Use GetInverse

 Rotation matrixes are normalized (and will soon changed to handle 90 rotations in special form),
so no need to have separate inverse matrix.

BUG=222483
TEST=no functionality change.

Review URL: https://codereview.chromium.org/14361002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@195238 0039d316-1c4b-4281-b951-d872f2087c98

ash/OWNERS

@@ -5,6 +5,8 @@ sky@chromium.org
 
 per-file ash_strings.grd=*
 per-file ash_chromeos_strings.grdp=*
+
+per-file ash_root_window_transformer.*=oshima@chromium.org
+per-file extended_desktop_unittest.*=oshima@chromium.org
 per-file root_window_controller*=oshima@chromium.org
 per-file screen_ash*=oshima@chromium.org
-per-file extended_desktop_unittest.*=oshima@chromium.org

ash/ash_root_window_transformer.cc

@@ -13,7 +13,6 @@ namespace ash {
 AshRootWindowTransformer::AshRootWindowTransformer(
     aura::RootWindow* root,
     const gfx::Transform& transform,
-    const gfx::Transform& inverted,
     const gfx::Insets& host_insets,
     float root_window_scale)
     : root_window_(root),
@@ -23,20 +22,18 @@ AshRootWindowTransformer::AshRootWindowTransformer(
   root_window_->layer()->SetForceRenderSurface(root_window_scale_ != 1.0f);
 
   gfx::Transform translate;
-  invert_transform_ = inverted;
-  invert_transform_.Scale(root_window_scale_, root_window_scale_);
 
   if (host_insets.top() != 0 || host_insets.left() != 0) {
     float device_scale_factor = ui::GetDeviceScaleFactor(root_window_->layer());
     float x_offset = host_insets.left() / device_scale_factor;
     float y_offset = host_insets.top() / device_scale_factor;
     translate.Translate(x_offset, y_offset);
-    invert_transform_.Translate(-x_offset, -y_offset);
   }
   float inverted_scale = 1.0f / root_window_scale_;
   translate.Scale(inverted_scale, inverted_scale);
-
   transform_ = translate * transform;
+
+  CHECK(transform_.GetInverse(&invert_transform_));
 }
 
 gfx::Transform AshRootWindowTransformer::GetTransform() const {

ash/ash_root_window_transformer.h

@@ -22,7 +22,6 @@ class ASH_EXPORT AshRootWindowTransformer : public aura::RootWindowTransformer {
  public:
   AshRootWindowTransformer(aura::RootWindow* root,
                            const gfx::Transform& transform,
-                           const gfx::Transform& inverted,
                            const gfx::Insets& insets,
                            float root_window_scale);
   // aura::RootWindowTransformer overrides:

ash/display/display_controller.cc

@@ -151,12 +151,6 @@ void RotateRootWindow(aura::RootWindow* root_window,
   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();
@@ -166,31 +160,22 @@ void RotateRootWindow(aura::RootWindow* root_window,
     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());