Piotr Osiewicz
bd6d385817
A minor thing I've spotted and decided to fix on the spot. It was being cloned twice within the body of that function (one of which was redundant even without this PR); now in most cases we go down from 2 clones to 0. Release Notes: - N/A
86 lines
2.3 KiB
Rust
86 lines
2.3 KiB
Rust
use refineable::Refineable as _;
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use crate::{
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Bounds, Element, ElementId, GlobalElementId, IntoElement, Pixels, Style, StyleRefinement,
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Styled, WindowContext,
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};
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/// Construct a canvas element with the given paint callback.
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/// Useful for adding short term custom drawing to a view.
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pub fn canvas<T>(
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prepaint: impl 'static + FnOnce(Bounds<Pixels>, &mut WindowContext) -> T,
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paint: impl 'static + FnOnce(Bounds<Pixels>, T, &mut WindowContext),
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) -> Canvas<T> {
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Canvas {
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prepaint: Some(Box::new(prepaint)),
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paint: Some(Box::new(paint)),
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style: StyleRefinement::default(),
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}
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}
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/// A canvas element, meant for accessing the low level paint API without defining a whole
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/// custom element
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pub struct Canvas<T> {
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prepaint: Option<Box<dyn FnOnce(Bounds<Pixels>, &mut WindowContext) -> T>>,
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paint: Option<Box<dyn FnOnce(Bounds<Pixels>, T, &mut WindowContext)>>,
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style: StyleRefinement,
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}
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impl<T: 'static> IntoElement for Canvas<T> {
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type Element = Self;
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fn into_element(self) -> Self::Element {
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self
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}
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}
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impl<T: 'static> Element for Canvas<T> {
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type RequestLayoutState = Style;
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type PrepaintState = Option<T>;
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fn id(&self) -> Option<ElementId> {
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None
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}
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fn request_layout(
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&mut self,
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_id: Option<&GlobalElementId>,
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cx: &mut WindowContext,
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) -> (crate::LayoutId, Self::RequestLayoutState) {
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let mut style = Style::default();
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style.refine(&self.style);
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let layout_id = cx.request_layout(style.clone(), []);
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(layout_id, style)
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}
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fn prepaint(
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&mut self,
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_id: Option<&GlobalElementId>,
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bounds: Bounds<Pixels>,
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_request_layout: &mut Style,
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cx: &mut WindowContext,
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) -> Option<T> {
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Some(self.prepaint.take().unwrap()(bounds, cx))
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}
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fn paint(
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&mut self,
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_id: Option<&GlobalElementId>,
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bounds: Bounds<Pixels>,
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style: &mut Style,
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prepaint: &mut Self::PrepaintState,
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cx: &mut WindowContext,
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) {
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let prepaint = prepaint.take().unwrap();
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style.paint(bounds, cx, |cx| {
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(self.paint.take().unwrap())(bounds, prepaint, cx)
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});
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}
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}
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impl<T> Styled for Canvas<T> {
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fn style(&mut self) -> &mut crate::StyleRefinement {
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&mut self.style
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}
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}
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