Resize the host when text scaling on windows changes.

If the text scale change delta is too small (e.g. 100% to 105% compared to 100% to 150%), Windows only sends a text scale change message. If the delta is large (e.g. 100% to 150%), Windows sends a text scale and window resize message.

Here's the new behavior: https://i.imgur.com/PAjwJSt.gif

Bug: 1087626
Change-Id: I5b6d86a6219d3e27128a5b221d401bcf001443ff
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2223123
Commit-Queue: John Pham <johnp@microsoft.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Peter Kasting <pkasting@chromium.org>
Cr-Commit-Position: refs/heads/master@{#775284}

ui/aura/test/aura_test_helper.cc

@@ -109,7 +109,7 @@ AuraTestHelper* AuraTestHelper::GetInstance() {
 void AuraTestHelper::SetUp() {
   display::Screen* screen = display::Screen::GetScreen();
   gfx::Size host_size(screen ? screen->GetPrimaryDisplay().GetSizeInPixel()
-                             : gfx::Size(800, 600));
+                             : kDefaultHostSize);
   test_screen_.reset(TestScreen::Create(host_size));
   // TODO(pkasting): Seems like we should either always set the screen instance,
   // or not create the screen/host if the test already has one; it doesn't make
@@ -198,6 +198,8 @@ client::CaptureClient* AuraTestHelper::GetCaptureClient() {
   return capture_client_.get();
 }
 
+constexpr gfx::Size AuraTestHelper::kDefaultHostSize;
+
 Env* AuraTestHelper::GetEnv() {
   if (env_)
     return env_.get();

ui/aura/test/aura_test_helper.h

@@ -67,6 +67,8 @@ class AuraTestHelper {
   virtual client::FocusClient* GetFocusClient();
   virtual client::CaptureClient* GetCaptureClient();
 
+  static constexpr gfx::Size kDefaultHostSize{800, 600};
+
   Env* GetEnv();
 
  protected:

ui/aura/test/test_screen.cc

@@ -70,12 +70,14 @@ WindowTreeHost* TestScreen::CreateHostForPrimaryDisplay() {
   return host_;
 }
 
-void TestScreen::SetDeviceScaleFactor(float device_scale_factor) {
+void TestScreen::SetDeviceScaleFactor(float device_scale_factor,
+                                      bool resize_host) {
   display::Display display(GetPrimaryDisplay());
   gfx::Rect bounds_in_pixel(display.GetSizeInPixel());
   display.SetScaleAndBounds(device_scale_factor, bounds_in_pixel);
   display_list().UpdateDisplay(display);
-  host_->OnHostResizedInPixels(bounds_in_pixel.size());
+  if (resize_host)
+    host_->OnHostResizedInPixels(bounds_in_pixel.size());
 }
 
 void TestScreen::SetColorSpace(const gfx::ColorSpace& color_space,

ui/aura/test/test_screen.h

@@ -33,7 +33,7 @@ class TestScreen : public display::ScreenBase, public WindowObserver {
 
   WindowTreeHost* CreateHostForPrimaryDisplay();
 
-  void SetDeviceScaleFactor(float device_scale_fator);
+  void SetDeviceScaleFactor(float device_scale_factor, bool resize_host = true);
   void SetColorSpace(
       const gfx::ColorSpace& color_space,
       float sdr_white_level = gfx::ColorSpace::kDefaultSDRWhiteLevel);

ui/aura/window_tree_host.cc

@@ -504,13 +504,18 @@ void WindowTreeHost::OnHostLostWindowCapture() {
 
 void WindowTreeHost::OnDisplayMetricsChanged(const display::Display& display,
                                              uint32_t metrics) {
-  if (metrics & DisplayObserver::DISPLAY_METRIC_COLOR_SPACE) {
-    display::Screen* screen = display::Screen::GetScreen();
-    if (compositor_ &&
-        display.id() == screen->GetDisplayNearestView(window()).id()) {
-      compositor_->SetDisplayColorSpaces(display.color_spaces());
-    }
-  }
+  if (metrics & DisplayObserver::DISPLAY_METRIC_COLOR_SPACE && compositor_ &&
+      display.id() == GetDisplayId())
+    compositor_->SetDisplayColorSpaces(display.color_spaces());
+
+// Chrome OS is handled in WindowTreeHostManager::OnDisplayMetricsChanged.
+// Chrome OS requires additional handling for the bounds that we do not need to
+// do for other OSes.
+#if !defined(OS_CHROMEOS)
+  if (metrics & DISPLAY_METRIC_DEVICE_SCALE_FACTOR &&
+      display.id() == GetDisplayId())
+    OnHostResizedInPixels(GetBoundsInPixels().size());
+#endif
 }
 
 gfx::Rect WindowTreeHost::GetTransformedRootWindowBoundsInPixels(

ui/aura/window_tree_host_unittest.cc

@@ -21,7 +21,9 @@ namespace aura {
 using WindowTreeHostTest = test::AuraTestBase;
 
 TEST_F(WindowTreeHostTest, DPIWindowSize) {
-  gfx::Rect starting_bounds(0, 0, 800, 600);
+  constexpr gfx::Rect starting_bounds(
+      aura::test::AuraTestHelper::kDefaultHostSize);
+
   EXPECT_EQ(starting_bounds.size(), host()->compositor()->size());
   EXPECT_EQ(starting_bounds, host()->GetBoundsInPixels());
   EXPECT_EQ(starting_bounds, root_window()->bounds());
@@ -113,6 +115,30 @@ TEST_F(WindowTreeHostTest, HoldPointerMovesOnChildResizing) {
 }
 #endif
 
+#if !defined(OS_CHROMEOS)
+// Tests if scale factor changes take effect. Previously a scale factor change
+// wouldn't take effect without a bounds change. For context see
+// https://crbug.com/1087626
+TEST_F(WindowTreeHostTest, ShouldHandleTextScale) {
+  constexpr gfx::Rect starting_bounds(
+      aura::test::AuraTestHelper::kDefaultHostSize);
+  auto asserter = [&](float test_scale_factor) {
+    test_screen()->SetDeviceScaleFactor(test_scale_factor, false);
+
+    EXPECT_EQ(starting_bounds, host()->GetBoundsInPixels());
+    // Size should be rounded up after scaling.
+    EXPECT_EQ(
+        gfx::ScaleToEnclosingRect(starting_bounds, 1.0f / test_scale_factor),
+        root_window()->bounds());
+    EXPECT_EQ(test_scale_factor, host()->device_scale_factor());
+  };
+
+  asserter(1.0f);
+  asserter(1.05f);
+  asserter(1.5f);
+}
+#endif
+
 TEST_F(WindowTreeHostTest, NoRewritesPostIME) {
   ui::test::TestEventRewriter event_rewriter;
   host()->AddEventRewriter(&event_rewriter);

ui/views/widget/desktop_aura/desktop_window_tree_host_linux.cc

@@ -184,23 +184,6 @@ Widget::MoveLoopResult DesktopWindowTreeHostLinux::RunMoveLoop(
                                                     escape_behavior);
 }
 
-void DesktopWindowTreeHostLinux::OnDisplayMetricsChanged(
-    const display::Display& display,
-    uint32_t changed_metrics) {
-  aura::WindowTreeHost::OnDisplayMetricsChanged(display, changed_metrics);
-
-  if ((changed_metrics & DISPLAY_METRIC_DEVICE_SCALE_FACTOR) &&
-      display::Screen::GetScreen()->GetDisplayNearestWindow(window()).id() ==
-          display.id()) {
-    // When the scale factor changes, also pretend that a resize
-    // occurred so that the window layout will be refreshed and a
-    // compositor redraw will be scheduled.  This is weird, but works.
-    // TODO(thomasanderson): Figure out a more direct way of doing
-    // this.
-    OnHostResizedInPixels(GetBoundsInPixels().size());
-  }
-}
-
 void DesktopWindowTreeHostLinux::DispatchEvent(ui::Event* event) {
   // The input can be disabled and the widget marked as non-active in case of
   // opened file-dialogs.

ui/views/widget/desktop_aura/desktop_window_tree_host_linux.h

@@ -92,10 +92,6 @@ class VIEWS_EXPORT DesktopWindowTreeHostLinux
   friend class DesktopWindowTreeHostX11Test;
   FRIEND_TEST_ALL_PREFIXES(DesktopWindowTreeHostLinuxTest, HitTest);
 
-  // Overridden from display::DisplayObserver via aura::WindowTreeHost:
-  void OnDisplayMetricsChanged(const display::Display& display,
-                               uint32_t changed_metrics) override;
-
   // DesktopWindowTreeHostPlatform overrides:
   void AddAdditionalInitProperties(
       const Widget::InitParams& params,