zng_view_api/

display_list.rs

//! Frame builder types.

use std::{
    ops,
    sync::{Arc, atomic::AtomicUsize},
};

use serde::{Deserialize, Serialize};

use crate::{
    AlphaType, BorderSide, ExtendMode, GradientStop, ImageRendering, LineOrientation, LineStyle, MixBlendMode, ReferenceFrameId,
    RepeatMode, TransformStyle,
    api_extension::{ApiExtensionId, ApiExtensionPayload},
    font::{FontId, GlyphInstance, GlyphOptions},
    image::ImageTextureId,
    window::FrameId,
};
use zng_unit::*;

/// Represents a builder for display items that will be rendered in the view process.
#[derive(Debug)]
pub struct DisplayListBuilder {
    frame_id: FrameId,
    list: Vec<DisplayItem>,

    clip_len: usize,
    mask_len: usize,
    space_len: usize,
    stacking_len: usize,

    seg_id: SegmentId,
    seg_id_gen: Arc<AtomicUsize>,
    segments: Vec<(SegmentId, usize)>,
    has_reuse_ranges: bool,
}
impl DisplayListBuilder {
    /// New default.
    pub fn new(frame_id: FrameId) -> Self {
        Self::with_capacity(frame_id, 100)
    }

    /// New with pre-allocation.
    pub fn with_capacity(frame_id: FrameId, capacity: usize) -> Self {
        Self {
            frame_id,
            list: Vec::with_capacity(capacity),

            clip_len: 1,
            mask_len: 1,
            space_len: 1,
            stacking_len: 1,
            seg_id: 0,
            seg_id_gen: Arc::new(AtomicUsize::new(1)),
            segments: vec![(0, 0)],
            has_reuse_ranges: false,
        }
    }

    /// Frame that will be rendered by this display list.
    pub fn frame_id(&self) -> FrameId {
        self.frame_id
    }

    /// Mark the start of a reuse range, the range can be completed with [`finish_reuse_range`].
    ///
    /// Reuse ranges can be nested.
    ///
    /// [`finish_reuse_range`]: Self::finish_reuse_range
    pub fn start_reuse_range(&mut self) -> ReuseStart {
        ReuseStart {
            frame_id: self.frame_id,
            seg_id: self.seg_id,
            start: self.list.len(),
            clip_len: self.clip_len,
            mask_len: self.mask_len,
            space_len: self.space_len,
            stacking_len: self.stacking_len,
        }
    }

    /// Mark the end of a reuse range.
    ///
    /// # Panics
    ///
    /// Panics if `start` was not generated by a call to [`start_reuse_range`] on the same builder.
    ///
    /// Panics if clips, masks, reference frames or stacking contexts where pushed inside the reuse range and not popped
    /// before the call to finish.
    ///
    /// [`start_reuse_range`]: Self::start_reuse_range
    pub fn finish_reuse_range(&mut self, start: ReuseStart) -> ReuseRange {
        assert_eq!(self.frame_id, start.frame_id, "reuse range not started by the same builder");
        assert_eq!(self.seg_id, start.seg_id, "reuse range not started by the same builder");
        assert_eq!(
            self.clip_len, start.clip_len,
            "reuse range cannot finish before all clips pushed inside it are popped"
        );
        assert_eq!(
            self.mask_len, start.mask_len,
            "reuse range cannot finish before all masks pushed inside it are popped"
        );
        assert_eq!(
            self.space_len, start.space_len,
            "reuse range cannot finish before all reference frames pushed inside it are popped"
        );
        assert_eq!(
            self.stacking_len, start.stacking_len,
            "reuse range cannot finish before all stacking contexts pushed inside it are popped"
        );
        debug_assert!(start.start <= self.list.len());

        self.has_reuse_ranges = true;

        ReuseRange {
            frame_id: self.frame_id,
            seg_id: self.seg_id,
            start: start.start,
            end: self.list.len(),
        }
    }

    /// Push a range of items to be copied from the previous display list on the same pipeline.
    ///
    /// Panics if `range` does not have a compatible pipeline id.
    pub fn push_reuse_range(&mut self, range: &ReuseRange) {
        if !range.is_empty() {
            self.list.push(DisplayItem::Reuse {
                frame_id: range.frame_id,
                seg_id: range.seg_id,
                start: range.start,
                end: range.end,
            });
        }
    }

    /// Start a new spatial context, must be paired with a call to [`pop_reference_frame`].
    ///
    /// If `transform_style` is `Preserve3D` if extends the 3D context of the parent. If the parent
    /// is not `Preserve3D` a stacking context with `Preserve3D` must be the next display item.
    ///
    /// [`pop_reference_frame`]: Self::pop_reference_frame
    pub fn push_reference_frame(
        &mut self,
        key: ReferenceFrameId,
        transform: FrameValue<PxTransform>,
        transform_style: TransformStyle,
        is_2d_scale_translation: bool,
    ) {
        debug_assert!(key.is_app_generated());

        self.space_len += 1;
        self.list.push(DisplayItem::PushReferenceFrame {
            id: key,
            transform,
            transform_style,
            is_2d_scale_translation,
        });
    }

    /// Finish the flat spatial context started by a call to [`push_reference_frame`].
    ///
    /// [`push_reference_frame`]: Self::push_reference_frame
    pub fn pop_reference_frame(&mut self) {
        debug_assert!(self.space_len > 1);
        self.space_len -= 1;
        self.list.push(DisplayItem::PopReferenceFrame);
    }

    /// Start a new filters context or extend 3D space, must be paired with a call to [`pop_stacking_context`].
    ///
    /// Note that `transform_style` is coerced to `Flat` if any filter is also set.
    ///
    /// [`pop_stacking_context`]: Self::pop_stacking_context
    pub fn push_stacking_context(&mut self, blend_mode: MixBlendMode, transform_style: TransformStyle, filters: &[FilterOp]) {
        self.stacking_len += 1;
        self.list.push(DisplayItem::PushStackingContext {
            blend_mode,
            transform_style,
            filters: filters.to_vec().into_boxed_slice(),
        })
    }

    /// Finish the filters context started by a call to [`push_stacking_context`].
    ///
    /// [`push_stacking_context`]: Self::push_stacking_context
    pub fn pop_stacking_context(&mut self) {
        debug_assert!(self.stacking_len > 1);
        self.stacking_len -= 1;
        self.list.push(DisplayItem::PopStackingContext);
    }

    /// Push a rectangular clip that will affect all pushed items until a paired call to [`pop_clip`].
    ///
    /// [`pop_clip`]: Self::pop_clip
    pub fn push_clip_rect(&mut self, clip_rect: PxRect, clip_out: bool) {
        self.clip_len += 1;
        self.list.push(DisplayItem::PushClipRect { clip_rect, clip_out });
    }

    /// Push a rectangular clip with rounded corners that will affect all pushed items until a paired call to [`pop_clip`].
    ///
    /// If `clip_out` is `true` only pixels outside the rounded rect are visible.
    ///
    /// [`pop_clip`]: Self::pop_clip
    pub fn push_clip_rounded_rect(&mut self, clip_rect: PxRect, corners: PxCornerRadius, clip_out: bool) {
        self.clip_len += 1;
        self.list.push(DisplayItem::PushClipRoundedRect {
            clip_rect,
            corners,
            clip_out,
        });
    }

    /// Pop a clip previously pushed by a call to [`push_clip_rect`]. Items pushed after this call are not
    /// clipped.
    ///
    /// [`push_clip_rect`]: Self::push_clip_rect
    pub fn pop_clip(&mut self) {
        debug_assert!(self.clip_len > 1);
        self.clip_len -= 1;
        self.list.push(DisplayItem::PopClip);
    }

    /// Push an image mask that will affect all pushed items until a paired call to [`pop_mask`].
    ///
    /// [`pop_mask`]: Self::pop_mask
    pub fn push_mask(&mut self, image_id: ImageTextureId, rect: PxRect) {
        self.mask_len += 1;
        self.list.push(DisplayItem::PushMask { image_id, rect })
    }

    /// Pop an image mask previously pushed by a call to [`push_mask`]. Items pushed after this call are not
    /// masked.
    ///
    /// [`push_mask`]: Self::push_mask
    pub fn pop_mask(&mut self) {
        debug_assert!(self.mask_len > 1);
        self.mask_len -= 1;
        self.list.push(DisplayItem::PopMask);
    }

    /// Push a normal border.
    #[expect(clippy::too_many_arguments)]
    pub fn push_border(
        &mut self,
        bounds: PxRect,
        widths: PxSideOffsets,
        top: BorderSide,
        right: BorderSide,
        bottom: BorderSide,
        left: BorderSide,
        radius: PxCornerRadius,
    ) {
        self.list.push(DisplayItem::Border {
            bounds,
            widths,
            sides: [top, right, bottom, left],
            radius,
        })
    }

    /// Push a nine-patch border.
    #[expect(clippy::too_many_arguments)]
    pub fn push_nine_patch_border(
        &mut self,
        bounds: PxRect,
        source: NinePatchSource,
        widths: PxSideOffsets,
        img_size: PxSize,
        slice: PxSideOffsets,
        fill: bool,
        repeat_horizontal: RepeatMode,
        repeat_vertical: RepeatMode,
    ) {
        self.list.push(DisplayItem::NinePatchBorder {
            bounds,
            source,
            widths,
            img_size,
            slice,
            fill,
            repeat_horizontal,
            repeat_vertical,
        })
    }

    /// Push a text run.
    pub fn push_text(
        &mut self,
        clip_rect: PxRect,
        font_id: FontId,
        glyphs: &[GlyphInstance],
        color: FrameValue<Rgba>,
        options: GlyphOptions,
    ) {
        self.list.push(DisplayItem::Text {
            clip_rect,
            font_id,
            glyphs: glyphs.to_vec().into_boxed_slice(),
            color,
            options,
        });
    }

    /// Push an image.
    #[expect(clippy::too_many_arguments)]
    pub fn push_image(
        &mut self,
        clip_rect: PxRect,
        image_id: ImageTextureId,
        image_size: PxSize,
        tile_size: PxSize,
        tile_spacing: PxSize,
        rendering: ImageRendering,
        alpha_type: AlphaType,
    ) {
        self.list.push(DisplayItem::Image {
            clip_rect,
            image_id,
            image_size,
            rendering,
            alpha_type,
            tile_size,
            tile_spacing,
        })
    }

    /// Push a color rectangle.
    pub fn push_color(&mut self, clip_rect: PxRect, color: FrameValue<Rgba>) {
        self.list.push(DisplayItem::Color { clip_rect, color })
    }

    /// Push a filter that applies to all rendered pixels behind `clip_rect`.
    pub fn push_backdrop_filter(&mut self, clip_rect: PxRect, filters: &[FilterOp]) {
        self.list.push(DisplayItem::BackdropFilter {
            clip_rect,
            filters: filters.to_vec().into_boxed_slice(),
        })
    }

    /// Push a linear gradient rectangle.
    #[expect(clippy::too_many_arguments)]
    pub fn push_linear_gradient(
        &mut self,
        clip_rect: PxRect,
        start_point: euclid::Point2D<f32, Px>,
        end_point: euclid::Point2D<f32, Px>,
        extend_mode: ExtendMode,
        stops: &[GradientStop],
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    ) {
        self.list.push(DisplayItem::LinearGradient {
            clip_rect,
            start_point,
            end_point,
            extend_mode,
            stops: stops.to_vec().into_boxed_slice(),
            tile_origin,
            tile_size,
            tile_spacing,
        })
    }

    /// Push a radial gradient rectangle.
    #[expect(clippy::too_many_arguments)]
    pub fn push_radial_gradient(
        &mut self,
        clip_rect: PxRect,
        center: euclid::Point2D<f32, Px>,
        radius: euclid::Size2D<f32, Px>,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: &[GradientStop],
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    ) {
        self.list.push(DisplayItem::RadialGradient {
            clip_rect,
            center,
            radius,
            start_offset,
            end_offset,
            extend_mode,
            stops: stops.to_vec().into_boxed_slice(),
            tile_origin,
            tile_size,
            tile_spacing,
        });
    }

    /// Push a conic gradient rectangle.
    #[expect(clippy::too_many_arguments)]
    pub fn push_conic_gradient(
        &mut self,
        clip_rect: PxRect,
        center: euclid::Point2D<f32, Px>,
        angle: AngleRadian,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: &[GradientStop],
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    ) {
        self.list.push(DisplayItem::ConicGradient {
            clip_rect,
            center,
            angle,
            start_offset,
            end_offset,
            extend_mode,
            stops: stops.to_vec().into_boxed_slice(),
            tile_origin,
            tile_size,
            tile_spacing,
        });
    }

    /// Push a styled vertical or horizontal line.
    pub fn push_line(&mut self, clip_rect: PxRect, color: Rgba, style: LineStyle, orientation: LineOrientation) {
        self.list.push(DisplayItem::Line {
            clip_rect,
            color,
            style,
            orientation,
        })
    }

    /// Push a custom extension payload.
    ///
    /// This can be used by custom renderer implementations to support custom items defined in the context
    /// of normal display items.
    ///
    /// There are two types of display items, normal items like [`push_color`] and context items like
    /// [`push_clip_rect`]-[`pop_clip`], if the extension is a normal item only the `push_extension` method must
    /// be called, if the extension is a context item the [`pop_extension`] must also be called.
    ///
    /// [`push_color`]: Self::push_color
    /// [`push_clip_rect`]: Self::push_clip_rect
    /// [`pop_clip`]: Self::pop_clip
    /// [`pop_extension`]: Self::pop_extension
    pub fn push_extension(&mut self, extension_id: ApiExtensionId, payload: ApiExtensionPayload) {
        self.list.push(DisplayItem::PushExtension { extension_id, payload })
    }

    /// Pop an extension previously pushed.
    ///
    /// Only required if the extension implementation requires it, item extensions do not need to pop.
    pub fn pop_extension(&mut self, extension_id: ApiExtensionId) {
        self.list.push(DisplayItem::PopExtension { extension_id })
    }

    /// Sets the backface visibility of all display items after this call.
    pub fn set_backface_visibility(&mut self, visible: bool) {
        self.list.push(DisplayItem::SetBackfaceVisibility { visible })
    }

    /// Number of display items.
    pub fn len(&self) -> usize {
        self.list.len()
    }

    /// Returns `true` if the list has no display items.
    pub fn is_empty(&self) -> bool {
        self.list.is_empty()
    }

    /// Create a display list builder that can be send to be build in parallel and then folded back onto
    /// this list using [`parallel_fold`].
    ///
    /// [`parallel_fold`]: Self::parallel_fold
    pub fn parallel_split(&self) -> Self {
        Self {
            frame_id: self.frame_id,
            list: vec![],
            clip_len: 1,
            mask_len: 1,
            space_len: 1,
            stacking_len: 1,
            seg_id: self.seg_id_gen.fetch_add(1, std::sync::atomic::Ordering::Relaxed),
            seg_id_gen: self.seg_id_gen.clone(),
            segments: vec![],
            has_reuse_ranges: false,
        }
    }

    /// Append the `split` onto `self`.
    ///
    /// # Panics
    ///
    /// Panics if `split` was not generated by a call to [`parallel_split`] on `self` or a
    /// *parent* display list.
    ///
    /// Panics if `split` has not closed all reference frames, clips or stacking contexts that it opened.
    ///
    /// [`parallel_split`]: Self::parallel_split
    pub fn parallel_fold(&mut self, mut split: Self) {
        assert!(
            Arc::ptr_eq(&self.seg_id_gen, &split.seg_id_gen),
            "cannot fold list not split from this one or parent"
        );
        assert_eq!(split.space_len, 1);
        assert_eq!(split.clip_len, 1);
        assert_eq!(split.mask_len, 1);
        assert_eq!(split.stacking_len, 1);

        if !self.list.is_empty() {
            for (_, offset) in &mut split.segments {
                *offset += self.list.len();
            }
        }

        if self.segments.is_empty() {
            self.segments = split.segments;
        } else {
            self.segments.append(&mut split.segments);
        }
        if split.has_reuse_ranges {
            self.segments.push((split.seg_id, self.list.len()));
        }

        if self.list.is_empty() {
            self.list = split.list;
        } else {
            self.list.append(&mut split.list);
        }
    }

    /// Returns the display list.
    pub fn finalize(self) -> DisplayList {
        DisplayList {
            frame_id: self.frame_id,
            list: self.list,
            segments: self.segments,
        }
    }
}

/// Id of the offset a parallel list folded onto the main list is at.
pub type SegmentId = usize;

/// Represents the start of a display list reuse range.
///
/// See [`DisplayListBuilder::start_reuse_range`] for more details.
pub struct ReuseStart {
    frame_id: FrameId,
    seg_id: SegmentId,
    start: usize,

    clip_len: usize,
    mask_len: usize,
    space_len: usize,
    stacking_len: usize,
}

/// Represents a display list reuse range.
///
/// See [`DisplayListBuilder::push_reuse_range`] for more details.
///
/// [`DisplayListBuilder::push_reuse_range`]: crate::display_list::DisplayListBuilder::push_reuse_range
#[derive(Debug, Clone)]
pub struct ReuseRange {
    frame_id: FrameId,
    seg_id: SegmentId,
    start: usize,
    end: usize,
}
impl ReuseRange {
    /// Frame that owns the reused items selected by this range.
    pub fn frame_id(&self) -> FrameId {
        self.frame_id
    }

    /// If the reuse range did not capture any display item.
    pub fn is_empty(&self) -> bool {
        self.start == self.end
    }
}

/// Represents a finalized display list.
///
/// See [`DisplayListBuilder::finalize`] for more details.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct DisplayList {
    frame_id: FrameId,
    list: Vec<DisplayItem>,
    segments: Vec<(SegmentId, usize)>,
}
impl DisplayList {
    /// Frame that will be rendered by this display list.
    pub fn frame_id(&self) -> FrameId {
        self.frame_id
    }

    /// Destructure the list.
    pub fn into_parts(self) -> (FrameId, Vec<DisplayItem>, Vec<(SegmentId, usize)>) {
        (self.frame_id, self.list, self.segments)
    }
}
impl ops::Deref for DisplayList {
    type Target = [DisplayItem];

    fn deref(&self) -> &Self::Target {
        &self.list
    }
}

/// Frame value binding ID.
///
/// This ID is defined by the app-process.
///
/// See [`FrameValue`] for more details.
#[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, serde::Serialize, serde::Deserialize)]
#[serde(transparent)]
pub struct FrameValueId(u64);

impl FrameValueId {
    /// Dummy ID, zero.
    pub const INVALID: Self = Self(0);
    /// Create the first valid ID.
    pub const fn first() -> Self {
        Self(1)
    }
    /// Create the next ID.
    ///
    /// IDs wrap around to [`first`] when the entire `u32` space is used, it is never `INVALID`.
    ///
    /// [`first`]: Self::first
    #[must_use]
    pub const fn next(self) -> Self {
        let r = Self(self.0.wrapping_add(1));
        if r.0 == Self::INVALID.0 { Self::first() } else { r }
    }
    /// Replace self with [`next`] and returns.
    ///
    /// [`next`]: Self::next
    #[must_use]
    pub fn incr(&mut self) -> Self {
        std::mem::replace(self, self.next())
    }
    /// Get the raw ID.
    pub const fn get(self) -> u64 {
        self.0
    }
    /// Create an ID using a custom value.
    ///
    /// Note that only the documented process must generate IDs, and that it must only
    /// generate IDs using this function or the [`next`] function.
    ///
    /// If the `id` is zero it will still be [`INVALID`] and handled differently by the other process,
    /// zero is never valid.
    ///
    /// [`next`]: Self::next
    /// [`INVALID`]: Self::INVALID
    pub const fn from_raw(id: u64) -> Self {
        Self(id)
    }
}

/// Represents a frame value that may be updated.
///
/// This value is send in a full frame request, after frame updates may be send targeting the key.
#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
pub enum FrameValue<T> {
    /// Value that is updated with frame update requests.
    Bind {
        /// ID that will be used to update the value.
        id: FrameValueId,
        /// Initial value.
        value: T,
        /// If the value will update rapidly.
        animating: bool,
    },
    /// Value is not updated, a new frame must be send to change this value.
    Value(T),
}
impl<T> FrameValue<T> {
    /// Reference the (initial) value.
    pub fn value(&self) -> &T {
        match self {
            FrameValue::Bind { value, .. } | FrameValue::Value(value) => value,
        }
    }

    /// Into the (initial) value.
    pub fn into_value(self) -> T {
        match self {
            FrameValue::Bind { value, .. } | FrameValue::Value(value) => value,
        }
    }

    /// Returns `true` if a new frame must be generated.
    fn update_bindable(value: &mut T, animating: &mut bool, update: &FrameValueUpdate<T>) -> bool
    where
        T: PartialEq + Copy,
    {
        // if changed to `true`, needs a frame to register the binding.
        //
        // if changed to `false`, needs a frame to un-register the binding so that the renderer can start caching
        // the tiles in the region again, we can't use the binding "one last time" because if a smaller region
        // continues animating it would keep refreshing the large region too.
        //
        // if continues to be `false` only needs to update if the value actually changed.
        let need_frame = (*animating != update.animating) || (!*animating && *value != update.value);

        *animating = update.animating;
        *value = update.value;

        need_frame
    }

    /// Returns `true` if a new frame must be generated.
    fn update_value(value: &mut T, update: &FrameValueUpdate<T>) -> bool
    where
        T: PartialEq + Copy,
    {
        if value != &update.value {
            *value = update.value;
            true
        } else {
            false
        }
    }
}
impl<T> From<T> for FrameValue<T> {
    fn from(value: T) -> Self {
        FrameValue::Value(value)
    }
}

/// Represents an update targeting a previously setup [`FrameValue`].
#[derive(Debug, Clone, Copy, Serialize, Deserialize)]
pub struct FrameValueUpdate<T> {
    /// Value ID.
    pub id: FrameValueId,
    /// New value.
    pub value: T,
    /// If the value is updating rapidly.
    pub animating: bool,
}

/// Represents one of the filters applied to a stacking context.
#[derive(Debug, Clone, Copy, PartialEq, Serialize, Deserialize)]
pub enum FilterOp {
    /// Blur, width and height in pixels.
    Blur(f32, f32),
    /// Brightness, in [0..=1] range.
    Brightness(f32),
    /// Contrast, in [0..=1] range.
    Contrast(f32),
    /// Grayscale, in [0..=1] range.
    Grayscale(f32),
    /// Hue shift, in degrees.
    HueRotate(f32),
    /// Invert, in [0..=1] range.
    Invert(f32),
    /// Opacity, in [0..=1] range, can be bound.
    Opacity(FrameValue<f32>),
    /// Saturation, in [0..=1] range.
    Saturate(f32),
    /// Sepia, in [0..=1] range.
    Sepia(f32),
    /// Pixel perfect shadow.
    DropShadow {
        /// Shadow offset.
        offset: euclid::Vector2D<f32, Px>,
        /// Shadow color.
        color: Rgba,
        /// Shadow blur.
        blur_radius: f32,
    },
    /// Custom filter.
    ///
    /// The color matrix is in the format of SVG color matrix, [0..5] is the first matrix row.
    ColorMatrix([f32; 20]),
    /// Fill with color.
    Flood(Rgba),
}

/// Display item in a [`DisplayList`].
#[allow(missing_docs)]
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum DisplayItem {
    Reuse {
        frame_id: FrameId,
        seg_id: SegmentId,
        start: usize,
        end: usize,
    },
    PushReferenceFrame {
        id: ReferenceFrameId,
        transform: FrameValue<PxTransform>,
        transform_style: TransformStyle,
        is_2d_scale_translation: bool,
    },
    PopReferenceFrame,

    PushStackingContext {
        transform_style: TransformStyle,
        blend_mode: MixBlendMode,
        filters: Box<[FilterOp]>,
    },
    PopStackingContext,

    PushClipRect {
        clip_rect: PxRect,
        clip_out: bool,
    },
    PushClipRoundedRect {
        clip_rect: PxRect,
        corners: PxCornerRadius,
        clip_out: bool,
    },
    PopClip,
    PushMask {
        image_id: ImageTextureId,
        rect: PxRect,
    },
    PopMask,

    Border {
        bounds: PxRect,
        widths: PxSideOffsets,
        sides: [BorderSide; 4],
        radius: PxCornerRadius,
    },
    NinePatchBorder {
        bounds: PxRect,
        source: NinePatchSource,
        widths: PxSideOffsets,
        img_size: PxSize,
        slice: PxSideOffsets,
        fill: bool,
        repeat_horizontal: RepeatMode,
        repeat_vertical: RepeatMode,
    },

    Text {
        clip_rect: PxRect,
        font_id: FontId,
        glyphs: Box<[GlyphInstance]>,
        color: FrameValue<Rgba>,
        options: GlyphOptions,
    },

    Image {
        clip_rect: PxRect,
        image_id: ImageTextureId,
        image_size: PxSize,
        rendering: ImageRendering,
        alpha_type: AlphaType,
        tile_size: PxSize,
        tile_spacing: PxSize,
    },

    Color {
        clip_rect: PxRect,
        color: FrameValue<Rgba>,
    },
    BackdropFilter {
        clip_rect: PxRect,
        filters: Box<[FilterOp]>,
    },

    LinearGradient {
        clip_rect: PxRect,
        start_point: euclid::Point2D<f32, Px>,
        end_point: euclid::Point2D<f32, Px>,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    },
    RadialGradient {
        clip_rect: PxRect,
        center: euclid::Point2D<f32, Px>,
        radius: euclid::Size2D<f32, Px>,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    },
    ConicGradient {
        clip_rect: PxRect,
        center: euclid::Point2D<f32, Px>,
        angle: AngleRadian,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
        tile_origin: PxPoint,
        tile_size: PxSize,
        tile_spacing: PxSize,
    },

    Line {
        clip_rect: PxRect,
        color: Rgba,
        style: LineStyle,
        orientation: LineOrientation,
    },

    PushExtension {
        extension_id: ApiExtensionId,
        payload: ApiExtensionPayload,
    },
    PopExtension {
        extension_id: ApiExtensionId,
    },

    SetBackfaceVisibility {
        visible: bool,
    },
}
impl DisplayItem {
    /// Update the value and returns if a new full frame must be rendered.
    pub fn update_transform(&mut self, t: &FrameValueUpdate<PxTransform>) -> bool {
        match self {
            DisplayItem::PushReferenceFrame {
                transform:
                    FrameValue::Bind {
                        id,
                        value,
                        animating: animation,
                    },
                ..
            } if *id == t.id => FrameValue::update_bindable(value, animation, t),
            _ => false,
        }
    }

    /// Update the value and returns if a new full frame must be rendered.
    pub fn update_float(&mut self, t: &FrameValueUpdate<f32>) -> bool {
        match self {
            DisplayItem::PushStackingContext { filters, .. } => {
                let mut new_frame = false;
                for filter in filters.iter_mut() {
                    match filter {
                        FilterOp::Opacity(FrameValue::Bind {
                            id,
                            value,
                            animating: animation,
                        }) if *id == t.id => {
                            new_frame |= FrameValue::update_bindable(value, animation, t);
                        }
                        _ => {}
                    }
                }
                new_frame
            }
            _ => false,
        }
    }

    /// Update the value and returns if a new full frame must be rendered.
    pub fn update_color(&mut self, t: &FrameValueUpdate<Rgba>) -> bool {
        match self {
            DisplayItem::Color {
                color:
                    FrameValue::Bind {
                        id,
                        value,
                        animating: animation,
                    },
                ..
            } if *id == t.id => FrameValue::update_bindable(value, animation, t),
            DisplayItem::Text {
                color: FrameValue::Bind { id, value, .. },
                ..
            } if *id == t.id => FrameValue::update_value(value, t),
            _ => false,
        }
    }
}

/// Nine-patch image source.
#[allow(missing_docs)]
#[derive(Debug, Clone, Serialize, Deserialize)]
pub enum NinePatchSource {
    Image {
        image_id: ImageTextureId,
        rendering: ImageRendering,
    },
    LinearGradient {
        start_point: euclid::Point2D<f32, Px>,
        end_point: euclid::Point2D<f32, Px>,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
    },
    RadialGradient {
        center: euclid::Point2D<f32, Px>,
        radius: euclid::Size2D<f32, Px>,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
    },
    ConicGradient {
        center: euclid::Point2D<f32, Px>,
        angle: AngleRadian,
        start_offset: f32,
        end_offset: f32,
        extend_mode: ExtendMode,
        stops: Box<[GradientStop]>,
    },
}