zng_wgt/node_events.rs
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use zng_app::widget::node::UiNodeOpMethod;
use crate::prelude::*;
/// Arguments for the node operation event properties.
#[derive(Clone, Debug)]
pub struct OnNodeOpArgs {
/// Operation.
///
/// Event args must be static so access to the full [`UiNodeOp`] is not possible, you can quickly
/// declare a new property with [`property`] and [`match_node`] if you want to affect the widget this way.
///
/// [`UiNodeOp`]: zng_app::widget::node::UiNodeOp
/// [`match_node`]: zng_app::widget::node::match_node
pub op: UiNodeOpMethod,
/// Number of times the handler was called.
///
/// The number is `1` for the first call and is not reset if the widget is re-inited.
pub count: usize,
/// Instant the handler was called.
pub timestamp: DInstant,
}
impl OnNodeOpArgs {
/// New args.
pub fn new(op: UiNodeOpMethod, count: usize, timestamp: DInstant) -> Self {
Self { op, count, timestamp }
}
/// New args with timestamp now.
pub fn now(op: UiNodeOpMethod, count: usize) -> Self {
Self::new(op, count, INSTANT.now())
}
}
/// On any node operation.
///
/// This property calls `handler` for any widget node operation, after the widget content has processed the operation. This means
/// that the `handler` is raised after any [`on_pre_node_op`] handler. Note that properties of [`NestGroup::EVENT`] or lower
/// can still process the operation before this event.
///
/// # Handlers
///
/// This property accepts any [`WidgetHandler`], including the async handlers. Use one of the handler macros, [`hn!`],
/// [`hn_once!`], [`async_hn!`] or [`async_hn_once!`], to declare a handler closure.
///
/// ## Async
///
/// The async handlers spawn a task that is associated with the widget, it will only update when the widget updates,
/// so the task *pauses* when the widget is deinited, and is *canceled* when the widget is dropped.
///
/// [`on_pre_node_op`]: fn@on_pre_node_op
/// [`NestGroup::EVENT`]: zng_app::widget::builder::NestGroup::EVENT
/// [`hn!`]: zng_app::handler::hn!
/// [`async_hn!`]: zng_app::handler::async_hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
/// [`async_hn_once!`]: zng_app::handler::async_hn_once!
/// [`WidgetHandler`]: zng_app::handler::WidgetHandler
#[property(EVENT)]
pub fn on_node_op(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_node_op_impl(child, handler, |_| true)
}
fn on_node_op_impl(
child: impl UiNode,
handler: impl WidgetHandler<OnNodeOpArgs>,
filter: impl Fn(UiNodeOpMethod) -> bool + Send + 'static,
) -> impl UiNode {
let mut handler = handler.cfg_boxed();
let mut count = 1;
match_node(child, move |child, op| {
let mtd = op.mtd();
child.op(op);
if filter(mtd) {
handler.event(&OnNodeOpArgs::now(mtd, count));
count = count.wrapping_add(1);
}
if let UiNodeOpMethod::Update = mtd {
handler.update();
}
})
}
/// Preview [`on_node_op`] event.
///
/// This property calls `handler` for any widget node operation, before most of the widget content processes the operation. This means
/// that the `handler` is raised before any [`on_node_op`] handler. Note that properties of [`NestGroup::EVENT`] or lower
/// can still process the operation before this event.
///
/// # Handlers
///
/// This property accepts any [`WidgetHandler`], including the async handlers. Use one of the handler macros, [`hn!`],
/// [`hn_once!`], [`async_hn!`] or [`async_hn_once!`], to declare a handler closure.
///
/// ## Async
///
/// The async handlers spawn a task that is associated with the widget, it will only update when the widget updates,
/// so the task *pauses* when the widget is deinited, and is *canceled* when the widget is dropped.
///
/// [`on_node_op`]: fn@on_node_op
/// [`NestGroup::EVENT`]: zng_app::widget::builder::NestGroup::EVENT
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
/// [`async_hn!`]: zng_app::handler::async_hn!
/// [`async_hn_once!`]: zng_app::handler::async_hn_once!
/// [`WidgetHandler`]: zng_app::handler::WidgetHandler
#[property(EVENT)]
pub fn on_pre_node_op(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_pre_node_op_impl(child, handler, |_| true)
}
fn on_pre_node_op_impl(
child: impl UiNode,
handler: impl WidgetHandler<OnNodeOpArgs>,
filter: impl Fn(UiNodeOpMethod) -> bool + Send + 'static,
) -> impl UiNode {
let mut handler = handler.cfg_boxed();
let mut count = 1;
match_node(child, move |_, op| {
if let UiNodeOp::Update { .. } = &op {
handler.update();
}
let mtd = op.mtd();
if filter(mtd) {
handler.event(&OnNodeOpArgs::now(mtd, count));
count = count.wrapping_add(1);
}
})
}
/// Widget initialized.
///
/// This property calls `handler` when the widget and its content initializes. Note that widgets
/// can be reinitialized, so the `handler` can be called more then once,
/// you can use one of the *once* handlers to only be called once or use the arguments [`count`](OnNodeOpArgs::count).
/// to determinate if you are in the first init.
///
/// Note that the widget is not in the [`WidgetInfoTree`] when this event happens, you can use [`on_info_init`] for initialization
/// that depends on the widget info.
///
/// # Handlers
///
/// This property accepts any [`WidgetHandler`], including the async handlers. Use one of the handler macros, [`hn!`],
/// [`hn_once!`], [`async_hn!`] or [`async_hn_once!`], to declare a handler closure.
///
/// ## Async
///
/// The async handlers spawn a task that is associated with the widget, it will only update when the widget updates,
/// so the task *pauses* when the widget is deinited, and is *canceled* when the widget is dropped.
///
/// [`on_info_init`]: fn@on_info_init
/// [`WidgetInfoTree`]: zng_app::widget::info::WidgetInfoTree
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
/// [`async_hn!`]: zng_app::handler::async_hn!
/// [`async_hn_once!`]: zng_app::handler::async_hn_once!
/// [`WidgetHandler`]: zng_app::handler::WidgetHandler
#[property(EVENT)]
pub fn on_init(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Init))
}
/// Preview [`on_init`] event.
///
/// [`on_init`]: fn@on_init
#[property(EVENT)]
pub fn on_pre_init(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_pre_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Init))
}
/// Widget info is now available.
///
/// This event fires after the first [`UiNode::info`] is built, after [`UiNode::init`]. This event can be used when
/// some widget initialization needs to happen, but the widget must be in the [`WidgetInfoTree`] for it to work.
///
/// # Handlers
///
/// This property accepts any [`WidgetHandler`], including the async handlers. Use one of the handler macros, [`hn!`],
/// [`hn_once!`], [`async_hn!`] or [`async_hn_once!`], to declare a handler closure.
///
/// ## Async
///
/// The async handlers spawn a task that is associated with the widget, it will only update when the widget updates,
/// so the task *pauses* when the widget is deinited, and is *canceled* when the widget is dropped.
///
/// [`WidgetInfoTree`]: zng_app::widget::info::WidgetInfoTree
///
/// [`UiNode::info`]: zng_app::widget::node::UiNode::info
/// [`UiNode::init`]: zng_app::widget::node::UiNode::init
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
/// [`async_hn!`]: zng_app::handler::async_hn!
/// [`async_hn_once!`]: zng_app::handler::async_hn_once!
/// [`WidgetHandler`]: zng_app::handler::WidgetHandler
#[property(EVENT)]
pub fn on_info_init(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
let mut handler = handler.cfg_boxed();
let mut count = 1;
enum State {
WaitInfo,
InfoInited,
Done,
}
let mut state = State::WaitInfo;
match_node(child, move |child, op| match op {
UiNodeOp::Init => {
state = State::WaitInfo;
}
UiNodeOp::Info { .. } => {
if let State::WaitInfo = &state {
state = State::InfoInited;
WIDGET.update();
}
}
UiNodeOp::Update { updates } => {
child.update(updates);
if let State::InfoInited = &state {
state = State::Done;
handler.event(&OnNodeOpArgs::now(UiNodeOpMethod::Update, count));
count = count.wrapping_add(1);
}
handler.update();
}
_ => {}
})
}
/// Widget [`update`](UiNode::update) event.
///
/// This property calls `handler` every UI update, after the widget content updates. Updates happen in
/// high volume in between idle moments, so the handler code should be considered a hot-path.
///
/// # Handlers
///
/// You can use one of the handler macros, [`hn!`] or [`hn_once!`], to declare a handler closure. You must avoid using the async
/// handlers as they cause an update every time the UI task advances from an await point causing another task to spawn.
///
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
#[property(EVENT)]
pub fn on_update(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Update))
}
/// Preview [`on_update`] event.
///
/// This property calls `handler` every time the UI updates, before the widget content updates. This means
/// that the `handler` is raised before any [`on_init`] handler.
///
/// # Handlers
///
/// You can use one of the handler macros, [`hn!`] or [`hn_once!`], to declare a handler closure. You must avoid using the async
/// handlers as they cause an update every time the UI task advances from an await point causing another task to spawn.
///
/// [`on_update`]: fn@on_update
/// [`on_init`]: fn@on_init
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
#[property(EVENT)]
pub fn on_pre_update(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_pre_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Update))
}
/// Widget deinited.
///
/// This property calls `handler` when the widget deinits, after the widget content deinits. Note that
/// widgets can be reinitialized so the `handler` can be called more then once,
/// you can use one of the *once* handlers to only be called once or use the arguments [`count`](OnNodeOpArgs::count)
/// to determinate if you are in the first deinit.
///
/// # Handlers
///
/// This property accepts the [`WidgetHandler`] that are not async. Use one of the handler macros, [`hn!`] or
/// [`hn_once!`], to declare a handler closure.
///
/// Note that async handlers do not work here because widget bound async tasks only advance past the first `.await`
/// during widget updates, but the widget is deinited before that. You can use [`UPDATES.run`] or [`task::spawn`] to start
/// an async task on deinit.
///
/// # Preview
///
/// You can use the [`on_pre_deinit`] event to receive this event before the widget content deinits.
///
/// [`UPDATES.run`]: zng_app::update::UPDATES::run
/// [`on_pre_deinit`]: fn@on_pre_deinit
/// [`WidgetHandler`]: zng_app::handler::WidgetHandler
/// [`hn!`]: zng_app::handler::hn!
/// [`hn_once!`]: zng_app::handler::hn_once!
/// [`task::spawn`]: zng_task::spawn
#[property(EVENT)]
pub fn on_deinit(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Deinit))
}
/// Preview [`on_deinit`] event.
///
/// [`on_deinit`]: fn@on_deinit
#[property(EVENT)]
pub fn on_pre_deinit(child: impl UiNode, handler: impl WidgetHandler<OnNodeOpArgs>) -> impl UiNode {
on_pre_node_op_impl(child, handler, |op| matches!(op, UiNodeOpMethod::Deinit))
}
/// If the widget has been initialized.
///
/// The `state` is set to `true` on init and to `false` on deinit. This property is useful for
/// declaring transition animations that play on init using `when` blocks.
#[property(CONTEXT)]
pub fn is_inited(child: impl UiNode, state: impl IntoVar<bool>) -> impl UiNode {
let state = state.into_var();
match_node(child, move |_, op| match op {
UiNodeOp::Init => {
let _ = state.set(true);
}
UiNodeOp::Deinit => {
let _ = state.set(false);
}
_ => {}
})
}