Correct android font weight (#2141)

Co-Authored-By: Drapich Piotr <drapich.piotr@gmail.com>

src/index.js

@@ -22,6 +22,7 @@ import './globals';
 import { getTranslation } from '../i18n-cache';
 import initialHtml from './initial-html';
 import setupApiFetch from './api-fetch-setup';
+import correctTextFontWeight from './text-font-weight-correct';
 import setupJetpackEditor from './jetpack-editor-setup';
 
 const gutenbergSetup = () => {
@@ -56,6 +57,7 @@ export class RootComponent extends React.Component {
 		super( props );
 		setupLocale( props.locale, props.translations );
 		setupApiFetch();
+		correctTextFontWeight();
 		setupJetpackEditor( props.jetpackState || { blogId: 1, isJetpackActive: true } );
 		require( '@wordpress/edit-post' ).initializeEditor();
 

src/text-font-weight-correct.js

@@ -0,0 +1,77 @@
+/**
+ * External dependencies
+ *
+ * @format
+ */
+
+/**
+ * External dependencies
+ */
+import { Platform, Text } from 'react-native';
+import { merge } from 'lodash';
+/**
+ * WordPress dependencies
+ */
+import { cloneElement } from '@wordpress/element';
+
+const textRender = Text.render;
+
+const getCorrectFontWeight = ( fontWeight ) => {
+	switch ( fontWeight ) {
+		case '100':
+		case '200':
+		case '300':
+			return {
+				fontFamily: 'sans-serif-thin',
+				fontWeight: 'normal',
+			};
+		case '400':
+			return {
+				fontFamily: 'sans-serif-light',
+				fontWeight: 'normal',
+			};
+		case '500':
+		case 'normal':
+			return {
+				fontFamily: 'sans-serif',
+				fontWeight: 'normal',
+			};
+		case '600':
+			return {
+				fontFamily: 'sans-serif-medium',
+				fontWeight: 'normal',
+			};
+		case '700':
+		case 'bold':
+			return {
+				fontFamily: 'sans-serif',
+				fontWeight: 'bold',
+			};
+		case '800':
+		case '900':
+			return {
+				fontFamily: 'sans-serif-medium',
+				fontWeight: 'bold',
+			};
+	}
+};
+
+const correctTextFontWeight = ( args ) => {
+	const baseText = textRender.call( this, args );
+	const { style } = baseText.props;
+
+	const flatStyle = Array.isArray( style ) ? merge( {}, ...style ) : style;
+	const shouldCorrectFontWeight = flatStyle && flatStyle.fontWeight;
+
+	return shouldCorrectFontWeight ?
+		cloneElement( baseText, {
+			style: [ flatStyle, getCorrectFontWeight( flatStyle.fontWeight ) ],
+		} ) :
+		baseText;
+};
+
+export default () => {
+	if ( Platform.OS === 'android' ) {
+		Text.render = correctTextFontWeight;
+	}
+};