From ab75236c5f0dcbedfaa6af51b182a75c0413a93f Mon Sep 17 00:00:00 2001
From: Michael Welsh <mike@ritual.co>
Date: Thu, 17 Aug 2017 17:05:20 -0400
Subject: [PATCH] Revert some of the animationProgress changes to revert to
 reflect absolutes

- Update header documentation to make it clear how animatinoSpeed and animationProgress interact
- Leave fixes in there that stop reversed animations "snapping" back
---
 lottie-ios/Classes/Private/LOTAnimationView.m | 26 +++----------------
 .../Classes/PublicHeaders/LOTAnimationView.h  |  5 +++-
 2 files changed, 7 insertions(+), 24 deletions(-)

diff --git a/lottie-ios/Classes/Private/LOTAnimationView.m b/lottie-ios/Classes/Private/LOTAnimationView.m
index 0fe50627cc..ea1375b3fa 100644
--- a/lottie-ios/Classes/Private/LOTAnimationView.m
+++ b/lottie-ios/Classes/Private/LOTAnimationView.m
@@ -210,27 +210,14 @@ static NSString * const kCompContainerAnimationKey = @"play";
   if (!_sceneModel) {
     return 0;
   }
-  CGFloat absoluteProgress = ((frame.floatValue - _sceneModel.startFrame.floatValue) / (_sceneModel.endFrame.floatValue - _sceneModel.startFrame.floatValue));
-  if ([self _isPlayingForwards]) {
-    return absoluteProgress;
-  } else {
-    // If the animation is playing backwards, the progress is inverted.
-    return 1 - absoluteProgress;
-  }
+  return ((frame.floatValue - _sceneModel.startFrame.floatValue) / (_sceneModel.endFrame.floatValue - _sceneModel.startFrame.floatValue));
 }
 
 - (NSNumber *)_frameForProgress:(CGFloat)progress {
   if (!_sceneModel) {
     return @0;
   }
-  CGFloat absoluteProgress = ((_sceneModel.endFrame.floatValue - _sceneModel.startFrame.floatValue) * progress);
-  if ([self _isPlayingForwards]) {
-    // If we're moving forward, then add the absolute progress to the start.
-    return @(absoluteProgress + _sceneModel.startFrame.floatValue);
-  } else {
-    // It the animation is playing backwards, subtract the progress from the end.
-    return @(_sceneModel.endFrame.floatValue - absoluteProgress);
-  }
+  return @(((_sceneModel.endFrame.floatValue - _sceneModel.startFrame.floatValue) * progress) + _sceneModel.startFrame.floatValue);
 }
 
 - (BOOL)_isPlayingForwards {
@@ -397,18 +384,11 @@ static NSString * const kCompContainerAnimationKey = @"play";
 }
 
 -(void)setAnimationSpeed:(CGFloat)animationSpeed {
-  BOOL directionChange = NO;
-  if ((animationSpeed >= 0 && _animationSpeed < 0) || (animationSpeed < 0 && _animationSpeed >= 0)) {
-    directionChange = YES;
-  }
   _animationSpeed = animationSpeed;
-  NSNumber *frame = [_compContainer.presentationLayer.currentFrame copy];
   if (_isAnimationPlaying && _sceneModel) {
+    NSNumber *frame = [_compContainer.presentationLayer.currentFrame copy];
     [self setProgressWithFrame:frame callCompletionIfNecessary:NO];
     [self playFromFrame:_playRangeStartFrame toFrame:_playRangeEndFrame withCompletion:self.completionBlock];
-  } else if (directionChange) {
-    // The progress needs to be re-calculated if the speed direction changes if the animation is not playing.
-    _animationProgress = [self _progressForFrame:frame];
   }
 }
 
diff --git a/lottie-ios/Classes/PublicHeaders/LOTAnimationView.h b/lottie-ios/Classes/PublicHeaders/LOTAnimationView.h
index 0ae5534e86..5bfb9f3c3f 100644
--- a/lottie-ios/Classes/PublicHeaders/LOTAnimationView.h
+++ b/lottie-ios/Classes/PublicHeaders/LOTAnimationView.h
@@ -46,9 +46,12 @@ typedef void (^LOTAnimationCompletionBlock)(BOOL animationFinished);
 
 // TODO
 /// Sets a progress from 0 - 1 of the animation. If the animation is playing it will stop and the compeltion block will be called.
+/// The animation progress is in terms of absolute progress of the defined animation and does not
+/// take into account negative speeds.
 @property (nonatomic, assign) CGFloat animationProgress;
 
-/// Sets the speed of the animation. Accepts a negative value for reversing animation
+/// Sets the speed of the animation. Accepts a negative value for reversing animation.
+/// Negative speeds do not affect animationProgress
 @property (nonatomic, assign) CGFloat animationSpeed;
 
 /// Read only of the duration in seconds of the animation at speed of 1