copying now uses it's own thread to avoid freezing the ui for larger images

src/app.rs

@@ -37,6 +37,8 @@ pub struct TerrainApp {
     generated: Option<GeneratedImages>,
     generation_receiver: Option<Receiver<Result<GeneratedImages, String>>>,
     generation_in_progress: bool,
+    copy_receiver: Option<Receiver<Result<String, String>>>,
+    copy_in_progress: bool,
     status_message: String,
 }
 
@@ -51,6 +53,8 @@ impl TerrainApp {
             generated: None,
             generation_receiver: None,
             generation_in_progress: false,
+            copy_receiver: None,
+            copy_in_progress: false,
             status_message: String::from("Adjust parameters and click Generate."),
         }
     }
@@ -108,6 +112,33 @@ impl TerrainApp {
         }
     }
 
+    fn poll_copy(&mut self, ctx: &Context) {
+        let Some(receiver) = &self.copy_receiver else {
+            return;
+        };
+
+        match receiver.try_recv() {
+            Ok(Ok(message)) => {
+                self.status_message = message;
+                self.copy_receiver = None;
+                self.copy_in_progress = false;
+            }
+            Ok(Err(error)) => {
+                self.status_message = error;
+                self.copy_receiver = None;
+                self.copy_in_progress = false;
+            }
+            Err(TryRecvError::Empty) => {
+                ctx.request_repaint();
+            }
+            Err(TryRecvError::Disconnected) => {
+                self.status_message = String::from("Copy worker disconnected.");
+                self.copy_receiver = None;
+                self.copy_in_progress = false;
+            }
+        }
+    }
+
     fn install_textures(&mut self, ctx: &Context, images: &GeneratedImages) {
         let heightmap = gray_to_color_image(&images.heightmap_image);
         let bumpmap = gray_to_color_image(&images.bumpmap_image);
@@ -119,27 +150,37 @@ impl TerrainApp {
     }
 
     fn copy_preview(&mut self, preview: PreviewFocus) {
+        if self.copy_in_progress {
+            self.status_message = String::from("Copy already in progress...");
+            return;
+        }
+
         let Some(generated) = &self.generated else {
             self.status_message = String::from("No generated image is available to copy.");
             return;
         };
 
         let image = match preview {
-            PreviewFocus::Heightmap => &generated.heightmap_image,
-            PreviewFocus::Bumpmap => &generated.bumpmap_image,
+            PreviewFocus::Heightmap => generated.heightmap_image.clone(),
+            PreviewFocus::Bumpmap => generated.bumpmap_image.clone(),
+        };
+        let success_message = match preview {
+            PreviewFocus::Heightmap => String::from("Heightmap copied to clipboard."),
+            PreviewFocus::Bumpmap => String::from("Bumpmap copied to clipboard."),
         };
 
-        match copy_gray_image_to_clipboard(image) {
-            Ok(()) => {
-                self.status_message = match preview {
-                    PreviewFocus::Heightmap => String::from("Heightmap copied to clipboard."),
-                    PreviewFocus::Bumpmap => String::from("Bumpmap copied to clipboard."),
-                };
-            }
-            Err(error) => {
-                self.status_message = format!("Failed to copy image: {error}");
-            }
-        }
+        let (tx, rx) = mpsc::channel();
+        self.copy_receiver = Some(rx);
+        self.copy_in_progress = true;
+        self.status_message = match preview {
+            PreviewFocus::Heightmap => String::from("Copying heightmap to clipboard..."),
+            PreviewFocus::Bumpmap => String::from("Copying bumpmap to clipboard..."),
+        };
+
+        thread::spawn(move || {
+            let result = copy_gray_image_to_clipboard(&image).map(|_| success_message);
+            let _ = tx.send(result);
+        });
     }
 
     fn preview_context_menu(response: &Response) -> bool {
@@ -236,6 +277,10 @@ impl TerrainApp {
                     ui.add_space(8.0);
                     ui.spinner();
                 }
+                if self.copy_in_progress {
+                    ui.add_space(4.0);
+                    ui.spinner();
+                }
 
                 ui.add_space(8.0);
                 ui.label(&self.status_message);
@@ -392,6 +437,7 @@ impl eframe::App for TerrainApp {
     fn update(&mut self, ctx: &Context, _frame: &mut eframe::Frame) {
         self.hovered_preview = None;
         self.poll_generation(ctx);
+        self.poll_copy(ctx);
         self.ui_left_panel(ctx);
         self.ui_right_panel(ctx);