Texture loading in egui (#1110)

* Move texture allocation into epaint/egui proper
* Add TextureHandle
* egui_glow: cast using bytemuck instead of unsafe code
* Optimize glium painter
* Optimize WebGL
* Add example of loading an image from file

egui-winit/src/epi.rs

@@ -55,10 +55,9 @@ pub fn handle_app_output(
     window: &winit::window::Window,
     current_pixels_per_point: f32,
     app_output: epi::backend::AppOutput,
-) -> epi::backend::TexAllocationData {
+) {
     let epi::backend::AppOutput {
         quit: _,
-        tex_allocation_data,
         window_size,
         window_title,
         decorated,
@@ -86,8 +85,6 @@ pub fn handle_app_output(
     if drag_window {
         let _ = window.drag_window();
     }
-
-    tex_allocation_data
 }
 
 // ----------------------------------------------------------------------------
@@ -244,16 +241,14 @@ impl EpiIntegration {
             .setup(&self.egui_ctx, &self.frame, self.persistence.storage());
         let app_output = self.frame.take_app_output();
         self.quit |= app_output.quit;
-        let tex_alloc_data =
-            crate::epi::handle_app_output(window, self.egui_ctx.pixels_per_point(), app_output);
-        self.frame.lock().output.tex_allocation_data = tex_alloc_data; // Do it later
+        crate::epi::handle_app_output(window, self.egui_ctx.pixels_per_point(), app_output);
     }
 
     fn warm_up(&mut self, window: &winit::window::Window) {
         let saved_memory: egui::Memory = self.egui_ctx.memory().clone();
         self.egui_ctx.memory().set_everything_is_visible(true);
-        let (_, tex_alloc_data, _) = self.update(window);
-        self.frame.lock().output.tex_allocation_data = tex_alloc_data; // handle it next frame
+        let (_, textures_delta, _) = self.update(window);
+        self.egui_ctx.output().textures_delta = textures_delta; // Handle it next frame
         *self.egui_ctx.memory() = saved_memory; // We don't want to remember that windows were huge.
         self.egui_ctx.clear_animations();
     }
@@ -273,11 +268,7 @@ impl EpiIntegration {
     pub fn update(
         &mut self,
         window: &winit::window::Window,
-    ) -> (
-        bool,
-        epi::backend::TexAllocationData,
-        Vec<egui::epaint::ClippedShape>,
-    ) {
+    ) -> (bool, egui::TexturesDelta, Vec<egui::epaint::ClippedShape>) {
         let frame_start = instant::Instant::now();
 
         let raw_input = self.egui_winit.take_egui_input(window);
@@ -286,18 +277,19 @@ impl EpiIntegration {
         });
 
         let needs_repaint = egui_output.needs_repaint;
-        self.egui_winit
+        let textures_delta = self
+            .egui_winit
             .handle_output(window, &self.egui_ctx, egui_output);
 
         let app_output = self.frame.take_app_output();
         self.quit |= app_output.quit;
-        let tex_allocation_data =
-            crate::epi::handle_app_output(window, self.egui_ctx.pixels_per_point(), app_output);
+
+        crate::epi::handle_app_output(window, self.egui_ctx.pixels_per_point(), app_output);
 
         let frame_time = (instant::Instant::now() - frame_start).as_secs_f64() as f32;
         self.frame.lock().info.cpu_usage = Some(frame_time);
 
-        (needs_repaint, tex_allocation_data, shapes)
+        (needs_repaint, textures_delta, shapes)
     }
 
     pub fn maybe_autosave(&mut self, window: &winit::window::Window) {

egui-winit/src/lib.rs

@@ -512,26 +512,39 @@ impl State {
         window: &winit::window::Window,
         egui_ctx: &egui::Context,
         output: egui::Output,
-    ) {
-        self.current_pixels_per_point = egui_ctx.pixels_per_point(); // someone can have changed it to scale the UI
-
+    ) -> egui::TexturesDelta {
         if egui_ctx.memory().options.screen_reader {
             self.screen_reader.speak(&output.events_description());
         }
 
-        self.set_cursor_icon(window, output.cursor_icon);
+        let egui::Output {
+            cursor_icon,
+            open_url,
+            copied_text,
+            needs_repaint: _,             // needs to be handled elsewhere
+            events: _,                    // handled above
+            mutable_text_under_cursor: _, // only used in egui_web
+            text_cursor_pos,
+            textures_delta,
+        } = output;
 
-        if let Some(open) = output.open_url {
-            open_url(&open.url);
+        self.current_pixels_per_point = egui_ctx.pixels_per_point(); // someone can have changed it to scale the UI
+
+        self.set_cursor_icon(window, cursor_icon);
+
+        if let Some(open_url) = open_url {
+            open_url_in_browser(&open_url.url);
         }
 
-        if !output.copied_text.is_empty() {
-            self.clipboard.set(output.copied_text);
+        if !copied_text.is_empty() {
+            self.clipboard.set(copied_text);
         }
 
-        if let Some(egui::Pos2 { x, y }) = output.text_cursor_pos {
+        if let Some(egui::Pos2 { x, y }) = text_cursor_pos {
             window.set_ime_position(winit::dpi::LogicalPosition { x, y });
         }
+
+        textures_delta
     }
 
     fn set_cursor_icon(&mut self, window: &winit::window::Window, cursor_icon: egui::CursorIcon) {
@@ -554,7 +567,7 @@ impl State {
     }
 }
 
-fn open_url(_url: &str) {
+fn open_url_in_browser(_url: &str) {
     #[cfg(feature = "webbrowser")]
     if let Err(err) = webbrowser::open(_url) {
         eprintln!("Failed to open url: {}", err);