gfx::Transform API clean-up

ash/wm/session_state_animator.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/wm/session_state_animator.h"
 
 #include "ash/shell.h"
 #include "ash/shell_window_ids.h"
 #include "ash/wm/window_animations.h"
 #include "ash/wm/workspace/workspace_animations.h"
 #include "ui/aura/client/aura_constants.h"
 #include "ui/aura/root_window.h"
 #include "ui/compositor/layer_animation_observer.h"
 #include "ui/compositor/layer_animation_sequence.h"
 #include "ui/views/widget/widget.h"
 
 namespace ash {
 namespace internal {
 
 namespace {
 
 // Slightly-smaller size that we scale the screen down to for the pre-lock and
 // pre-shutdown states.
 const float kSlowCloseSizeRatio = 0.95f;
 
 // Maximum opacity of white layer when animating pre-shutdown state.
 const float kPartialFadeRatio = 0.3f;
 
+// Minimum size. Not zero as it causes numeric issues.
+const float kMinimumScale = 1e-4f;
+
 // Returns the transform that should be applied to containers for the slow-close
 // animation.
 gfx::Transform GetSlowCloseTransform() {
   gfx::Size root_size = Shell::GetPrimaryRootWindow()->bounds().size();
   gfx::Transform transform;
-  transform.SetScale(kSlowCloseSizeRatio, kSlowCloseSizeRatio);
-  transform.ConcatTranslate(
+  transform.Translate(
       floor(0.5 * (1.0 - kSlowCloseSizeRatio) * root_size.width() + 0.5),
       floor(0.5 * (1.0 - kSlowCloseSizeRatio) * root_size.height() + 0.5));
-  return transform;
+  transform.Scale(kSlowCloseSizeRatio, kSlowCloseSizeRatio);
+ return transform;
 }
 
 // Returns the transform that should be applied to containers for the fast-close
 // animation.
 gfx::Transform GetFastCloseTransform() {
   gfx::Size root_size = Shell::GetPrimaryRootWindow()->bounds().size();
   gfx::Transform transform;
-  transform.SetScale(0.0, 0.0);
-  transform.ConcatTranslate(floor(0.5 * root_size.width() + 0.5),
-                            floor(0.5 * root_size.height() + 0.5));
+  transform.Translate(floor(0.5 * root_size.width() + 0.5),
+                      floor(0.5 * root_size.height() + 0.5));
+  transform.Scale(kMinimumScale, kMinimumScale);
   return transform;
 }
 
 // Slowly shrinks |window| to a slightly-smaller size.
 void StartSlowCloseAnimationForWindow(aura::Window* window,
                                       base::TimeDelta duration,
                                       ui::LayerAnimationObserver* observer) {
   ui::LayerAnimator* animator = window->layer()->GetAnimator();
   animator->set_preemption_strategy(
       ui::LayerAnimator::IMMEDIATELY_ANIMATE_TO_NEW_TARGET);
@@ skipping 439 matching lines @@
   foreground_->SetColor(SK_ColorWHITE);
   foreground_->GetWidget()->Show();
 }
 
 void SessionStateAnimator::DropForeground() {
   foreground_.reset();
 }
 
 }  // namespace internal
 }  // namespace ash