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