Merge pull request #3416 from meganrogge/merogge/pixelPerfect

pixel perfect canvas rendering of box and block characters

addons/xterm-addon-webgl/src/WebglRenderer.ts

@@ -230,7 +230,7 @@ export class WebglRenderer extends Disposable implements IRenderer {
       return;
     }
 
-    const atlas = acquireCharAtlas(this._terminal, this._colors, this.dimensions.scaledCharWidth, this.dimensions.scaledCharHeight);
+    const atlas = acquireCharAtlas(this._terminal, this._colors, this.dimensions.scaledCellWidth, this.dimensions.scaledCellHeight, this.dimensions.scaledCharWidth, this.dimensions.scaledCharHeight);
     if (!('getRasterizedGlyph' in atlas)) {
       throw new Error('The webgl renderer only works with the webgl char atlas');
     }

addons/xterm-addon-webgl/src/atlas/CharAtlasCache.ts

@@ -28,10 +28,12 @@ const charAtlasCache: ICharAtlasCacheEntry[] = [];
 export function acquireCharAtlas(
   terminal: Terminal,
   colors: IColorSet,
+  scaledCellWidth: number,
+  scaledCellHeight: number,
   scaledCharWidth: number,
   scaledCharHeight: number
 ): WebglCharAtlas {
-  const newConfig = generateConfig(scaledCharWidth, scaledCharHeight, terminal, colors);
+  const newConfig = generateConfig(scaledCellWidth, scaledCellHeight, scaledCharWidth, scaledCharHeight, terminal, colors);
 
   // Check to see if the terminal already owns this config
   for (let i = 0; i < charAtlasCache.length; i++) {

addons/xterm-addon-webgl/src/atlas/CharAtlasUtils.ts

@@ -13,7 +13,7 @@ const NULL_COLOR: IColor = {
   rgba: 0
 };
 
-export function generateConfig(scaledCharWidth: number, scaledCharHeight: number, terminal: Terminal, colors: IColorSet): ICharAtlasConfig {
+export function generateConfig(scaledCellWidth: number, scaledCellHeight: number, scaledCharWidth: number, scaledCharHeight: number, terminal: Terminal, colors: IColorSet): ICharAtlasConfig {
   // null out some fields that don't matter
   const clonedColors: IColorSet = {
     foreground: colors.foreground,
@@ -28,7 +28,12 @@ export function generateConfig(scaledCharWidth: number, scaledCharHeight: number
     contrastCache: colors.contrastCache
   };
   return {
+    customGlyphs: terminal.getOption('customGlyphs'),
     devicePixelRatio: window.devicePixelRatio,
+    letterSpacing: terminal.getOption('letterSpacing'),
+    lineHeight: terminal.getOption('lineHeight'),
+    scaledCellWidth,
+    scaledCellHeight,
     scaledCharWidth,
     scaledCharHeight,
     fontFamily: terminal.getOption('fontFamily'),
@@ -49,6 +54,9 @@ export function configEquals(a: ICharAtlasConfig, b: ICharAtlasConfig): boolean
     }
   }
   return a.devicePixelRatio === b.devicePixelRatio &&
+      a.customGlyphs === b.customGlyphs &&
+      a.lineHeight === b.lineHeight &&
+      a.letterSpacing === b.letterSpacing &&
       a.fontFamily === b.fontFamily &&
       a.fontSize === b.fontSize &&
       a.fontWeight === b.fontWeight &&

addons/xterm-addon-webgl/src/atlas/Types.d.ts

@@ -17,11 +17,16 @@ export interface IGlyphIdentifier {
 }
 
 export interface ICharAtlasConfig {
+  customGlyphs: boolean;
   devicePixelRatio: number;
+  letterSpacing: number;
+  lineHeight: number;
   fontSize: number;
   fontFamily: string;
   fontWeight: FontWeight;
   fontWeightBold: FontWeight;
+  scaledCellWidth: number;
+  scaledCellHeight: number;
   scaledCharWidth: number;
   scaledCharHeight: number;
   allowTransparency: boolean;

addons/xterm-addon-webgl/src/atlas/WebglCharAtlas.ts

@@ -12,6 +12,7 @@ import { IColor } from 'browser/Types';
 import { IDisposable } from 'xterm';
 import { AttributeData } from 'common/buffer/AttributeData';
 import { channels, rgba } from 'browser/Color';
+import { tryDrawCustomChar } from 'browser/renderer/CustomGlyphs';
 
 // In practice we're probably never going to exhaust a texture this large. For debugging purposes,
 // however, it can be useful to set this to a really tiny value, to verify that LRU eviction works.
@@ -83,8 +84,8 @@ export class WebglCharAtlas implements IDisposable {
     this._cacheCtx = throwIfFalsy(this.cacheCanvas.getContext('2d', { alpha: true }));
 
     this._tmpCanvas = document.createElement('canvas');
-    this._tmpCanvas.width = this._config.scaledCharWidth * 4 + TMP_CANVAS_GLYPH_PADDING * 2;
-    this._tmpCanvas.height = this._config.scaledCharHeight + TMP_CANVAS_GLYPH_PADDING * 2;
+    this._tmpCanvas.width = this._config.scaledCellWidth * 4 + TMP_CANVAS_GLYPH_PADDING * 2;
+    this._tmpCanvas.height = this._config.scaledCellHeight + TMP_CANVAS_GLYPH_PADDING * 2;
     this._tmpCtx = throwIfFalsy(this._tmpCanvas.getContext('2d', { alpha: this._config.allowTransparency }));
   }
 
@@ -390,8 +391,16 @@ export class WebglCharAtlas implements IDisposable {
     // For powerline glyphs left/top padding is excluded (https://github.com/microsoft/vscode/issues/120129)
     const padding = isPowerlineGlyph ? 0 : TMP_CANVAS_GLYPH_PADDING;
 
+    // Draw custom characters if applicable
+    let drawSuccess = false;
+    if (this._config.customGlyphs !== false) {
+      drawSuccess = tryDrawCustomChar(this._tmpCtx, chars, padding, padding, this._config.scaledCellWidth, this._config.scaledCellHeight);
+    }
+
     // Draw the character
-    this._tmpCtx.fillText(chars, padding, padding + this._config.scaledCharHeight);
+    if (!drawSuccess) {
+      this._tmpCtx.fillText(chars, padding, padding + this._config.scaledCharHeight);
+    }
 
     // Draw underline and strikethrough
     if (underline || strikethrough) {

addons/xterm-addon-webgl/src/renderLayer/BaseRenderLayer.ts

@@ -92,7 +92,7 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     if (this._scaledCharWidth <= 0 && this._scaledCharHeight <= 0) {
       return;
     }
-    this._charAtlas = acquireCharAtlas(terminal, colorSet, this._scaledCharWidth, this._scaledCharHeight);
+    this._charAtlas = acquireCharAtlas(terminal, colorSet, this._scaledCellWidth, this._scaledCellHeight, this._scaledCharWidth, this._scaledCharHeight);
     this._charAtlas.warmUp();
   }
 

addons/xterm-addon-webgl/test/WebglRenderer.api.ts

@@ -3,11 +3,11 @@
  * @license MIT
  */
 
-import { ITerminalOptions } from '../../../src/common/Types';
-import { ITheme } from 'xterm';
 import { assert } from 'chai';
-import { openTerminal, pollFor, writeSync, getBrowserType } from '../../../out-test/api/TestUtils';
 import { Browser, Page } from 'playwright';
+import { ITheme } from 'xterm';
+import { getBrowserType, openTerminal, pollFor, writeSync } from '../../../out-test/api/TestUtils';
+import { ITerminalOptions } from '../../../src/common/Types';
 
 const APP = 'http://127.0.0.1:3001/test';
 
@@ -890,6 +890,20 @@ async function getCellColor(col: number, row: number): Promise<number[]> {
   return await page.evaluate(`Array.from(window.result)`);
 }
 
+async function getCellPixels(col: number, row: number): Promise<number[]> {
+  await page.evaluate(`
+    window.gl = window.term._core._renderService._renderer._gl;
+    window.result = new Uint8Array(window.d.scaledCellWidth * window.d.scaledCellHeight * 4);
+    window.d = window.term._core._renderService.dimensions;
+    window.gl.readPixels(
+      Math.floor(${col - 1} * window.d.scaledCellWidth),
+      Math.floor(window.gl.drawingBufferHeight - ${row} * window.d.scaledCellHeight),
+      window.d.scaledCellWidth, window.d.scaledCellHeight, window.gl.RGBA, window.gl.UNSIGNED_BYTE, window.result
+    );
+  `);
+  return await page.evaluate(`Array.from(window.result)`);
+}
+
 async function setupBrowser(options: ITerminalOptions = { rendererType: 'dom' }): Promise<void> {
   const browserType = getBrowserType();
   browser = await browserType.launch({

demo/client.ts

@@ -147,6 +147,7 @@ if (document.location.pathname === '/test') {
   createTerminal();
   document.getElementById('dispose').addEventListener('click', disposeRecreateButtonHandler);
   document.getElementById('serialize').addEventListener('click', serializeButtonHandler);
+  document.getElementById('custom-glyph').addEventListener('click', writeCustomGlyphHandler);
 }
 
 function createTerminal(): void {
@@ -431,3 +432,49 @@ function serializeButtonHandler(): void {
     term.write(output);
   }
 }
+
+
+function writeCustomGlyphHandler() {
+  term.write('\n\r');
+  term.write('\n\r');
+  term.write('Box styles:       ┎┰┒┍┯┑╓╥╖╒╤╕ ┏┳┓┌┲┓┌┬┐┏┱┐\n\r');
+  term.write('┌─┬─┐ ┏━┳━┓ ╔═╦═╗ ┠╂┨┝┿┥╟╫╢╞╪╡ ┡╇┩├╊┫┢╈┪┣╉┤\n\r');
+  term.write('│ │ │ ┃ ┃ ┃ ║ ║ ║ ┖┸┚┕┷┙╙╨╜╘╧╛ └┴┘└┺┛┗┻┛┗┹┘\n\r');
+  term.write('├─┼─┤ ┣━╋━┫ ╠═╬═╣ ┏┱┐┌┲┓┌┬┐┌┬┐ ┏┳┓┌┮┓┌┬┐┏┭┐\n\r');
+  term.write('│ │ │ ┃ ┃ ┃ ║ ║ ║ ┡╃┤├╄┩├╆┪┢╅┤ ┞╀┦├┾┫┟╁┧┣┽┤\n\r');
+  term.write('└─┴─┘ ┗━┻━┛ ╚═╩═╝ └┴┘└┴┘└┺┛┗┹┘ └┴┘└┶┛┗┻┛┗┵┘\n\r');
+  term.write('\n\r');
+  term.write('Other:\n\r');
+  term.write('╭─╮ ╲ ╱ ╷╻╎╏┆┇┊┋ ╺╾╴ ╌╌╌ ┄┄┄ ┈┈┈\n\r');
+  term.write('│ │  ╳  ╽╿╎╏┆┇┊┋ ╶╼╸ ╍╍╍ ┅┅┅ ┉┉┉\n\r');
+  term.write('╰─╯ ╱ ╲ ╹╵╎╏┆┇┊┋\n\r');
+  term.write('\n\r');
+  term.write('All box drawing characters:\n\r');
+  term.write('─ ━ │ ┃ ┄ ┅ ┆ ┇ ┈ ┉ ┊ ┋ ┌ ┍ ┎ ┏\n\r');
+  term.write('┐ ┑ ┒ ┓ └ ┕ ┖ ┗ ┘ ┙ ┚ ┛ ├ ┝ ┞ ┟\n\r');
+  term.write('┠ ┡ ┢ ┣ ┤ ┥ ┦ ┧ ┨ ┩ ┪ ┫ ┬ ┭ ┮ ┯\n\r');
+  term.write('┰ ┱ ┲ ┳ ┴ ┵ ┶ ┷ ┸ ┹ ┺ ┻ ┼ ┽ ┾ ┿\n\r');
+  term.write('╀ ╁ ╂ ╃ ╄ ╅ ╆ ╇ ╈ ╉ ╊ ╋ ╌ ╍ ╎ ╏\n\r');
+  term.write('═ ║ ╒ ╓ ╔ ╕ ╖ ╗ ╘ ╙ ╚ ╛ ╜ ╝ ╞ ╟\n\r');
+  term.write('╠ ╡ ╢ ╣ ╤ ╥ ╦ ╧ ╨ ╩ ╪ ╫ ╬ ╭ ╮ ╯\n\r');
+  term.write('╰ ╱ ╲ ╳ ╴ ╵ ╶ ╷ ╸ ╹ ╺ ╻ ╼ ╽ ╾ ╿\n\r');
+  term.write('Box drawing alignment tests:\x1b[31m                                          █\n\r');
+  term.write('                                                                      ▉\n\r');
+  term.write('  ╔══╦══╗  ┌──┬──┐  ╭──┬──╮  ╭──┬──╮  ┏━━┳━━┓  ┎┒┏┑   ╷  ╻ ┏┯┓ ┌┰┐    ▊ ╱╲╱╲╳╳╳\n\r');
+  term.write('  ║┌─╨─┐║  │╔═╧═╗│  │╒═╪═╕│  │╓─╁─╖│  ┃┌─╂─┐┃  ┗╃╄┙  ╶┼╴╺╋╸┠┼┨ ┝╋┥    ▋ ╲╱╲╱╳╳╳\n\r');
+  term.write('  ║│╲ ╱│║  │║   ║│  ││ │ ││  │║ ┃ ║│  ┃│ ╿ │┃  ┍╅╆┓   ╵  ╹ ┗┷┛ └┸┘    ▌ ╱╲╱╲╳╳╳\n\r');
+  term.write('  ╠╡ ╳ ╞╣  ├╢   ╟┤  ├┼─┼─┼┤  ├╫─╂─╫┤  ┣┿╾┼╼┿┫  ┕┛┖┚     ┌┄┄┐ ╎ ┏┅┅┓ ┋ ▍ ╲╱╲╱╳╳╳\n\r');
+  term.write('  ║│╱ ╲│║  │║   ║│  ││ │ ││  │║ ┃ ║│  ┃│ ╽ │┃  ░░▒▒▓▓██ ┊  ┆ ╎ ╏  ┇ ┋ ▎\n\r');
+  term.write('  ║└─╥─┘║  │╚═╤═╝│  │╘═╪═╛│  │╙─╀─╜│  ┃└─╂─┘┃  ░░▒▒▓▓██ ┊  ┆ ╎ ╏  ┇ ┋ ▏\n\r');
+  term.write('  ╚══╩══╝  └──┴──┘  ╰──┴──╯  ╰──┴──╯  ┗━━┻━━┛           └╌╌┘ ╎ ┗╍╍┛ ┋  ▁▂▃▄▅▆▇█\n\r');
+  term.write('Box drawing alignment tests:\x1b[32m                                          █\n\r');
+  term.write('                                                                      ▉\n\r');
+  term.write('  ╔══╦══╗  ┌──┬──┐  ╭──┬──╮  ╭──┬──╮  ┏━━┳━━┓  ┎┒┏┑   ╷  ╻ ┏┯┓ ┌┰┐    ▊ ╱╲╱╲╳╳╳\n\r');
+  term.write('  ║┌─╨─┐║  │╔═╧═╗│  │╒═╪═╕│  │╓─╁─╖│  ┃┌─╂─┐┃  ┗╃╄┙  ╶┼╴╺╋╸┠┼┨ ┝╋┥    ▋ ╲╱╲╱╳╳╳\n\r');
+  term.write('  ║│╲ ╱│║  │║   ║│  ││ │ ││  │║ ┃ ║│  ┃│ ╿ │┃  ┍╅╆┓   ╵  ╹ ┗┷┛ └┸┘    ▌ ╱╲╱╲╳╳╳\n\r');
+  term.write('  ╠╡ ╳ ╞╣  ├╢   ╟┤  ├┼─┼─┼┤  ├╫─╂─╫┤  ┣┿╾┼╼┿┫  ┕┛┖┚     ┌┄┄┐ ╎ ┏┅┅┓ ┋ ▍ ╲╱╲╱╳╳╳\n\r');
+  term.write('  ║│╱ ╲│║  │║   ║│  ││ │ ││  │║ ┃ ║│  ┃│ ╽ │┃  ░░▒▒▓▓██ ┊  ┆ ╎ ╏  ┇ ┋ ▎\n\r');
+  term.write('  ║└─╥─┘║  │╚═╤═╝│  │╘═╪═╛│  │╙─╀─╜│  ┃└─╂─┘┃  ░░▒▒▓▓██ ┊  ┆ ╎ ╏  ┇ ┋ ▏\n\r');
+  term.write('  ╚══╩══╝  └──┴──┘  ╰──┴──╯  ╰──┴──╯  ┗━━┻━━┛           └╌╌┘ ╎ ┗╍╍┛ ┋  ▁▂▃▄▅▆▇█\n\r');
+  window.scrollTo(0, 0);
+}

demo/index.html

@@ -50,6 +50,7 @@
     </div>
     <hr/>
     <button id="dispose" title="This is used to testing memory leaks">Dispose terminal</button>
+    <button id="custom-glyph" title="Write custom box drawing and block element characters to the terminal">Test custom glyphs</button>
     <script src="dist/client-bundle.js" defer ></script>
   </body>
 </html>

src/browser/Terminal.ts

@@ -224,6 +224,7 @@ export class Terminal extends CoreTerminal implements ITerminal {
         // The DOM renderer needs a row refresh to update the cursor styles
         this.refresh(this.buffer.y, this.buffer.y);
         break;
+      case 'customGlyphs':
       case 'drawBoldTextInBrightColors':
       case 'letterSpacing':
       case 'lineHeight':

src/browser/renderer/BaseRenderLayer.ts

@@ -17,6 +17,7 @@ import { IBufferService, IOptionsService } from 'common/services/Services';
 import { throwIfFalsy } from 'browser/renderer/RendererUtils';
 import { channels, color, rgba } from 'browser/Color';
 import { removeElementFromParent } from 'browser/Dom';
+import { tryDrawCustomChar } from 'browser/renderer/CustomGlyphs';
 
 export abstract class BaseRenderLayer implements IRenderLayer {
   private _canvas: HTMLCanvasElement;
@@ -259,10 +260,20 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     this._ctx.font = this._getFont(false, false);
     this._ctx.textBaseline = 'ideographic';
     this._clipRow(y);
-    this._ctx.fillText(
-      cell.getChars(),
-      x * this._scaledCellWidth + this._scaledCharLeft,
-      y * this._scaledCellHeight + this._scaledCharTop + this._scaledCharHeight);
+
+    // Draw custom characters if applicable
+    let drawSuccess = false;
+    if (this._optionsService.options.customGlyphs !== false) {
+      drawSuccess = tryDrawCustomChar(this._ctx, cell.getChars(), x * this._scaledCellWidth, y * this._scaledCellHeight, this._scaledCellWidth, this._scaledCellHeight);
+    }
+
+    // Draw the character
+    if (!drawSuccess) {
+      this._ctx.fillText(
+        cell.getChars(),
+        x * this._scaledCellWidth + this._scaledCharLeft,
+        y * this._scaledCellHeight + this._scaledCharTop + this._scaledCharHeight);
+    }
   }
 
   /**
@@ -373,14 +384,25 @@ export abstract class BaseRenderLayer implements IRenderLayer {
     if (cell.isDim()) {
       this._ctx.globalAlpha = DIM_OPACITY;
     }
+
+    // Draw custom characters if applicable
+    let drawSuccess = false;
+    if (this._optionsService.options.customGlyphs !== false) {
+      drawSuccess = tryDrawCustomChar(this._ctx, cell.getChars(), x * this._scaledCellWidth, y * this._scaledCellHeight, this._scaledCellWidth, this._scaledCellHeight);
+    }
+
     // Draw the character
-    this._ctx.fillText(
-      cell.getChars(),
-      x * this._scaledCellWidth + this._scaledCharLeft,
-      y * this._scaledCellHeight + this._scaledCharTop + this._scaledCharHeight);
+    if (!drawSuccess) {
+      this._ctx.fillText(
+        cell.getChars(),
+        x * this._scaledCellWidth + this._scaledCharLeft,
+        y * this._scaledCellHeight + this._scaledCharTop + this._scaledCharHeight);
+    }
+
     this._ctx.restore();
   }
 
+
   /**
    * Clips a row to ensure no pixels will be drawn outside the cells in the row.
    * @param y The row to clip.

src/common/services/OptionsService.ts

@@ -21,6 +21,7 @@ export const DEFAULT_OPTIONS: ITerminalOptions = Object.freeze({
   cursorBlink: false,
   cursorStyle: 'block',
   cursorWidth: 1,
+  customGlyphs: true,
   bellSound:  DEFAULT_BELL_SOUND,
   bellStyle: 'none',
   drawBoldTextInBrightColors: true,

src/common/services/Services.ts

@@ -244,6 +244,7 @@ export interface ITerminalOptions {
   cursorBlink: boolean;
   cursorStyle: 'block' | 'underline' | 'bar';
   cursorWidth: number;
+  customGlyphs: boolean;
   disableStdin: boolean;
   drawBoldTextInBrightColors: boolean;
   fastScrollModifier: 'alt' | 'ctrl' | 'shift' | undefined;

typings/xterm-headless.d.ts

@@ -78,6 +78,14 @@ declare module 'xterm-headless' {
      */
     cursorWidth?: number;
 
+    /**
+     * Whether to draw custom glyphs for block element and box drawing characters instead of using
+     * the font. This should typically result in better rendering with continuous lines, even when
+     * line height and letter spacing is used. Note that this doesn't work with the DOM renderer
+     * which renders all characters using the font. The default is true.
+     */
+     customGlyphs?: boolean;
+
     /**
      * Whether input should be disabled.
      */

typings/xterm.d.ts

@@ -90,6 +90,14 @@ declare module 'xterm' {
      */
     cursorWidth?: number;
 
+    /**
+     * Whether to draw custom glyphs for block element and box drawing characters instead of using
+     * the font. This should typically result in better rendering with continuous lines, even when
+     * line height and letter spacing is used. Note that this doesn't work with the DOM renderer
+     * which renders all characters using the font. The default is true.
+     */
+    customGlyphs?: boolean;
+
     /**
      * Whether input should be disabled.
      */