handwritin: Grow and shrink the canvas without refreshing

src/handwriting/mod.rs

@@ -105,20 +105,9 @@ struct MeshContext {
 
     pub pixels_per_point: f32,
 
-    /// Canvas size in points
-    pub size: Vec2,
-
     pub stroke: Stroke,
 }
 
-impl MeshContext {
-    /// Calculate canvas size in pixels
-    pub fn pixel_size(&self) -> [usize; 2] {
-        let Vec2 { x, y } = self.size * self.pixels_per_point;
-        [x, y].map(|f| f.ceil() as usize)
-    }
-}
-
 impl Default for Handwriting {
     fn default() -> Self {
         Self {
@@ -379,7 +368,6 @@ impl Handwriting {
         let new_context = MeshContext {
             ui_theme: ui.ctx().theme(),
             pixels_per_point: ui.pixels_per_point(),
-            size: mesh_rect.size(),
             stroke: style.stroke,
         };
 
@@ -388,6 +376,13 @@ impl Handwriting {
             self.e.refresh_texture = true;
         }
 
+        let [px_width, px_height] = {
+            let Vec2 { x, y } = mesh_rect.size() * new_context.pixels_per_point;
+            [x, y].map(|f| f.ceil() as usize)
+        };
+
+        self.e.canvas_rasterizer.set_size(px_width, px_height);
+
         if self.e.refresh_texture {
             // ...if we do, rasterize the entire texture from scratch
             self.refresh_texture(style, new_context);
@@ -457,11 +452,10 @@ impl Handwriting {
         //    debug_assert!(vertex.pos.y.is_finite(), "{} must be finite", vertex.pos.y);
         //}
 
-        let [px_x, px_y] = mesh_context.pixel_size();
         let point_to_pixel = TSTransform::from_scaling(mesh_context.pixels_per_point);
         let triangles = mesh_triangles(&self.e.mesh);
 
-        self.e.canvas_rasterizer.clear_and_set_size(px_x, px_y);
+        self.e.canvas_rasterizer.clear();
         self.e
             .canvas_rasterizer
             .rasterize(point_to_pixel, triangles);