Merge pull request #6497 from electron/windows-thumbnail

Add setThumbnailClip API on Windows

atom/browser/api/atom_api_window.cc

@@ -649,6 +649,12 @@ bool Window::IsWindowMessageHooked(UINT message) {
 void Window::UnhookAllWindowMessages() {
   messages_callback_map_.clear();
 }
+
+bool Window::SetThumbnailClip(const gfx::Rect& region) {
+  auto window = static_cast<NativeWindowViews*>(window_.get());
+  return window->taskbar_host().SetThumbnailClip(
+      window_->GetAcceleratedWidget(), region);
+}
 #endif
 
 #if defined(TOOLKIT_VIEWS)
@@ -836,6 +842,7 @@ void Window::BuildPrototype(v8::Isolate* isolate,
       .SetMethod("isWindowMessageHooked", &Window::IsWindowMessageHooked)
       .SetMethod("unhookWindowMessage", &Window::UnhookWindowMessage)
       .SetMethod("unhookAllWindowMessages", &Window::UnhookAllWindowMessages)
+      .SetMethod("setThumbnailClip", &Window::SetThumbnailClip)
 #endif
 #if defined(TOOLKIT_VIEWS)
       .SetMethod("setIcon", &Window::SetIcon)

atom/browser/api/atom_api_window.h

@@ -179,6 +179,7 @@ class Window : public mate::TrackableObject<Window>,
   bool IsWindowMessageHooked(UINT message);
   void UnhookWindowMessage(UINT message);
   void UnhookAllWindowMessages();
+  bool SetThumbnailClip(const gfx::Rect& region);
 #endif
 
 #if defined(TOOLKIT_VIEWS)

atom/browser/ui/win/taskbar_host.cc

@@ -142,6 +142,22 @@ bool TaskbarHost::SetOverlayIcon(
       window, icon.get(), base::UTF8ToUTF16(text).c_str()));
 }
 
+bool TaskbarHost::SetThumbnailClip(HWND window, const gfx::Rect& region) {
+  if (!InitializeTaskbar())
+    return false;
+
+  if (region.IsEmpty()) {
+    return SUCCEEDED(taskbar_->SetThumbnailClip(window, NULL));
+  } else {
+    RECT rect;
+    rect.left = region.x();
+    rect.right = region.right();
+    rect.top = region.y();
+    rect.bottom = region.bottom();
+    return SUCCEEDED(taskbar_->SetThumbnailClip(window, &rect));
+  }
+}
+
 bool TaskbarHost::HandleThumbarButtonEvent(int button_id) {
   if (ContainsKey(callback_map_, button_id)) {
     auto callback = callback_map_[button_id];

atom/browser/ui/win/taskbar_host.h

@@ -13,6 +13,7 @@
 
 #include "base/callback.h"
 #include "base/win/scoped_comptr.h"
+#include "ui/gfx/geometry/rect.h"
 #include "ui/gfx/image/image.h"
 
 namespace atom {
@@ -40,6 +41,9 @@ class TaskbarHost {
   bool SetOverlayIcon(
       HWND window, const gfx::Image& overlay, const std::string& text);
 
+  // Set the region of the window to show as a thumbnail in taskbar.
+  bool TaskbarHost::SetThumbnailClip(HWND window, const gfx::Rect& region);
+
   // Called by the window that there is a button in thumbar clicked.
   bool HandleThumbarButtonEvent(int button_id);
 

docs/api/browser-window.md

@@ -985,6 +985,17 @@ The `flags` is an array that can include following `String`s:
   button state is drawn. This value is intended for instances where the button
   is used in a notification.
 
+#### `win.setThumbnailClip(region)` _Windows_
+
+* `region` - Object
+  * `x` Integer - x-position of region
+  * `y` Integer - y-position of region
+  * `width` Integer - width of region
+  * `height` Integer - height of region
+
+Sets the region of the window to show as the thumbnail image displayed when
+hovering over the window in the taskbar.
+
 #### `win.showDefinitionForSelection()` _macOS_
 
 Same as `webContents.showDefinitionForSelection()`.