Add Shape::Callback to do custom rendering inside of an egui UI (#1351)

* Add Shape::Callback to do custom rendering inside of an egui UI
* Use Rc<glow::Context> everywhere
* Remove trait WebPainter
* Add glow::Context to epi::App::setup

egui/src/context.rs

@@ -122,7 +122,7 @@ impl ContextImpl {
 ///
 /// ``` no_run
 /// # fn handle_platform_output(_: egui::PlatformOutput) {}
-/// # fn paint(textures_detla: egui::TexturesDelta, _: Vec<egui::ClippedMesh>) {}
+/// # fn paint(textures_detla: egui::TexturesDelta, _: Vec<egui::ClippedPrimitive>) {}
 /// let mut ctx = egui::Context::default();
 ///
 /// // Game loop:
@@ -137,8 +137,8 @@ impl ContextImpl {
 ///         });
 ///     });
 ///     handle_platform_output(full_output.platform_output);
-///     let clipped_meshes = ctx.tessellate(full_output.shapes); // create triangles to paint
-///     paint(full_output.textures_delta, clipped_meshes);
+///     let clipped_primitives = ctx.tessellate(full_output.shapes); // create triangles to paint
+///     paint(full_output.textures_delta, clipped_primitives);
 /// }
 /// ```
 #[derive(Clone)]
@@ -773,7 +773,7 @@ impl Context {
     }
 
     /// Tessellate the given shapes into triangle meshes.
-    pub fn tessellate(&self, shapes: Vec<ClippedShape>) -> Vec<ClippedMesh> {
+    pub fn tessellate(&self, shapes: Vec<ClippedShape>) -> Vec<ClippedPrimitive> {
         // A tempting optimization is to reuse the tessellation from last frame if the
         // shapes are the same, but just comparing the shapes takes about 50% of the time
         // it takes to tessellate them, so it is not a worth optimization.
@@ -782,13 +782,13 @@ impl Context {
         tessellation_options.pixels_per_point = self.pixels_per_point();
         tessellation_options.aa_size = 1.0 / self.pixels_per_point();
         let paint_stats = PaintStats::from_shapes(&shapes);
-        let clipped_meshes = tessellator::tessellate_shapes(
+        let clipped_primitives = tessellator::tessellate_shapes(
             shapes,
             tessellation_options,
             self.fonts().font_image_size(),
         );
-        self.write().paint_stats = paint_stats.with_clipped_meshes(&clipped_meshes);
-        clipped_meshes
+        self.write().paint_stats = paint_stats.with_clipped_primitives(&clipped_primitives);
+        clipped_primitives
     }
 
     // ---------------------------------------------------------------------
@@ -1246,3 +1246,10 @@ impl Context {
         self.set_style(style);
     }
 }
+
+#[cfg(test)]
+#[test]
+fn context_impl_send_sync() {
+    fn assert_send_sync<T: Send + Sync>() {}
+    assert_send_sync::<Context>();
+}

egui/src/introspection.rs

@@ -91,9 +91,10 @@ impl Widget for &epaint::stats::PaintStats {
                 shape_path,
                 shape_mesh,
                 shape_vec,
+                num_callbacks,
                 text_shape_vertices,
                 text_shape_indices,
-                clipped_meshes,
+                clipped_primitives,
                 vertices,
                 indices,
             } = self;
@@ -104,6 +105,7 @@ impl Widget for &epaint::stats::PaintStats {
             label(ui, shape_path, "paths");
             label(ui, shape_mesh, "nested meshes");
             label(ui, shape_vec, "nested shapes");
+            ui.label(format!("{} callbacks", num_callbacks));
             ui.add_space(10.0);
 
             ui.label("Text shapes:");
@@ -113,7 +115,7 @@ impl Widget for &epaint::stats::PaintStats {
             ui.add_space(10.0);
 
             ui.label("Tessellated (and culled):");
-            label(ui, clipped_meshes, "clipped_meshes")
+            label(ui, clipped_primitives, "clipped_primitives")
                 .on_hover_text("Number of separate clip rectangles");
             label(ui, vertices, "vertices");
             label(ui, indices, "indices").on_hover_text("Three 32-bit indices per triangles");

egui/src/lib.rs

@@ -112,7 +112,7 @@
 //! ``` no_run
 //! # fn handle_platform_output(_: egui::PlatformOutput) {}
 //! # fn gather_input() -> egui::RawInput { egui::RawInput::default() }
-//! # fn paint(textures_detla: egui::TexturesDelta, _: Vec<egui::ClippedMesh>) {}
+//! # fn paint(textures_detla: egui::TexturesDelta, _: Vec<egui::ClippedPrimitive>) {}
 //! let mut ctx = egui::Context::default();
 //!
 //! // Game loop:
@@ -128,8 +128,8 @@
 //!         });
 //!     });
 //!     handle_platform_output(full_output.platform_output);
-//!     let clipped_meshes = ctx.tessellate(full_output.shapes); // create triangles to paint
-//!     paint(full_output.textures_delta, clipped_meshes);
+//!     let clipped_primitives = ctx.tessellate(full_output.shapes); // create triangles to paint
+//!     paint(full_output.textures_delta, clipped_primitives);
 //! }
 //! ```
 //!
@@ -386,8 +386,8 @@ pub use epaint::{
     color, mutex,
     text::{FontData, FontDefinitions, FontFamily, FontId, FontTweak},
     textures::TexturesDelta,
-    AlphaImage, ClippedMesh, Color32, ColorImage, ImageData, Mesh, Rgba, Rounding, Shape, Stroke,
-    TextureHandle, TextureId,
+    AlphaImage, ClippedPrimitive, Color32, ColorImage, ImageData, Mesh, Rgba, Rounding, Shape,
+    Stroke, TextureHandle, TextureId,
 };
 
 pub mod text {