Pods/lottie-ios/lottie-ios/Classes/Extensions/LOTRadialGradientLayer.m
//
//  LOTAnimationView
//  LottieAnimator
//
//  Created by Brandon Withrow on 12/14/15.
//  Copyright © 2015 Brandon Withrow. All rights reserved.
//

#import "LOTRadialGradientLayer.h"
#import "CGGeometry+LOTAdditions.h"

@implementation LOTRadialGradientLayer

@dynamic isRadial;
@dynamic startPoint;
@dynamic endPoint;
@dynamic colors;
@dynamic locations;

+ (BOOL)needsDisplayForKey:(NSString *)key {
  if ([key isEqualToString:@"startPoint"] ||
      [key isEqualToString:@"endPoint"] ||
      [key isEqualToString:@"colors"] ||
      [key isEqualToString:@"locations"] ||
      [key isEqualToString:@"isRadial"]) {
    return YES;
  }
  return [super needsDisplayForKey:key];
}

- (id)actionForKey:(NSString *)key {
  id action = self.actions[key];
  if (action) {
    if (action == [NSNull null]) {
      return nil;
    }
    return action;
  }
  
  if ([key isEqualToString:@"startPoint"] ||
      [key isEqualToString:@"endPoint"] ||
      [key isEqualToString:@"colors"] ||
      [key isEqualToString:@"locations"] ||
      [key isEqualToString:@"isRadial"]) {
    CABasicAnimation *theAnimation = [CABasicAnimation animationWithKeyPath:key];
    theAnimation.fromValue = [self.presentationLayer valueForKey:key];
    return theAnimation;
  }
  return [super actionForKey:key];
}

- (void)drawInContext:(CGContextRef)ctx {
  if (self.colors.count == 0) {
    return;
  }
    
  NSInteger numberOfLocations = self.locations.count;
  CGColorRef colorRef = (__bridge CGColorRef)[self.colors objectAtIndex:0];
  NSInteger numberOfComponents = CGColorGetNumberOfComponents(colorRef);
  CGColorSpaceRef colorSpace = CGColorGetColorSpace(colorRef);
  
  CGPoint origin = self.startPoint;
  CGFloat radius = LOT_PointDistanceFromPoint(self.startPoint, self.endPoint);
  
  CGFloat gradientLocations[numberOfLocations];
  CGFloat gradientComponents[numberOfLocations * numberOfComponents];
  
  for (NSInteger locationIndex = 0; locationIndex < numberOfLocations; locationIndex++) {
    
    gradientLocations[locationIndex] = [self.locations[locationIndex] floatValue];
    const CGFloat *colorComponents = CGColorGetComponents((__bridge CGColorRef)self.colors[locationIndex]);
    
    for (NSInteger componentIndex = 0; componentIndex < numberOfComponents; componentIndex++) {
      gradientComponents[numberOfComponents * locationIndex + componentIndex] = colorComponents[componentIndex];
    }
  }
  
  CGGradientRef gradient = CGGradientCreateWithColorComponents(colorSpace, gradientComponents, gradientLocations, numberOfLocations);
  
  if (self.isRadial) {
    CGContextDrawRadialGradient(ctx, gradient, origin, 0, origin, radius, kCGGradientDrawsAfterEndLocation);
  } else {
    CGContextDrawLinearGradient(ctx, gradient, self.startPoint, self.endPoint, kCGGradientDrawsBeforeStartLocation | kCGGradientDrawsAfterEndLocation);
  }
  
  CGGradientRelease(gradient);
}

@end
