Implement adjustsFontSizeToFit on Android (#26389)

Summary: This adds support for `adjustsFontSizeToFit` and `minimumFontScale` on Android. The implementation tries to match closely the behaviour on iOS (hardcoded 4px min size for example). It uses a simpler linear algorithm for now, opened to improving it now if it is a deal breaker or in a follow up. See https://twitter.com/janicduplessis/status/1171147709979516929 for a more detailed thread about the implementation ## Changelog [Android] [Added] - Implement `adjustsFontSizeToFit` on Android Pull Request resolved: #26389 Test Plan: Tested by adding the existing `adjustsFontSizeToFit` example from the iOS text page to android. Also added a case for limiting size by using `maxHeight` instead of `numberOfLines`. Reviewed By: mdvacca Differential Revision: D17285473 Pulled By: JoshuaGross fbshipit-source-id: 43dbdb05e2d6418e9a390d11f921518bfa58e697
facebook · Feb 13, 2020 · 474861f · 474861f
1 parent 048b537
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diff --git a/RNTester/js/examples/Text/TextExample.android.js b/RNTester/js/examples/Text/TextExample.android.js
@@ -16,7 +16,7 @@ const React = require('react');
 const TextInlineView = require('../../components/TextInlineView');
 const TextLegend = require('../../components/TextLegend');
 
-const {StyleSheet, Text, View} = require('react-native');
+const {LayoutAnimation, StyleSheet, Text, View} = require('react-native');
 
 class Entity extends React.Component<{|children: React.Node|}> {
   render() {
@@ -70,10 +70,137 @@ class AttributeToggler extends React.Component<{...}, $FlowFixMeState> {
   }
 }
 
+type AdjustingFontSizeProps = $ReadOnly<{||}>;
+
+type AdjustingFontSizeState = {|
+  dynamicText: string,
+  shouldRender: boolean,
+|};
+
+class AdjustingFontSize extends React.Component<
+  AdjustingFontSizeProps,
+  AdjustingFontSizeState,
+> {
+  state = {
+    dynamicText: '',
+    shouldRender: true,
+  };
+
+  reset = () => {
+    LayoutAnimation.easeInEaseOut();
+    this.setState({
+      shouldRender: false,
+    });
+    setTimeout(() => {
+      LayoutAnimation.easeInEaseOut();
+      this.setState({
+        dynamicText: '',
+        shouldRender: true,
+      });
+    }, 300);
+  };
+
+  addText = () => {
+    this.setState({
+      dynamicText:
+        this.state.dynamicText +
+        (Math.floor((Math.random() * 10) % 2) ? ' foo' : ' bar'),
+    });
+  };
+
+  removeText = () => {
+    this.setState({
+      dynamicText: this.state.dynamicText.slice(
+        0,
+        this.state.dynamicText.length - 4,
+      ),
+    });
+  };
+
+  render() {
+    if (!this.state.shouldRender) {
+      return <View />;
+    }
+    return (
+      <View>
+        <Text
+          ellipsizeMode="tail"
+          numberOfLines={1}
+          style={{fontSize: 36, marginVertical: 6}}>
+          Truncated text is baaaaad.
+        </Text>
+        <Text
+          numberOfLines={1}
+          adjustsFontSizeToFit={true}
+          style={{fontSize: 40, marginVertical: 6}}>
+          Shrinking to fit available space is much better!
+        </Text>
+
+        <Text
+          adjustsFontSizeToFit={true}
+          numberOfLines={1}
+          style={{fontSize: 30, marginVertical: 6}}>
+          {'Add text to me to watch me shrink!' + ' ' + this.state.dynamicText}
+        </Text>
+
+        <Text
+          adjustsFontSizeToFit={true}
+          numberOfLines={4}
+          style={{fontSize: 20, marginVertical: 6}}>
+          {'Multiline text component shrinking is supported, watch as this reeeeaaaally loooooong teeeeeeext grooooows and then shriiiinks as you add text to me! ioahsdia soady auydoa aoisyd aosdy ' +
+            ' ' +
+            this.state.dynamicText}
+        </Text>
+
+        <Text
+          adjustsFontSizeToFit={true}
+          style={{fontSize: 20, marginVertical: 6, maxHeight: 50}}>
+          {'Text limited by height, watch as this reeeeaaaally loooooong teeeeeeext grooooows and then shriiiinks as you add text to me! ioahsdia soady auydoa aoisyd aosdy ' +
+            ' ' +
+            this.state.dynamicText}
+        </Text>
+
+        <Text
+          adjustsFontSizeToFit={true}
+          numberOfLines={1}
+          style={{marginVertical: 6}}>
+          <Text style={{fontSize: 14}}>
+            {'Differently sized nested elements will shrink together. '}
+          </Text>
+          <Text style={{fontSize: 20}}>
+            {'LARGE TEXT! ' + this.state.dynamicText}
+          </Text>
+        </Text>
+
+        <View
+          style={{
+            flexDirection: 'row',
+            justifyContent: 'space-around',
+            marginTop: 5,
+            marginVertical: 6,
+          }}>
+          <Text style={{backgroundColor: '#ffaaaa'}} onPress={this.reset}>
+            Reset
+          </Text>
+          <Text style={{backgroundColor: '#aaaaff'}} onPress={this.removeText}>
+            Remove Text
+          </Text>
+          <Text style={{backgroundColor: '#aaffaa'}} onPress={this.addText}>
+            Add Text
+          </Text>
+        </View>
+      </View>
+    );
+  }
+}
+
 class TextExample extends React.Component<{...}> {
   render(): React.Node {
     return (
       <RNTesterPage title="<Text>">
+        <RNTesterBlock title="Dynamic Font Size Adjustment">
+          <AdjustingFontSize />
+        </RNTesterBlock>
         <RNTesterBlock title="Wrap">
           <Text>
             The text should wrap if it goes on multiple lines. See, this is

diff --git a/RNTester/js/examples/Text/TextExample.ios.js b/RNTester/js/examples/Text/TextExample.ios.js
@@ -222,6 +222,14 @@ class AdjustingFontSize extends React.Component<
             this.state.dynamicText}
         </Text>
 
+        <Text
+          adjustsFontSizeToFit={true}
+          style={{fontSize: 20, marginVertical: 6, maxHeight: 50}}>
+          {'Text limited by height, watch as this reeeeaaaally loooooong teeeeeeext grooooows and then shriiiinks as you add text to me! ioahsdia soady auydoa aoisyd aosdy ' +
+            ' ' +
+            this.state.dynamicText}
+        </Text>
+
         <Text
           adjustsFontSizeToFit={true}
           numberOfLines={1}

diff --git a/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewProps.java b/ReactAndroid/src/main/java/com/facebook/react/uimanager/ViewProps.java
@@ -90,6 +90,8 @@ public class ViewProps {
   public static final String NEEDS_OFFSCREEN_ALPHA_COMPOSITING = "needsOffscreenAlphaCompositing";
   public static final String NUMBER_OF_LINES = "numberOfLines";
   public static final String ELLIPSIZE_MODE = "ellipsizeMode";
+  public static final String ADJUSTS_FONT_SIZE_TO_FIT = "adjustsFontSizeToFit";
+  public static final String MINIMUM_FONT_SCALE = "minimumFontScale";
   public static final String ON = "on";
   public static final String RESIZE_MODE = "resizeMode";
   public static final String RESIZE_METHOD = "resizeMethod";

diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactBaseTextShadowNode.java b/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactBaseTextShadowNode.java
@@ -319,7 +319,6 @@ protected Spannable spannedFromShadowNode(
       (Build.VERSION.SDK_INT < Build.VERSION_CODES.M) ? 0 : Layout.HYPHENATION_FREQUENCY_NONE;
   protected int mJustificationMode =
       (Build.VERSION.SDK_INT < Build.VERSION_CODES.O) ? 0 : Layout.JUSTIFICATION_MODE_NONE;
-  protected TextTransform mTextTransform = TextTransform.UNSET;
 
   protected float mTextShadowOffsetDx = 0;
   protected float mTextShadowOffsetDy = 0;
@@ -329,6 +328,8 @@ protected Spannable spannedFromShadowNode(
   protected boolean mIsUnderlineTextDecorationSet = false;
   protected boolean mIsLineThroughTextDecorationSet = false;
   protected boolean mIncludeFontPadding = true;
+  protected boolean mAdjustsFontSizeToFit = false;
+  protected float mMinimumFontScale = 0;
 
   /**
    * mFontStyle can be {@link Typeface#NORMAL} or {@link Typeface#ITALIC}. mFontWeight can be {@link
@@ -605,4 +606,20 @@ public void setTextTransform(@Nullable String textTransform) {
     }
     markUpdated();
   }
+
+  @ReactProp(name = ViewProps.ADJUSTS_FONT_SIZE_TO_FIT)
+  public void setAdjustFontSizeToFit(boolean adjustsFontSizeToFit) {
+    if (adjustsFontSizeToFit != mAdjustsFontSizeToFit) {
+      mAdjustsFontSizeToFit = adjustsFontSizeToFit;
+      markUpdated();
+    }
+  }
+
+  @ReactProp(name = ViewProps.MINIMUM_FONT_SCALE)
+  public void setMinimumFontScale(float minimumFontScale) {
+    if (minimumFontScale != mMinimumFontScale) {
+      mMinimumFontScale = minimumFontScale;
+      markUpdated();
+    }
+  }
 }
diff --git a/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactTextAnchorViewManager.java b/ReactAndroid/src/main/java/com/facebook/react/views/text/ReactTextAnchorViewManager.java
@@ -60,6 +60,11 @@ public void setEllipsizeMode(ReactTextView view, @Nullable String ellipsizeMode)
     }
   }
 
+  @ReactProp(name = ViewProps.ADJUSTS_FONT_SIZE_TO_FIT)
+  public void setAdjustFontSizeToFit(ReactTextView view, boolean adjustsFontSizeToFit) {
+    view.setAdjustFontSizeToFit(adjustsFontSizeToFit);
+  }
+
   @ReactProp(name = ViewProps.TEXT_ALIGN_VERTICAL)
   public void setTextAlignVertical(ReactTextView view, @Nullable String textAlignVertical) {
     if (textAlignVertical == null || "auto".equals(textAlignVertical)) {