75 lines
2.2 KiB
Rust
75 lines
2.2 KiB
Rust
//! Write a graphics backend.
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use iced_native::image;
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use iced_native::svg;
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use iced_native::text;
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use iced_native::{Font, Point, Size};
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/// The graphics backend of a [`Renderer`].
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///
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/// [`Renderer`]: crate::Renderer
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pub trait Backend {
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/// Trims the measurements cache.
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///
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/// This method is currently necessary to properly trim the text cache in
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/// `iced_wgpu` and `iced_glow` because of limitations in the text rendering
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/// pipeline. It will be removed in the future.
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fn trim_measurements(&mut self) {}
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}
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pub trait Text {
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/// The icon font of the backend.
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const ICON_FONT: Font;
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/// The `char` representing a ✔ icon in the [`ICON_FONT`].
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///
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/// [`ICON_FONT`]: Self::ICON_FONT
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const CHECKMARK_ICON: char;
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/// The `char` representing a ▼ icon in the built-in [`ICON_FONT`].
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///
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/// [`ICON_FONT`]: Self::ICON_FONT
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const ARROW_DOWN_ICON: char;
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/// Returns the default size of text.
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fn default_size(&self) -> u16;
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/// Measures the text contents with the given size and font,
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/// returning the size of a laid out paragraph that fits in the provided
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/// bounds.
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fn measure(
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&self,
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contents: &str,
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size: f32,
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font: Font,
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bounds: Size,
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) -> (f32, f32);
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/// Tests whether the provided point is within the boundaries of [`Text`]
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/// laid out with the given parameters, returning information about
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/// the nearest character.
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///
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/// If nearest_only is true, the hit test does not consider whether the
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/// the point is interior to any glyph bounds, returning only the character
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/// with the nearest centeroid.
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fn hit_test(
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&self,
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contents: &str,
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size: f32,
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font: Font,
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bounds: Size,
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point: Point,
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nearest_only: bool,
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) -> Option<text::Hit>;
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}
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/// A graphics backend that supports image rendering.
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pub trait Image {
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/// Returns the dimensions of the provided image.
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fn dimensions(&self, handle: &image::Handle) -> (u32, u32);
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}
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/// A graphics backend that supports SVG rendering.
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pub trait Svg {
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/// Returns the viewport dimensions of the provided SVG.
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fn viewport_dimensions(&self, handle: &svg::Handle) -> (u32, u32);
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}
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