Swiftgram/lottie-ios/Classes/AnimatableProperties/LOTAnimatableColorValue.m

//
//  LOTAnimatableColorValue.m
//  LottieAnimator
//
//  Created by brandon_withrow on 6/23/16.
//  Copyright © 2016 Brandon Withrow. All rights reserved.
//

#import "LOTAnimatableColorValue.h"

@interface LOTAnimatableColorValue ()

@property (nonatomic, readonly) NSArray *colorKeyframes;
@property (nonatomic, readonly) NSArray<NSNumber *> *keyTimes;
@property (nonatomic, readonly) NSArray<CAMediaTimingFunction *> *timingFunctions;
@property (nonatomic, readonly) NSTimeInterval delay;
@property (nonatomic, readonly) NSTimeInterval duration;

@property (nonatomic, readonly) NSNumber *startFrame;
@property (nonatomic, readonly) NSNumber *durationFrames;
@property (nonatomic, readonly) NSNumber *frameRate;

@end

@implementation LOTAnimatableColorValue

- (instancetype)initWithColorValues:(NSDictionary *)colorValues frameRate:(NSNumber *)frameRate {
  self = [super init];
  if (self) {
    _frameRate = frameRate;
    NSArray *value = colorValues[@"k"];
    if ([value isKindOfClass:[NSArray class]] &&
        [[(NSArray *)value firstObject] isKindOfClass:[NSDictionary class]] &&
        [(NSArray *)value firstObject][@"t"]) {
      //Keyframes
      [self _buildAnimationForKeyframes:value];
    } else {
      //Single Value, no animation
      _initialColor = [[self _colorValueFromArray:value] copy];
    }
    if (colorValues[@"x"]) {
        NSLog(@"%s: Warning: expressions are not supported", __PRETTY_FUNCTION__);
    }
  }
  return self;
}

- (void)_buildAnimationForKeyframes:(NSArray<NSDictionary *> *)keyframes {
  NSMutableArray *keyTimes = [NSMutableArray array];
  NSMutableArray *timingFunctions = [NSMutableArray array];
  NSMutableArray *colorValues = [NSMutableArray array];
  
  _startFrame = keyframes.firstObject[@"t"];
  NSNumber *endFrame = keyframes.lastObject[@"t"];
  
  NSAssert((_startFrame && endFrame && _startFrame.integerValue < endFrame.integerValue),
           @"Lottie: Keyframe animation has incorrect time values or invalid number of keyframes");

  // Calculate time duration
  _durationFrames = @(endFrame.floatValue - _startFrame.floatValue);
  
  _duration = _durationFrames.floatValue / _frameRate.floatValue;
  _delay = _startFrame.floatValue / _frameRate.floatValue;
  
  BOOL addStartValue = YES;
  BOOL addTimePadding = NO;
  UIColor *outColor = nil;
  
  for (NSDictionary *keyframe in keyframes) {
    // Get keyframe time value
    NSNumber *frame = keyframe[@"t"];
    // Calculate percentage value for keyframe.
    //CA Animations accept time values of 0-1 as a percentage of animation completed.
    NSNumber *timePercentage = @((frame.floatValue - _startFrame.floatValue) / _durationFrames.floatValue);
    
    if (outColor) {
      //add out value
      [colorValues addObject:(id)[[outColor copy] CGColor]];
      [timingFunctions addObject:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
      outColor = nil;
    }
    
    UIColor *startColor = [self _colorValueFromArray:keyframe[@"s"]];
    if (addStartValue) {
      // Add start value
      if (startColor) {
        if (keyframe == keyframes.firstObject) {
          _initialColor = startColor;
        }
        [colorValues addObject:(id)[[startColor copy] CGColor]];
        if (timingFunctions.count) {
          [timingFunctions addObject:[CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear]];
        }
      }
      addStartValue = NO;
    }
    
    if (addTimePadding) {
      // add time padding
      NSNumber *holdPercentage = @(timePercentage.floatValue - 0.00001);
      [keyTimes addObject:[holdPercentage copy]];
      addTimePadding = NO;
    }
    
    // add end value if present for keyframe
    UIColor *endColor = [self _colorValueFromArray:keyframe[@"e"]];
    if (endColor) {
      [colorValues addObject:(id)[[endColor copy] CGColor]];
      /*
       * Timing Function for time interpolations between keyframes
       * Should be n-1 where n is the number of keyframes
       */
      CAMediaTimingFunction *timingFunction;
      NSDictionary *timingControlPoint1 = keyframe[@"o"];
      NSDictionary *timingControlPoint2 = keyframe[@"i"];
      
      if (timingControlPoint1 && timingControlPoint2) {
        // Easing function
        CGPoint cp1 = [self _pointFromValueDict:timingControlPoint1];
        CGPoint cp2 = [self _pointFromValueDict:timingControlPoint2];
        timingFunction = [CAMediaTimingFunction functionWithControlPoints:cp1.x :cp1.y :cp2.x :cp2.y];
      } else {
        // No easing function specified, fallback to linear
        timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionLinear];
      }
      [timingFunctions addObject:timingFunction];
    }
    
    // add time
    [keyTimes addObject:timePercentage];
    
    // Check if keyframe is a hold keyframe
    if ([keyframe[@"h"] boolValue]) {
      // set out value as start and flag next frame accordinly
      outColor = startColor;
      addStartValue = YES;
      addTimePadding = YES;
    }
  }

  _colorKeyframes = colorValues;
  _keyTimes = keyTimes;
  _timingFunctions = timingFunctions;
}

- (UIColor *)_colorValueFromArray:(NSArray<NSNumber *>  *)colorArray {
  if (colorArray.count == 4) {
    BOOL shouldUse255 = NO;
    for (NSNumber *number in colorArray) {
      if (number.floatValue > 1) {
        shouldUse255 = YES;
      }
    }
    
    
    
    return [UIColor colorWithRed:colorArray[0].floatValue / (shouldUse255 ? 255.f : 1.f)
                           green:colorArray[1].floatValue / (shouldUse255 ? 255.f : 1.f)
                            blue:colorArray[2].floatValue / (shouldUse255 ? 255.f : 1.f)
                           alpha:colorArray[3].floatValue / (shouldUse255 ? 255.f : 1.f)];
  }
  return nil;
}

- (CGPoint)_pointFromValueDict:(NSDictionary *)values {
  NSNumber *xValue = @0, *yValue = @0;
  if ([values[@"x"] isKindOfClass:[NSNumber class]]) {
    xValue = values[@"x"];
  } else if ([values[@"x"] isKindOfClass:[NSArray class]]) {
    xValue = values[@"x"][0];
  }
  
  if ([values[@"y"] isKindOfClass:[NSNumber class]]) {
    yValue = values[@"y"];
  } else if ([values[@"y"] isKindOfClass:[NSArray class]]) {
    yValue = values[@"y"][0];
  }
  
  return CGPointMake([xValue floatValue], [yValue floatValue]);
}

- (BOOL)hasAnimation {
  return (self.colorKeyframes.count > 0);
}

- (nullable CAKeyframeAnimation *)animationForKeyPath:(nonnull NSString *)keypath {
  if (self.hasAnimation == NO) {
    return nil;
  }
  CAKeyframeAnimation *keyframeAnimation = [CAKeyframeAnimation animationWithKeyPath:keypath];
  keyframeAnimation.keyTimes = self.keyTimes;
  keyframeAnimation.values = self.colorKeyframes;
  keyframeAnimation.timingFunctions = self.timingFunctions;
  keyframeAnimation.duration = self.duration;
  keyframeAnimation.beginTime = self.delay;
  keyframeAnimation.fillMode = kCAFillModeForwards;
  return keyframeAnimation;
}

- (NSString *)description {
  return self.initialColor.description;
}

@end