Antonio Scandurra
0490c609fb
We're not using this yet but this will be useful to avoid rendering unnecessary portions of text.
88 lines
2.2 KiB
Rust
88 lines
2.2 KiB
Rust
use crate::{
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fonts::TextStyle,
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geometry::{
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rect::RectF,
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vector::{vec2f, Vector2F},
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},
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json::{json, ToJson},
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DebugContext, Element, ElementBox, Event, EventContext, LayoutContext, PaintContext,
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SizeConstraint,
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};
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pub struct LineBox {
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child: ElementBox,
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style: TextStyle,
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}
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impl LineBox {
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pub fn new(child: ElementBox, style: TextStyle) -> Self {
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Self { child, style }
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}
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}
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impl Element for LineBox {
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type LayoutState = f32;
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type PaintState = ();
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fn layout(
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&mut self,
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constraint: SizeConstraint,
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cx: &mut LayoutContext,
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) -> (Vector2F, Self::LayoutState) {
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let line_height = cx
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.font_cache
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.line_height(self.style.font_id, self.style.font_size);
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let character_height = cx
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.font_cache
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.ascent(self.style.font_id, self.style.font_size)
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+ cx.font_cache
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.descent(self.style.font_id, self.style.font_size);
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let child_max = vec2f(constraint.max.x(), character_height);
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let child_size = self.child.layout(
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SizeConstraint::new(constraint.min.min(child_max), child_max),
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cx,
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);
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let size = vec2f(child_size.x(), line_height);
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(size, (line_height - character_height) / 2.)
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}
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fn paint(
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&mut self,
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bounds: RectF,
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visible_bounds: RectF,
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padding_top: &mut f32,
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cx: &mut PaintContext,
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) -> Self::PaintState {
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self.child.paint(
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bounds.origin() + vec2f(0., *padding_top),
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visible_bounds,
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cx,
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);
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}
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fn dispatch_event(
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&mut self,
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event: &Event,
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_: RectF,
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_: &mut Self::LayoutState,
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_: &mut Self::PaintState,
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cx: &mut EventContext,
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) -> bool {
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self.child.dispatch_event(event, cx)
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}
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fn debug(
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&self,
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bounds: RectF,
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_: &Self::LayoutState,
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_: &Self::PaintState,
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cx: &DebugContext,
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) -> serde_json::Value {
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json!({
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"bounds": bounds.to_json(),
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"style": self.style.to_json(),
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"child": self.child.debug(cx),
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})
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}
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}
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