Swiftgram/AsyncDisplayKit/Details/ASTextNodeCoreTextAdditions.m

/* 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 "ASTextNodeCoreTextAdditions.h"

#import <CoreText/CTFont.h>
#import <CoreText/CTStringAttributes.h>

#pragma mark - Public
BOOL ASAttributeWithNameIsUnsupportedCoreTextAttribute(NSString *attributeName)
{
  static NSSet *coreTextAttributes;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    coreTextAttributes = [NSSet setWithObjects:(__bridge id)kCTForegroundColorAttributeName,
                          kCTForegroundColorFromContextAttributeName,
                          kCTForegroundColorAttributeName,
                          kCTStrokeColorAttributeName,
                          kCTUnderlineStyleAttributeName,
                          kCTVerticalFormsAttributeName,
                          kCTRunDelegateAttributeName,
                          kCTBaselineClassAttributeName,
                          kCTBaselineInfoAttributeName,
                          kCTBaselineReferenceInfoAttributeName,
                          kCTUnderlineColorAttributeName,
                          nil];
  });
  return [coreTextAttributes containsObject:attributeName];
}

NSDictionary *NSAttributedStringAttributesForCoreTextAttributes(NSDictionary *coreTextAttributes)
{
  NSMutableDictionary *cleanAttributes = [[NSMutableDictionary alloc] initWithCapacity:coreTextAttributes.count];

  [coreTextAttributes enumerateKeysAndObjectsUsingBlock:^(NSString *coreTextKey, id coreTextValue, BOOL *stop) {
    // The following attributes are not supported on NSAttributedString. Should they become available, we should add them.
    /*
     kCTForegroundColorFromContextAttributeName
     kCTSuperscriptAttributeName
     kCTGlyphInfoAttributeName
     kCTCharacterShapeAttributeName
     kCTLanguageAttributeName
     kCTRunDelegateAttributeName
     kCTBaselineClassAttributeName
     kCTBaselineInfoAttributeName
     kCTBaselineReferenceInfoAttributeName
     kCTWritingDirectionAttributeName
     kCTUnderlineColorAttributeName
     */

    // Conversely, the following attributes are not supported on CFAttributedString. Should they become available, we should add them.
    /*
     NSStrikethroughStyleAttributeName
     NSShadowAttributeName
     NSBackgroundColorAttributeName
     */

    // kCTFontAttributeName -> NSFontAttributeName
    if ([coreTextKey isEqualToString:(NSString *)kCTFontAttributeName]) {
      CTFontRef coreTextFont = (__bridge CTFontRef)coreTextValue;
      NSString *fontName = (__bridge_transfer NSString *)CTFontCopyPostScriptName(coreTextFont);
      CGFloat fontSize = CTFontGetSize(coreTextFont);

      cleanAttributes[NSFontAttributeName] = [UIFont fontWithName:fontName size:fontSize];
    }
    // kCTKernAttributeName -> NSKernAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTKernAttributeName]) {
      cleanAttributes[NSKernAttributeName] = (NSNumber *)coreTextValue;
    }
    // kCTLigatureAttributeName -> NSLigatureAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTLigatureAttributeName]) {
      cleanAttributes[NSLigatureAttributeName] = (NSNumber *)coreTextValue;
    }
    // kCTForegroundColorAttributeName -> NSForegroundColorAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTForegroundColorAttributeName]) {
      cleanAttributes[NSForegroundColorAttributeName] = [UIColor colorWithCGColor:(CGColorRef)coreTextValue];
    }
    // kCTParagraphStyleAttributeName -> NSParagraphStyleAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTParagraphStyleAttributeName]) {
      cleanAttributes[NSParagraphStyleAttributeName] = [NSParagraphStyle paragraphStyleWithCTParagraphStyle:(CTParagraphStyleRef)coreTextValue];
    }
    // kCTStrokeWidthAttributeName -> NSStrokeWidthAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTStrokeWidthAttributeName]) {
      cleanAttributes[NSStrokeWidthAttributeName] = (NSNumber *)coreTextValue;
    }
    // kCTStrokeColorAttributeName -> NSStrokeColorAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTStrokeColorAttributeName]) {
      cleanAttributes[NSStrokeColorAttributeName] = [UIColor colorWithCGColor:(CGColorRef)coreTextValue];
    }
    // kCTUnderlineStyleAttributeName -> NSUnderlineStyleAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTUnderlineStyleAttributeName]) {
      cleanAttributes[NSUnderlineStyleAttributeName] = (NSNumber *)coreTextValue;
    }
    // kCTVerticalFormsAttributeName -> NSVerticalGlyphFormAttributeName
    else if ([coreTextKey isEqualToString:(NSString *)kCTVerticalFormsAttributeName]) {
      BOOL flag = (BOOL)CFBooleanGetValue((CFBooleanRef)coreTextValue);
      cleanAttributes[NSVerticalGlyphFormAttributeName] = @((int)flag); // NSVerticalGlyphFormAttributeName is documented to be an NSNumber with an integer that's either 0 or 1.
    }
    // Don't filter out any internal text attributes
    else if (!ASAttributeWithNameIsUnsupportedCoreTextAttribute(coreTextKey)){
      cleanAttributes[coreTextKey] = coreTextValue;
    }
  }];

  return cleanAttributes;
}

NSAttributedString *ASCleanseAttributedStringOfCoreTextAttributes(NSAttributedString *dirtyAttributedString)
{
  if (!dirtyAttributedString)
    return nil;

  // First see if there are any core text attributes on the string
  __block BOOL containsCoreTextAttributes = NO;
  [dirtyAttributedString enumerateAttributesInRange:NSMakeRange(0, dirtyAttributedString.length)
                                            options:0
                                         usingBlock:^(NSDictionary *dirtyAttributes, NSRange range, BOOL *stop) {
                                           [dirtyAttributes enumerateKeysAndObjectsUsingBlock:^(NSString *coreTextKey, id coreTextValue, BOOL *innerStop) {
                                             if (ASAttributeWithNameIsUnsupportedCoreTextAttribute(coreTextKey)) {
                                               containsCoreTextAttributes = YES;
                                               *innerStop = YES;
                                             }
                                           }];
                                           *stop = containsCoreTextAttributes;
                                         }];
  if (containsCoreTextAttributes) {

    NSString *plainString = dirtyAttributedString.string;
    NSMutableAttributedString *cleanAttributedString = [[NSMutableAttributedString alloc] initWithString:plainString];

    // Iterate over all of the attributes, cleaning them as appropriate and applying them as we go.
    [dirtyAttributedString enumerateAttributesInRange:NSMakeRange(0, plainString.length)
                                              options:0
                                           usingBlock:^(NSDictionary *dirtyAttributes, NSRange range, BOOL *stop) {
                                             [cleanAttributedString addAttributes:NSAttributedStringAttributesForCoreTextAttributes(dirtyAttributes) range:range];
                                           }];

    return cleanAttributedString;
  } else {
    return dirtyAttributedString;
  }
}

#pragma mark -
#pragma mark -
@implementation NSParagraphStyle (ASTextNodeCoreTextAdditions)

+ (instancetype)paragraphStyleWithCTParagraphStyle:(CTParagraphStyleRef)coreTextParagraphStyle;
{
  NSMutableParagraphStyle *newParagraphStyle = [[NSMutableParagraphStyle alloc] init];

  if (!coreTextParagraphStyle)
    return newParagraphStyle;

  // The following paragraph style specifiers are not supported on NSParagraphStyle. Should they become available, we should add them.
  /*
   kCTParagraphStyleSpecifierTabStops
   kCTParagraphStyleSpecifierDefaultTabInterval
   kCTParagraphStyleSpecifierMaximumLineSpacing
   kCTParagraphStyleSpecifierMinimumLineSpacing
   kCTParagraphStyleSpecifierLineSpacingAdjustment
   kCTParagraphStyleSpecifierLineBoundsOptions
   */

  // Conversely, the following paragraph styles are not supported on CTParagraphStyle. Should they become available, we should add them.
  /*
   hyphenationFactor
   */

  // kCTParagraphStyleSpecifierAlignment -> alignment
  CTTextAlignment coreTextAlignment;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierAlignment, sizeof(coreTextAlignment), &coreTextAlignment))
    newParagraphStyle.alignment = NSTextAlignmentFromCTTextAlignment(coreTextAlignment);

  // kCTParagraphStyleSpecifierFirstLineHeadIndent -> firstLineHeadIndent
  CGFloat firstLineHeadIndent;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierFirstLineHeadIndent, sizeof(firstLineHeadIndent), &firstLineHeadIndent))
    newParagraphStyle.firstLineHeadIndent = firstLineHeadIndent;

  // kCTParagraphStyleSpecifierHeadIndent -> headIndent
  CGFloat headIndent;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierHeadIndent, sizeof(headIndent), &headIndent))
    newParagraphStyle.headIndent = headIndent;

  // kCTParagraphStyleSpecifierTailIndent -> tailIndent
  CGFloat tailIndent;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierTailIndent, sizeof(tailIndent), &tailIndent))
    newParagraphStyle.tailIndent = tailIndent;

  // kCTParagraphStyleSpecifierLineBreakMode -> lineBreakMode
  CTLineBreakMode coreTextLineBreakMode;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierLineBreakMode, sizeof(coreTextLineBreakMode), &coreTextLineBreakMode))
    newParagraphStyle.lineBreakMode = (NSLineBreakMode)coreTextLineBreakMode; // They're the same enum.

  // kCTParagraphStyleSpecifierLineHeightMultiple -> lineHeightMultiple
  CGFloat lineHeightMultiple;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierLineHeightMultiple, sizeof(lineHeightMultiple), &lineHeightMultiple))
    newParagraphStyle.lineHeightMultiple = lineHeightMultiple;

  // kCTParagraphStyleSpecifierMaximumLineHeight -> maximumLineHeight
  CGFloat maximumLineHeight;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierMaximumLineHeight, sizeof(maximumLineHeight), &maximumLineHeight))
    newParagraphStyle.maximumLineHeight = maximumLineHeight;

  // kCTParagraphStyleSpecifierMinimumLineHeight -> minimumLineHeight
  CGFloat minimumLineHeight;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierMinimumLineHeight, sizeof(minimumLineHeight), &minimumLineHeight))
    newParagraphStyle.minimumLineHeight = minimumLineHeight;

  // kCTParagraphStyleSpecifierLineSpacing -> lineSpacing
  // Note that kCTParagraphStyleSpecifierLineSpacing is deprecated and will die soon. We should not be using it.
  CGFloat lineSpacing;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierLineSpacing, sizeof(lineSpacing), &lineSpacing))
    newParagraphStyle.lineSpacing = lineSpacing;

  // kCTParagraphStyleSpecifierParagraphSpacing -> paragraphSpacing
  CGFloat paragraphSpacing;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierParagraphSpacing, sizeof(paragraphSpacing), &paragraphSpacing))
    newParagraphStyle.paragraphSpacing = paragraphSpacing;

  // kCTParagraphStyleSpecifierParagraphSpacingBefore -> paragraphSpacingBefore
  CGFloat paragraphSpacingBefore;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierParagraphSpacingBefore, sizeof(paragraphSpacingBefore), &paragraphSpacingBefore))
    newParagraphStyle.paragraphSpacingBefore = paragraphSpacingBefore;

  // kCTParagraphStyleSpecifierBaseWritingDirection -> baseWritingDirection
  CTWritingDirection coreTextBaseWritingDirection;
  if (CTParagraphStyleGetValueForSpecifier(coreTextParagraphStyle, kCTParagraphStyleSpecifierBaseWritingDirection, sizeof(coreTextBaseWritingDirection), &coreTextBaseWritingDirection))
    newParagraphStyle.baseWritingDirection = (NSWritingDirection)coreTextBaseWritingDirection; // They're the same enum.

  return newParagraphStyle;
}

@end