Support 'px' format in lineHeight option

addons/addon-webgl/src/CharAtlasUtils.ts

@@ -10,6 +10,15 @@ import { IColorSet, ReadonlyColorSet } from 'browser/Types';
 import { NULL_COLOR } from 'common/Color';
 
 export function generateConfig(deviceCellWidth: number, deviceCellHeight: number, deviceCharWidth: number, deviceCharHeight: number, options: Required<ITerminalOptions>, colors: ReadonlyColorSet, devicePixelRatio: number, deviceMaxTextureSize: number): ICharAtlasConfig {
+  // Convert lineHeight to a numeric multiplier for the char atlas
+  // If it's a px value, calculate the equivalent multiplier
+  let lineHeightMultiplier: number = typeof options.lineHeight === 'number' ? options.lineHeight : 1;
+  if (typeof options.lineHeight === 'string' && options.lineHeight.endsWith('px')) {
+    const pxValue = parseFloat(options.lineHeight.slice(0, -2));
+    // Calculate the multiplier based on font size
+    lineHeightMultiplier = pxValue / options.fontSize;
+  }
+
   // null out some fields that don't matter
   const clonedColors: IColorSet = {
     foreground: colors.foreground,
@@ -36,7 +45,7 @@ export function generateConfig(deviceCellWidth: number, deviceCellHeight: number
     devicePixelRatio,
     deviceMaxTextureSize,
     letterSpacing: options.letterSpacing,
-    lineHeight: options.lineHeight,
+    lineHeight: lineHeightMultiplier,
     deviceCellWidth: deviceCellWidth,
     deviceCellHeight: deviceCellHeight,
     deviceCharWidth: deviceCharWidth,

addons/addon-webgl/src/WebglRenderer.ts

@@ -27,6 +27,19 @@ import { addDisposableListener } from 'vs/base/browser/dom';
 import { combinedDisposable, Disposable, MutableDisposable, toDisposable } from 'vs/base/common/lifecycle';
 import { createRenderDimensions } from 'browser/renderer/shared/RendererUtils';
 
+/**
+ * Calculates the line height in pixels based on the lineHeight option and character height.
+ */
+function calculateLineHeightInPixels(lineHeight: number | string, charHeight: number): number {
+  if (typeof lineHeight === 'string' && lineHeight.endsWith('px')) {
+    const pxValue = parseFloat(lineHeight.slice(0, -2));
+    // Ensure the pixel value is at least as large as the character height
+    return Math.max(pxValue, charHeight);
+  }
+  // Numeric lineHeight acts as a multiplier
+  return Math.floor(charHeight * (lineHeight as number));
+}
+
 export class WebglRenderer extends Disposable implements IRenderer {
   private _renderLayers: IRenderLayer[];
   private _cursorBlinkStateManager: MutableDisposable<CursorBlinkStateManager> = new MutableDisposable();
@@ -570,14 +583,14 @@ export class WebglRenderer extends Disposable implements IRenderer {
     // cell.
     this.dimensions.device.char.height = Math.ceil(this._charSizeService.height * this._devicePixelRatio);
 
-    // Calculate the device cell height, if lineHeight is _not_ 1, the resulting value will be
-    // floored since lineHeight can never be lower then 1, this guarentees the device cell height
-    // will always be larger than device char height.
-    this.dimensions.device.cell.height = Math.floor(this.dimensions.device.char.height * this._optionsService.rawOptions.lineHeight);
+    // Calculate the device cell height, supporting both numeric multipliers and 'px' values
+    this.dimensions.device.cell.height = calculateLineHeightInPixels(this._optionsService.rawOptions.lineHeight, this.dimensions.device.char.height);
 
     // Calculate the y offset within a cell that glyph should draw at in order for it to be centered
     // correctly within the cell.
-    this.dimensions.device.char.top = this._optionsService.rawOptions.lineHeight === 1 ? 0 : Math.round((this.dimensions.device.cell.height - this.dimensions.device.char.height) / 2);
+    const isDefaultLineHeight = (typeof this._optionsService.rawOptions.lineHeight === 'number' && this._optionsService.rawOptions.lineHeight === 1) ||
+                               (typeof this._optionsService.rawOptions.lineHeight === 'string' && this.dimensions.device.cell.height === this.dimensions.device.char.height);
+    this.dimensions.device.char.top = isDefaultLineHeight ? 0 : Math.round((this.dimensions.device.cell.height - this.dimensions.device.char.height) / 2);
 
     // Calculate the device cell width, taking the letterSpacing into account.
     this.dimensions.device.cell.width = this.dimensions.device.char.width + Math.round(this._optionsService.rawOptions.letterSpacing);

src/browser/renderer/LineHeight.test.ts

@@ -0,0 +1,78 @@
+/**
+ * Copyright (c) 2023 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+
+/**
+ * Calculates the line height in pixels based on the lineHeight option and character height.
+ * This is the same function used in both DomRenderer and WebglRenderer.
+ */
+function calculateLineHeightInPixels(lineHeight: number | string, charHeight: number): number {
+  if (typeof lineHeight === 'string' && lineHeight.endsWith('px')) {
+    const pxValue = parseFloat(lineHeight.slice(0, -2));
+    // Ensure the pixel value is at least as large as the character height
+    return Math.max(pxValue, charHeight);
+  }
+  // Numeric lineHeight acts as a multiplier
+  return Math.floor(charHeight * (lineHeight as number));
+}
+
+describe('calculateLineHeightInPixels', () => {
+  describe('numeric lineHeight', () => {
+    it('should calculate correctly with multiplier 1', () => {
+      assert.equal(calculateLineHeightInPixels(1, 20), 20);
+    });
+
+    it('should calculate correctly with multiplier 1.2', () => {
+      assert.equal(calculateLineHeightInPixels(1.2, 20), 24);
+    });
+
+    it('should calculate correctly with multiplier 1.5', () => {
+      assert.equal(calculateLineHeightInPixels(1.5, 20), 30);
+    });
+
+    it('should floor the result', () => {
+      assert.equal(calculateLineHeightInPixels(1.3, 20), 26); // Math.floor(26)
+    });
+  });
+
+  describe('string lineHeight with px format', () => {
+    it('should use px value directly when larger than char height', () => {
+      assert.equal(calculateLineHeightInPixels('25px', 20), 25);
+    });
+
+    it('should use char height when px value is smaller', () => {
+      assert.equal(calculateLineHeightInPixels('15px', 20), 20);
+    });
+
+    it('should handle decimal px values', () => {
+      assert.equal(calculateLineHeightInPixels('23.5px', 20), 23.5);
+    });
+
+    it('should handle edge case where px equals char height', () => {
+      assert.equal(calculateLineHeightInPixels('20px', 20), 20);
+    });
+
+    it('should handle very large px values', () => {
+      assert.equal(calculateLineHeightInPixels('100px', 20), 100);
+    });
+  });
+
+  describe('edge cases', () => {
+    it('should handle zero char height with numeric multiplier', () => {
+      assert.equal(calculateLineHeightInPixels(1.5, 0), 0);
+    });
+
+    it('should handle zero char height with px value', () => {
+      assert.equal(calculateLineHeightInPixels('25px', 0), 25);
+    });
+
+    it('should handle 1px with various char heights', () => {
+      assert.equal(calculateLineHeightInPixels('1px', 5), 5);
+      assert.equal(calculateLineHeightInPixels('1px', 20), 20);
+      assert.equal(calculateLineHeightInPixels('1px', 0), 1);
+    });
+  });
+});

src/browser/renderer/dom/DomRenderer.ts

@@ -24,6 +24,19 @@ const BG_CLASS_PREFIX = 'xterm-bg-';
 const FOCUS_CLASS = 'xterm-focus';
 const SELECTION_CLASS = 'xterm-selection';
 
+/**
+ * Calculates the line height in pixels based on the lineHeight option and character height.
+ */
+function calculateLineHeightInPixels(lineHeight: number | string, charHeight: number): number {
+  if (typeof lineHeight === 'string' && lineHeight.endsWith('px')) {
+    const pxValue = parseFloat(lineHeight.slice(0, -2));
+    // Ensure the pixel value is at least as large as the character height
+    return Math.max(pxValue, charHeight);
+  }
+  // Numeric lineHeight acts as a multiplier
+  return Math.floor(charHeight * (lineHeight as number));
+}
+
 let nextTerminalId = 1;
 
 /**
@@ -116,7 +129,7 @@ export class DomRenderer extends Disposable implements IRenderer {
     this.dimensions.device.char.width = this._charSizeService.width * dpr;
     this.dimensions.device.char.height = Math.ceil(this._charSizeService.height * dpr);
     this.dimensions.device.cell.width = this.dimensions.device.char.width + Math.round(this._optionsService.rawOptions.letterSpacing);
-    this.dimensions.device.cell.height = Math.floor(this.dimensions.device.char.height * this._optionsService.rawOptions.lineHeight);
+    this.dimensions.device.cell.height = calculateLineHeightInPixels(this._optionsService.rawOptions.lineHeight, this.dimensions.device.char.height);
     this.dimensions.device.char.left = 0;
     this.dimensions.device.char.top = 0;
     this.dimensions.device.canvas.width = this.dimensions.device.cell.width * this._bufferService.cols;

src/common/services/OptionsService.lineHeight.test.ts

@@ -0,0 +1,86 @@
+/**
+ * Copyright (c) 2023 The xterm.js authors. All rights reserved.
+ * @license MIT
+ */
+
+import { assert } from 'chai';
+import { OptionsService } from 'common/services/OptionsService';
+
+describe('OptionsService lineHeight', () => {
+  let optionsService: OptionsService;
+
+  beforeEach(() => {
+    optionsService = new OptionsService({});
+  });
+
+  describe('numeric lineHeight', () => {
+    it('should accept numeric values', () => {
+      optionsService.options.lineHeight = 1.5;
+      assert.equal(optionsService.rawOptions.lineHeight, 1.5);
+    });
+
+    it('should reject values less than 1', () => {
+      assert.throws(() => optionsService.options.lineHeight = 0.5);
+    });
+
+    it('should accept 1 as minimum value', () => {
+      optionsService.options.lineHeight = 1;
+      assert.equal(optionsService.rawOptions.lineHeight, 1);
+    });
+  });
+
+  describe('string lineHeight with px format', () => {
+    it('should accept px values', () => {
+      optionsService.options.lineHeight = '24px';
+      assert.equal(optionsService.rawOptions.lineHeight, '24px');
+    });
+
+    it('should accept decimal px values', () => {
+      optionsService.options.lineHeight = '23.5px';
+      assert.equal(optionsService.rawOptions.lineHeight, '23.5px');
+    });
+
+    it('should reject px values less than 1', () => {
+      assert.throws(() => optionsService.options.lineHeight = '0.5px');
+    });
+
+    it('should accept 1px as minimum value', () => {
+      optionsService.options.lineHeight = '1px';
+      assert.equal(optionsService.rawOptions.lineHeight, '1px');
+    });
+
+    it('should reject non-px string values', () => {
+      assert.throws(() => optionsService.options.lineHeight = '24' as any);
+      assert.throws(() => optionsService.options.lineHeight = '24em' as any);
+      assert.throws(() => optionsService.options.lineHeight = 'normal' as any);
+    });
+
+    it('should reject invalid px values', () => {
+      assert.throws(() => optionsService.options.lineHeight = 'invalidpx' as any);
+      assert.throws(() => optionsService.options.lineHeight = 'px' as any);
+    });
+  });
+
+  describe('invalid lineHeight types', () => {
+    it('should reject null', () => {
+      assert.throws(() => optionsService.options.lineHeight = null as any);
+    });
+
+    it('should reject undefined when explicitly set', () => {
+      assert.throws(() => optionsService.options.lineHeight = undefined as any);
+    });
+
+    it('should reject boolean values', () => {
+      assert.throws(() => optionsService.options.lineHeight = true as any);
+      assert.throws(() => optionsService.options.lineHeight = false as any);
+    });
+
+    it('should reject arrays', () => {
+      assert.throws(() => optionsService.options.lineHeight = [] as any);
+    });
+
+    it('should reject objects', () => {
+      assert.throws(() => optionsService.options.lineHeight = {} as any);
+    });
+  });
+});

src/common/services/OptionsService.ts

@@ -172,12 +172,31 @@ export class OptionsService extends Disposable implements IOptionsService {
       case 'cursorWidth':
         value = Math.floor(value);
         // Fall through for bounds check
-      case 'lineHeight':
       case 'tabStopWidth':
         if (value < 1) {
           throw new Error(`${key} cannot be less than 1, value: ${value}`);
         }
         break;
+      case 'lineHeight':
+        if (typeof value === 'string') {
+          // Handle 'px' format
+          if (value.endsWith('px')) {
+            const pxValue = parseFloat(value.slice(0, -2));
+            if (isNaN(pxValue) || pxValue < 1) {
+              throw new Error(`${key} with 'px' format must be a valid number >= 1, value: ${value}`);
+            }
+            // Keep the string value as-is for downstream processing
+          } else {
+            throw new Error(`${key} string value must end with 'px', value: ${value}`);
+          }
+        } else if (typeof value === 'number') {
+          if (value < 1) {
+            throw new Error(`${key} cannot be less than 1, value: ${value}`);
+          }
+        } else {
+          throw new Error(`${key} must be a number or string with 'px' suffix, value: ${value}`);
+        }
+        break;
       case 'minimumContrastRatio':
         value = Math.max(1, Math.min(21, Math.round(value * 10) / 10));
         break;

src/common/services/Services.ts

@@ -231,7 +231,7 @@ export interface ITerminalOptions {
   fontWeightBold?: FontWeight;
   ignoreBracketedPasteMode?: boolean;
   letterSpacing?: number;
-  lineHeight?: number;
+  lineHeight?: number | string;
   linkHandler?: ILinkHandler | null;
   logLevel?: LogLevel;
   logger?: ILogger | null;

typings/xterm-headless.d.ts

@@ -94,9 +94,11 @@ declare module '@xterm/headless' {
     letterSpacing?: number;
 
     /**
-     * The line height used to render text.
+     * The line height used to render text. This can be specified as:
+     * - A number (e.g., 1.2) which acts as a multiplier of the font size
+     * - A string with 'px' suffix (e.g., '24px') which specifies an absolute pixel height
      */
-    lineHeight?: number;
+    lineHeight?: number | string;
 
     /**
      * What log level to use, this will log for all levels below and including

typings/xterm.d.ts

@@ -152,9 +152,11 @@ declare module '@xterm/xterm' {
     letterSpacing?: number;
 
     /**
-     * The line height used to render text.
+     * The line height used to render text. This can be specified as:
+     * - A number (e.g., 1.2) which acts as a multiplier of the font size
+     * - A string with 'px' suffix (e.g., '24px') which specifies an absolute pixel height
      */
-    lineHeight?: number;
+    lineHeight?: number | string;
 
     /**
      * The handler for OSC 8 hyperlinks. Links will use the `confirm` browser