Test changing React's font manager

Author: stevenpetryk

Libraries/Text/RCTTextAttributes.m

@@ -93,27 +93,27 @@ - (NSParagraphStyle *)effectiveParagraphStyle
         alignment = NSTextAlignmentRight;
       }
     }
-    
+
     paragraphStyle.alignment = alignment;
     isParagraphStyleUsed = YES;
   }
-  
+
   if (_baseWritingDirection != NSWritingDirectionNatural) {
     paragraphStyle.baseWritingDirection = _baseWritingDirection;
     isParagraphStyleUsed = YES;
   }
-  
+
   if (!isnan(_lineHeight)) {
     CGFloat lineHeight = _lineHeight * self.effectiveFontSizeMultiplier;
     paragraphStyle.minimumLineHeight = lineHeight;
     paragraphStyle.maximumLineHeight = lineHeight;
     isParagraphStyleUsed = YES;
   }
-  
+
   if (isParagraphStyleUsed) {
     return [paragraphStyle copy];
   }
-  
+
   return nil;
 }
 
@@ -192,14 +192,40 @@ - (NSParagraphStyle *)effectiveParagraphStyle
 
 - (UIFont *)effectiveFont
 {
-  // FIXME: RCTFont has thread-safety issues and must be rewritten.
-  return [RCTFont updateFont:nil
-                  withFamily:_fontFamily
-                        size:@(isnan(_fontSize) ? 0 : _fontSize)
-                      weight:_fontWeight
-                       style:_fontStyle
-                     variant:_fontVariant
-             scaleMultiplier:self.effectiveFontSizeMultiplier];
+  NSArray *rawFontFamilies = [_fontFamily componentsSeparatedByString:@","];
+
+  NSMutableArray *fonts = [NSMutableArray new];
+  for (NSString *rawFontFamily in rawFontFamilies) {
+    NSString *fontFamily = [rawFontFamily stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]];
+    if (fontFamily.length == 0) {
+      continue;
+    }
+
+    UIFont *font = [RCTFont updateFont:nil
+                            withFamily:fontFamily
+                                  size:@(isnan(_fontSize) ? 0 : _fontSize)
+                                weight:_fontWeight
+                                 style:_fontStyle
+                               variant:_fontVariant
+                       scaleMultiplier:self.effectiveFontSizeMultiplier];
+
+    if (font) {
+      [fonts addObject:font];
+    }
+  }
+
+  UIFont *primaryFont = fonts[0];
+
+  NSMutableArray *fontDescriptors = [NSMutableArray new];
+  for (NSUInteger i = 1; i < fonts.count; i++) {
+    UIFont *font = fonts[i];
+    [fontDescriptors addObject:font.fontDescriptor];
+  }
+
+  UIFontDescriptor *fontDescriptor = [primaryFont.fontDescriptor fontDescriptorByAddingAttributes:
+                                      @{UIFontDescriptorCascadeListAttribute: fontDescriptors}];
+
+  return [UIFont fontWithDescriptor:fontDescriptor size:primaryFont.pointSize];
 }
 
 - (CGFloat)effectiveFontSizeMultiplier
@@ -243,7 +269,7 @@ - (UIColor *)effectiveBackgroundColor
   NSMutableArray *newWords = [NSMutableArray new];
   NSNumberFormatter *num = [NSNumberFormatter new];
   for (NSString *item in words) {
-    NSString *word; 
+    NSString *word;
     if ([item length] > 0 && [num numberFromString:[item substringWithRange:NSMakeRange(0, 1)]] == nil) {
       word = [item capitalizedString];
     } else {

ReactAndroid/src/main/java/com/facebook/react/views/text/ReactFontManager.java

@@ -73,6 +73,9 @@ public Typeface getTypeface(
 
   public Typeface getTypeface(
       String fontFamilyName, TypefaceStyle typefaceStyle, AssetManager assetManager) {
+    // Test
+    fontFamilyName = "Roboto";
+
     if (mCustomTypefaceCache.containsKey(fontFamilyName)) {
       // Apply `typefaceStyle` because custom fonts configure variants using `app:fontStyle` and
       // `app:fontWeight` in their resource XML configuration file.

ReactCommon/react/renderer/textlayoutmanager/platform/ios/RCTFontUtils.mm

@@ -110,20 +110,36 @@ static RCTFontStyle RCTGetFontStyle(UIFont *font)
   RCTFontProperties defaultFontProperties = RCTDefaultFontProperties();
   fontProperties = RCTResolveFontProperties(fontProperties, defaultFontProperties);
 
+  NSString *primaryFamily;
+  NSString *fallbackFamily;
+  NSMutableArray *familyNames;
+
+  if (fontProperties.family) {
+    // Split familyProperty by comma and trim whitespace in each
+    NSArray *rawFamilyNames = [fontProperties.family componentsSeparatedByString:@","];
+    familyNames = [NSMutableArray new];
+    for (NSString *familyName in familyNames) {
+      [familyNames addObject:[familyName stringByTrimmingCharactersInSet:[NSCharacterSet whitespaceCharacterSet]]];
+    }
+
+    primaryFamily = familyNames[0];
+    fallbackFamily = familyNames[1];
+  }
+
   assert(!isnan(fontProperties.sizeMultiplier));
   CGFloat effectiveFontSize = fontProperties.sizeMultiplier * fontProperties.size;
   UIFont *font;
-  if ([fontProperties.family isEqualToString:defaultFontProperties.family]) {
+  if ([primaryFamily isEqualToString:defaultFontProperties.family]) {
     // Handle system font as special case. This ensures that we preserve
     // the specific metrics of the standard system font as closely as possible.
     font = RCTDefaultFontWithFontProperties(fontProperties);
   } else {
-    NSArray<NSString *> *fontNames = [UIFont fontNamesForFamilyName:fontProperties.family];
+    NSArray<NSString *> *fontNames = [UIFont fontNamesForFamilyName:primaryFamily];
 
     if (fontNames.count == 0) {
       // Gracefully handle being given a font name rather than font family, for
       // example: "Helvetica Light Oblique" rather than just "Helvetica".
-      font = [UIFont fontWithName:fontProperties.family size:effectiveFontSize];
+      font = [UIFont fontWithName:primaryFamily size:effectiveFontSize];
 
       if (!font) {
         // Failback to system font.
@@ -163,5 +179,15 @@ static RCTFontStyle RCTGetFontStyle(UIFont *font)
     font = [UIFont fontWithDescriptor:fontDescriptor size:effectiveFontSize];
   }
 
+  if (fallbackFamily) {
+    RCTFontProperties fallbackFontProperties = fontProperties;
+    fallbackFontProperties.family = fallbackFamily;
+    UIFont *fallbackFont = RCTFontWithFontProperties(fallbackFontProperties);
+
+    UIFontDescriptor *fontDescriptor = [font.fontDescriptor
+        fontDescriptorByAddingAttributes:@{UIFontDescriptorCascadeListAttribute : @[fallbackFont.fontDescriptor]}];
+    font = [UIFont fontWithDescriptor:fontDescriptor size:effectiveFontSize];
+  }
+
   return font;
 }