components/List/src/MDCBaseCell.m

// Copyright 2018-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 "MDCBaseCell.h"
#import "MDCSelfSizingLayoutAttributes.h"

#import "MaterialElevation.h"
#import "MaterialInk.h"
#import "MaterialRipple.h"
#import "MaterialShadowElevations.h"
#import "MaterialShadowLayer.h"

@interface MDCBaseCell ()

@property(nonatomic, assign) CGPoint lastTouch;
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
@property(strong, nonatomic, nonnull) MDCInkView *inkView;
#pragma clang diagnostic pop
@property(strong, nonatomic, nonnull) MDCRippleView *rippleView;
@property(strong, nonatomic, nonnull) UIColor *initialRippleViewRippleColor;

@end

@implementation MDCBaseCell

@synthesize mdc_overrideBaseElevation = _mdc_overrideBaseElevation;
@synthesize mdc_elevationDidChangeBlock = _mdc_elevationDidChangeBlock;

#pragma mark Object Lifecycle

- (instancetype)initWithFrame:(CGRect)frame {
  self = [super initWithFrame:frame];
  if (self) {
    [self commonMDCBaseCellInit];
  }
  return self;
}

- (instancetype)initWithCoder:(NSCoder *)aDecoder {
  self = [super initWithCoder:aDecoder];
  if (self) {
    [self commonMDCBaseCellInit];
  }
  return self;
}

#pragma mark Setup

- (void)commonMDCBaseCellInit {
  if (!self.inkView) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
    self.inkView = [[MDCInkView alloc] initWithFrame:self.bounds];
#pragma clang diagnostic pop
  }
  _inkView.usesLegacyInkRipple = NO;
  [self addSubview:_inkView];
  if (!self.rippleView) {
    self.rippleView = [[MDCRippleView alloc] initWithFrame:self.bounds];
    _initialRippleViewRippleColor = self.rippleView.rippleColor;
  }
  _mdc_overrideBaseElevation = -1;
}

#pragma mark Ink

- (void)startInk {
  [self.inkView startTouchBeganAtPoint:_lastTouch animated:YES withCompletion:nil];
}

- (void)endInk {
  [self.inkView startTouchEndAtPoint:_lastTouch animated:YES withCompletion:nil];
}

#pragma mark Shadow

- (UIBezierPath *)boundingPath {
  return [UIBezierPath bezierPathWithRoundedRect:self.bounds cornerRadius:self.layer.cornerRadius];
}

- (void)updateShadowElevation {
  self.layer.shadowPath = [self boundingPath].CGPath;
  [self.shadowLayer setElevation:self.elevation];
}

#pragma mark - UIResponder

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {
  UITouch *touch = [touches anyObject];
  CGPoint location = [touch locationInView:self];
  self.lastTouch = location;
  // Call super only after -lastTouch has been recorded, since super can call -setHighlighted:.
  [super touchesBegan:touches withEvent:event];
}

#pragma mark UIView Overrides

+ (Class)layerClass {
  return [MDCShadowLayer class];
}

- (void)layoutSubviews {
  [super layoutSubviews];
  [self updateShadowElevation];
  self.inkView.frame = self.bounds;
}

- (void)traitCollectionDidChange:(UITraitCollection *)previousTraitCollection {
  [super traitCollectionDidChange:previousTraitCollection];

  if (self.traitCollectionDidChangeBlock) {
    self.traitCollectionDidChangeBlock(self, previousTraitCollection);
  }
}

#pragma mark UICollectionViewCell Overrides

- (void)setHighlighted:(BOOL)highlighted {
  [super setHighlighted:highlighted];
  if (highlighted) {
    [self startInk];
    [self.rippleView beginRippleTouchDownAtPoint:_lastTouch animated:YES completion:nil];
  } else {
    [self endInk];
    [self.rippleView beginRippleTouchUpAnimated:YES completion:nil];
  }
}

- (void)prepareForReuse {
  [super prepareForReuse];
  self.elevation = 0;
  self.rippleColor = nil;
  [self.inkView cancelAllAnimationsAnimated:NO];
  [self.rippleView cancelAllRipplesAnimated:NO completion:nil];
}

- (UICollectionViewLayoutAttributes *)preferredLayoutAttributesFittingAttributes:
    (UICollectionViewLayoutAttributes *)layoutAttributes {
  if (![layoutAttributes conformsToProtocol:@protocol(MDCSelfSizingLayoutAttributes)]) {
    return [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
  }
  UICollectionViewLayoutAttributes<MDCSelfSizingLayoutAttributes> *attr = (id)layoutAttributes;
  BOOL isFixedWidth = [attr respondsToSelector:@selector(isFixedWidth)] ? attr.isFixedWidth : NO;
  BOOL isFixedHeight = [attr respondsToSelector:@selector(isFixedHeight)] ? attr.isFixedHeight : NO;
  NSLayoutConstraint *constraint;
  if (isFixedWidth && isFixedHeight) {
    return layoutAttributes;
  } else if (isFixedWidth) {
    constraint = [self.contentView.widthAnchor constraintEqualToConstant:attr.size.width];
  } else if (isFixedHeight) {
    constraint = [self.contentView.heightAnchor constraintEqualToConstant:attr.size.height];
  } else {
    return [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
  }
  constraint.active = YES;
  [self layoutIfNeeded];
  UICollectionViewLayoutAttributes *preferredAttributes =
      [super preferredLayoutAttributesFittingAttributes:layoutAttributes];
  constraint.active = NO;
  return preferredAttributes;
}

#pragma mark Accessors

- (void)setElevation:(MDCShadowElevation)elevation {
  if (elevation == _elevation) {
    return;
  }
  _elevation = elevation;
  [self updateShadowElevation];
  [self mdc_elevationDidChange];
}

- (CGFloat)mdc_currentElevation {
  return self.elevation;
}

- (void)setInkColor:(UIColor *)inkColor {
  if ([self.inkColor isEqual:inkColor]) {
    return;
  }
  self.inkView.inkColor = inkColor;
}

- (UIColor *)inkColor {
  return self.inkView.inkColor;
}

- (void)setRippleColor:(UIColor *)rippleColor {
  if (CGColorEqualToColor(self.rippleView.rippleColor.CGColor, rippleColor.CGColor)) {
    return;
  }
  self.rippleView.rippleColor = rippleColor ?: self.initialRippleViewRippleColor;
}

- (UIColor *)rippleColor {
  return self.rippleView.rippleColor;
}

- (MDCShadowLayer *)shadowLayer {
  if ([self.layer isKindOfClass:[MDCShadowLayer class]]) {
    return (MDCShadowLayer *)self.layer;
  }
  return nil;
}

- (void)setEnableRippleBehavior:(BOOL)enableRippleBehavior {
  if (_enableRippleBehavior == enableRippleBehavior) {
    return;
  }
  _enableRippleBehavior = enableRippleBehavior;

  if (enableRippleBehavior) {
    [self.inkView removeFromSuperview];
    self.rippleView.frame = self.bounds;
    [self addSubview:self.rippleView];
  } else {
    [self.rippleView removeFromSuperview];
    [self addSubview:self.inkView];
  }
}

@end