better text rendering

src/layout/text.rs

@@ -1,4 +1,6 @@
-use cosmic_text::{Attrs, AttrsList, Buffer, Family, FontSystem, Metrics, SwashCache};
+use cosmic_text::{
+    Attrs, AttrsList, Buffer, Family, FontSystem, Metrics, SwashCache, SwashContent,
+};
 use image::{Rgba, RgbaImage};
 
 use crate::{
@@ -79,7 +81,7 @@ impl TextData {
         // should probably do texture packing and things if possible.
         // very visible if you add just a couple of wrapping texts and resize window
         // should also be timed to figure out exactly what points need to be sped up
-        let mut pixels = HashMap::default();
+        let mut pixels = HashMap::<_, [u8; 4]>::default();
         let mut min_x = 0;
         let mut min_y = 0;
         let mut max_x = 0;
@@ -99,20 +101,46 @@ impl TextData {
                     None => cosmic_color,
                 };
 
-                self.swash_cache.with_pixels(
-                    &mut self.font_system,
-                    physical_glyph.cache_key,
-                    glyph_color,
-                    |x, y, color| {
-                        let x = physical_glyph.x + x;
-                        let y = run.line_y as i32 + physical_glyph.y + y;
-                        min_x = min_x.min(x);
-                        min_y = min_y.min(y);
-                        max_x = max_x.max(x);
-                        max_y = max_y.max(y);
-                        pixels.insert((x, y), Rgba(color.as_rgba()));
-                    },
-                );
+                if let Some(img) = self
+                    .swash_cache
+                    .get_image(&mut self.font_system, physical_glyph.cache_key)
+                {
+                    let mut pos = img.placement;
+                    pos.left += physical_glyph.x;
+                    pos.top = physical_glyph.y + run.line_y as i32 - pos.top;
+                    min_x = min_x.min(pos.left);
+                    min_y = min_y.min(pos.top);
+                    max_x = max_x.max(pos.left + pos.width as i32);
+                    max_y = max_y.max(pos.top + pos.height as i32);
+                    let mut merge = |i, color: [u8; 4]| {
+                        let x = i % pos.width as usize;
+                        let y = i / pos.width as usize;
+                        let pos = (x as i32 + pos.left, y as i32 + pos.top);
+                        if let Some(pixel) = pixels.get_mut(&pos) {
+                            for i in 0..4 {
+                                pixel[i] = color[i].saturating_add(pixel[i]);
+                            }
+                        } else {
+                            pixels.insert(pos, color);
+                        }
+                    };
+                    match img.content {
+                        SwashContent::Mask => {
+                            for (i, a) in img.data.iter().enumerate() {
+                                let mut color = glyph_color.as_rgba();
+                                color[3] = ((color[3] as u32 * *a as u32) / u8::MAX as u32) as u8;
+                                merge(i, color);
+                            }
+                        }
+                        SwashContent::SubpixelMask => todo!(),
+                        SwashContent::Color => {
+                            let (colors, _) = img.data.as_chunks::<4>();
+                            for (i, color) in colors.iter().enumerate() {
+                                merge(i, *color);
+                            }
+                        }
+                    }
+                }
             }
             max_width = max_width.max(run.line_w);
             height += run.line_height;
@@ -120,10 +148,11 @@ impl TextData {
         let img_width = (max_x - min_x + 1) as u32;
         let img_height = (max_y - min_y + 1) as u32;
         let mut image = RgbaImage::new(img_width, img_height);
+
         for ((x, y), color) in pixels {
             let x = (x - min_x) as u32;
             let y = (y - min_y) as u32;
-            image.put_pixel(x, y, color);
+            image.put_pixel(x, y, Rgba(color));
         }
         TextTexture {
             handle: textures.add(image),