ComponentKit/Components/CKButtonComponent.mm

/*
 *  Copyright (c) 2014-present, Facebook, Inc.
 *  All rights reserved.
 *
 *  This source code is licensed under the BSD-style license found in the
 *  LICENSE file in the root directory of this source tree. An additional grant
 *  of patent rights can be found in the PATENTS file in the same directory.
 *
 */

#import "CKButtonComponent.h"

#import <array>

#import <RenderCore/RCAssert.h>
#import <ComponentKit/CKInternalHelpers.h>

#import "CKComponentSubclass.h"

struct CKStateConfiguration {
  NSString *title;
  UIColor *titleColor;
  UIImage *image;
  UIImage *backgroundImage;

  bool operator==(const CKStateConfiguration &other) const
  {
    return RCObjectIsEqual(title, other.title)
    && RCObjectIsEqual(titleColor, other.titleColor)
    && RCObjectIsEqual(image, other.image)
    && RCObjectIsEqual(backgroundImage, other.backgroundImage);
  }
};

/** Use indexForState to map from UIControlState to an array index. */
typedef std::array<CKStateConfiguration, 8> CKStateConfigurationArray;

@interface CKButtonComponentConfiguration : NSObject
{
@public
  CKStateConfigurationArray _configurations;
  NSUInteger _precomputedHash;
}
@end

@interface CKButtonWithExtendedTapArea : UIButton
/// The outset for tap target expansion
@property (nonatomic, assign) UIEdgeInsets tapTargetExpansion;
@end

@implementation CKButtonComponent
{
  CGSize _intrinsicSize;
}

- (instancetype)initWithAction:(const CKAction<UIEvent *>)action
                       options:(const CKButtonComponentOptions &)options
{
  static const CKComponentViewAttribute titleFontAttribute = {"CKButtonComponent.titleFont", ^(UIButton *button, id value) {
    button.titleLabel.font = value;
  }};

  static const CKComponentViewAttribute titleAlignmentAttribute = {"CKButtonComponent.titleAlignment", ^(UIButton *button, id value) {
    button.titleLabel.textAlignment = (NSTextAlignment)[value integerValue];
  }};

  static const CKComponentViewAttribute numberOfLinesAttribute = {"CKButtonComponent.numberOfLines", ^(UIButton *button, id value) {
    button.titleLabel.numberOfLines = [value integerValue];
  }};

  static const CKComponentViewAttribute lineBreakModeAttribute = {"CKButtonComponent.lineBreakMode", ^(UIButton *button, id value) {
    button.titleLabel.lineBreakMode = (NSLineBreakMode)[value integerValue];
  }};

  static const CKComponentViewAttribute configurationAttribute = {
    "CKButtonComponent.config",
    ^(UIButton *view, CKButtonComponentConfiguration *config) {
      enumerateAllStates(^(UIControlState state) {
        const CKStateConfiguration &stateConfig = config->_configurations[indexForState(state)];
        if (stateConfig.title) {
          [view setTitle:stateConfig.title forState:state];
        }
        if (stateConfig.titleColor) {
          [view setTitleColor:stateConfig.titleColor forState:state];
        }
        if (stateConfig.image) {
          [view setImage:stateConfig.image forState:state];
        }
        if (stateConfig.backgroundImage) {
          [view setBackgroundImage:stateConfig.backgroundImage forState:state];
        }
      });
    },
    // No unapplicator.
    nil,
    ^(UIButton *view, CKButtonComponentConfiguration *oldConfig, CKButtonComponentConfiguration *newConfig) {
      enumerateAllStates(^(UIControlState state) {
        const CKStateConfiguration &oldStateConfig = oldConfig->_configurations[indexForState(state)];
        const CKStateConfiguration &newStateConfig = newConfig->_configurations[indexForState(state)];
        if (!RCObjectIsEqual(oldStateConfig.title, newStateConfig.title)) {
          [view setTitle:newStateConfig.title forState:state];
        }
        if (!RCObjectIsEqual(oldStateConfig.titleColor, newStateConfig.titleColor)) {
          [view setTitleColor:newStateConfig.titleColor forState:state];
        }
        if (!RCObjectIsEqual(oldStateConfig.image, newStateConfig.image)) {
          [view setImage:newStateConfig.image forState:state];
        }
        if (!RCObjectIsEqual(oldStateConfig.backgroundImage, newStateConfig.backgroundImage)) {
          [view setBackgroundImage:newStateConfig.backgroundImage forState:state];
        }
      });
    }
  };

  UIEdgeInsets contentEdgeInsets = options.contentEdgeInsets;
  const auto attributesContentEdgeInsets = options.attributes.find(@selector(setContentEdgeInsets:));
  if (attributesContentEdgeInsets != options.attributes.end()) {
    contentEdgeInsets = [attributesContentEdgeInsets->second UIEdgeInsetsValue];
  }

  UIEdgeInsets titleEdgeInsets = options.titleEdgeInsets;
  const auto attributesTitleEdgeInsets = options.attributes.find(@selector(setTitleEdgeInsets:));
  if (attributesTitleEdgeInsets != options.attributes.end()) {
    titleEdgeInsets = [attributesTitleEdgeInsets->second UIEdgeInsetsValue];
  }

  UIEdgeInsets imageEdgeInsets = options.imageEdgeInsets;
  const auto attributesImageEdgeInsets = options.attributes.find(@selector(setImageEdgeInsets:));
  if (attributesImageEdgeInsets != options.attributes.end()) {
    imageEdgeInsets = [attributesImageEdgeInsets->second UIEdgeInsetsValue];
  }

  CKViewComponentAttributeValueMap attributes(options.attributes);
  attributes.insert({
    {configurationAttribute, configurationFromOptions(options)},
    {titleFontAttribute, options.titleFont},
    {titleAlignmentAttribute, options.titleAlignment},
    {numberOfLinesAttribute, options.numberOfLines},
    {lineBreakModeAttribute, options.lineBreakMode},
    {@selector(setSelected:), options.selected},
    {@selector(setEnabled:), options.enabled},
    {@selector(setContentEdgeInsets:), contentEdgeInsets},
    {@selector(setTitleEdgeInsets:), titleEdgeInsets},
    {@selector(setImageEdgeInsets:), imageEdgeInsets},
    {@selector(setTapTargetExpansion:), options.tapTargetExpansion},
    CKComponentActionAttribute(action, UIControlEventTouchUpInside),
  });

  RCAccessibilityContext accessibilityContext(options.accessibilityContext);
  if (!accessibilityContext.extra[CKAccessibilityExtraActionKey]) {
    NSMutableDictionary *extra = [accessibilityContext.extra mutableCopy] ?: [NSMutableDictionary new];
    extra[CKAccessibilityExtraActionKey] = CKAccessibilityExtraActionValue(CKAction<>::demotedFrom(action, static_cast<UIEvent*>(nil)));
    accessibilityContext.extra = extra;
  }

  self = [super initWithView:{
    [CKButtonWithExtendedTapArea class],
    std::move(attributes),
    std::move(accessibilityContext)
  } size:options.size];

  if (self != nil) {
  #if !TARGET_OS_TV
    const UIControlState state = (options.selected ? UIControlStateSelected : UIControlStateNormal)
    | (options.enabled ? UIControlStateNormal : UIControlStateDisabled);
    _intrinsicSize = intrinsicSize(valueForState(options.titles.getMap(), state),
                                   options.numberOfLines,
                                   options.titleFont,
                                   valueForState(options.images.getMap(), state),
                                   valueForState(options.backgroundImages.getMap(), state),
                                   contentEdgeInsets,
                                   titleEdgeInsets,
                                   imageEdgeInsets);

  #else
    // `labelFontSize` is unavailable on tvOS
    _intrinsicSize = {INFINITY, INFINITY};
  #endif // !TARGET_OS_TV
  }
  return self;
}

- (RCLayout)computeLayoutThatFits:(CKSizeRange)constrainedSize
{
  return {self, constrainedSize.clamp(_intrinsicSize)};
}

static CKButtonComponentConfiguration *configurationFromOptions(const CKButtonComponentOptions &options)
{
  CKButtonComponentConfiguration *const config = [[CKButtonComponentConfiguration alloc] init];
  CKStateConfigurationArray &configs = config->_configurations;
  NSUInteger hash = 0;
  for (const auto& it : options.titles.getMap()) {
    configs[indexForState(it.first)].title = it.second;
    hash ^= (it.first ^ [it.second hash]);
  }
  for (const auto& it : options.titleColors.getMap()) {
    configs[indexForState(it.first)].titleColor = it.second;
    hash ^= (it.first ^ [it.second hash]);
  }
  for (const auto& it : options.images.getMap()) {
    configs[indexForState(it.first)].image = it.second;
    hash ^= (it.first ^ [it.second hash]);
  }
  for (const auto& it : options.backgroundImages.getMap()) {
    configs[indexForState(it.first)].backgroundImage = it.second;
    hash ^= (it.first ^ [it.second hash]);
  }
  config->_precomputedHash = hash;
  return config;
}

template<typename T>
static T valueForState(const std::unordered_map<UIControlState, T> &m, UIControlState state)
{
  auto it = m.find(state);
  if (it != m.end()) {
    return it->second;
  }
  // "If a title is not specified for a state, the default behavior is to use the title associated with the
  // UIControlStateNormal state." (Similarly for other attributes.)
  it = m.find(UIControlStateNormal);
  if (it != m.end()) {
    return it->second;
  }
  return nil;
}

#if !TARGET_OS_TV // `labelFontSize` is unavailable on tvOS
static CGSize intrinsicSize(NSString *title, NSInteger numberOfLines, UIFont *titleFont, UIImage *image,
                            UIImage *backgroundImage, UIEdgeInsets contentEdgeInsets, UIEdgeInsets titleEdgeInsets, UIEdgeInsets imageEdgeInsets)
{
  UIFont *const font = titleFont ?: [UIFont systemFontOfSize:[UIFont labelFontSize]];
  const CGSize titleSize = [title sizeWithAttributes:@{NSFontAttributeName: font}];

  RCCWarn(numberOfLines > 0, @"Setting numberOfLines to 0 or less can create unpredictible behaviour between displaying the label and the buttons size. UIButton's titleLabel property isn't bound to the bounds of it's housing UIButton, which can lead to the text displaying incorrectly.");

  const CGFloat labelHeight = (numberOfLines > 1)
                            ? ceilf(font.lineHeight) * CGFloat(numberOfLines)
                            : ceilf(titleSize.height);

  const CGSize imageSize = image.size;
  const CGSize contentSize = {
    CKRoundValueToPixelGrid(ceilf(titleSize.width) + imageEdgeInsets.right + titleEdgeInsets.left + imageEdgeInsets.left + titleEdgeInsets.right + imageSize.width + contentEdgeInsets.left + contentEdgeInsets.right, YES, NO),
    CKRoundValueToPixelGrid(MAX(labelHeight, imageSize.height) + MAX(titleEdgeInsets.top, imageEdgeInsets.top) + MAX(titleEdgeInsets.bottom, imageEdgeInsets.bottom) + contentEdgeInsets.top + contentEdgeInsets.bottom, YES, NO)
  };
  const CGSize backgroundImageSize = backgroundImage.size;
  return {
    MAX(backgroundImageSize.width, contentSize.width),
    MAX(backgroundImageSize.height, contentSize.height)
  };
}
#endif // !TARGET_OS_TV

/**
 Note this only enumerates through the default UIControlStates, not any application-defined or system-reserved ones.
 It excludes any states with both UIControlStateHighlighted and UIControlStateDisabled set as that is an invalid value.
 (UIButton will, surprisingly enough, throw away one of the bits if they are set together instead of ignoring it.)
 */
static void enumerateAllStates(void (^block)(UIControlState))
{
  for (int highlighted = 0; highlighted < 2; highlighted++) {
    for (int disabled = 0; disabled < 2; disabled++) {
      for (int selected = 0; selected < 2; selected++) {
        const UIControlState state = (highlighted ? UIControlStateHighlighted : 0) | (disabled ? UIControlStateDisabled : 0) | (selected ? UIControlStateSelected : 0);
        if (state & UIControlStateHighlighted && state & UIControlStateDisabled) {
          continue;
        }
        if (block) {
          block(state);
        }
      }
    }
  }
}

static inline NSUInteger indexForState(UIControlState state)
{
  return 0 +
  (state & UIControlStateHighlighted ? 4 : 0) +
  (state & UIControlStateDisabled ? 2 : 0) +
  (state & UIControlStateSelected ? 1 : 0);
}

@end

@implementation CKButtonComponentConfiguration

- (BOOL)isEqual:(id)object
{
  if (self == object) {
    return YES;
  } else if ([object isKindOfClass:[self class]]) {
    CKButtonComponentConfiguration *const other = object;
    return _configurations == other->_configurations;
  }
  return NO;
}

- (NSUInteger)hash
{
  return _precomputedHash;
}

@end

@implementation CKButtonWithExtendedTapArea : UIButton

-(BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event
{
  return CGRectContainsPoint(UIEdgeInsetsInsetRect(self.bounds, self.tapTargetExpansion), point);
}

@end