feat: support multiple line-height units (#2952)

.changeset/tame-yaks-speak.md

@@ -0,0 +1,6 @@
+---
+"@react-pdf/layout": patch
+"@react-pdf/stylesheet": patch
+---
+
+feat: support multiple line-height units

packages/layout/src/text/getAttributedString.js

@@ -63,6 +63,7 @@ const getFragments = (fontStore, instance, parentLink, level = 0) => {
     color,
     opacity,
     fontSize,
+    lineHeight,
     direction,
     verticalAlign,
     backgroundColor,
@@ -81,7 +82,6 @@ const getFragments = (fontStore, instance, parentLink, level = 0) => {
     strikeColor: textDecorationColor || color,
     underlineColor: textDecorationColor || color,
     link: parentLink || instance.props?.src || instance.props?.href,
-    lineHeight: lineHeight ? lineHeight * fontSize : null,
     align: textAlign || (direction === 'rtl' ? 'right' : 'left'),
   };
 

packages/stylesheet/src/transform/index.js

@@ -2,21 +2,23 @@ import transformUnits from './units';
 import transformColor from './colors';
 import processTransform from './transform';
 import processFontWeight from './fontWeight';
+import processLineHeight from './lineHeight';
 import processObjectPosition from './objectPosition';
 import processTransformOrigin from './transformOrigin';
 import castFloat from '../utils/castFloat';
 
 const handlers = {
   transform: processTransform,
   fontWeight: processFontWeight,
+  lineHeight: processLineHeight,
   objectPositionX: processObjectPosition,
   objectPositionY: processObjectPosition,
   transformOriginX: processTransformOrigin,
   transformOriginY: processTransformOrigin,
 };
 
-const transformStyle = (key, value, container) => {
-  const result = handlers[key] ? handlers[key](value) : value;
+const transformStyle = (key, value, styles, container) => {
+  const result = handlers[key] ? handlers[key](value, styles) : value;
 
   return transformColor(transformUnits(container, castFloat(result)));
 };
@@ -33,16 +35,16 @@ const transformStyle = (key, value, container) => {
  * @param {Object} container
  * @returns {Transform} transform function
  */
-const transform = (container) => (style) => {
-  if (!style) return style;
+const transform = (container) => (styles) => {
+  if (!styles) return styles;
 
-  const propsArray = Object.keys(style);
+  const propsArray = Object.keys(styles);
   const resolvedStyle = {};
 
   for (let i = 0; i < propsArray.length; i += 1) {
     const key = propsArray[i];
-    const value = style[key];
-    const transformed = transformStyle(key, value, container);
+    const value = styles[key];
+    const transformed = transformStyle(key, value, styles, container);
 
     resolvedStyle[key] = transformed;
   }

packages/stylesheet/src/transform/lineHeight.js

@@ -0,0 +1,18 @@
+/* eslint-disable no-restricted-globals */
+
+import { matchPercent } from '@react-pdf/fns';
+
+const processLineHeight = (value, styles) => {
+  if (value === '') return value;
+
+  const { fontSize = 18 } = styles;
+
+  // Percent values: use this number multiplied by the element's font size
+  const { percent } = matchPercent(value) || {};
+  if (percent) return percent * fontSize;
+
+  // Unitless values: use this number multiplied by the element's font size
+  return isNaN(value) ? value : value * fontSize;
+};
+
+export default processLineHeight;

packages/stylesheet/tests/transform.test.js

@@ -105,6 +105,56 @@ describe('stylesheet transform', () => {
     });
   });
 
+  describe('transform lineHeight', () => {
+    test('should transform unitless number amount', () => {
+      const styles = transformStyles({ lineHeight: 2 });
+
+      expect(styles.lineHeight).toBe(18 * 2);
+    });
+
+    test('should transform unitless number amount with font-size', () => {
+      const styles = transformStyles({ lineHeight: 2, fontSize: 10 });
+
+      expect(styles.lineHeight).toBe(10 * 2);
+    });
+
+    test('should transform unitless string amount', () => {
+      const styles = transformStyles({ lineHeight: '2' });
+
+      expect(styles.lineHeight).toBe(18 * 2);
+    });
+
+    test('should transform unitless string amount with font-size', () => {
+      const styles = transformStyles({ lineHeight: '2', fontSize: 10 });
+
+      expect(styles.lineHeight).toBe(10 * 2);
+    });
+
+    test('should transform percentage amount', () => {
+      const styles = transformStyles({ lineHeight: '200%' });
+
+      expect(styles.lineHeight).toBe(18 * 2);
+    });
+
+    test('should transform percentage amount with font-size', () => {
+      const styles = transformStyles({ lineHeight: '200%', fontSize: 10 });
+
+      expect(styles.lineHeight).toBe(10 * 2);
+    });
+
+    test('should transform height px dimensions', () => {
+      const styles = transformStyles({ lineHeight: '20px' });
+
+      expect(styles.lineHeight).toBe(20);
+    });
+
+    test('should transform width mm dimensions', () => {
+      const styles = transformStyles({ lineHeight: '20mm' });
+
+      expect(styles.lineHeight).toBeCloseTo(56.69, 1);
+    });
+  });
+
   describe('transform colors', () => {
     test('should keep hex values as they are', () => {
       const styles = transformStyles({ color: '#0000FF' });