Use GetInverse

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 <cmath>
 #include <map>
 
@@ skipping 133 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 inverse of the
-  // rotate+translate matrix to compensate for computation error in
-  // the inverted matrix. Ideally, SkMatrix should have special
-  // 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 pixel.
   float one_pixel = 1.0f / display.device_scale_factor();
   switch (info.rotation()) {
     case gfx::Display::ROTATE_0:
       break;
     case gfx::Display::ROTATE_90:
       rotate.Translate(display.bounds().height() - one_pixel, 0);
       rotate.Rotate(90);
-      reverse_rotate.Rotate(270);
-      reverse_rotate.Translate(-(display.bounds().height() - one_pixel), 0);
       break;
     case gfx::Display::ROTATE_270:
       rotate.Translate(0, display.bounds().width() - one_pixel);
       rotate.Rotate(270);
-      reverse_rotate.Rotate(90);
-      reverse_rotate.Translate(0, -(display.bounds().width() - one_pixel));
       break;
     case gfx::Display::ROTATE_180:
       rotate.Translate(display.bounds().width() - one_pixel,
                        display.bounds().height() - one_pixel);
       rotate.Rotate(180);
-      reverse_rotate.Rotate(180);
-      reverse_rotate.Translate(-(display.bounds().width() - one_pixel),
-                               -(display.bounds().height() - one_pixel));
       break;
   }
   RoundNearZero(&rotate);
-  RoundNearZero(&reverse_rotate);
 
   scoped_ptr<aura::RootWindowTransformer> transformer(
       new AshRootWindowTransformer(root_window,
                                    rotate,
-                                   reverse_rotate,
                                    info.GetOverscanInsetsInPixel(),
                                    info.ui_scale()));
   root_window->SetRootWindowTransformer(transformer.Pass());
 }
 
 void SetDisplayPropertiesOnHostWindow(aura::RootWindow* root,
                                       const gfx::Display& display) {
   internal::DisplayInfo info =
       GetDisplayManager()->GetDisplayInfo(display.id());
 #if defined(OS_CHROMEOS)
@@ skipping 829 matching lines @@
 }
 
 void DisplayController::OnFadeOutForSwapDisplayFinished() {
 #if defined(OS_CHROMEOS)
   SetPrimaryDisplay(ScreenAsh::GetSecondaryDisplay());
   Shell::GetInstance()->output_configurator_animation()->StartFadeInAnimation();
 #endif
 }
 
 }  // namespace ash