Animated Rotation

views/animation/screen_rotation.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 "views/animation/screen_rotation.h"
+
+#include "base/debug/trace_event.h"
+#include "ui/base/animation/slide_animation.h"
+#include "ui/gfx/interpolated_transform.h"
+#include "ui/gfx/rect.h"
+#include "ui/gfx/transform.h"
+#include "views/view.h"
+
+namespace views {
+
+////////////////////////////////////////////////////////////////////////////////
+// ScreenRotation public:
+//
+
+void ScreenRotation::Perform(View* root,
+                             float old_degrees,
+                             float new_degrees) {
+  if (old_degrees != new_degrees)
+    new ScreenRotation(root, old_degrees, new_degrees);
+}
+
+////////////////////////////////////////////////////////////////////////////////
+// ScreenRotation private:
+//
+
+ScreenRotation::ScreenRotation(View* root,
+                               float old_degrees,
+                               float new_degrees)
+    : root_(root),

[sky, 2011/07/27 22:16:19]

This will crash if the view is deleted before the animation completes.

+      old_degrees_(old_degrees),
+      new_degrees_(new_degrees) {
+  animation_.reset(new ui::SlideAnimation(this));
+  animation_->SetTweenType(ui::Tween::LINEAR);
+  animation_->SetSlideDuration(1000);
+  Start();
+}
+
+void ScreenRotation::AnimationProgressed(const ui::Animation* anim) {
+  if (!interpolated_transform_.get())
+    return;
+
+  float t = static_cast<float>(anim->GetCurrentValue());
+  if (root_->painting_enabled())
+    root_->set_painting_enabled(false);
+  root_->SetTransform(interpolated_transform_->Interpolate(t));

[sky, 2011/07/27 22:16:19]

Animations should be handled at the layer/texture level and independent of
views. That way they can easily be handled by another thread/process. This is
the point of the LayerPropertySetter class.

+  root_->ScheduleComposite();
+}
+
+void ScreenRotation::AnimationEnded(const ui::Animation* anim) {
+  TRACE_EVENT_END0("ScreenRotation", "Start rotating");
+  // TODO(vollick) massage matrix so that entries sufficiently close
+  // to 0, 1, or -1 are clamped to these values. The idea is to fight
+  // accumulated numeric error due to successive rotations.
+  ui::Transform xform = root_->GetTransform();
+  gfx::Point origin;
+  xform.TransformPoint(origin);
+  ui::Transform translation;
+  translation.SetTranslate(new_origin_.x() - origin.x(),
+                           new_origin_.y() - origin.y());
+  xform.ConcatTransform(translation);
+  root_->SetTransform(xform);
+  root_->SetBounds(0, 0, new_size_.width(), new_size_.height());
+  root_->set_painting_enabled(true);
+  root_->SchedulePaint();
+  delete this;
+}
+
+int ScreenRotation::NormalizeAngle(int degrees) {
+  while (degrees <= -180) degrees += 360;
+  while (degrees > 180) degrees -= 360;
+  return degrees;
+}
+
+void ScreenRotation::Start() {
+  TRACE_EVENT_BEGIN0("ScreenRotation", "Start rotating");
+  if (!root_->layer()) {
+    root_->SetPaintToLayer(true);
+    root_->SchedulePaint();
+  }
+
+  int degrees = new_degrees_ - old_degrees_;
+  degrees = NormalizeAngle(degrees);
+
+  // No rotation required.
+  if (degrees == 0)
+    return;
+
+  gfx::Point old_pivot;
+  gfx::Point new_pivot;
+
+  switch (degrees) {
+    case 90:
+      new_origin_ = old_pivot = gfx::Point(root_->width(), 0);
+      new_pivot.SetPoint(root_->width(), root_->height());
+      new_size_.SetSize(root_->height(), root_->width());
+      break;
+    case -90:
+      new_origin_ = new_pivot = gfx::Point(0, root_->height());
+      new_size_.SetSize(root_->height(), root_->width());
+      break;
+    case 180:
+      new_pivot = old_pivot = gfx::Point(root_->width() / 2,
+                                         root_->height() / 2);
+      new_origin_.SetPoint(root_->width(), root_->height());
+      new_size_.SetSize(root_->width(), root_->height());
+      break;
+  }
+
+  // Convert points to world space.
+  const ui::Transform& xform = root_->GetTransform();
+  xform.TransformPoint(old_pivot);
+  xform.TransformPoint(new_pivot);
+  xform.TransformPoint(new_origin_);
+
+  scoped_ptr<ui::InterpolatedTransform> rotation(
+      new ui::InterpolatedTransformAboutPivot(
+          old_pivot,
+          new ui::InterpolatedRotation(0, degrees)));
+
+  scoped_ptr<ui::InterpolatedTransform> translation(
+      new ui::InterpolatedTranslation(
+          gfx::Point(0, 0),
+          gfx::Point(new_pivot.x() - old_pivot.x(),
+                     new_pivot.y() - old_pivot.y())));
+
+  interpolated_transform_.reset(
+      new ui::InterpolatedConstantTransform(xform));
+
+  rotation->SetChild(translation.release());
+  interpolated_transform_->SetChild(rotation.release());
+
+  animation_->Show();
+}
+
+} // namespace views