text update for more code reuse + much better caching

src/core/text/mod.rs

@@ -0,0 +1,130 @@
+mod build;
+mod edit;
+
+pub use build::*;
+pub use edit::*;
+
+use crate::{prelude::*, util::MutDetect};
+use cosmic_text::{Attrs, Metrics, Shaping};
+use std::ops::{Deref, DerefMut};
+
+pub struct Text {
+    pub content: MutDetect<String>,
+    view: TextView,
+}
+
+pub struct TextView {
+    pub attrs: MutDetect<TextAttrs>,
+    pub buf: MutDetect<TextBuffer>,
+    // cache
+    tex: Option<TextTexture>,
+    width: Option<f32>,
+}
+
+impl TextView {
+    pub fn new(buf: TextBuffer, attrs: TextAttrs) -> Self {
+        Self {
+            attrs: attrs.into(),
+            buf: buf.into(),
+            tex: None,
+            width: None,
+        }
+    }
+    pub fn draw(&mut self, ctx: &mut SizeCtx) -> TextTexture {
+        let width = if self.attrs.wrap {
+            Some(ctx.px_size().x)
+        } else {
+            None
+        };
+        if width == self.width
+            && let Some(tex) = &self.tex
+            && !self.attrs.changed
+            && !self.buf.changed
+        {
+            return tex.clone();
+        }
+        self.width = width;
+        let font_system = &mut ctx.text.font_system;
+        self.attrs.apply(font_system, &mut self.buf, width);
+        self.buf.shape_until_scroll(font_system, false);
+        let tex = ctx.draw_text(&mut self.buf, &self.attrs);
+        self.tex = Some(tex.clone());
+        self.attrs.changed = false;
+        self.buf.changed = false;
+        tex
+    }
+    pub fn tex(&self) -> Option<&TextTexture> {
+        self.tex.as_ref()
+    }
+}
+
+impl Text {
+    pub fn new(content: impl Into<String>) -> Self {
+        let attrs = TextAttrs::default();
+        let buf = TextBuffer::new_empty(Metrics::new(attrs.font_size, attrs.line_height));
+        Self {
+            content: content.into().into(),
+            view: TextView::new(buf, attrs),
+        }
+    }
+    fn update_buf(&mut self, ctx: &mut SizeCtx) -> TextTexture {
+        if self.content.changed {
+            self.content.changed = false;
+            self.view.buf.set_text(
+                &mut ctx.text.font_system,
+                &self.content,
+                &Attrs::new().family(self.view.attrs.family),
+                Shaping::Advanced,
+            );
+        }
+        self.view.draw(ctx)
+    }
+}
+
+impl Widget for Text {
+    fn draw(&mut self, painter: &mut Painter) {
+        let tex = self.update_buf(&mut painter.size_ctx());
+        let region = text_region(&tex, self.align);
+        painter.texture_within(&tex.handle, region);
+    }
+
+    fn desired_size(&mut self, ctx: &mut SizeCtx) -> UiVec2 {
+        UiVec2::abs(self.update_buf(ctx).size())
+    }
+}
+
+pub fn text_region(tex: &TextTexture, align: Align) -> UiRegion {
+    let tex_dims = tex.handle.size();
+    let mut region = UiRegion::from_size_align(tex.size(), align);
+    region.top_left.abs += tex.top_left;
+    region.bot_right.abs = region.top_left.abs + tex_dims;
+    region
+}
+
+impl Deref for Text {
+    type Target = TextAttrs;
+
+    fn deref(&self) -> &Self::Target {
+        &self.view
+    }
+}
+
+impl DerefMut for Text {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.view
+    }
+}
+
+impl Deref for TextView {
+    type Target = TextAttrs;
+
+    fn deref(&self) -> &Self::Target {
+        &self.attrs
+    }
+}
+
+impl DerefMut for TextView {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.attrs
+    }
+}