components/PageControl/src/private/MDCPageControlIndicator.m

/*
 Copyright 2015-present the Material Components for iOS authors. All Rights Reserved.

 Licensed under the Apache License, Version 2.0 (the "License");
 you may not use this file except in compliance with the License.
 You may obtain a copy of the License at

 http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */

#import "MDCPageControlIndicator.h"

static const NSTimeInterval kPageControlIndicatorAnimationDuration = 0.3;
static NSString *const kPageControlIndicatorAnimationKey = @"fadeInScaleUp";

@implementation MDCPageControlIndicator {
  BOOL _isAnimating;
}

- (instancetype)initWithCenter:(CGPoint)center radius:(CGFloat)radius {
  self = [super init];
  if (self) {
    self.frame = CGRectMake(center.x - radius, center.y - radius, radius * 2, radius * 2);
    self.path = [self circlePathWithRadius:radius];
    self.zPosition = 1;
  }
  return self;
}

- (void)setColor:(UIColor *)color {
  // Override here to disable implicit layer animation.
  _color = color;
  [CATransaction begin];
  [CATransaction setDisableActions:YES];
  CGColorRef cgColor = _color.CGColor;
  self.fillColor = cgColor;
  [super setOpacity:(float)CGColorGetAlpha(cgColor)];
  [CATransaction commit];
}

- (void)setOpacity:(float)opacity {
  // Override here to disable implicit layer animation.
  [CATransaction begin];
  [CATransaction setDisableActions:YES];
  [super setOpacity:opacity];
  [CATransaction commit];
}

- (void)revealIndicator {
  // Scale indicator from zero to full size while fading in.
  CABasicAnimation *scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
  scaleAnimation.fromValue = [NSValue valueWithCATransform3D:CATransform3DMakeScale(0.0, 0.0, 0.0)];
  scaleAnimation.toValue = [NSValue valueWithCATransform3D:CATransform3DIdentity];

  CABasicAnimation *fadeAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
  fadeAnimation.fromValue = @(0);
  fadeAnimation.toValue = @(self.opacity);

  CAAnimationGroup *group = [CAAnimationGroup animation];
  group.duration = kPageControlIndicatorAnimationDuration;
  group.fillMode = kCAFillModeForwards;
  group.removedOnCompletion = YES;
  group.animations = @[ scaleAnimation, fadeAnimation ];
  [self addAnimation:group forKey:kPageControlIndicatorAnimationKey];

  // Default value.
  self.hidden = NO;
}

- (void)updateIndicatorTransformX:(CGFloat)transformX
                         animated:(BOOL)animated
                         duration:(NSTimeInterval)duration
              mediaTimingFunction:(CAMediaTimingFunction *)timingFunction {
  [CATransaction begin];
  [CATransaction setDisableActions:!animated];
  [CATransaction setAnimationDuration:duration];
  [CATransaction setAnimationTimingFunction:timingFunction];
  self.transform = CATransform3DMakeTranslation(transformX, 0, 0);
  [CATransaction commit];
}

- (void)updateIndicatorTransformX:(CGFloat)transformX {
  // Disable animation of this transform.
  [CATransaction begin];
  [CATransaction setDisableActions:YES];
  self.transform = CATransform3DMakeTranslation(transformX, 0, 0);
  [CATransaction commit];
}

#pragma mark - Private

- (CGPathRef)circlePathWithRadius:(CGFloat)radius {
  return [UIBezierPath bezierPathWithRoundedRect:CGRectMake(0, 0, radius * 2, radius * 2)
                                    cornerRadius:radius]
      .CGPath;
}

@end