react-native/React/Views/RCTFont.mm

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 *
 * This source code is licensed under the MIT license found in the
 * LICENSE file in the root directory of this source tree.
 */

#import "RCTAssert.h"
#import "RCTFont.h"
#import "RCTLog.h"

#import <CoreText/CoreText.h>

#import <mutex>

#if !defined(__IPHONE_8_2) || __IPHONE_OS_VERSION_MIN_REQUIRED < __IPHONE_8_2

// These constants are defined in iPhone SDK 8.2, but the app cannot run on
// iOS < 8.2 unless we redefine them here. If you target iOS 8.2 or above
// as a base target, the standard constants will be used instead.
// These constants can only be removed when React Native drops iOS8 support.

#define UIFontWeightUltraLight -0.8
#define UIFontWeightThin -0.6
#define UIFontWeightLight -0.4
#define UIFontWeightRegular 0
#define UIFontWeightMedium 0.23
#define UIFontWeightSemibold 0.3
#define UIFontWeightBold 0.4
#define UIFontWeightHeavy 0.56
#define UIFontWeightBlack 0.62

#endif

typedef CGFloat RCTFontWeight;
static RCTFontWeight weightOfFont(UIFont *font)
{
  static NSArray *fontNames;
  static NSArray *fontWeights;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    // We use two arrays instead of one map because
    // the order is important for suffix matching.
    fontNames = @[
      @"normal",
      @"ultralight",
      @"thin",
      @"light",
      @"regular",
      @"medium",
      @"semibold",
      @"demibold",
      @"extrabold",
      @"bold",
      @"heavy",
      @"black"
    ];
    fontWeights = @[
      @(UIFontWeightRegular),
      @(UIFontWeightUltraLight),
      @(UIFontWeightThin),
      @(UIFontWeightLight),
      @(UIFontWeightRegular),
      @(UIFontWeightMedium),
      @(UIFontWeightSemibold),
      @(UIFontWeightSemibold),
      @(UIFontWeightHeavy),
      @(UIFontWeightBold),
      @(UIFontWeightHeavy),
      @(UIFontWeightBlack)
    ];
  });

  for (NSInteger i = 0; i < fontNames.count; i++) {
    if ([font.fontName.lowercaseString hasSuffix:fontNames[i]]) {
      return (RCTFontWeight)[fontWeights[i] doubleValue];
    }
  }

  NSDictionary *traits = [font.fontDescriptor objectForKey:UIFontDescriptorTraitsAttribute];
  return (RCTFontWeight)[traits[UIFontWeightTrait] doubleValue];
}

static BOOL isItalicFont(UIFont *font)
{
  NSDictionary *traits = [font.fontDescriptor objectForKey:UIFontDescriptorTraitsAttribute];
  UIFontDescriptorSymbolicTraits symbolicTraits = [traits[UIFontSymbolicTrait] unsignedIntValue];
  return (symbolicTraits & UIFontDescriptorTraitItalic) != 0;
}

static BOOL isCondensedFont(UIFont *font)
{
  NSDictionary *traits = [font.fontDescriptor objectForKey:UIFontDescriptorTraitsAttribute];
  UIFontDescriptorSymbolicTraits symbolicTraits = [traits[UIFontSymbolicTrait] unsignedIntValue];
  return (symbolicTraits & UIFontDescriptorTraitCondensed) != 0;
}

static RCTFontHandler defaultFontHandler;

void RCTSetDefaultFontHandler(RCTFontHandler handler) {
  defaultFontHandler = handler;
}

BOOL RCTHasFontHandlerSet() {
  return defaultFontHandler != nil;
}

// We pass a string description of the font weight to the defaultFontHandler because UIFontWeight
// is not defined pre-iOS 8.2.
// Furthermore, UIFontWeight's are lossy floats, so we must use an inexact compare to figure out
// which one we actually have.
static inline BOOL CompareFontWeights(UIFontWeight firstWeight, UIFontWeight secondWeight) {
#if CGFLOAT_IS_DOUBLE
  return fabs(firstWeight - secondWeight) < 0.01;
#else
  return fabsf(firstWeight - secondWeight) < 0.01;
#endif
}

static NSString *FontWeightDescriptionFromUIFontWeight(UIFontWeight fontWeight)
{
  if (CompareFontWeights(fontWeight, UIFontWeightUltraLight)) {
    return @"ultralight";
  } else if (CompareFontWeights(fontWeight, UIFontWeightThin)) {
    return @"thin";
  } else if (CompareFontWeights(fontWeight, UIFontWeightLight)) {
    return @"light";
  } else if (CompareFontWeights(fontWeight, UIFontWeightRegular)) {
    return @"regular";
  } else if (CompareFontWeights(fontWeight, UIFontWeightMedium)) {
    return @"medium";
  } else if (CompareFontWeights(fontWeight, UIFontWeightSemibold)) {
    return @"semibold";
  } else if (CompareFontWeights(fontWeight, UIFontWeightBold)) {
    return @"bold";
  } else if (CompareFontWeights(fontWeight, UIFontWeightHeavy)) {
    return @"heavy";
  } else if (CompareFontWeights(fontWeight, UIFontWeightBlack)) {
    return @"black";
  }
  RCTAssert(NO, @"Unknown UIFontWeight passed in: %f", fontWeight);
  return @"regular";
}

static UIFont *cachedSystemFont(CGFloat size, RCTFontWeight weight)
{
  static NSCache *fontCache;
  static std::mutex fontCacheMutex;

  NSString *cacheKey = [NSString stringWithFormat:@"%.1f/%.2f", size, weight];
  UIFont *font;
  {
    std::lock_guard<std::mutex> lock(fontCacheMutex);
    if (!fontCache) {
      fontCache = [NSCache new];
    }
    font = [fontCache objectForKey:cacheKey];
  }

  if (!font) {
    if (defaultFontHandler) {
      NSString *fontWeightDescription = FontWeightDescriptionFromUIFontWeight(weight);
      font = defaultFontHandler(size, fontWeightDescription);
    } else if ([UIFont respondsToSelector:@selector(systemFontOfSize:weight:)]) {
      // Only supported on iOS8.2 and above
      font = [UIFont systemFontOfSize:size weight:weight];
    } else {
      if (weight >= UIFontWeightBold) {
        font = [UIFont boldSystemFontOfSize:size];
      } else if (weight >= UIFontWeightMedium) {
        font = [UIFont fontWithName:@"HelveticaNeue-Medium" size:size];
      } else if (weight <= UIFontWeightLight) {
        font = [UIFont fontWithName:@"HelveticaNeue-Light" size:size];
      } else {
        font = [UIFont systemFontOfSize:size];
      }
    }

    {
      std::lock_guard<std::mutex> lock(fontCacheMutex);
      [fontCache setObject:font forKey:cacheKey];
    }
  }

  return font;
}

@implementation RCTConvert (RCTFont)

+ (UIFont *)UIFont:(id)json
{
  json = [self NSDictionary:json];
  return [RCTFont updateFont:nil
                  withFamily:[RCTConvert NSString:json[@"fontFamily"]]
                        size:[RCTConvert NSNumber:json[@"fontSize"]]
                      weight:[RCTConvert NSString:json[@"fontWeight"]]
                       style:[RCTConvert NSString:json[@"fontStyle"]]
                     variant:[RCTConvert NSStringArray:json[@"fontVariant"]]
             scaleMultiplier:1];
}

RCT_ENUM_CONVERTER(RCTFontWeight, (@{
                                     @"normal": @(UIFontWeightRegular),
                                     @"bold": @(UIFontWeightBold),
                                     @"100": @(UIFontWeightUltraLight),
                                     @"200": @(UIFontWeightThin),
                                     @"300": @(UIFontWeightLight),
                                     @"400": @(UIFontWeightRegular),
                                     @"500": @(UIFontWeightMedium),
                                     @"600": @(UIFontWeightSemibold),
                                     @"700": @(UIFontWeightBold),
                                     @"800": @(UIFontWeightHeavy),
                                     @"900": @(UIFontWeightBlack),
                                     }), UIFontWeightRegular, doubleValue)

typedef BOOL RCTFontStyle;
RCT_ENUM_CONVERTER(RCTFontStyle, (@{
                                    @"normal": @NO,
                                    @"italic": @YES,
                                    @"oblique": @YES,
                                    }), NO, boolValue)

typedef NSDictionary RCTFontVariantDescriptor;
+ (RCTFontVariantDescriptor *)RCTFontVariantDescriptor:(id)json
{
  static NSDictionary *mapping;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    mapping = @{
      @"small-caps": @{
          UIFontFeatureTypeIdentifierKey: @(kLowerCaseType),
          UIFontFeatureSelectorIdentifierKey: @(kLowerCaseSmallCapsSelector),
          },
      @"oldstyle-nums": @{
          UIFontFeatureTypeIdentifierKey: @(kNumberCaseType),
          UIFontFeatureSelectorIdentifierKey: @(kLowerCaseNumbersSelector),
          },
      @"lining-nums": @{
          UIFontFeatureTypeIdentifierKey: @(kNumberCaseType),
          UIFontFeatureSelectorIdentifierKey: @(kUpperCaseNumbersSelector),
          },
      @"tabular-nums": @{
          UIFontFeatureTypeIdentifierKey: @(kNumberSpacingType),
          UIFontFeatureSelectorIdentifierKey: @(kMonospacedNumbersSelector),
          },
      @"proportional-nums": @{
          UIFontFeatureTypeIdentifierKey: @(kNumberSpacingType),
          UIFontFeatureSelectorIdentifierKey: @(kProportionalNumbersSelector),
          },
      };
  });
  RCTFontVariantDescriptor *value = mapping[json];
  if (RCT_DEBUG && !value && [json description].length > 0) {
    RCTLogError(@"Invalid RCTFontVariantDescriptor '%@'. should be one of: %@", json,
                [[mapping allKeys] sortedArrayUsingSelector:@selector(caseInsensitiveCompare:)]);
  }
  return value;
}

RCT_ARRAY_CONVERTER(RCTFontVariantDescriptor)

@end

@implementation RCTFont

+ (UIFont *)updateFont:(UIFont *)font
            withFamily:(NSString *)family
                  size:(NSNumber *)size
                weight:(NSString *)weight
                 style:(NSString *)style
               variant:(NSArray<RCTFontVariantDescriptor *> *)variant
       scaleMultiplier:(CGFloat)scaleMultiplier
{
  // Defaults
  static NSString *defaultFontFamily;
  static dispatch_once_t onceToken;
  dispatch_once(&onceToken, ^{
    defaultFontFamily = [UIFont systemFontOfSize:14].familyName;
  });
  const RCTFontWeight defaultFontWeight = UIFontWeightRegular;
  const CGFloat defaultFontSize = 14;

  // Initialize properties to defaults
  CGFloat fontSize = defaultFontSize;
  RCTFontWeight fontWeight = defaultFontWeight;
  NSString *familyName = defaultFontFamily;
  BOOL isItalic = NO;
  BOOL isCondensed = NO;

  if (font) {
    familyName = font.familyName ?: defaultFontFamily;
    fontSize = font.pointSize ?: defaultFontSize;
    fontWeight = weightOfFont(font);
    isItalic = isItalicFont(font);
    isCondensed = isCondensedFont(font);
  }

  // Get font attributes
  fontSize = [RCTConvert CGFloat:size] ?: fontSize;
  if (scaleMultiplier > 0.0 && scaleMultiplier != 1.0) {
    fontSize = round(fontSize * scaleMultiplier);
  }
  familyName = [RCTConvert NSString:family] ?: familyName;
  isItalic = style ? [RCTConvert RCTFontStyle:style] : isItalic;
  fontWeight = weight ? [RCTConvert RCTFontWeight:weight] : fontWeight;

  BOOL didFindFont = NO;

  // Handle system font as special case. This ensures that we preserve
  // the specific metrics of the standard system font as closely as possible.
  if ([familyName isEqual:defaultFontFamily] || [familyName isEqualToString:@"System"]) {
    font = cachedSystemFont(fontSize, fontWeight);
    if (font) {
      didFindFont = YES;

      if (isItalic || isCondensed) {
        UIFontDescriptor *fontDescriptor = [font fontDescriptor];
        UIFontDescriptorSymbolicTraits symbolicTraits = fontDescriptor.symbolicTraits;
        if (isItalic) {
          symbolicTraits |= UIFontDescriptorTraitItalic;
        }
        if (isCondensed) {
          symbolicTraits |= UIFontDescriptorTraitCondensed;
        }
        fontDescriptor = [fontDescriptor fontDescriptorWithSymbolicTraits:symbolicTraits];
        font = [UIFont fontWithDescriptor:fontDescriptor size:fontSize];
      }
    }
  }

  // Gracefully handle being given a font name rather than font family, for
  // example: "Helvetica Light Oblique" rather than just "Helvetica".
  if (!didFindFont && [UIFont fontNamesForFamilyName:familyName].count == 0) {
    font = [UIFont fontWithName:familyName size:fontSize];
    if (font) {
      // It's actually a font name, not a font family name,
      // but we'll do what was meant, not what was said.
      familyName = font.familyName;
      fontWeight = weight ? fontWeight : weightOfFont(font);
      isItalic = style ? isItalic : isItalicFont(font);
      isCondensed = isCondensedFont(font);
    } else {
      // Not a valid font or family
      RCTLogError(@"Unrecognized font family '%@'", familyName);
      if ([UIFont respondsToSelector:@selector(systemFontOfSize:weight:)]) {
        font = [UIFont systemFontOfSize:fontSize weight:fontWeight];
      } else if (fontWeight > UIFontWeightRegular) {
        font = [UIFont boldSystemFontOfSize:fontSize];
      } else {
        font = [UIFont systemFontOfSize:fontSize];
      }
    }
  }

  // Get the closest font that matches the given weight for the fontFamily
  CGFloat closestWeight = INFINITY;
  for (NSString *name in [UIFont fontNamesForFamilyName:familyName]) {
    UIFont *match = [UIFont fontWithName:name size:fontSize];
    if (isItalic == isItalicFont(match) &&
        isCondensed == isCondensedFont(match)) {
      CGFloat testWeight = weightOfFont(match);
      if (ABS(testWeight - fontWeight) < ABS(closestWeight - fontWeight)) {
        font = match;
        closestWeight = testWeight;
      }
    }
  }

  // If we still don't have a match at least return the first font in the fontFamily
  // This is to support built-in font Zapfino and other custom single font families like Impact
  if (!font) {
    NSArray *names = [UIFont fontNamesForFamilyName:familyName];
    if (names.count > 0) {
      font = [UIFont fontWithName:names[0] size:fontSize];
    }
  }

  // Apply font variants to font object
  if (variant) {
    NSArray *fontFeatures = [RCTConvert RCTFontVariantDescriptorArray:variant];
    UIFontDescriptor *fontDescriptor = [font.fontDescriptor fontDescriptorByAddingAttributes:@{
      UIFontDescriptorFeatureSettingsAttribute: fontFeatures
    }];
    font = [UIFont fontWithDescriptor:fontDescriptor size:fontSize];
  }

  return font;
}

+ (UIFont *)updateFont:(UIFont *)font withFamily:(NSString *)family
{
  return [self updateFont:font withFamily:family size:nil weight:nil style:nil variant:nil scaleMultiplier:1];
}

+ (UIFont *)updateFont:(UIFont *)font withSize:(NSNumber *)size
{
  return [self updateFont:font withFamily:nil size:size weight:nil style:nil variant:nil scaleMultiplier:1];
}

+ (UIFont *)updateFont:(UIFont *)font withWeight:(NSString *)weight
{
  return [self updateFont:font withFamily:nil size:nil weight:weight style:nil variant:nil scaleMultiplier:1];
}

+ (UIFont *)updateFont:(UIFont *)font withStyle:(NSString *)style
{
  return [self updateFont:font withFamily:nil size:nil weight:nil style:style variant:nil scaleMultiplier:1];
}

@end