Animated Rotation

chrome/browser/ui/touch/animation/screen_rotation_setter.cc

+// Copyright (c) 2011 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 "chrome/browser/ui/touch/animation/screen_rotation_setter.h"
+
+#include "base/memory/scoped_ptr.h"
+#include "chrome/browser/ui/touch/animation/screen_rotation.h"
+#include "ui/gfx/compositor/layer.h"
+#include "ui/gfx/interpolated_transform.h"
+#include "views/layer_property_setter.h"
+#include "views/view.h"
+
+namespace {
+
+static int SymmetricRound(float x) {
+  return static_cast<int>(
+    x > 0
+      ? std::floor(x + 0.5f)
+      : std::ceil(x - 0.5f));
+}
+
+// A screen rotation setter is a LayerPropertySetter that initiates screen
+// rotations in response to calls to |SetTransform|. Calls to |SetBounds| are
+// applied to the layer immediately.
+class ScreenRotationSetter : public views::LayerPropertySetter,
+                             public ScreenRotationListener {
+ public:
+  explicit ScreenRotationSetter(views::View* view);
+
+  // implementation of LayerPropertySetter
+  virtual void Installed(ui::Layer* layer) OVERRIDE;
+  virtual void Uninstalled(ui::Layer* layer) OVERRIDE;
+  virtual void SetTransform(ui::Layer* layer,
+                            const ui::Transform& transform) OVERRIDE;
+  virtual void SetBounds(ui::Layer* layer, const gfx::Rect& bounds) OVERRIDE;
+
+  // implementation of ScreenRotationListener
+  virtual void OnScreenRotationCompleted(const ui::Transform& final_transform,
+                                         const gfx::Rect& final_rect) OVERRIDE;
+
+ private:
+  // This is the currently animating rotation. We hang onto it so that if a
+  // call to |SetTransform| is made during the rotation, we can update the
+  // target orientation of this rotation.
+  scoped_ptr<ScreenRotation> rotation_;
+
+  // If a call to set bounds happens during a rotation its effect is delayed
+  // until the rotation completes. If this happens several times, only the last
+  // call to SetBounds will have any effect.
+  scoped_ptr<gfx::Rect> pending_bounds_;
+
+  // The screen rotation setter is associated with a view so that the view's
+  // bounds may be set when the animation completes.
+  views::View* view_;
+
+  DISALLOW_COPY_AND_ASSIGN(ScreenRotationSetter);
+};
+
+
+ScreenRotationSetter::ScreenRotationSetter(views::View* view) : view_(view) {
+}
+
+void ScreenRotationSetter::Installed(ui::Layer* layer) OVERRIDE {
+}
+
+void ScreenRotationSetter::Uninstalled(ui::Layer* layer) OVERRIDE {
+  if (rotation_.get())
+    rotation_->Stop();
+}
+
+void ScreenRotationSetter::SetTransform(ui::Layer* layer,
+                                        const ui::Transform& transform) {
+  float degrees;
+  if (!ui::InterpolatedTransform::FactorTRS(transform, NULL, &degrees, NULL))
+    return;
+
+  if (rotation_.get()) {
+    rotation_->SetTarget(SymmetricRound(degrees));
+  } else {
+    float old_degrees;
+    if (ui::InterpolatedTransform::FactorTRS(layer->transform(),
+                                             NULL,
+                                             &old_degrees,
+                                             NULL)) {
+      rotation_.reset(new ScreenRotation(view_,
+                                         this,
+                                         SymmetricRound(old_degrees),
+                                         SymmetricRound(degrees)));
+    }
+  }
+}
+
+void ScreenRotationSetter::SetBounds(ui::Layer* layer,
+                                     const gfx::Rect& bounds) {
+  // cache bounds changes during an animation.
+  if (rotation_.get())
+    pending_bounds_.reset(new gfx::Rect(bounds));
+  else
+    layer->SetBounds(bounds);
+}
+
+void ScreenRotationSetter::OnScreenRotationCompleted(
+    const ui::Transform& final_transform,
+    const gfx::Rect& final_bounds) {
+  // destroy the animation.
+  rotation_.reset();
+  if (pending_bounds_.get() && view_->layer()) {
+    // If there are any pending bounds changes, they will have already been
+    // applied to the view, and are waiting to be applied to the layer.
+    view_->layer()->SetBounds(*pending_bounds_);
+    pending_bounds_.reset();
+  } else {
+    // Otherwise we may have new bounds as the result of the completed screen
+    // rotation. Apply these to the view.
+    view_->SetBoundsRect(final_bounds);
+  }
+}
+
+}  // namespace
+
+views::LayerPropertySetter* ScreenRotationSetterFactory::Create(
+    views::View* view) {
+  return new ScreenRotationSetter(view);
+}