a74ce29c1a
The `TextAtlas` will have an initial size of `256` (we could make this configurable) and `try_allocate` will keep track of the glyphs in use in the current frame, returning `None` when the LRU glyph is in use. In that case, `TextRenderer::prepare` will return `PrepareError::AtlasFull` with the `ContentType` of the atlas that is full. The user of the library can then call `TextAtlas::grow` with the provided `ContentType` to obtain a bigger atlas (by `256`). A `TextAtlas::grow` call clears the whole atlas and, as a result, all of the `prepare` calls need to be repeated in a frame until they all succeed. Overall, the atlas will rarely need to grow and so the calls will not need to be repated often. Finally, the user needs to call `TextAtlas::trim` at the end of the frame. This allows us to clear the glyphs in use collection in the atlas. Maybe there is a better way to model this in an API that forces the user to trim the atlas (e.g. make `trim` return a new type and changing `prepare` and `render` to take that type instead).
110 lines
3.1 KiB
Rust
110 lines
3.1 KiB
Rust
//! Glyphon provides a simple way to render 2D text with [wpgu], [cosmic-text] and [etagere].
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//!
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//! [wpgu]: https://github.com/gfx-rs/wgpu
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//! [cosmic-text]: https://github.com/pop-os/cosmic-text
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//! [etagere]: https://github.com/nical/etagere
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mod error;
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mod text_atlas;
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mod text_render;
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pub use error::{PrepareError, RenderError};
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pub use text_atlas::{ColorMode, TextAtlas};
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pub use text_render::ContentType;
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pub use text_render::TextRenderer;
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// Re-export all top-level types from `cosmic-text` for convenience.
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pub use cosmic_text::{
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self, fontdb, Action, Affinity, Attrs, AttrsList, AttrsOwned, Buffer, BufferLine, CacheKey,
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Color, Command, Cursor, Edit, Editor, Family, FamilyOwned, Font, FontSystem, LayoutCursor,
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LayoutGlyph, LayoutLine, LayoutRun, LayoutRunIter, Metrics, ShapeGlyph, ShapeLine, ShapeSpan,
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ShapeWord, Stretch, Style, SubpixelBin, SwashCache, SwashContent, SwashImage, Weight, Wrap,
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};
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use etagere::AllocId;
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pub(crate) enum GpuCacheStatus {
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InAtlas {
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x: u16,
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y: u16,
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content_type: ContentType,
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},
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SkipRasterization,
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}
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pub(crate) struct GlyphDetails {
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width: u16,
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height: u16,
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gpu_cache: GpuCacheStatus,
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atlas_id: Option<AllocId>,
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top: i16,
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left: i16,
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}
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#[repr(C)]
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#[derive(Clone, Copy, Debug)]
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pub(crate) struct GlyphToRender {
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pos: [i32; 2],
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dim: [u16; 2],
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uv: [u16; 2],
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color: u32,
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content_type: u32,
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depth: f32,
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}
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/// The screen resolution to use when rendering text.
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#[repr(C)]
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub struct Resolution {
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/// The width of the screen in pixels.
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pub width: u32,
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/// The height of the screen in pixels.
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pub height: u32,
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}
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#[repr(C)]
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub(crate) struct Params {
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screen_resolution: Resolution,
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_pad: [u32; 2],
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}
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/// Controls the visible area of the text. Any text outside of the visible area will be clipped.
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#[derive(Clone, Copy, Debug, Eq, PartialEq)]
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pub struct TextBounds {
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/// The position of the left edge of the visible area.
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pub left: i32,
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/// The position of the top edge of the visible area.
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pub top: i32,
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/// The position of the right edge of the visible area.
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pub right: i32,
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/// The position of the bottom edge of the visible area.
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pub bottom: i32,
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}
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/// The default visible area doesn't clip any text.
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impl Default for TextBounds {
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fn default() -> Self {
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Self {
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left: i32::MIN,
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top: i32::MIN,
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right: i32::MAX,
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bottom: i32::MAX,
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}
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}
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}
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/// A text area containing text to be rendered along with its overflow behavior.
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pub struct TextArea<'a> {
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/// The buffer containing the text to be rendered.
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pub buffer: &'a Buffer,
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/// The left edge of the buffer.
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pub left: i32,
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/// The top edge of the buffer.
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pub top: i32,
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/// The visible bounds of the text area. This is used to clip the text and doesn't have to
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/// match the `left` and `top` values.
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pub bounds: TextBounds,
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// The default color of the text area.
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pub default_color: Color,
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}
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