Interpolated transforms

ui/gfx/interpolated_transform.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 "ui/gfx/interpolated_transform.h"
+
+#include "base/logging.h"
+#include "ui/base/animation/tween.h"
+
+namespace ui {
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedTransform
+//
+
+InterpolatedTransform::InterpolatedTransform()
+    : start_time_(0.0f),
+      end_time_(1.0f) {
+}
+
+InterpolatedTransform::InterpolatedTransform(float start_time,
+                                             float end_time)
+    : start_time_(start_time),
+      end_time_(end_time) {
+}
+
+InterpolatedTransform::~InterpolatedTransform() {}
+
+ui::Transform InterpolatedTransform::Interpolate(float t) const {
+  ui::Transform result = InterpolateButDoNotCompose(t);
+  if (child_.get()) {
+    result.ConcatTransform(child_->Interpolate(t));
+  }
+  return result;
+}
+
+void InterpolatedTransform::SetChild(InterpolatedTransform* child) {
+  child_.reset(child);
+}
+
+inline float InterpolatedTransform::ValueBetween(float time,
+                                                 float start_value,
+                                                 float end_value) const {
+  // can't handle NaN
+  DCHECK(time == time && start_time_ == start_time_ && end_time_ == end_time_);
+  if (time != time || start_time_ != start_time_ || end_time_ != end_time_)
+    return start_value;
+
+  // Ok if equal -- we'll get a step function. Note: if end_time_ ==
+  // start_time_ == x, then if none of the numbers are NaN, then it
+  // must be true that time < x or time >= x, so we will return early
+  // due to one of the following if statements.
+  DCHECK(end_time_ >= start_time_);
+
+  if (time < start_time_)
+    return start_value;
+
+  if (time >= end_time_)
+    return end_value;
+
+  float t = (time - start_time_) / (end_time_ - start_time_);
+  return static_cast<float>(Tween::ValueBetween(t, start_value, end_value));
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedRotation
+//
+
+InterpolatedRotation::InterpolatedRotation(float start_degrees,
+                                           float end_degrees)
+    : InterpolatedTransform(),
+      start_degrees_(start_degrees),
+      end_degrees_(end_degrees) {
+}
+
+InterpolatedRotation::InterpolatedRotation(float start_degrees,
+                                           float end_degrees,
+                                           float start_time,
+                                           float end_time)
+    : InterpolatedTransform(start_time, end_time),
+      start_degrees_(start_degrees),
+      end_degrees_(end_degrees) {
+}
+
+InterpolatedRotation::~InterpolatedRotation() {}
+
+ui::Transform InterpolatedRotation::InterpolateButDoNotCompose(float t) const {
+  ui::Transform result;
+  result.SetRotate(ValueBetween(t, start_degrees_, end_degrees_));
+  return result;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedScale
+//
+
+InterpolatedScale::InterpolatedScale(float start_scale,
+                                     float end_scale)
+    : InterpolatedTransform(),
+      start_scale_(start_scale),
+      end_scale_(end_scale) {
+}
+
+InterpolatedScale::InterpolatedScale(float start_scale,
+                                     float end_scale,
+                                     float start_time,
+                                     float end_time)
+    : InterpolatedTransform(start_time, end_time),
+      start_scale_(start_scale),
+      end_scale_(end_scale) {
+}
+
+InterpolatedScale::~InterpolatedScale() {}
+
+ui::Transform InterpolatedScale::InterpolateButDoNotCompose(float t) const {
+  ui::Transform result;
+  float interpolated_scale = ValueBetween(t, start_scale_, end_scale_);
+  //TODO(vollick) 3d xforms.
+  result.SetScale(interpolated_scale, interpolated_scale);
+  return result;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedTranslation
+//
+
+InterpolatedTranslation::InterpolatedTranslation(const gfx::Point& start_pos,
+                                                 const gfx::Point& end_pos)
+    : InterpolatedTransform(),
+      start_pos_(start_pos),
+      end_pos_(end_pos) {
+}
+
+InterpolatedTranslation::InterpolatedTranslation(const gfx::Point& start_pos,
+                                                 const gfx::Point& end_pos,
+                                                 float start_time,
+                                                 float end_time)
+    : InterpolatedTransform(start_time, end_time),
+      start_pos_(start_pos),
+      end_pos_(end_pos) {
+}
+
+InterpolatedTranslation::~InterpolatedTranslation() {}
+
+ui::Transform
+InterpolatedTranslation::InterpolateButDoNotCompose(float t) const {
+  ui::Transform result;
+  //TODO(vollick) 3d xforms.

[sky, 2011/06/28 18:43:46]

nit: '//TODO' -> '// TODO'

+  result.SetTranslate(ValueBetween(t, start_pos_.x(), end_pos_.x()),
+                      ValueBetween(t, start_pos_.y(), end_pos_.y()));
+
+  return result;
+}
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedConstantTransform
+//
+
+InterpolatedConstantTransform::InterpolatedConstantTransform(
+  const ui::Transform& transform)
+    : InterpolatedTransform(),
+  transform_(transform) {
+}
+
+ui::Transform
+InterpolatedConstantTransform::InterpolateButDoNotCompose(float t) const {
+  return transform_;
+}
+
+InterpolatedConstantTransform::~InterpolatedConstantTransform() {}
+
+///////////////////////////////////////////////////////////////////////////////
+// InterpolatedTransformAboutPivot
+//
+
+InterpolatedTransformAboutPivot::InterpolatedTransformAboutPivot(
+  const gfx::Point& pivot,
+  InterpolatedTransform* transform)
+    : InterpolatedTransform() {
+  Init(pivot, transform);
+}
+
+InterpolatedTransformAboutPivot::InterpolatedTransformAboutPivot(
+  const gfx::Point& pivot,
+  InterpolatedTransform* transform,
+  float start_time,
+  float end_time)
+    : InterpolatedTransform() {
+  Init(pivot, transform);
+}
+
+InterpolatedTransformAboutPivot::~InterpolatedTransformAboutPivot() {}
+
+ui::Transform
+InterpolatedTransformAboutPivot::InterpolateButDoNotCompose(float t) const {
+  if (transform_.get()) {
+    return transform_->Interpolate(t);
+  }
+  return ui::Transform();
+}
+
+void InterpolatedTransformAboutPivot::Init(const gfx::Point& pivot,
+                                           InterpolatedTransform* xform) {
+  ui::Transform to_pivot;
+  ui::Transform from_pivot;
+  to_pivot.SetTranslate(-pivot.x(), -pivot.y());
+  from_pivot.SetTranslate(pivot.x(), pivot.y());
+
+  scoped_ptr<InterpolatedTransform> pre_transform(
+    new InterpolatedConstantTransform(to_pivot));
+  scoped_ptr<InterpolatedTransform> post_transform(
+    new InterpolatedConstantTransform(from_pivot));
+
+  pre_transform->SetChild(xform);
+  xform->SetChild(post_transform.release());
+  transform_.reset(pre_transform.release());
+}
+
+} // namespace ui