Add Dynamic Type support for iOS (Paper and Fabric) (#35017)

Summary:
This adds Dynamic Type support in iOS as described [here](react-native-community/discussions-and-proposals#519).

`Text` elements have a new prop, `dynamicTypeRamp`, that allows users to specify which font ramp a particular `Text` element should take on as the OS's accessibility setting for text size. The different types line up with different values of `UIFontTextStyle`. If not specified, we default to the current behavior.

~~For the moment, this change is only for Paper. I tried applying a corresponding change to Fabric by adding an additional field to [`facebook::react::TextAttributes`](https://github.com/facebook/react-native/blob/main/ReactCommon/react/renderer/attributedstring/TextAttributes.h) and changing [`RCTEffectiveFontSizeMultiplierFromTextAttributes`](https://github.com/facebook/react-native/blob/afb124dcf0cdf0db525acc7cfd2cea2742c64068/ReactCommon/react/renderer/textlayoutmanager/platform/ios/RCTAttributedTextUtils.mm#L79-L84) to use that new field, but in the process I discovered that this function doesn't seem to ever get called, hence [this bug](#34990

## Changelog

[iOS] [Added] - Dynamic Type support

Pull Request resolved: #35017

Test Plan:
Validated with a test page in RNTester. Screenshots follow:

A) Default text size
B) Largest non-accessibility text size
C) Largest accessibility text size, split across two screenshots due to size

| A | B | C |
|-|-|-|
| ![Simulator Screen Shot - iPad (9th generation) - 2022-10-18 at 16 17 08](https://user-images.githubusercontent.com/717674/196562746-c8bbf53d-3c70-4e55-8600-0cfed8aacf5d.png) | ![Simulator Screen Shot - iPad (9th generation) - 2022-10-18 at 16 17 55](https://user-images.githubusercontent.com/717674/196563051-68bb0e34-c573-47ed-8c19-58ae45a7ce2b.png) | ![Simulator Screen Shot - iPad (9th generation) - 2022-10-18 at 16 18 33](https://user-images.githubusercontent.com/717674/196563185-61ede5ee-e79e-4af5-84a7-8f1e230a25f8.png) |
||| ![Simulator Screen Shot - iPad (9th generation) - 2022-10-18 at 16 18 42](https://user-images.githubusercontent.com/717674/196563208-2242efa2-5f24-466d-80f5-eb57a7678a67.png) |

Reviewed By: sammy-SC

Differential Revision: D40779346

Pulled By: NickGerleman

fbshipit-source-id: efc7a8e9810a93afc82c5def97af15a2e8453d90

BUCK

@@ -267,6 +267,7 @@ REACT_PUBLIC_HEADERS = {
     "React/RCTDevLoadingViewProtocol.h": RCTDEVSUPPORT_PATH + "RCTDevLoadingViewProtocol.h",
     "React/RCTDevLoadingViewSetEnabled.h": RCTDEVSUPPORT_PATH + "RCTDevLoadingViewSetEnabled.h",
     "React/RCTDisplayLink.h": RCTBASE_PATH + "RCTDisplayLink.h",
+    "React/RCTDynamicTypeRamp.h": RCTLIB_PATH + "Text/Text/RCTDynamicTypeRamp.h",
     "React/RCTErrorCustomizer.h": RCTBASE_PATH + "RCTErrorCustomizer.h",
     "React/RCTErrorInfo.h": RCTBASE_PATH + "RCTErrorInfo.h",
     # NOTE: RCTEventDispatcher.h is exported from CoreModules:CoreModulesApple

Libraries/Text/BaseText/RCTBaseTextViewManager.m

@@ -36,6 +36,7 @@ - (RCTShadowView *)shadowView
 RCT_REMAP_SHADOW_PROPERTY(fontStyle, textAttributes.fontStyle, NSString)
 RCT_REMAP_SHADOW_PROPERTY(fontVariant, textAttributes.fontVariant, NSArray)
 RCT_REMAP_SHADOW_PROPERTY(allowFontScaling, textAttributes.allowFontScaling, BOOL)
+RCT_REMAP_SHADOW_PROPERTY(dynamicTypeRamp, textAttributes.dynamicTypeRamp, RCTDynamicTypeRamp)
 RCT_REMAP_SHADOW_PROPERTY(maxFontSizeMultiplier, textAttributes.maxFontSizeMultiplier, CGFloat)
 RCT_REMAP_SHADOW_PROPERTY(letterSpacing, textAttributes.letterSpacing, CGFloat)
 // Paragraph Styles

Libraries/Text/RCTTextAttributes.h

@@ -7,6 +7,7 @@
 
 #import <UIKit/UIKit.h>
 
+#import <React/RCTDynamicTypeRamp.h>
 #import <React/RCTTextDecorationLineType.h>
 
 #import "RCTTextTransform.h"
@@ -36,6 +37,7 @@ extern NSString *const RCTTextAttributesTagAttributeName;
 @property (nonatomic, copy, nullable) NSString *fontStyle;
 @property (nonatomic, copy, nullable) NSArray<NSString *> *fontVariant;
 @property (nonatomic, assign) BOOL allowFontScaling;
+@property (nonatomic, assign) RCTDynamicTypeRamp dynamicTypeRamp;
 @property (nonatomic, assign) CGFloat letterSpacing;
 // Paragraph Styles
 @property (nonatomic, assign) CGFloat lineHeight;

Libraries/Text/RCTTextAttributes.m

@@ -59,6 +59,8 @@ - (void)applyTextAttributes:(RCTTextAttributes *)textAttributes
   _fontStyle = textAttributes->_fontStyle ?: _fontStyle;
   _fontVariant = textAttributes->_fontVariant ?: _fontVariant;
   _allowFontScaling = textAttributes->_allowFontScaling || _allowFontScaling; // *
+  _dynamicTypeRamp = textAttributes->_dynamicTypeRamp != RCTDynamicTypeRampUndefined ? textAttributes->_dynamicTypeRamp
+                                                                                     : _dynamicTypeRamp;
   _letterSpacing = !isnan(textAttributes->_letterSpacing) ? textAttributes->_letterSpacing : _letterSpacing;
 
   // Paragraph Styles
@@ -230,6 +232,12 @@ - (CGFloat)effectiveFontSizeMultiplier
 
   if (fontScalingEnabled) {
     CGFloat fontSizeMultiplier = !isnan(_fontSizeMultiplier) ? _fontSizeMultiplier : 1.0;
+    if (_dynamicTypeRamp != RCTDynamicTypeRampUndefined) {
+      UIFontMetrics *fontMetrics = RCTUIFontMetricsForDynamicTypeRamp(_dynamicTypeRamp);
+      // Using a specific font size reduces rounding errors from -scaledValueForValue:
+      CGFloat requestedSize = isnan(_fontSize) ? RCTBaseSizeForDynamicTypeRamp(_dynamicTypeRamp) : _fontSize;
+      fontSizeMultiplier = [fontMetrics scaledValueForValue:requestedSize] / requestedSize;
+    }
     CGFloat maxFontSizeMultiplier = !isnan(_maxFontSizeMultiplier) ? _maxFontSizeMultiplier : 0.0;
     return maxFontSizeMultiplier >= 1.0 ? fminf(maxFontSizeMultiplier, fontSizeMultiplier) : fontSizeMultiplier;
   } else {
@@ -324,7 +332,7 @@ - (BOOL)isEqual:(RCTTextAttributes *)textAttributes
       RCTTextAttributesCompareFloats(_fontSizeMultiplier) && RCTTextAttributesCompareFloats(_maxFontSizeMultiplier) &&
       RCTTextAttributesCompareStrings(_fontWeight) && RCTTextAttributesCompareObjects(_fontStyle) &&
       RCTTextAttributesCompareObjects(_fontVariant) && RCTTextAttributesCompareOthers(_allowFontScaling) &&
-      RCTTextAttributesCompareFloats(_letterSpacing) &&
+      RCTTextAttributesCompareOthers(_dynamicTypeRamp) && RCTTextAttributesCompareFloats(_letterSpacing) &&
       // Paragraph Styles
       RCTTextAttributesCompareFloats(_lineHeight) && RCTTextAttributesCompareFloats(_alignment) &&
       RCTTextAttributesCompareOthers(_baseWritingDirection) && RCTTextAttributesCompareOthers(_lineBreakStrategy) &&

Libraries/Text/Text.d.ts

@@ -26,6 +26,23 @@ export interface TextPropsIOS {
    */
   adjustsFontSizeToFit?: boolean | undefined;
 
+  /**
+   * The Dynamic Text scale ramp to apply to this element on iOS.
+   */
+  dynamicTypeRamp?:
+    | 'caption2'
+    | 'caption1'
+    | 'footnote'
+    | 'subheadline'
+    | 'callout'
+    | 'body'
+    | 'headline'
+    | 'title3'
+    | 'title2'
+    | 'title1'
+    | 'largeTitle'
+    | undefined;
+
   /**
    * Specifies smallest possible scale a font can reach when adjustsFontSizeToFit is enabled. (values 0.01-1.0).
    */

Libraries/Text/Text/RCTDynamicTypeRamp.h

@@ -0,0 +1,37 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+#import <Foundation/Foundation.h>
+
+#import <React/RCTConvert.h>
+
+typedef NS_ENUM(NSInteger, RCTDynamicTypeRamp) {
+  RCTDynamicTypeRampUndefined,
+  RCTDynamicTypeRampCaption2,
+  RCTDynamicTypeRampCaption1,
+  RCTDynamicTypeRampFootnote,
+  RCTDynamicTypeRampSubheadline,
+  RCTDynamicTypeRampCallout,
+  RCTDynamicTypeRampBody,
+  RCTDynamicTypeRampHeadline,
+  RCTDynamicTypeRampTitle3,
+  RCTDynamicTypeRampTitle2,
+  RCTDynamicTypeRampTitle1,
+  RCTDynamicTypeRampLargeTitle
+};
+
+@interface RCTConvert (DynamicTypeRamp)
+
++ (RCTDynamicTypeRamp)RCTDynamicTypeRamp:(nullable id)json;
+
+@end
+
+/// Generates a `UIFontMetrics` instance representing a particular Dynamic Type ramp.
+UIFontMetrics *_Nonnull RCTUIFontMetricsForDynamicTypeRamp(RCTDynamicTypeRamp dynamicTypeRamp);
+/// The "reference" size for a particular font scale ramp, equal to a text element's size under default text size
+/// settings.
+CGFloat RCTBaseSizeForDynamicTypeRamp(RCTDynamicTypeRamp dynamicTypeRamp);

Libraries/Text/Text/RCTDynamicTypeRamp.m

@@ -0,0 +1,82 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and 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/RCTDynamicTypeRamp.h>
+
+@implementation RCTConvert (DynamicTypeRamp)
+
+RCT_ENUM_CONVERTER(
+    RCTDynamicTypeRamp,
+    (@{
+      @"caption2" : @(RCTDynamicTypeRampCaption2),
+      @"caption1" : @(RCTDynamicTypeRampCaption1),
+      @"footnote" : @(RCTDynamicTypeRampFootnote),
+      @"subheadline" : @(RCTDynamicTypeRampSubheadline),
+      @"callout" : @(RCTDynamicTypeRampCallout),
+      @"body" : @(RCTDynamicTypeRampBody),
+      @"headline" : @(RCTDynamicTypeRampHeadline),
+      @"title3" : @(RCTDynamicTypeRampTitle3),
+      @"title2" : @(RCTDynamicTypeRampTitle2),
+      @"title1" : @(RCTDynamicTypeRampTitle1),
+      @"largeTitle" : @(RCTDynamicTypeRampLargeTitle),
+    }),
+    RCTDynamicTypeRampUndefined,
+    integerValue)
+
+@end
+
+UIFontMetrics *RCTUIFontMetricsForDynamicTypeRamp(RCTDynamicTypeRamp dynamicTypeRamp)
+{
+  static NSDictionary<NSNumber *, UIFontTextStyle> *mapping;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    mapping = @{
+      @(RCTDynamicTypeRampCaption2) : UIFontTextStyleCaption2,
+      @(RCTDynamicTypeRampCaption1) : UIFontTextStyleCaption1,
+      @(RCTDynamicTypeRampFootnote) : UIFontTextStyleFootnote,
+      @(RCTDynamicTypeRampSubheadline) : UIFontTextStyleSubheadline,
+      @(RCTDynamicTypeRampCallout) : UIFontTextStyleCallout,
+      @(RCTDynamicTypeRampBody) : UIFontTextStyleBody,
+      @(RCTDynamicTypeRampHeadline) : UIFontTextStyleHeadline,
+      @(RCTDynamicTypeRampTitle3) : UIFontTextStyleTitle3,
+      @(RCTDynamicTypeRampTitle2) : UIFontTextStyleTitle2,
+      @(RCTDynamicTypeRampTitle1) : UIFontTextStyleTitle1,
+      @(RCTDynamicTypeRampLargeTitle) : UIFontTextStyleLargeTitle,
+    };
+  });
+
+  id textStyle =
+      mapping[@(dynamicTypeRamp)] ?: UIFontTextStyleBody; // Default to body if we don't recognize the specified ramp
+  return [UIFontMetrics metricsForTextStyle:textStyle];
+}
+
+CGFloat RCTBaseSizeForDynamicTypeRamp(RCTDynamicTypeRamp dynamicTypeRamp)
+{
+  static NSDictionary<NSNumber *, NSNumber *> *mapping;
+  static dispatch_once_t onceToken;
+  dispatch_once(&onceToken, ^{
+    // Values taken from
+    // https://developer.apple.com/design/human-interface-guidelines/foundations/typography/#specifications
+    mapping = @{
+      @(RCTDynamicTypeRampCaption2) : @11,
+      @(RCTDynamicTypeRampCaption1) : @12,
+      @(RCTDynamicTypeRampFootnote) : @13,
+      @(RCTDynamicTypeRampSubheadline) : @15,
+      @(RCTDynamicTypeRampCallout) : @16,
+      @(RCTDynamicTypeRampBody) : @17,
+      @(RCTDynamicTypeRampHeadline) : @17,
+      @(RCTDynamicTypeRampTitle3) : @20,
+      @(RCTDynamicTypeRampTitle2) : @22,
+      @(RCTDynamicTypeRampTitle1) : @28,
+      @(RCTDynamicTypeRampLargeTitle) : @34,
+    };
+  });
+
+  NSNumber *baseSize =
+      mapping[@(dynamicTypeRamp)] ?: @17; // Default to body size if we don't recognize the specified ramp
+  return CGFLOAT_IS_DOUBLE ? [baseSize doubleValue] : [baseSize floatValue];
+}

Libraries/Text/TextNativeComponent.js

@@ -34,6 +34,7 @@ const textViewConfig = {
     numberOfLines: true,
     ellipsizeMode: true,
     allowFontScaling: true,
+    dynamicTypeRamp: true,
     maxFontSizeMultiplier: true,
     disabled: true,
     selectable: true,

Libraries/Text/TextProps.js

@@ -228,6 +228,23 @@ export type TextProps = $ReadOnly<{|
    */
   adjustsFontSizeToFit?: ?boolean,
 
+  /**
+   * The Dynamic Text scale ramp to apply to this element on iOS.
+   */
+  dynamicTypeRamp?: ?(
+    | 'caption2'
+    | 'caption1'
+    | 'footnote'
+    | 'subheadline'
+    | 'callout'
+    | 'body'
+    | 'headline'
+    | 'title3'
+    | 'title2'
+    | 'title1'
+    | 'largeTitle'
+  ),
+
   /**
    * Smallest possible scale a font can reach.
    *

ReactCommon/react/renderer/attributedstring/TextAttributes.cpp

@@ -46,6 +46,9 @@ void TextAttributes::apply(TextAttributes textAttributes) {
   allowFontScaling = textAttributes.allowFontScaling.has_value()
       ? textAttributes.allowFontScaling
       : allowFontScaling;
+  dynamicTypeRamp = textAttributes.dynamicTypeRamp.has_value()
+      ? textAttributes.dynamicTypeRamp
+      : dynamicTypeRamp;
   letterSpacing = !std::isnan(textAttributes.letterSpacing)
       ? textAttributes.letterSpacing
       : letterSpacing;
@@ -111,6 +114,7 @@ bool TextAttributes::operator==(const TextAttributes &rhs) const {
              fontStyle,
              fontVariant,
              allowFontScaling,
+             dynamicTypeRamp,
              alignment,
              baseWritingDirection,
              lineBreakStrategy,
@@ -131,6 +135,7 @@ bool TextAttributes::operator==(const TextAttributes &rhs) const {
              rhs.fontStyle,
              rhs.fontVariant,
              rhs.allowFontScaling,
+             rhs.dynamicTypeRamp,
              rhs.alignment,
              rhs.baseWritingDirection,
              rhs.lineBreakStrategy,
@@ -186,6 +191,7 @@ SharedDebugStringConvertibleList TextAttributes::getDebugProps() const {
       debugStringConvertibleItem("fontStyle", fontStyle),
       debugStringConvertibleItem("fontVariant", fontVariant),
       debugStringConvertibleItem("allowFontScaling", allowFontScaling),
+      debugStringConvertibleItem("dynamicTypeRamp", dynamicTypeRamp),
       debugStringConvertibleItem("letterSpacing", letterSpacing),
 
       // Paragraph Styles

ReactCommon/react/renderer/attributedstring/TextAttributes.h

@@ -51,6 +51,7 @@ class TextAttributes : public DebugStringConvertible {
   std::optional<FontStyle> fontStyle{};
   std::optional<FontVariant> fontVariant{};
   std::optional<bool> allowFontScaling{};
+  std::optional<DynamicTypeRamp> dynamicTypeRamp{};
   Float letterSpacing{std::numeric_limits<Float>::quiet_NaN()};
   std::optional<TextTransform> textTransform{};
 

ReactCommon/react/renderer/attributedstring/conversions.h

@@ -34,6 +34,84 @@
 namespace facebook {
 namespace react {
 
+inline std::string toString(const DynamicTypeRamp &dynamicTypeRamp) {
+  switch (dynamicTypeRamp) {
+    case DynamicTypeRamp::Caption2:
+      return "caption2";
+    case DynamicTypeRamp::Caption1:
+      return "caption1";
+    case DynamicTypeRamp::Footnote:
+      return "footnote";
+    case DynamicTypeRamp::Subheadline:
+      return "subheadline";
+    case DynamicTypeRamp::Callout:
+      return "callout";
+    case DynamicTypeRamp::Body:
+      return "body";
+    case DynamicTypeRamp::Headline:
+      return "headline";
+    case DynamicTypeRamp::Title3:
+      return "title3";
+    case DynamicTypeRamp::Title2:
+      return "title2";
+    case DynamicTypeRamp::Title1:
+      return "title1";
+    case DynamicTypeRamp::LargeTitle:
+      return "largeTitle";
+  }
+
+  LOG(ERROR) << "Unsupported DynamicTypeRamp value";
+  react_native_assert(false);
+
+  // Sane default in case of parsing errors
+  return "body";
+}
+
+inline void fromRawValue(
+    const PropsParserContext &context,
+    const RawValue &value,
+    DynamicTypeRamp &result) {
+  react_native_assert(value.hasType<std::string>());
+  if (value.hasType<std::string>()) {
+    auto string = (std::string)value;
+    if (string == "caption2") {
+      result = DynamicTypeRamp::Caption2;
+    } else if (string == "caption1") {
+      result = DynamicTypeRamp::Caption1;
+    } else if (string == "footnote") {
+      result = DynamicTypeRamp::Footnote;
+    } else if (string == "subheadline") {
+      result = DynamicTypeRamp::Subheadline;
+    } else if (string == "callout") {
+      result = DynamicTypeRamp::Callout;
+    } else if (string == "body") {
+      result = DynamicTypeRamp::Body;
+    } else if (string == "headline") {
+      result = DynamicTypeRamp::Headline;
+    } else if (string == "title3") {
+      result = DynamicTypeRamp::Title3;
+    } else if (string == "title2") {
+      result = DynamicTypeRamp::Title2;
+    } else if (string == "title1") {
+      result = DynamicTypeRamp::Title1;
+    } else if (string == "largeTitle") {
+      result = DynamicTypeRamp::LargeTitle;
+    } else {
+      // sane default
+      LOG(ERROR) << "Unsupported DynamicTypeRamp value: " << string;
+      react_native_assert(false);
+      result = DynamicTypeRamp::Body;
+    }
+    return;
+  }
+
+  LOG(ERROR) << "Unsupported DynamicTypeRamp type";
+  react_native_assert(false);
+
+  // Sane default in case of parsing errors
+  result = DynamicTypeRamp::Body;
+}
+
 inline std::string toString(const EllipsizeMode &ellipsisMode) {
   switch (ellipsisMode) {
     case EllipsizeMode::Clip: