react-native/Libraries/Text/Text/RCTTextView.m

/*
 * Copyright (c) Facebook, Inc. and its affiliates.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import <React/RCTTextView.h>

#import <MobileCoreServices/UTCoreTypes.h>

#import <React/RCTUtils.h>
#import <React/UIView+React.h>

#import <React/RCTTextShadowView.h>

@implementation RCTTextView
{
  CAShapeLayer *_highlightLayer;
  UILongPressGestureRecognizer *_longPressGestureRecognizer;

  NSArray<UIView *> *_Nullable _descendantViews;
  NSTextStorage *_Nullable _textStorage;
  CGRect _contentFrame;
}

- (instancetype)initWithFrame:(CGRect)frame
{
  if (self = [super initWithFrame:frame]) {
    self.isAccessibilityElement = YES;
    self.accessibilityTraits |= UIAccessibilityTraitStaticText;
    self.opaque = NO;
    self.contentMode = UIViewContentModeRedraw;
  }
  return self;
}

- (NSString *)description
{
  NSString *superDescription = super.description;
  NSRange semicolonRange = [superDescription rangeOfString:@";"];
  NSString *replacement = [NSString stringWithFormat:@"; reactTag: %@; text: %@", self.reactTag, _textStorage.string];
  return [superDescription stringByReplacingCharactersInRange:semicolonRange withString:replacement];
}

- (void)setSelectable:(BOOL)selectable
{
  if (_selectable == selectable) {
    return;
  }

  _selectable = selectable;

  if (_selectable) {
    [self enableContextMenu];
  }
  else {
    [self disableContextMenu];
  }
}

- (void)reactSetFrame:(CGRect)frame
{
  // Text looks super weird if its frame is animated.
  // This disables the frame animation, without affecting opacity, etc.
  [UIView performWithoutAnimation:^{
    [super reactSetFrame:frame];
  }];
}

- (void)didUpdateReactSubviews
{
  // Do nothing, as subviews are managed by `setTextStorage:` method
}

- (void)setTextStorage:(NSTextStorage *)textStorage
          contentFrame:(CGRect)contentFrame
       descendantViews:(NSArray<UIView *> *)descendantViews
{
  _textStorage = textStorage;
  _contentFrame = contentFrame;

  // FIXME: Optimize this.
  for (UIView *view in _descendantViews) {
    [view removeFromSuperview];
  }

  _descendantViews = descendantViews;

  for (UIView *view in descendantViews) {
    [self addSubview:view];
  }

  [self setNeedsDisplay];
}

- (void)drawRect:(CGRect)rect
{
  [super drawRect:rect];
  if (!_textStorage) {
    return;
  }


  NSLayoutManager *layoutManager = _textStorage.layoutManagers.firstObject;
  NSTextContainer *textContainer = layoutManager.textContainers.firstObject;

#if TARGET_OS_MACCATALYST
  CGContextRef context = UIGraphicsGetCurrentContext();
  CGContextSaveGState(context);
  // NSLayoutManager tries to draw text with sub-pixel anti-aliasing by default on
  // macOS, but rendering SPAA onto a transparent background produces poor results.
  // CATextLayer disables font smoothing by default now on macOS; we follow suit.
  CGContextSetShouldSmoothFonts(context, NO);
#endif
  
  NSRange glyphRange = [layoutManager glyphRangeForTextContainer:textContainer];
  [layoutManager drawBackgroundForGlyphRange:glyphRange atPoint:_contentFrame.origin];
  [layoutManager drawGlyphsForGlyphRange:glyphRange atPoint:_contentFrame.origin];

  __block UIBezierPath *highlightPath = nil;
  NSRange characterRange = [layoutManager characterRangeForGlyphRange:glyphRange
                                                     actualGlyphRange:NULL];
  [_textStorage enumerateAttribute:RCTTextAttributesIsHighlightedAttributeName
                           inRange:characterRange
                           options:0
                        usingBlock:
    ^(NSNumber *value, NSRange range, __unused BOOL *stop) {
      if (!value.boolValue) {
        return;
      }

      [layoutManager enumerateEnclosingRectsForGlyphRange:range
                                 withinSelectedGlyphRange:range
                                          inTextContainer:textContainer
                                               usingBlock:
        ^(CGRect enclosingRect, __unused BOOL *anotherStop) {
          UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectInset(enclosingRect, -2, -2) cornerRadius:2];
          if (highlightPath) {
            [highlightPath appendPath:path];
          } else {
            highlightPath = path;
          }
        }
      ];
  }];

  if (highlightPath) {
    if (!_highlightLayer) {
      _highlightLayer = [CAShapeLayer layer];
      _highlightLayer.fillColor = [UIColor colorWithWhite:0 alpha:0.25].CGColor;
      [self.layer addSublayer:_highlightLayer];
    }
    _highlightLayer.position = _contentFrame.origin;
    _highlightLayer.path = highlightPath.CGPath;
  } else {
    [_highlightLayer removeFromSuperlayer];
    _highlightLayer = nil;
  }
  
#if TARGET_OS_MACCATALYST
  CGContextRestoreGState(context);
#endif
}


- (NSNumber *)reactTagAtPoint:(CGPoint)point
{
  NSNumber *reactTag = self.reactTag;

  CGFloat fraction;
  NSLayoutManager *layoutManager = _textStorage.layoutManagers.firstObject;
  NSTextContainer *textContainer = layoutManager.textContainers.firstObject;
  NSUInteger characterIndex = [layoutManager characterIndexForPoint:point
                                                    inTextContainer:textContainer
                           fractionOfDistanceBetweenInsertionPoints:&fraction];

  // If the point is not before (fraction == 0.0) the first character and not
  // after (fraction == 1.0) the last character, then the attribute is valid.
  if (_textStorage.length > 0 && (fraction > 0 || characterIndex > 0) && (fraction < 1 || characterIndex < _textStorage.length - 1)) {
    reactTag = [_textStorage attribute:RCTTextAttributesTagAttributeName atIndex:characterIndex effectiveRange:NULL];
  }

  return reactTag;
}

- (void)didMoveToWindow
{
  [super didMoveToWindow];

  if (!self.window) {
    self.layer.contents = nil;
    if (_highlightLayer) {
      [_highlightLayer removeFromSuperlayer];
      _highlightLayer = nil;
    }
  } else if (_textStorage) {
    [self setNeedsDisplay];
  }
}

#pragma mark - Accessibility

- (NSString *)accessibilityLabel
{
  NSString *superAccessibilityLabel = [super accessibilityLabel];
  if (superAccessibilityLabel) {
    return superAccessibilityLabel;
  }
  return _textStorage.string;
}

#pragma mark - Context Menu

- (void)enableContextMenu
{
  _longPressGestureRecognizer = [[UILongPressGestureRecognizer alloc] initWithTarget:self action:@selector(handleLongPress:)];
  [self addGestureRecognizer:_longPressGestureRecognizer];
}

- (void)disableContextMenu
{
  [self removeGestureRecognizer:_longPressGestureRecognizer];
  _longPressGestureRecognizer = nil;
}

- (void)handleLongPress:(UILongPressGestureRecognizer *)gesture
{
  // TODO: Adopt showMenuFromRect (necessary for UIKitForMac)
#if !TARGET_OS_UIKITFORMAC
  UIMenuController *menuController = [UIMenuController sharedMenuController];

  if (menuController.isMenuVisible) {
    return;
  }

  if (!self.isFirstResponder) {
    [self becomeFirstResponder];
  }

  [menuController setTargetRect:self.bounds inView:self];
  [menuController setMenuVisible:YES animated:YES];
#endif
}

- (BOOL)canBecomeFirstResponder
{
  return _selectable;
}

- (BOOL)canPerformAction:(SEL)action withSender:(id)sender
{
  if (_selectable && action == @selector(copy:)) {
    return YES;
  }

  return [self.nextResponder canPerformAction:action withSender:sender];
}

- (void)copy:(id)sender
{
  NSAttributedString *attributedText = _textStorage;

  NSMutableDictionary *item = [NSMutableDictionary new];

  NSData *rtf = [attributedText dataFromRange:NSMakeRange(0, attributedText.length)
                           documentAttributes:@{NSDocumentTypeDocumentAttribute: NSRTFDTextDocumentType}
                                        error:nil];

  if (rtf) {
    [item setObject:rtf forKey:(id)kUTTypeFlatRTFD];
  }

  [item setObject:attributedText.string forKey:(id)kUTTypeUTF8PlainText];

  UIPasteboard *pasteboard = [UIPasteboard generalPasteboard];
  pasteboard.items = @[item];
}

@end