///
/// The modifications done in `set_feature` are visible only in the [`FONT_FEATURES_VAR`] in this context, and features
/// already set in a parent context are included.
pub fn with_font_feature<C, S, V, D>(child: C, state: V, set_feature: D) -> UiNode
where
    C: IntoUiNode,
    S: VarValue,
    V: IntoVar<S>,
    D: FnMut(&mut FontFeatures, S) -> S + Send + 'static,
{
    let mut set_feature = set_feature;
    with_context_var(
        child,
        FONT_FEATURES_VAR,
        merge_var!(FONT_FEATURES_VAR, state.into_var(), move |features, state| {
            let mut features = features.clone();
            set_feature(&mut features, state.clone());
            features
        }),
    )
}

/// Sets font variations.
///
/// **Note:** This property fully replaces the font variations for the widget and descendants, use [`with_font_variation`]
/// to create a property that sets a variation but retains others from the context.
#[property(CONTEXT, default(FONT_VARIATIONS_VAR), widget_impl(FontFeaturesMix<P>))]
pub fn font_variations(child: impl IntoUiNode, variations: impl IntoVar<FontVariations>) -> UiNode {
    with_context_var(child, FONT_VARIATIONS_VAR, variations)
}

/// Sets font features.
///
/// **Note:** This property fully replaces the font variations for the widget and descendants, use [`with_font_variation`]
/// to create a property that sets a variation but retains others from the context.
#[property(CONTEXT, default(FONT_FEATURES_VAR), widget_impl(FontFeaturesMix<P>))]
pub fn font_features(child: impl IntoUiNode, features: impl IntoVar<FontFeatures>) -> UiNode {
    with_context_var(child, FONT_FEATURES_VAR, features)
}

/// Sets the font kerning feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_kerning(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.kerning().set(s))
}

/// Sets the font common ligatures features.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_common_lig(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.common_lig().set(s))
}

/// Sets the font discretionary ligatures feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_discretionary_lig(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.discretionary_lig().set(s))
}

/// Sets the font historical ligatures feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_historical_lig(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.historical_lig().set(s))
}

/// Sets the font contextual alternatives feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_contextual_alt(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.contextual_alt().set(s))
}

/// Sets the font capital variant features.
#[property(CONTEXT, default(CapsVariant::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_caps(child: impl IntoUiNode, state: impl IntoVar<CapsVariant>) -> UiNode {
    with_font_feature(child, state, |f, s| f.caps().set(s))
}

/// Sets the font numeric variant features.
#[property(CONTEXT, default(NumVariant::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_numeric(child: impl IntoUiNode, state: impl IntoVar<NumVariant>) -> UiNode {
    with_font_feature(child, state, |f, s| f.numeric().set(s))
}

/// Sets the font numeric spacing features.
#[property(CONTEXT, default(NumSpacing::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_num_spacing(child: impl IntoUiNode, state: impl IntoVar<NumSpacing>) -> UiNode {
    with_font_feature(child, state, |f, s| f.num_spacing().set(s))
}

/// Sets the font numeric fraction features.
#[property(CONTEXT, default(NumFraction::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_num_fraction(child: impl IntoUiNode, state: impl IntoVar<NumFraction>) -> UiNode {
    with_font_feature(child, state, |f, s| f.num_fraction().set(s))
}

/// Sets the font swash features.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_swash(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.swash().set(s))
}

/// Sets the font stylistic alternative feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_stylistic(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.stylistic().set(s))
}

/// Sets the font historical forms alternative feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_historical_forms(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.historical_forms().set(s))
}

/// Sets the font ornaments alternative feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_ornaments(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.ornaments().set(s))
}

/// Sets the font annotation alternative feature.
#[property(CONTEXT, default(FontFeatureState::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_annotation(child: impl IntoUiNode, state: impl IntoVar<FontFeatureState>) -> UiNode {
    with_font_feature(child, state, |f, s| f.annotation().set(s))
}

/// Sets the font stylistic set alternative feature.
#[property(CONTEXT, default(FontStyleSet::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_style_set(child: impl IntoUiNode, state: impl IntoVar<FontStyleSet>) -> UiNode {
    with_font_feature(child, state, |f, s| f.style_set().set(s))
}

/// Sets the font character variant alternative feature.
#[property(CONTEXT, default(CharVariant::auto()), widget_impl(FontFeaturesMix<P>))]
pub fn font_char_variant(child: impl IntoUiNode, state: impl IntoVar<CharVariant>) -> UiNode {
    with_font_feature(child, state, |f, s| f.char_variant().set(s))
}

/// Sets the font sub/super script position alternative feature.
#[property(CONTEXT, default(FontPosition::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_position(child: impl IntoUiNode, state: impl IntoVar<FontPosition>) -> UiNode {
    with_font_feature(child, state, |f, s| f.position().set(s))
}

/// Sets the Japanese logographic set.
#[property(CONTEXT, default(JpVariant::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_jp_variant(child: impl IntoUiNode, state: impl IntoVar<JpVariant>) -> UiNode {
    with_font_feature(child, state, |f, s| f.jp_variant().set(s))
}

/// Sets the Chinese logographic set.
#[property(CONTEXT, default(CnVariant::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_cn_variant(child: impl IntoUiNode, state: impl IntoVar<CnVariant>) -> UiNode {
    with_font_feature(child, state, |f, s| f.cn_variant().set(s))
}

/// Sets the East Asian figure width.
#[property(CONTEXT, default(EastAsianWidth::Auto), widget_impl(FontFeaturesMix<P>))]
pub fn font_ea_width(child: impl IntoUiNode, state: impl IntoVar<EastAsianWidth>) -> UiNode {
    with_font_feature(child, state, |f, s| f.ea_width().set(s))
}

/// Text edit properties.
///
/// All properties in this mixin affects [`Text!`] nodes inside the widget where they are set.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct TextEditMix<P>(P);

context_var! {
    /// Text is editable.
    pub static TEXT_EDITABLE_VAR: bool = false;

    /// Text is selectable.
    pub static TEXT_SELECTABLE_VAR: bool = false;
    /// Text only starts selection from mouse or touch if the Alt modifier is pressed.
    pub static TEXT_SELECTABLE_ALT_ONLY_VAR: bool = false;

    /// Accepts `'\t'` input when editable.
    pub static ACCEPTS_TAB_VAR: bool = false;

    /// Accepts `'\n'` input when editable.
    pub static ACCEPTS_ENTER_VAR: bool = false;

    /// Caret color, inherits from [`FONT_COLOR_VAR`].
    pub static CARET_COLOR_VAR: Rgba = FONT_COLOR_VAR;

    /// Interactive caret visual.
    pub static INTERACTIVE_CARET_VISUAL_VAR: WidgetFn<CaretShape> = wgt_fn!(|s| super::node::default_interactive_caret_visual(s));

    /// Interactive caret mode.
    pub static INTERACTIVE_CARET_VAR: InteractiveCaretMode = InteractiveCaretMode::default();

    /// Selection background color.
    pub static SELECTION_COLOR_VAR: Rgba = colors::AZURE.with_alpha(30.pct());

    /// If text parse updated for every text change.
    pub static TXT_PARSE_LIVE_VAR: bool = true;

    /// Debounce time for change stop.
    pub static CHANGE_STOP_DELAY_VAR: Duration = 1.secs();

    /// Auto selection on keyboard focus.
    pub static AUTO_SELECTION_VAR: AutoSelection = AutoSelection::default();

    /// Maximum number of characters that can be input.
    ///
    /// Zero means no limit. Is zero by default.
    pub static MAX_CHARS_COUNT_VAR: usize = 0;

    /// Replacement character used when obscuring text.
    pub static OBSCURING_CHAR_VAR: char = '•';

    /// If text characters are replaced with [`OBSCURING_CHAR_VAR`] for rendering.
    pub static OBSCURE_TXT_VAR: bool = false;

    pub(super) static TXT_PARSE_PENDING_VAR: bool = false;
}

impl TextEditMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&TEXT_EDITABLE_VAR);
        set.insert(&TEXT_SELECTABLE_VAR);
        set.insert(&TEXT_SELECTABLE_ALT_ONLY_VAR);
        set.insert(&ACCEPTS_ENTER_VAR);
        set.insert(&CARET_COLOR_VAR);
        set.insert(&INTERACTIVE_CARET_VISUAL_VAR);
        set.insert(&INTERACTIVE_CARET_VAR);
        set.insert(&SELECTION_COLOR_VAR);
        set.insert(&TXT_PARSE_LIVE_VAR);
        set.insert(&CHANGE_STOP_DELAY_VAR);
        set.insert(&AUTO_SELECTION_VAR);
        set.insert(&MAX_CHARS_COUNT_VAR);
        set.insert(&OBSCURING_CHAR_VAR);
        set.insert(&OBSCURE_TXT_VAR);
    }
}

/// Defines the position of an interactive caret in relation to the selection.
///
/// See [`interactive_caret_visual`](fn@interactive_caret_visual) for more details.
#[derive(Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
pub enum CaretShape {
    /// Caret defines the selection start in LTR and end in RTL text.
    SelectionLeft,
    /// Caret defines the selection end in LTR and start in RTL text.
    SelectionRight,
    /// Caret defines the insert point, when there is no selection.
    Insert,
}
impl fmt::Debug for CaretShape {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if f.alternate() {
            write!(f, "CaretShape::")?;
        }
        match self {
            Self::SelectionLeft => write!(f, "SelectionLeft"),
            Self::SelectionRight => write!(f, "SelectionRight"),
            Self::Insert => write!(f, "Insert"),
        }
    }
}

/// Defines when the interactive carets are used.
#[derive(Default, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
pub enum InteractiveCaretMode {
    /// Uses interactive carets only for touch selections, uses non-interactive caret for other selections.
    #[default]
    TouchOnly,
    /// Uses interactive carets for all selections.
    Enabled,
    /// Uses non-interactive carets for all selections.
    Disabled,
}
impl fmt::Debug for InteractiveCaretMode {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if f.alternate() {
            write!(f, "InteractiveCaretMode::")?;
        }
        match self {
            Self::TouchOnly => write!(f, "TouchOnly"),
            Self::Enabled => write!(f, "Enabled"),
            Self::Disabled => write!(f, "Disabled"),
        }
    }
}
impl_from_and_into_var! {
    fn from(enabled: bool) -> InteractiveCaretMode {
        if enabled {
            InteractiveCaretMode::Enabled
        } else {
            InteractiveCaretMode::Disabled
        }
    }
}

/// Enable text caret, input and makes the widget focusable.
///
/// If the `txt` variable is read-only, this is ignored, if the var is writeable this
/// enables text input and modifies the variable.
///
/// Sets the [`TEXT_EDITABLE_VAR`].
#[property(CONTEXT, default(TEXT_EDITABLE_VAR), widget_impl(TextEditMix<P>))]
pub fn txt_editable(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, TEXT_EDITABLE_VAR, enabled)
}

/// Enable text selection, copy and makes the widget focusable.
///
/// Note that if the text widget subscribes to mouse or touch events the selection gestures will interfere with those events,
/// you can enable [`txt_selectable_alt_only`] so that pointer selection gestures only start when the Alt keyboard modifier is pressed.
///
/// Sets the [`TEXT_SELECTABLE_VAR`].
///
/// [`txt_selectable_alt_only`]: fn@txt_selectable_alt_only
#[property(CONTEXT, default(TEXT_SELECTABLE_VAR), widget_impl(TextEditMix<P>))]
pub fn txt_selectable(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, TEXT_SELECTABLE_VAR, enabled)
}

/// Only start mouse and touch selections from this widget when the Alt keyboard modifier is pressed.
///
/// Note that this property does not enable text selection, [`txt_selectable`] must be enabled on the widget or parent.
///
/// This property is ignored if the text is also editable. Selections started from sibling widgets in rich text also expand
/// inside this widget normally, this property only applies to selection started from this widget.
///
/// Sets the [`TEXT_SELECTABLE_ALT_ONLY_VAR`].
///
/// [`txt_selectable`]: fn@txt_selectable
#[property(CONTEXT, default(TEXT_SELECTABLE_ALT_ONLY_VAR), widget_impl(TextEditMix<P>))]
pub fn txt_selectable_alt_only(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, TEXT_SELECTABLE_ALT_ONLY_VAR, enabled)
}

/// If the `'\t'` character is inserted when tab is pressed and the text is editable.
///
/// If not enabled or the text is not editable, then pressing tab moves the focus like normal.
///
/// Sets the [`ACCEPTS_TAB_VAR`].
#[property(CONTEXT, default(ACCEPTS_TAB_VAR), widget_impl(TextEditMix<P>))]
pub fn accepts_tab(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, ACCEPTS_TAB_VAR, enabled)
}

/// If the `'\n'` character is inserted when enter is pressed and the text is editable.
///
/// Sets the [`ACCEPTS_ENTER_VAR`].
#[property(CONTEXT, default(ACCEPTS_ENTER_VAR), widget_impl(TextEditMix<P>))]
pub fn accepts_enter(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, ACCEPTS_ENTER_VAR, enabled)
}

/// Defines the color of the non-interactive caret.
///
/// Sets the [`CARET_COLOR_VAR`].
#[property(CONTEXT, default(CARET_COLOR_VAR), widget_impl(TextEditMix<P>))]
pub fn caret_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, CARET_COLOR_VAR, color)
}

/// Defines custom caret visual for interactive caret.
///
/// The `visual` node becomes the content of a [layered widget] at the `ADORNER+1` layer, the text widget context is
/// propagated so contextual variables and value work seamless inside the node.
///
/// The `visual` node must set one special value during layout, the [`set_interactive_caret_spot`] must be called to
/// set the offset to the middle of the caret line in the visual inner-bounds, this is used to position the caret.
///
/// Sets the [`INTERACTIVE_CARET_VISUAL_VAR`].
///
/// [layered widget]: zng_wgt_layer
/// [`set_interactive_caret_spot`]: super::node::set_interactive_caret_spot
#[property(CONTEXT, default(INTERACTIVE_CARET_VISUAL_VAR), widget_impl(TextEditMix<P>))]
pub fn interactive_caret_visual(child: impl IntoUiNode, visual: impl IntoVar<WidgetFn<CaretShape>>) -> UiNode {
    with_context_var(child, INTERACTIVE_CARET_VISUAL_VAR, visual)
}

/// Defines when the interactive carets are used.
///
/// By default only uses interactive carets for touch selections.
#[property(CONTEXT, default(INTERACTIVE_CARET_VAR), widget_impl(TextEditMix<P>))]
pub fn interactive_caret(child: impl IntoUiNode, mode: impl IntoVar<InteractiveCaretMode>) -> UiNode {
    with_context_var(child, INTERACTIVE_CARET_VAR, mode)
}

/// Sets the [`SELECTION_COLOR_VAR`].
#[property(CONTEXT, default(SELECTION_COLOR_VAR), widget_impl(TextEditMix<P>))]
pub fn selection_color(child: impl IntoUiNode, color: impl IntoVar<Rgba>) -> UiNode {
    with_context_var(child, SELECTION_COLOR_VAR, color)
}

/// If [`txt_parse`] tries to parse after any text change immediately.
///
/// This is enabled by default, if disabled the [`PARSE_CMD`] can be used to update pending parse.
///
/// This property sets the [`TXT_PARSE_LIVE_VAR`].
///
/// [`txt_parse`]: fn@super::txt_parse
/// [`PARSE_CMD`]: super::cmd::PARSE_CMD
#[property(CONTEXT, default(TXT_PARSE_LIVE_VAR), widget_impl(TextEditMix<P>))]
pub fn txt_parse_live(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, TXT_PARSE_LIVE_VAR, enabled)
}

/// Disable live parsing and parse on change stop.
///
/// This property sets [`txt_parse_live`] and [`on_change_stop`] on the widget.
///
/// Consider increasing the [`change_stop_delay`] if the text can change after parse.
///
/// [`txt_parse_live`]: fn@txt_parse_live
/// [`on_change_stop`]: fn@on_change_stop
/// [`change_stop_delay`]: fn@change_stop_delay
#[property(EVENT, widget_impl(TextEditMix<P>))]
pub fn txt_parse_on_stop(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    let enabled = enabled.into_var();
    let child = txt_parse_live(child, enabled.map(|&b| !b));
    on_change_stop(
        child,
        hn!(|_| {
            if enabled.get() {
                super::cmd::PARSE_CMD.scoped(WIDGET.id()).notify();
            }
        }),
    )
}

/// Maximum number of characters that can be input.
///
/// Zero means no limit. Is zero by default.
///
/// This property sets the [`MAX_CHARS_COUNT_VAR`].
#[property(CONTEXT, default(MAX_CHARS_COUNT_VAR), widget_impl(TextEditMix<P>))]
pub fn max_chars_count(child: impl IntoUiNode, max: impl IntoVar<usize>) -> UiNode {
    with_context_var(child, MAX_CHARS_COUNT_VAR, max)
}

/// If text has changed but [`txt_parse`] has not tried to parse the new text yet.
///
/// This can only be `true` if [`txt_parse_live`] is `false`.
///
/// [`txt_parse`]: fn@super::txt_parse
/// [`txt_parse_live`]: fn@txt_parse_live
#[property(CONTEXT, default(false), widget_impl(TextEditMix<P>))]
pub fn is_parse_pending(child: impl IntoUiNode, state: impl IntoVar<bool>) -> UiNode {
    // reverse context, `txt_parse` sets `TXT_PARSE_PENDING_VAR`
    with_context_var(child, TXT_PARSE_PENDING_VAR, state)
}

/// Called after the text changed and interaction has stopped.
///
/// The `handler` will be called after change and [`change_stop_delay`] elapses, or the widget loses focus,
/// or the [`Key::Enter`] is pressed and [`accepts_enter`] is `false`.
///
/// [`change_stop_delay`]: fn@change_stop_delay
/// [`accepts_enter`]: fn@accepts_enter
/// [`Key::Enter`]: zng_ext_input::keyboard::Key::Enter
#[property(EVENT, widget_impl(TextEditMix<P>))]
pub fn on_change_stop(child: impl IntoUiNode, handler: Handler<ChangeStopArgs>) -> UiNode {
    super::node::on_change_stop(child, handler)
}

/// Debounce time for [`on_change_stop`].
///
/// After the text stops changing and `delay` is elapsed the change stop handled is called, even
/// if the widget is still focused.
///
/// Is `1.secs()` by default.
///
/// Sets [`CHANGE_STOP_DELAY_VAR`].
///
/// [`on_change_stop`]: fn@on_change_stop
#[property(CONTEXT, default(CHANGE_STOP_DELAY_VAR), widget_impl(TextEditMix<P>))]
pub fn change_stop_delay(child: impl IntoUiNode, delay: impl IntoVar<Duration>) -> UiNode {
    with_context_var(child, CHANGE_STOP_DELAY_VAR, delay)
}

/// Auto-selection on focus change when the text is selectable.
///
/// If enabled on keyboard focus all text is selected and on blur any selection is cleared.
///
/// In rich text contexts applies to all sub-component texts.
#[property(CONTEXT, default(AUTO_SELECTION_VAR), widget_impl(TextEditMix<P>))]
pub fn auto_selection(child: impl IntoUiNode, mode: impl IntoVar<AutoSelection>) -> UiNode {
    with_context_var(child, AUTO_SELECTION_VAR, mode)
}

/// Replacement character used when obscuring text.
///
/// When [`obscure_txt`] is enabled the text characters are replaced by this one.
///
/// [`obscure_txt`]: fn@obscure_txt
#[property(CONTEXT, default(OBSCURING_CHAR_VAR), widget_impl(TextEditMix<P>))]
pub fn obscuring_char(child: impl IntoUiNode, character: impl IntoVar<char>) -> UiNode {
    with_context_var(child, OBSCURING_CHAR_VAR, character)
}

/// Enable typed text obscuring in render.
///
/// When enabled each text character is replaced with [`obscuring_char`], cut, copy and undo commands are disabled.
///
/// Note that the text variable is still **plain text** in memory, a memory dump while the widget is filled can leak
/// the password, this is a potential security problem shared by apps that accept typed passwords. To mitigate the problem
/// don't use automatic crash reports with memory dump, drop the widget and the text variable as soon as possible,
/// design the app to show the password widget last to minimize its lifetime.
///
/// [`obscuring_char`]: fn@obscuring_char
#[property(CONTEXT, default(OBSCURE_TXT_VAR), widget_impl(TextEditMix<P>))]
pub fn obscure_txt(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    with_context_var(child, OBSCURE_TXT_VAR, enabled)
}

bitflags! {
    /// Defines when text is auto-selected on focus change.
    ///
    /// In a rich text context applies across all sub component texts.
    #[derive(Clone, Copy, PartialEq, Eq, Debug, serde::Serialize, serde::Deserialize)]
    pub struct AutoSelection: u8 {
        /// No auto-selection.
        const DISABLED = 0;
        /// Clear selection on blur if the widget is not the ALT return focus and is not the parent scope return focus.
        ///
        /// This is the default behavior.
        const CLEAR_ON_BLUR = 0b0000_0001;
        /// Select all on keyboard initiated focus.
        const ALL_ON_FOCUS_KEYBOARD = 0b0000_0010;
        /// Select all on pointer release if the pointer press event caused the focus to happen and it did not change
        /// the selection and there is no selection on release.
        const ALL_ON_FOCUS_POINTER = 0b0000_0100;
        /// All auto-selection features enabled.
        const ENABLED = 0b0000_0111;
    }
}
impl_from_and_into_var! {
    fn from(enabled: bool) -> AutoSelection {
        if enabled { AutoSelection::ENABLED } else { AutoSelection::DISABLED }
    }
}
impl Default for AutoSelection {
    fn default() -> Self {
        Self::CLEAR_ON_BLUR
    }
}

/// Arguments for [`on_change_stop`].
///
/// [`on_change_stop`]: fn@on_change_stop
#[derive(Debug, Clone)]
#[non_exhaustive]
pub struct ChangeStopArgs {
    /// Event cause.
    pub cause: ChangeStopCause,
}
impl ChangeStopArgs {
    /// New args.
    pub fn new(cause: ChangeStopCause) -> Self {
        Self { cause }
    }
}

/// Cause of an [`on_change_stop`].
///
/// [`on_change_stop`]: fn@on_change_stop
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ChangeStopCause {
    /// The [`change_stop_delay`] elapsed.
    ///
    /// [`change_stop_delay`]: fn@change_stop_delay
    DelayElapsed,
    /// The [`Key::Enter`] was pressed and [`accepts_enter`] is `false`.
    ///
    /// [`Key::Enter`]: zng_ext_input::keyboard::Key::Enter
    /// [`accepts_enter`]: fn@accepts_enter
    Enter,
    /// The widget lost keyboard focus.
    Blur,
}

/// Display info of edit caret position.
#[derive(Debug, PartialEq, Eq, Hash, Copy, Clone, serde::Serialize, serde::Deserialize)]
pub struct CaretStatus {
    index: usize,
    line: u32,
    column: u32,
}
impl CaretStatus {
    /// Status for text without caret.
    pub fn none() -> Self {
        Self {
            index: usize::MAX,
            line: 0,
            column: 0,
        }
    }

    /// New position from char index and text.
    ///
    /// # Panics
    ///
    /// Panics if `index` is greater then `text` length.
    pub fn new(index: usize, text: &SegmentedText) -> Self {
        assert!(index <= text.text().len());

        if text.text().is_empty() {
            Self { line: 1, column: 1, index }
        } else {
            let mut line = 1;
            let mut line_start = 0;
            for seg in text.segs() {
                if seg.end > index {
                    break;
                }
                if let TextSegmentKind::LineBreak = seg.kind {
                    line += 1;
                    line_start = seg.end;
                }
            }

            let column = text.text()[line_start..index].chars().count() + 1;

            Self {
                line,
                column: column as _,
                index,
            }
        }
    }

    /// Char index on the text string, starts a 0, can be the length of the text.
    pub fn index(&self) -> Option<usize> {
        match self.index {
            usize::MAX => None,
            i => Some(i),
        }
    }

    /// Display line, starts at 1.
    ///
    /// Note that this does not count soft line breaks (wrapped lines), this is the actual text line.
    pub fn line(&self) -> Option<NonZeroU32> {
        NonZeroU32::new(self.line)
    }

    /// Display column, starts at 1.
    ///
    /// This is the char count from the start of the text line to the index.
    pub fn column(&self) -> Option<NonZeroU32> {
        NonZeroU32::new(self.column)
    }
}
impl fmt::Display for CaretStatus {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        if self.index().is_some() {
            write!(f, "Ln {}, Col {}", self.line, self.column)
        } else {
            Ok(())
        }
    }
}

/// Represents the number of lines and number of wrap lines in a text.
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum LinesWrapCount {
    /// No line wrap.
    ///
    /// The associated value is the number of lines.
    NoWrap(usize),
    /// Some text lines have more than one wrap line.
    ///
    /// The associated value is a vec of wrap-line count for each text line, is `1` for lines that don't wrap.
    Wrap(Vec<u32>),
}
impl LinesWrapCount {
    /// Gets the number of text lines.
    pub fn lines_len(&self) -> usize {
        match self {
            Self::NoWrap(l) => *l,
            Self::Wrap(lns) => lns.len(),
        }
    }
}

/// Text paragraph properties.
///
/// The base [`Text!`] widget only implements minimal support for paragraphs, rich text widgets will probably
/// segment paragraphs into sub widgets and may ignore [`PARAGRAPH_BREAK_VAR`] depending on the source text format.
///
/// [`Text!`]: struct@crate::Text
#[widget_mixin]
pub struct ParagraphMix<P>(P);

context_var! {
    /// Defines how the text is split in paragraphs.
    ///
    /// Is `None` by default.
    pub static PARAGRAPH_BREAK_VAR: ParagraphBreak = ParagraphBreak::default();

    /// Extra paragraph spacing of text blocks.
    pub static PARAGRAPH_SPACING_VAR: ParagraphSpacing = 1.em();

    /// Spacing applied at start of paragraphs.
    pub static PARAGRAPH_INDENT_VAR: Indentation = Indentation::default();
}

impl ParagraphMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&PARAGRAPH_BREAK_VAR);
        set.insert(&PARAGRAPH_SPACING_VAR);
        set.insert(&PARAGRAPH_INDENT_VAR);
    }
}

/// Defines paragraphs in the text.
///
/// In the base `Text!` widget this defines how [`paragraph_spacing`] and [`paragraph_indent`] are applied.
///
/// Other rich text widgets usually segment paragraphs into widgets and may ignore this property, depending on
/// the source text format.
///
/// Sets the [`PARAGRAPH_BREAK_VAR`].
#[property(CONTEXT, default(PARAGRAPH_BREAK_VAR), widget_impl(ParagraphMix<P>))]
pub fn paragraph_break(child: impl IntoUiNode, mode: impl IntoVar<ParagraphBreak>) -> UiNode {
    with_context_var(child, PARAGRAPH_BREAK_VAR, mode)
}

/// Extra spacing in-between paragraphs.
///
/// The default value is `1.em()`. Note that [`paragraph_break`] defines the entire text as a single paragraph
/// by default, so this will not be applied by default on the base [`Text!`] widget.
///
/// Sets the [`PARAGRAPH_SPACING_VAR`].
///
/// [`Text!`]: struct@crate::Text
/// [`paragraph_break`]: fn@paragraph_break
#[property(CONTEXT, default(PARAGRAPH_SPACING_VAR), widget_impl(ParagraphMix<P>))]
pub fn paragraph_spacing(child: impl IntoUiNode, extra: impl IntoVar<ParagraphSpacing>) -> UiNode {
    with_context_var(child, PARAGRAPH_SPACING_VAR, extra)
}

/// Extra spacing added at the start of lines in a paragraph.
///
/// This can be set to a width `Length` to insert spacing at the start of each first line,
/// or it can be set to `(Length, true)` to hang all lines except the first.
///
/// See [`paragraph_break`] for how to define paragraphs.
///
/// Sets the [`PARAGRAPH_INDENT_VAR`].
///
/// [`paragraph_break`]: fn@paragraph_break
#[property(CONTEXT, default(PARAGRAPH_INDENT_VAR), widget_impl(ParagraphMix<P>))]
pub fn paragraph_indent(child: impl IntoUiNode, indent: impl IntoVar<Indentation>) -> UiNode {
    with_context_var(child, PARAGRAPH_INDENT_VAR, indent)
}

/// Selection toolbar properties.
#[widget_mixin]
pub struct SelectionToolbarMix<P>(P);

context_var! {
    /// Selection toolbar function.
    pub static SELECTION_TOOLBAR_FN_VAR: WidgetFn<SelectionToolbarArgs> = WidgetFn::nil();
    /// Position the selection toolbar in relation to the bounding box of all selection rectangles.
    pub static SELECTION_TOOLBAR_ANCHOR_VAR: AnchorOffset = AnchorOffset::out_top();
}

impl SelectionToolbarMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&SELECTION_TOOLBAR_FN_VAR);
        set.insert(&SELECTION_TOOLBAR_ANCHOR_VAR);
    }
}

/// Defines the floating mini-toolbar that shows near a new text selection.
///
/// The `toolbar` is used
#[property(CONTEXT, widget_impl(SelectionToolbarMix<P>))]
pub fn selection_toolbar(child: impl IntoUiNode, toolbar: impl IntoUiNode) -> UiNode {
    selection_toolbar_fn(child, WidgetFn::singleton(toolbar))
}

/// Defines the floating mini-toolbar that shows near a new text selection.
///
/// Sets the [`SELECTION_TOOLBAR_FN_VAR`].
#[property(CONTEXT, default(SELECTION_TOOLBAR_FN_VAR), widget_impl(SelectionToolbarMix<P>))]
pub fn selection_toolbar_fn(child: impl IntoUiNode, toolbar: impl IntoVar<WidgetFn<SelectionToolbarArgs>>) -> UiNode {
    with_context_var(child, SELECTION_TOOLBAR_FN_VAR, toolbar)
}

/// Arguments for [`selection_toolbar_fn`].
///
/// [`selection_toolbar_fn`]: fn@selection_toolbar_fn
#[non_exhaustive]
pub struct SelectionToolbarArgs {
    /// ID of the widget the toolbar is anchored to.
    pub anchor_id: WidgetId,
    /// Text was selected through touch interaction.
    pub is_touch: bool,
}
impl SelectionToolbarArgs {
    /// New args.
    pub fn new(anchor_id: impl Into<WidgetId>, is_touch: bool) -> Self {
        Self {
            anchor_id: anchor_id.into(),
            is_touch,
        }
    }
}

/// Position the selection toolbar in relation to the bounding box of all selection rectangles.
///
/// See [`selection_toolbar_fn`](fn@selection_toolbar_fn).
///
/// Sets the [`SELECTION_TOOLBAR_ANCHOR_VAR`].
#[property(CONTEXT, default(SELECTION_TOOLBAR_ANCHOR_VAR), widget_impl(SelectionToolbarMix<P>))]
pub fn selection_toolbar_anchor(child: impl IntoUiNode, offset: impl IntoVar<AnchorOffset>) -> UiNode {
    with_context_var(child, SELECTION_TOOLBAR_ANCHOR_VAR, offset)
}

/// Properties that probes various state from the text widget.
#[widget_mixin]
pub struct TextInspectMix<P>(P);

impl TextInspectMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        let _ = set;
    }
}

/// Gets the caret char index, if the text is editable.
#[property(EVENT, default(None), widget_impl(TextInspectMix<P>))]
pub fn get_caret_index(child: impl IntoUiNode, index: impl IntoVar<Option<CaretIndex>>) -> UiNode {
    super::node::get_caret_index(child, index)
}

/// Gets the caret display status, if the text is editable.
#[property(EVENT, default(CaretStatus::none()), widget_impl(TextInspectMix<P>))]
pub fn get_caret_status(child: impl IntoUiNode, status: impl IntoVar<CaretStatus>) -> UiNode {
    super::node::get_caret_status(child, status)
}

/// Gets the number of lines in the text, including wrap lines.
///
/// This is very cheap, the text widget already has the length, but it does include wrapped lines. You
/// can use [`get_lines_wrap_count`] to get text lines and a count of wrapped lines for each.
///
/// [`get_lines_wrap_count`]: fn@get_lines_wrap_count
#[property(CHILD_LAYOUT+100, default(0), widget_impl(TextInspectMix<P>))]
pub fn get_lines_len(child: impl IntoUiNode, len: impl IntoVar<usize>) -> UiNode {
    super::node::get_lines_len(child, len)
}

/// Gets the number of wrap lines per text lines.
#[property(CHILD_LAYOUT+100, default(LinesWrapCount::NoWrap(0)), widget_impl(TextInspectMix<P>))]
pub fn get_lines_wrap_count(child: impl IntoUiNode, lines: impl IntoVar<LinesWrapCount>) -> UiNode {
    super::node::get_lines_wrap_count(child, lines)
}

/// Gets the number of character in the text.
#[property(EVENT, default(0), widget_impl(TextInspectMix<P>))]
pub fn get_chars_count(child: impl IntoUiNode, chars: impl IntoVar<usize>) -> UiNode {
    let chars = chars.into_var();
    match_node(child, move |_, op| {
        if let UiNodeOp::Init = op {
            let ctx = super::node::TEXT.resolved();
            chars.set_from_map(&ctx.txt, |t| t.chars().count());
            let handle = ctx.txt.bind_map(&chars, |t| t.chars().count());
            WIDGET.push_var_handle(handle);
        }
    })
}

/// Highlight a text range.
///
/// This property must be set in the text widget.
#[property(CHILD_LAYOUT+100, widget_impl(TextInspectMix<P>))]
pub fn txt_highlight(child: impl IntoUiNode, range: impl IntoVar<std::ops::Range<CaretIndex>>, color: impl IntoVar<Rgba>) -> UiNode {
    let range = range.into_var();
    let color = color.into_var();
    let color_key = FrameValueKey::new_unique();
    match_node(child, move |_, op| match op {
        UiNodeOp::Init => {
            WIDGET.sub_var_render(&range).sub_var_render_update(&color);
        }
        UiNodeOp::Render { frame } => {
            let l_txt = super::node::TEXT.laidout();
            let r_txt = super::node::TEXT.resolved();
            let r_txt = r_txt.segmented_text.text();

            for line_rect in l_txt.shaped_text.highlight_rects(range.get(), r_txt) {
                frame.push_color(line_rect, color_key.bind_var(&color, |c| *c));
            }
        }
        UiNodeOp::RenderUpdate { update } => {
            if let Some(color_update) = color_key.update_var(&color, |c| *c) {
                update.update_color(color_update)
            }
        }
        _ => {}
    })
}

/// Gets a vector of font and ranges.
///
/// This property must be set in the text widget.
#[property(CHILD_LAYOUT+100, widget_impl(TextInspectMix<P>))]
pub fn get_font_use(child: impl IntoUiNode, font_use: impl IntoVar<Vec<(Font, std::ops::Range<usize>)>>) -> UiNode {
    let font_use = font_use.into_var();
    let mut shaped_text_version = u32::MAX;
    match_node(child, move |c, op| {
        if let UiNodeOp::Layout { wl, final_size } = op {
            *final_size = c.layout(wl);

            let ctx = crate::node::TEXT.laidout();

            if ctx.shaped_text_version != shaped_text_version && font_use.capabilities().can_modify() {
                shaped_text_version = ctx.shaped_text_version;

                let mut r = vec![];

                for seg in ctx.shaped_text.lines().flat_map(|l| l.segs()) {
                    let mut seg_glyph_i = 0;
                    let seg_range = seg.text_range();

                    for (font, glyphs) in seg.glyphs() {
                        if r.is_empty() {
                            r.push((font.clone(), 0..seg_range.end));
                        } else {
                            let last_i = r.len() - 1;
                            if &r[last_i].0 != font {
                                let seg_char_i = seg.clusters()[seg_glyph_i] as usize;

                                let char_i = seg_range.start + seg_char_i;
                                r[last_i].1.end = char_i;
                                r.push((font.clone(), char_i..seg_range.end));
                            }
                        }
                        seg_glyph_i += glyphs.len();
                    }
                }

                font_use.set(r);
            }
        }
    })
}

/// If widget or rich context has selection.
///
/// If set on a text widget gets if the local text has a selection, otherwise gets if the rich text context has a selection.
#[property(EVENT, widget_impl(TextInspectMix<P>))]
pub fn has_selection(child: impl IntoUiNode, state: impl IntoVar<bool>) -> UiNode {
    let state = state.into_var();
    match_node(child, move |c, op| {
        let mut update = false;
        match &op {
            UiNodeOp::Init => {
                update = true;
            }
            UiNodeOp::Deinit => {
                state.set(false);
            }
            UiNodeOp::Event { .. } => {
                update = true;
            }
            UiNodeOp::Update { .. } => {
                update = true;
            }
            _ => {}
        }

        c.op(op);

        if update {
            let new = if let Some(ctx) = TEXT.try_rich() {
                ctx.caret.selection_index.is_some()
            } else if let Some(ctx) = TEXT.try_resolved() {
                ctx.caret.selection_index.is_some()
            } else {
                false
            };
            if new != state.get() {
                state.set(new);
            }
        }
    })
}

/// Gets the selected text in the widget.
#[property(EVENT, default(Txt::from_static("")), widget_impl(TextInspectMix<P>))]
pub fn get_selection(child: impl IntoUiNode, state: impl IntoVar<Txt>) -> UiNode {
    let state = state.into_var();
    let mut last_sel = (CaretIndex::ZERO, None::<CaretIndex>);
    match_node(child, move |c, op| {
        let mut update = false;
        match &op {
            UiNodeOp::Init => {
                update = true;
            }
            UiNodeOp::Deinit => {
                state.set(Txt::from_static(""));
            }
            UiNodeOp::Event { .. } => {
                update = true;
            }
            UiNodeOp::Update { .. } => {
                update = true;
            }
            _ => {}
        }

        c.op(op);

        if update && let Some(ctx) = TEXT.try_resolved() {
            let new_sel = (ctx.caret.index.unwrap_or(CaretIndex::ZERO), ctx.caret.selection_index);

            if last_sel != new_sel {
                last_sel = new_sel;

                let txt = if let Some(range) = ctx.caret.selection_char_range() {
                    Txt::from_str(&ctx.segmented_text.text()[range])
                } else {
                    Txt::from_static("")
                };

                state.set(txt);
            }
        }
    })
}

/// Rich text properties.
///
/// Note that these properties are usually set in parent panels of text widgets.
#[widget_mixin]
pub struct RichTextMix<P>(P);

context_var! {
    /// Selection toolbar function.
    pub static RICH_TEXT_FOCUSED_Z_VAR: Option<ZIndex> = ZIndex::FRONT;
}

impl RichTextMix<()> {
    /// Insert context variables used by properties in this mixin.
    pub fn context_vars_set(set: &mut ContextValueSet) {
        set.insert(&RICH_TEXT_FOCUSED_Z_VAR);
    }
}

/// Defines a *rich text* context.
///
/// When enabled text widget descendants of this widget edit the text across the widgets,
/// for example, the caret position moves to the next text widget when it reaches the start/end of the first text widget.
///
/// Nested rich text contexts are allowed and are all part of the outermost context, enabling this property in all nested
/// wrap panels is recommended as it enables some rich text behavior like bringing the focused widget to front to avoid
/// clipping the caret.
///
/// When enabled and not nested the widget will handle text commands, it also broadcasts focus change events to all text descendants.
#[property(CONTEXT, default(false), widget_impl(RichTextMix<P>))]
pub fn rich_text(child: impl IntoUiNode, enabled: impl IntoVar<bool>) -> UiNode {
    crate::node::rich_text_node(child, enabled)
}

/// Defines the Z-index set on inner text (and nested rich text) widgets when focus is within.
///
/// Is [`ZIndex::FRONT`] by default, so that the caret visual is not clipped when the insert point is at
/// an edge between texts. Set to `None` to not change the Z-index on focus.
///
/// Sets the [`RICH_TEXT_FOCUSED_Z_VAR`].
#[property(CONTEXT, default(RICH_TEXT_FOCUSED_Z_VAR), widget_impl(RichTextMix<P>))]
pub fn rich_text_focused_z(child: impl IntoUiNode, z_index: impl IntoVar<Option<ZIndex>>) -> UiNode {
    with_context_var(child, RICH_TEXT_FOCUSED_Z_VAR, z_index)
}