Bug 1751360 - Fix broken fullscreen behavior on Windows r=mhowell,han…

…dyman

Differential Revision: https://phabricator.services.mozilla.com/D137089

widget/windows/nsWindow.cpp

@@ -2294,54 +2294,66 @@ static UINT GetCurrentShowCmd(HWND aWnd) {
   return pl.showCmd;
 }
 
-// Maximize, minimize or restore the window.
-void nsWindow::SetSizeMode(nsSizeMode aMode) {
-  // Let's not try and do anything if we're already in that state.
-  // (This is needed to prevent problems when calling window.minimize(), which
-  // calls us directly, and then the OS triggers another call to us.)
-  if (aMode == mSizeMode) return;
-
-  // If we are still displaying a maximized pre-XUL skeleton UI, ignore the
-  // noise of sizemode changes. Once we have "shown" the window for the first
-  // time (called nsWindow::Show(true), even though the window is already
-  // technically displayed), we will again accept sizemode changes.
-  if (mIsShowingPreXULSkeletonUI && WasPreXULSkeletonUIMaximized()) {
-    return;
-  }
-
+void nsWindow::SetSizeModeInternal(nsSizeMode aMode) {
   // save the requested state
   mLastSizeMode = mSizeMode;
   nsBaseWidget::SetSizeMode(aMode);
   if (mIsVisible) {
-    int mode;
-
     switch (aMode) {
       case nsSizeMode_Fullscreen:
-        mode = SW_SHOW;
+        ::ShowWindow(mWnd, SW_SHOW);
         break;
 
       case nsSizeMode_Maximized:
-        mode = SW_MAXIMIZE;
+        ::ShowWindow(mWnd, SW_MAXIMIZE);
         break;
 
       case nsSizeMode_Minimized:
-        mode = SW_MINIMIZE;
+        ::ShowWindow(mWnd, SW_MINIMIZE);
         break;
 
       default:
-        mode = SW_RESTORE;
+        // Don't call ::ShowWindow if we're trying to "restore" a window that is
+        // already in a normal state.  Prevents a bug where snapping to one side
+        // of the screen and then minimizing would cause Windows to forget our
+        // window's correct restored position/size.
+        if (GetCurrentShowCmd(mWnd) != SW_SHOWNORMAL) {
+          ::ShowWindow(mWnd, SW_RESTORE);
+        }
     }
+  }
 
-    // Don't call ::ShowWindow if we're trying to "restore" a window that is
-    // already in a normal state.  Prevents a bug where snapping to one side
-    // of the screen and then minimizing would cause Windows to forget our
-    // window's correct restored position/size.
-    if (!(GetCurrentShowCmd(mWnd) == SW_SHOWNORMAL && mode == SW_RESTORE)) {
-      ::ShowWindow(mWnd, mode);
-    }
-    // we activate here to ensure that the right child window is focused
-    if (mode == SW_MAXIMIZE || mode == SW_SHOW)
-      DispatchFocusToTopLevelWindow(true);
+  // we activate here to ensure that the right child window is focused
+  if (mIsVisible && (aMode == nsSizeMode_Maximized || aMode == nsSizeMode_Fullscreen)) {
+    DispatchFocusToTopLevelWindow(true);
+  }
+}
+
+// Maximize, minimize or restore the window.
+void nsWindow::SetSizeMode(nsSizeMode aMode) {
+  // If we are still displaying a maximized pre-XUL skeleton UI, ignore the
+  // noise of sizemode changes. Once we have "shown" the window for the first
+  // time (called nsWindow::Show(true), even though the window is already
+  // technically displayed), we will again accept sizemode changes.
+  if (mIsShowingPreXULSkeletonUI && WasPreXULSkeletonUIMaximized()) {
+    return;
+  }
+
+  // Let's not try and do anything if we're already in that state.
+  // (This is needed to prevent problems when calling window.minimize(), which
+  // calls us directly, and then the OS triggers another call to us.)
+  if (aMode == mSizeMode) return;
+
+  if (aMode == nsSizeMode_Fullscreen) {
+    MakeFullScreen(true, nullptr);
+  } else if ((mSizeMode == nsSizeMode_Fullscreen) && (aMode == nsSizeMode_Normal)) {
+    // If we are in fullscreen mode, minimize should work like normal and
+    // return us to fullscreen mode when unminimized. Maximize isn't really
+    // available and won't do anything. "Restore" should do the same thing as
+    // requesting to end fullscreen.
+    MakeFullScreen(false, nullptr);
+  } else {
+    SetSizeModeInternal(aMode);
   }
 }
 
@@ -3667,25 +3679,32 @@ void nsWindow::CleanupFullscreenTransition() {
 }
 
 nsresult nsWindow::MakeFullScreen(bool aFullScreen, nsIScreen* aTargetScreen) {
-  // taskbarInfo will be nullptr pre Windows 7 until Bug 680227 is resolved.
-  nsCOMPtr<nsIWinTaskbar> taskbarInfo = do_GetService(NS_TASKBAR_CONTRACTID);
+  if (mFullscreenMode == aFullScreen) {
+    return NS_OK;
+  }
 
   if (mWidgetListener) {
     mWidgetListener->FullscreenWillChange(aFullScreen);
   }
 
   mFullscreenMode = aFullScreen;
   if (aFullScreen) {
-    if (mSizeMode == nsSizeMode_Fullscreen) return NS_OK;
     mOldSizeMode = mSizeMode;
-    SetSizeMode(nsSizeMode_Fullscreen);
-
-    // Notify the taskbar that we will be entering full screen mode.
-    if (taskbarInfo) {
-      taskbarInfo->PrepareFullScreenHWND(mWnd, TRUE);
-    }
+    SetSizeModeInternal(nsSizeMode_Fullscreen);
   } else {
-    SetSizeMode(mOldSizeMode);
+    if (mSizeMode != mOldSizeMode) {
+      SetSizeModeInternal(mOldSizeMode);
+    }
+
+    MOZ_ASSERT(mSizeMode == mOldSizeMode);
+  }
+
+  // taskbarInfo will be nullptr pre Windows 7 until Bug 680227 is resolved.
+  nsCOMPtr<nsIWinTaskbar> taskbarInfo = do_GetService(NS_TASKBAR_CONTRACTID);
+
+  // Notify the taskbar that we will be entering full screen mode.
+  if (aFullScreen && taskbarInfo) {
+    taskbarInfo->PrepareFullScreenHWND(mWnd, TRUE);
   }
 
   // If we are going fullscreen, the window size continues to change
@@ -3697,7 +3716,9 @@ nsresult nsWindow::MakeFullScreen(bool aFullScreen, nsIScreen* aTargetScreen) {
   // be called once per fullscreen request.
   nsBaseWidget::InfallibleMakeFullScreen(aFullScreen, aTargetScreen);
 
-  if (mIsVisible && !aFullScreen && mOldSizeMode == nsSizeMode_Normal) {
+  if (mIsVisible && !aFullScreen && mSizeMode == nsSizeMode_Normal) {
+    MOZ_ASSERT(mSizeMode == mOldSizeMode);
+
     // Ensure the window exiting fullscreen get activated. Window
     // activation might be bypassed in SetSizeMode.
     DispatchFocusToTopLevelWindow(true);

widget/windows/nsWindow.h

@@ -537,6 +537,8 @@ class nsWindow final : public nsWindowBase {
                                        const WinPointerInfo& aPointerInfo,
                                        mozilla::MouseButton aButton);
 
+  void SetSizeModeInternal(nsSizeMode aMode);
+
  protected:
   static bool IsAsyncResponseEvent(UINT aMsg, LRESULT& aResult);
   void IPCWindowProcHandler(UINT& msg, WPARAM& wParam, LPARAM& lParam);