fontWeight behavior changed on Android between <0.60.0 and >= 0.60.0 - now high font weights can default to low ones

[iamacup]

Prior to 0.60.0 font weights that were not supported but were high would default to the nearest 'bold' font. Now they just default to a non-bold font.

React Native version:

Steps To Reproduce

1a. react-native init AwesomeProject (at time of writing defaults to version 0.60.3)
2a. Use this code in App.js

import React, {Fragment} from 'react';
import { Text, SafeAreaView } from 'react-native';

const App = () => {
  return (
      <SafeAreaView>
        <Text style={{fontWeight: '900'}}>FONT WEIGHT 900</Text>
        <Text style={{fontWeight: '800'}}>FONT WEIGHT 800</Text>
        <Text style={{fontWeight: '700'}}>FONT WEIGHT 700</Text>
        <Text style={{fontWeight: '600'}}>FONT WEIGHT 600</Text>
        <Text style={{fontWeight: '500'}}>FONT WEIGHT 500</Text>
        <Text style={{fontWeight: '400'}}>FONT WEIGHT 400</Text>
        <Text style={{fontWeight: '300'}}>FONT WEIGHT 300</Text>
        <Text style={{fontWeight: '200'}}>FONT WEIGHT 200</Text>
        <Text style={{fontWeight: '100'}}>FONT WEIGHT 100</Text>
      </SafeAreaView>
  );
};

export default App;

3a. Run the app in an emulator or on device
4a. Output: https://imgur.com/VEpgKzC

react-native info

  info Fetching system and libraries information...
  System:
      OS: macOS 10.14.5
      CPU: (8) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
      Memory: 1.28 GB / 16.00 GB
      Shell: 3.2.57 - /bin/bash
    Binaries:
      Node: 12.2.0 - /usr/local/bin/node
      Yarn: 1.15.2 - /usr/local/bin/yarn
      npm: 6.10.0 - /usr/local/bin/npm
      Watchman: 4.9.0 - /usr/local/bin/watchman
    SDKs:
      iOS SDK:
        Platforms: iOS 12.2, macOS 10.14, tvOS 12.2, watchOS 5.2
      Android SDK:
        API Levels: 23, 28
        Build Tools: 28.0.3
        System Images: android-28 | Intel x86 Atom_64, android-28 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom
    IDEs:
      Android Studio: 3.4 AI-183.6156.11.34.5692245
      Xcode: 10.2.1/10E1001 - /usr/bin/xcodebuild
    npmPackages:
      react: 16.8.6 => 16.8.6 
      react-native: 0.60.3 => 0.60.3 
    npmGlobalPackages:
      create-react-native-app: 1.0.0
      react-native-cli: 2.0.1
    

THEN

1b. react-native init AwesomeProject2 --version 0.59.9
2b. Use code from above in App.js
3b. Run the app in an emulator or on device
4b. Output: https://imgur.com/ZW9hZGU

react-native info

  info 
    React Native Environment Info:
      System:
        OS: macOS 10.14.5
        CPU: (8) x64 Intel(R) Core(TM) i7-7700HQ CPU @ 2.80GHz
        Memory: 1.34 GB / 16.00 GB
        Shell: 3.2.57 - /bin/bash
      Binaries:
        Node: 12.2.0 - /usr/local/bin/node
        Yarn: 1.15.2 - /usr/local/bin/yarn
        npm: 6.10.0 - /usr/local/bin/npm
        Watchman: 4.9.0 - /usr/local/bin/watchman
      SDKs:
        iOS SDK:
          Platforms: iOS 12.2, macOS 10.14, tvOS 12.2, watchOS 5.2
        Android SDK:
          API Levels: 23, 28
          Build Tools: 28.0.3
          System Images: android-28 | Intel x86 Atom_64, android-28 | Google APIs Intel x86 Atom, android-28 | Google Play Intel x86 Atom
      IDEs:
        Android Studio: 3.4 AI-183.6156.11.34.5692245
        Xcode: 10.2.1/10E1001 - /usr/bin/xcodebuild
      npmPackages:
        react: 16.8.3 => 16.8.3 
        react-native: 0.59.9 => 0.59.9 
      npmGlobalPackages:
        create-react-native-app: 1.0.0
        react-native-cli: 2.0.1
  

Describe what you expected to happen:

When an unsupported font weight is higher than a supported, non standard font weight, the default should be picked as the fatter one not the skinny one.

Snack, code example, or link to a repository:

[RobinCsl]

It looks like this originates from this commit 3915c0f#diff-d4141c42bc6789637b6fdc7754ec1dd9

In particular, the commit message says:

This change might break texts where fontWeight use improperly, because this PR removes conversion of values above 500 to BOLD and below 500 to normal.

[iamacup]

I don't really know if this is an issue or not then - this is the code i am using to 'fix' the fonts in my code base, this does not apply if you are using custom fonts and it is not using the roboto default which does not seem to support very many font weights out of the box.

iOS:

Android:

const oldRender = Text.render;

const settings = [
// we use this empty object for when there is no weight specified
  {},
  {
    fontFamily: 'sans-serif-thin',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif-light',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif-medium',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif',
    fontWeight: 'bold',
  }, {
    fontFamily: 'sans-serif-medium',
    fontWeight: 'bold',
  },
];

const defaultIndex = 0;

Text.render = (...args) => {
  const origin = oldRender.call(this, ...args);

  if (Platform.OS === 'android') {
    let useIndex = defaultIndex;

    if (typeof origin.props.style !== 'undefined' && typeof origin.props.style.fontWeight !== 'undefined') {
      const { fontWeight } = origin.props.style;

      if (fontWeight === '100' || fontWeight === '200' || fontWeight === '300') {
        useIndex = 1;
      } else if (fontWeight === '400') {
        useIndex = 2;
      } else if (fontWeight === '500' || fontWeight === 'normal') {
        useIndex = 3;
      } else if (fontWeight === '600') {
        useIndex = 4;
      } else if (fontWeight === '700' || fontWeight === 'bold') {
        useIndex = 5;
      } else if (fontWeight === '800' || fontWeight === '900') {
        useIndex = 6;
      }
    }

    return React.cloneElement(origin, {
      style: [settings[defaultIndex], Platform.OS === 'android' ? { fontFamily: 'Roboto' } : {}, origin.props.style, settings[useIndex]],
    });
  }

  return origin;
};

[steventilator]

Shouldn't this issue be open? It's definitely not desired behaviour if a fontWeight of '900' defaults to Roboto Regular on Android. This essentially means I have to either use the hack mentioned by @iamacup or use a custom font that includes all the font weights I need.

[jorgemasta]

I don't really know if this is an issue or not then - this is the code i am using to 'fix' the fonts in my code base, this does not apply if you are using custom fonts and it is not using the roboto default which does not seem to support very many font weights out of the box.

iOS:

Android:

const oldRender = Text.render;

const settings = [{
    fontFamily: 'sans-serif-thin',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif-light',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif-medium',
    fontWeight: 'normal',
  }, {
    fontFamily: 'sans-serif',
    fontWeight: 'bold',
  }, {
    fontFamily: 'sans-serif-medium',
    fontWeight: 'bold',
  }
];

const defaultIndex = 2;

Text.render = (...args) => {
  const origin = oldRender.call(this, ...args);

  if (Platform.OS === 'android') {
    let useIndex = defaultIndex;

    if (typeof origin.props.style !== 'undefined' && typeof origin.props.style.fontWeight !== 'undefined') {
      const { fontWeight } = origin.props.style;

      if (fontWeight === '100' || fontWeight === '200' || fontWeight === '300') {
        useIndex = 0;
      } else if (fontWeight === '400') {
        useIndex = 1;
      } else if (fontWeight === '500' || fontWeight === 'normal') {
        useIndex = 2;
      } else if (fontWeight === '600') {
        useIndex = 3;
      } else if (fontWeight === '700' || fontWeight === 'bold') {
        useIndex = 4;
      } else if (fontWeight === '800' || fontWeight === '900') {
        useIndex = 5;
      }
    }

    return React.cloneElement(origin, {
      style: [settings[defaultIndex], origin.props.style, settings[useIndex]],
    });
  }

  return origin;
};

@iamacup
Could you explain a bit more about your solution?

[gaodeng]

+1

Shouldn't this issue be open? It's definitely not desired behaviour if a fontWeight of '900' defaults to Roboto Regular on Android. This essentially means I have to either use the hack mentioned by @iamacup or use a custom font that includes all the font weights I need.

@iamacup Could you re-open this issue?

[iamacup]

Done :)

@jorgemasta His solution is simulating the previous font weight rendering on android. I ended up using his solution to do something similar in our code base for our custom text component.

// @flow
import * as React from 'react';
import { StyleSheet, Text as RNText, Platform } from 'react-native';

type Props = {|
    ...
    style: {} | number | $ReadOnlyArray<?{} | ?number | null>,
    title: ?boolean,
    medium: ?boolean,
    italic?: ?boolean,
|};

const styles = StyleSheet.create({
	...
    medium: { fontWeight: '500' },
	androidMedium: {
		fontFamily: 'Roboto-Medium',
		fontWeight: '500',
	},
	roboto100: {
		fontFamily: 'Roboto-Thin',
	},
	roboto100Italic: {
		fontFamily: 'Roboto-ThinItalic',
	},
	roboto300: {
		fontFamily: 'Roboto-Light',
	},
	roboto300Italic: {
		fontFamily: 'Roboto-LightItalic',
	},
	roboto400: {
		fontFamily: 'Roboto-Regular',
	},
	roboto400Italic: {
		fontFamily: 'Roboto-Italic',
	},
	roboto500: {
		fontFamily: 'Roboto-Medium',
	},
	roboto500Italic: {
		fontFamily: 'Roboto-MediumItalic',
	},
	roboto700: {
		fontFamily: 'Roboto-Bold',
	},
	roboto700Italic: {
		fontFamily: 'Roboto-BoldItalic',
	},
	roboto900: {
		fontFamily: 'Roboto-Black',
	},
	roboto900Italic: {
		fontFamily: 'Roboto-BlackItalic',
	},
});

...

const androidGetFontWeightStyles = ({
	title,
	medium,
	italic,
	style,
}: Props): {} => {
	if (title || medium) {
		return styles.androidMedium;
	}

	// $FlowFixMe
	if (style && style.fontWeight !== undefined) {
		// $FlowFixMe
		const isItalic = italic || style.fontStyle === 'italic';
		const fontFamilyStyle =
			styles[`roboto${style.fontWeight}${isItalic ? 'Italic' : ''}`];
		if (fontFamilyStyle) {
			return fontFamilyStyle;
		}
	}

	return {};
};

const getFontWeightStyles = (props: Props): {} => {
	if (Platform.OS === 'android') {
		return androidGetFontWeightStyles(props);
	}

	if (props.title || props.medium) {
		return styles.medium;
	}

	return {};
};

export default function Text(props: Props) {
    ...

	const textStyles = [
		...
		getFontWeightStyles(props),
	];
    
    ...
    
	return (
		<RNText style={textStyles}>
			...
		</RNText>
	);
}

...

[dulmandakh]

I introduced the change to add support for other font weights natively and fix parity with iOS. Custom font weight support wasn't available when RN emerged, but added later in SDK 25 or 26.