Upstream iOS UI utilities.

ios/chrome/browser/ui/reversed_animation.mm

Index: ios/chrome/browser/ui/reversed_animation.mm
diff --git a/ios/chrome/browser/ui/reversed_animation.mm b/ios/chrome/browser/ui/reversed_animation.mm
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+// Copyright 2014 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 "ios/chrome/browser/ui/reversed_animation.h"
+
+#import <QuartzCore/QuartzCore.h>
+#include <algorithm>
+#include <cmath>
+
+#include "base/logging.h"
+#include "base/mac/objc_property_releaser.h"
+
+@protocol ReversedAnimationProtocol;
+typedef CAAnimation<ReversedAnimationProtocol> ReversedAnimation;
+
+namespace {
+// Enum type used to denote the direction of a reversed animation relative to
+// the original animation's direction.
+typedef enum {
+  ANIMATION_DIRECTION_NORMAL,
+  ANIMATION_DIRECTION_REVERSE
+} AnimationDirection;
+// Returns the AnimationDirection opposite of |direction|.
+AnimationDirection AnimationDirectionOpposite(AnimationDirection direction) {
+  return direction == ANIMATION_DIRECTION_NORMAL ? ANIMATION_DIRECTION_REVERSE
+                                                 : ANIMATION_DIRECTION_NORMAL;
+}
+}  // namespace
+
+// Returns an animation that reverses |animation| when added to |layer|, given
+// that |animation| is in |parent|'s timespace, which begins at
+// |parentBeginTime|.
+CAAnimation* CAAnimationMakeReverse(CAAnimation* animation,
+                                    CALayer* layer,
+                                    CAAnimationGroup* parent,
+                                    CFTimeInterval parentBeginTime);
+// Updates |reversedAnimation|'s properties for |animationToReverse|, given that
+// |animationToReverse| is in |parent|'s timespace, which begins at
+// |parentBeginTime|.
+void UpdateReversedAnimation(ReversedAnimation* reversedAnimation,
+                             CAAnimation* animationToReverse,
+                             CALayer* layer,
+                             CAAnimationGroup* parent,
+                             CFTimeInterval parentBeginTime);
+
+#pragma mark - ReversedAnimation protocol
+
+@protocol ReversedAnimationProtocol<NSObject>
+
+// The original animation that's being played in reverse.
+@property(nonatomic, retain) CAAnimation* originalAnimation;
+// The current direction for the animation.
+@property(nonatomic, assign) AnimationDirection animationDirection;
+// The offset into the original animation's duration at the begining of the
+// reverse animation.
+@property(nonatomic, assign) CFTimeInterval animationTimeOffset;
+
+@end
+
+#pragma mark - ReversedBasicAnimation
+
+@interface ReversedBasicAnimation
+    : CABasicAnimation<ReversedAnimationProtocol> {
+  base::mac::ObjCPropertyReleaser _propertyReleaser_ReversedBasicAnimation;
+}
+
+// Returns an animation that performs |animation| in reverse when added to
+// |layer|.  |parentBeginTime| should be set to the beginTime in absolute time
+// of |animation|'s parent in the timing hierarchy.
++ (instancetype)reversedAnimationForAnimation:(CABasicAnimation*)animation
+                                     forLayer:(CALayer*)layer
+                                       parent:(CAAnimationGroup*)parent
+                              parentBeginTime:(CFTimeInterval)parentBeginTime;
+
+@end
+
+@implementation ReversedBasicAnimation
+
+@synthesize originalAnimation = _originalAnimation;
+@synthesize animationDirection = _animationDirection;
+@synthesize animationTimeOffset = _animationTimeOffset;
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    _propertyReleaser_ReversedBasicAnimation.Init(
+        self, [ReversedBasicAnimation class]);
+  }
+  return self;
+}
+
+- (instancetype)copyWithZone:(NSZone*)zone {
+  ReversedBasicAnimation* copy = [super copyWithZone:zone];
+  copy.originalAnimation = self.originalAnimation;
+  copy.animationDirection = self.animationDirection;
+  copy.animationTimeOffset = self.animationTimeOffset;
+  return copy;
+}
+
++ (instancetype)reversedAnimationForAnimation:(CABasicAnimation*)animation
+                                     forLayer:(CALayer*)layer
+                                       parent:(CAAnimationGroup*)parent
+                              parentBeginTime:(CFTimeInterval)parentBeginTime {
+  // Create new animation and copy properties.  Note that we can't use |-copy|
+  // because we need the new animation to be the correct class.
+  NSString* keyPath = animation.keyPath;
+  CFTimeInterval now =
+      [layer convertTime:CACurrentMediaTime() fromLayer:nil] - parentBeginTime;
+  ReversedBasicAnimation* reversedAnimation =
+      [ReversedBasicAnimation animationWithKeyPath:keyPath];
+  UpdateReversedAnimation(reversedAnimation, animation, layer, parent,
+                          parentBeginTime);
+
+  // Update from and to values.
+  BOOL isReversed =
+      reversedAnimation.animationDirection == ANIMATION_DIRECTION_REVERSE;
+  CABasicAnimation* originalBasicAnimation =
+      static_cast<CABasicAnimation*>(reversedAnimation.originalAnimation);
+  reversedAnimation.toValue = isReversed ? originalBasicAnimation.fromValue
+                                         : originalBasicAnimation.toValue;
+  if (now > animation.beginTime &&
+      now < animation.beginTime + animation.duration) {
+    // Use the presentation layer's current value for reversals that occur mid-
+    // animation.
+    reversedAnimation.fromValue =
+        [[layer presentationLayer] valueForKeyPath:keyPath];
+  } else {
+    reversedAnimation.fromValue = isReversed ? originalBasicAnimation.toValue
+                                             : originalBasicAnimation.fromValue;
+  }
+  return reversedAnimation;
+}
+
+@end
+
+#pragma mark - ReversedAnimationGroup
+
+@interface ReversedAnimationGroup
+    : CAAnimationGroup<ReversedAnimationProtocol> {
+  base::mac::ObjCPropertyReleaser _propertyReleaser_ReversedAnimationGroup;
+}
+
+// Returns an animation that performs |animation| in reverse when added to
+// |layer|.  |parentBeginTime| should be set to the beginTime in absolute time
+// of the animation group to which |animation| belongs.
++ (instancetype)reversedAnimationGroupForGroup:(CAAnimationGroup*)group
+                                      forLayer:(CALayer*)layer
+                                        parent:(CAAnimationGroup*)parent
+                               parentBeginTime:(CFTimeInterval)parentBeginTime;
+
+@end
+
+@implementation ReversedAnimationGroup
+
+@synthesize originalAnimation = _originalAnimation;
+@synthesize animationDirection = _animationDirection;
+@synthesize animationTimeOffset = _animationTimeOffset;
+
+- (instancetype)init {
+  self = [super init];
+  if (self) {
+    _propertyReleaser_ReversedAnimationGroup.Init(
+        self, [ReversedAnimationGroup class]);
+  }
+  return self;
+}
+
+- (instancetype)copyWithZone:(NSZone*)zone {
+  ReversedAnimationGroup* copy = [super copyWithZone:zone];
+  copy.originalAnimation = self.originalAnimation;
+  copy.animationDirection = self.animationDirection;
+  copy.animationTimeOffset = self.animationTimeOffset;
+  return copy;
+}
+
++ (instancetype)reversedAnimationGroupForGroup:(CAAnimationGroup*)group
+                                      forLayer:(CALayer*)layer
+                                        parent:(CAAnimationGroup*)parent
+                               parentBeginTime:(CFTimeInterval)parentBeginTime {
+  // Create new animation and copy properties.  Note that we can't use |-copy|
+  // because we need the new animation to be the correct class.
+  ReversedAnimationGroup* reversedGroup = [ReversedAnimationGroup animation];
+  UpdateReversedAnimation(reversedGroup, group, layer, parent, parentBeginTime);
+
+  // Reverse the animations of the original group.
+  NSMutableArray* reversedAnimations = [NSMutableArray array];
+  for (CAAnimation* animation in group.animations) {
+    CAAnimation* reversedAnimation = CAAnimationMakeReverse(
+        animation, layer, group, group.beginTime + parentBeginTime);
+    [reversedAnimations addObject:reversedAnimation];
+  }
+  reversedGroup.animations = reversedAnimations;
+
+  return reversedGroup;
+}
+
+@end
+
+#pragma mark - animation_util functions
+
+CAAnimation* CAAnimationMakeReverse(CAAnimation* animation, CALayer* layer) {
+  return CAAnimationMakeReverse(animation, layer, nil, layer.beginTime);
+}
+
+CAAnimation* CAAnimationMakeReverse(CAAnimation* animation,
+                                    CALayer* layer,
+                                    CAAnimationGroup* parent,
+                                    CFTimeInterval parentBeginTime) {
+  CAAnimation* reversedAnimation = nil;
+  if ([animation isKindOfClass:[CABasicAnimation class]]) {
+    CABasicAnimation* basicAnimation =
+        static_cast<CABasicAnimation*>(animation);
+    reversedAnimation =
+        [ReversedBasicAnimation reversedAnimationForAnimation:basicAnimation
+                                                     forLayer:layer
+                                                       parent:parent
+                                              parentBeginTime:parentBeginTime];
+  } else if ([animation isKindOfClass:[CAAnimationGroup class]]) {
+    CAAnimationGroup* animationGroup =
+        static_cast<CAAnimationGroup*>(animation);
+    reversedAnimation =
+        [ReversedAnimationGroup reversedAnimationGroupForGroup:animationGroup
+                                                      forLayer:layer
+                                                        parent:parent
+                                               parentBeginTime:parentBeginTime];
+  } else {
+    // TODO(kkhorimoto): Investigate possible general-case reversals.  It may
+    // be possible to implement this by manipulating the CAMediaTiming
+    // properties.
+  }
+  return reversedAnimation;
+}
+
+void UpdateReversedAnimation(ReversedAnimation* reversedAnimation,
+                             CAAnimation* animationToReverse,
+                             CALayer* layer,
+                             CAAnimationGroup* parent,
+                             CFTimeInterval parentBeginTime) {
+  // Copy properties.
+  CFTimeInterval now =
+      [layer convertTime:CACurrentMediaTime() fromLayer:nil] - parentBeginTime;
+  reversedAnimation.fillMode = animationToReverse.fillMode;
+  reversedAnimation.removedOnCompletion =
+      animationToReverse.removedOnCompletion;
+  reversedAnimation.timingFunction = animationToReverse.timingFunction;
+
+  // Extract the previous reversal if it exists.
+  ReversedAnimation* previousReversedAnimation = nil;
+  Protocol* reversedAnimationProtocol = @protocol(ReversedAnimationProtocol);
+  if ([animationToReverse conformsToProtocol:reversedAnimationProtocol]) {
+    previousReversedAnimation =
+        static_cast<ReversedAnimation*>(animationToReverse);
+    animationToReverse = previousReversedAnimation.originalAnimation;
+  }
+  reversedAnimation.originalAnimation = animationToReverse;
+  reversedAnimation.animationDirection =
+      previousReversedAnimation
+          ? AnimationDirectionOpposite(
+                previousReversedAnimation.animationDirection)
+          : ANIMATION_DIRECTION_REVERSE;
+
+  CAAnimation* previousAnimation = previousReversedAnimation
+                                       ? previousReversedAnimation
+                                       : animationToReverse;
+  BOOL isReversed =
+      reversedAnimation.animationDirection == ANIMATION_DIRECTION_REVERSE;
+  if (now < previousAnimation.beginTime) {
+    // Reversal occurs before previous animation begins.
+    reversedAnimation.beginTime = 2.0 * now - previousAnimation.beginTime -
+                                  reversedAnimation.originalAnimation.duration;
+    reversedAnimation.duration = reversedAnimation.originalAnimation.duration;
+    reversedAnimation.animationTimeOffset =
+        isReversed ? 0 : reversedAnimation.originalAnimation.duration;
+  } else if (now < previousAnimation.beginTime + previousAnimation.duration) {
+    // Reversal occurs while the previous animation is occurring.
+    reversedAnimation.beginTime = 0;
+    CFTimeInterval timeDelta = now - previousAnimation.beginTime;
+    reversedAnimation.animationTimeOffset =
+        previousReversedAnimation.animationTimeOffset +
+        (isReversed ? 1.0 : -1.0) * timeDelta;
+    reversedAnimation.duration =
+        isReversed ? reversedAnimation.animationTimeOffset
+                   : reversedAnimation.originalAnimation.duration -
+                         reversedAnimation.animationTimeOffset;
+  } else {
+    // Reversal occurs after the previous animation has ended.
+    if (!parentBeginTime) {
+      // If the parent's begin time is zero, the animation is using absolute
+      // time as its beginTime.
+      reversedAnimation.beginTime =
+          2.0 * now - previousAnimation.beginTime - previousAnimation.duration;
+    } else {
+      CFTimeInterval previousEndTime =
+          previousAnimation.beginTime + previousAnimation.duration;
+      if (now > parent.duration) {
+        // The animation's parent has already ended, so use the difference
+        // between the parent's ending and the previous animation's end.
+        reversedAnimation.beginTime = parent.duration - previousEndTime;
+      } else {
+        // The parent hasn't ended, so use the difference between the current
+        // time and the previous animation's end.
+        reversedAnimation.beginTime = now - previousEndTime;
+      }
+    }
+    reversedAnimation.duration = reversedAnimation.originalAnimation.duration;
+    reversedAnimation.animationTimeOffset =
+        isReversed ? reversedAnimation.originalAnimation.duration : 0;
+  }
+}
+
+void ReverseAnimationsForKeyForLayers(NSString* key, NSArray* layers) {
+  for (CALayer* layer in layers) {
+    CAAnimation* reversedAnimation =
+        CAAnimationMakeReverse([layer animationForKey:key], layer);
+    [layer removeAnimationForKey:key];
+    [layer addAnimation:reversedAnimation forKey:key];
+  }
+}