fix: `webContents.capturePage()` for hidden windows on Windows/Linux (#40186)

fix: capturePage for hidden windows on Windows/Linux

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Shelley Vohr <[email protected]>

shell/browser/api/electron_api_web_contents.cc

@@ -509,9 +509,16 @@ base::IDMap<WebContents*>& GetAllWebContents() {
 void OnCapturePageDone(gin_helper::Promise<gfx::Image> promise,
                        base::ScopedClosureRunner capture_handle,
                        const SkBitmap& bitmap) {
+  auto ui_task_runner = content::GetUIThreadTaskRunner({});
+  if (!ui_task_runner->RunsTasksInCurrentSequence()) {
+    ui_task_runner->PostTask(
+        FROM_HERE, base::BindOnce(&OnCapturePageDone, std::move(promise),
+                                  std::move(capture_handle), bitmap));
+    return;
+  }
+
   // Hack to enable transparency in captured image
   promise.Resolve(gfx::Image::CreateFrom1xBitmap(bitmap));
-
   capture_handle.RunAndReset();
 }
 
@@ -3473,22 +3480,16 @@ v8::Local<v8::Promise> WebContents::CapturePage(gin::Arguments* args) {
   }
 
   auto* const view = web_contents()->GetRenderWidgetHostView();
-  if (!view) {
+  if (!view || view->GetViewBounds().size().IsEmpty()) {
     promise.Resolve(gfx::Image());
     return handle;
   }
 
-#if !BUILDFLAG(IS_MAC)
-  // If the view's renderer is suspended this may fail on Windows/Linux -
-  // bail if so. See CopyFromSurface in
-  // content/public/browser/render_widget_host_view.h.
-  auto* rfh = web_contents()->GetPrimaryMainFrame();
-  if (rfh &&
-      rfh->GetVisibilityState() == blink::mojom::PageVisibilityState::kHidden) {
-    promise.Resolve(gfx::Image());
+  if (!view->IsSurfaceAvailableForCopy()) {
+    promise.RejectWithErrorMessage(
+        "Current display surface not available for capture");
     return handle;
   }
-#endif  // BUILDFLAG(IS_MAC)
 
   auto capture_handle = web_contents()->IncrementCapturerCount(
       rect.size(), stay_hidden, stay_awake);

spec/api-browser-window-spec.ts

@@ -2215,7 +2215,22 @@ describe('BrowserWindow module', () => {
       expect(visible).to.equal('hidden');
     });
 
-    it('resolves after the window is hidden', async () => {
+    it('resolves when the window is occluded', async () => {
+      const w1 = new BrowserWindow({ show: false });
+      w1.loadFile(path.join(fixtures, 'pages', 'a.html'));
+      await once(w1, 'ready-to-show');
+      w1.show();
+
+      const w2 = new BrowserWindow({ show: false });
+      w2.loadFile(path.join(fixtures, 'pages', 'a.html'));
+      await once(w2, 'ready-to-show');
+      w2.show();
+
+      const visibleImage = await w1.capturePage();
+      expect(visibleImage.isEmpty()).to.equal(false);
+    });
+
+    it('resolves when the window is not visible', async () => {
       const w = new BrowserWindow({ show: false });
       w.loadFile(path.join(fixtures, 'pages', 'a.html'));
       await once(w, 'ready-to-show');
@@ -2224,21 +2239,10 @@ describe('BrowserWindow module', () => {
       const visibleImage = await w.capturePage();
       expect(visibleImage.isEmpty()).to.equal(false);
 
-      w.hide();
+      w.minimize();
 
       const hiddenImage = await w.capturePage();
-      const isEmpty = process.platform !== 'darwin';
-      expect(hiddenImage.isEmpty()).to.equal(isEmpty);
-    });
-
-    it('resolves after the window is hidden and capturer count is non-zero', async () => {
-      const w = new BrowserWindow({ show: false });
-      w.webContents.setBackgroundThrottling(false);
-      w.loadFile(path.join(fixtures, 'pages', 'a.html'));
-      await once(w, 'ready-to-show');
-
-      const image = await w.capturePage();
-      expect(image.isEmpty()).to.equal(false);
+      expect(hiddenImage.isEmpty()).to.equal(false);
     });
 
     it('preserves transparency', async () => {