Manually compute inverted matrix for screen rotation

ash/display/display_controller.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/display/display_controller.h"
 
 #include <algorithm>
 
 #include "ash/ash_switches.h"
 #include "ash/display/display_manager.h"
@@ skipping 116 matching lines @@
 #if defined(OS_WIN)
   // Windows 8 bots refused to resize the host window, and
   // updating the transform results in incorrectly resizing
   // the root window. Don't apply the transform unless
   // necessary so that unit tests pass on win8 bots.
   if (info.rotation() == root_window->GetProperty(kRotationPropertyKey))
     return;
   root_window->SetProperty(kRotationPropertyKey, info.rotation());
 #endif
   gfx::Transform rotate;
+  // TODO(oshima): Manually complute the invert of the

[sky, 2013/03/25 16:04:32]

complute -> compute
invert -> inverse

[oshima, 2013/03/25 17:49:31]

Done.

+  // rotate+translate matrix to compensate computation error in

[sky, 2013/03/25 16:04:32]

'to compensate' -> 'to compensate for'

[oshima, 2013/03/25 17:49:31]

Done.

+  // inverted matrix. Ideally, SkMatrix should have special

[sky, 2013/03/25 16:04:32]

inverted -> the intervted

[oshima, 2013/03/25 17:49:31]

Done.

+  // case handling for rotate+translate case. crbug.com/222483.
+  gfx::Transform reverse_rotate;
+
   // The origin is (0, 0), so the translate width/height must be reduced by 1.
   switch (info.rotation()) {
     case gfx::Display::ROTATE_0:
       break;
     case gfx::Display::ROTATE_90:
       rotate.Translate(display.bounds().height() - 1, 0);
       rotate.Rotate(90);
+      // Rotate 270 instead of 90 as it will cause calcuration error.
+      reverse_rotate.Rotate(270);
+      reverse_rotate.Translate(-(display.bounds().height() - 1), 0);
       break;
     case gfx::Display::ROTATE_270:
       rotate.Translate(0, display.bounds().width() - 1);
       rotate.Rotate(270);
+      reverse_rotate.Rotate(90);
+      reverse_rotate.Translate(0, -(display.bounds().width() - 1));
       break;
     case gfx::Display::ROTATE_180:
       rotate.Translate(display.bounds().width() - 1,
                        display.bounds().height() - 1);
       rotate.Rotate(180);
+      reverse_rotate.Rotate(180);
+      reverse_rotate.Translate(-(display.bounds().width() - 1),
+                               -(display.bounds().height() - 1));
       break;
   }
-  root_window->SetTransform(rotate);
+  root_window->SetTransformPair(rotate, reverse_rotate);
 }
 
 void SetDisplayPropertiesOnHostWindow(aura::RootWindow* root,
                                       const gfx::Display& display) {
   internal::DisplayInfo info =
       GetDisplayManager()->GetDisplayInfo(display.id());
 #if defined(OS_CHROMEOS)
   // Native window property (Atom in X11) that specifies the display's
   // rotation, scale factor and if it's internal display.  They are
   // read and used by touchpad/mouse driver directly on X (contact
@@ skipping 718 matching lines @@
 }
 
 void DisplayController::OnFadeOutForSwapDisplayFinished() {
 #if defined(OS_CHROMEOS)
   SetPrimaryDisplay(ScreenAsh::GetSecondaryDisplay());
   Shell::GetInstance()->output_configurator_animation()->StartFadeInAnimation();
 #endif
 }
 
 }  // namespace ash