xterm.js/src/browser/renderer/dom/WidthCache.test.ts

/**
 * Copyright (c) 2023 The xterm.js authors. All rights reserved.
 * @license MIT
 */

import * as assert from 'assert';
import { IWidthCacheFontVariantCanvas, WidthCache, WidthCacheSettings } from './WidthCache';


class MockWidthCacheFontVariantCanvas implements IWidthCacheFontVariantCanvas {
  public widths: { [key: string]: number } = {};

  public setFont(_fontFamily: string, _fontSize: number, _fontWeight: unknown, _italic: boolean): void {
  }

  public measure(c: string): number {
    return this.widths[c] ?? 5;
  }
}

export class TestWidthCache extends WidthCache {
  public get flat(): Float32Array {
    return (this as any)._flat;
  }
  public get holey(): Map<string, number> | undefined {
    return (this as any)._holey;
  }
  public get canvasElements(): MockWidthCacheFontVariantCanvas[] {
    return (this as any)._canvasElements;
  }

  constructor() {
    super(() => new MockWidthCacheFontVariantCanvas());
  }

  public setWidths(widths: { [key: string]: number }): void {
    for (const canvas of this.canvasElements) {
      canvas.widths = widths;
    }
  }
}


function castf32(v: number): number {
  const buffer = new Float32Array(1);
  buffer[0] = v;
  return buffer[0];
}


describe('WidthCache', () => {
  let wc: TestWidthCache;
  beforeEach(() => {
    wc = new TestWidthCache();
    wc.setFont('monospace', 15, 'normal', 'bold');
  });
  describe('cache invalidation', () => {
    beforeEach(() => {
      wc.flat.fill(1.23);
      wc.holey?.set('a', 2.34);
    });
    it('can cache values', () => {
      assert.deepStrictEqual(wc.flat[0], castf32(1.23));
      assert.deepStrictEqual(wc.holey?.get('a'), 2.34);
      assert.deepStrictEqual(wc.holey?.size, 1);
    });
    it('clear resets cache entries', () => {
      wc.clear();
      assert.deepStrictEqual(wc.flat[0], castf32(WidthCacheSettings.FLAT_UNSET));
      assert.deepStrictEqual(wc.holey?.get('a'), undefined);
      assert.deepStrictEqual(wc.holey?.size, 0);
    });
    it('setFont with changed font name', () => {
      wc.setFont('Arial', 15, 'normal', 'bold');
      assert.deepStrictEqual(wc.flat[0], castf32(WidthCacheSettings.FLAT_UNSET));
      assert.deepStrictEqual(wc.holey?.get('a'), undefined);
      assert.deepStrictEqual(wc.holey?.size, 0);
    });
    it('setFont with changed font size', () => {
      wc.setFont('monospace', 14, 'normal', 'bold');
      assert.deepStrictEqual(wc.flat[0], castf32(WidthCacheSettings.FLAT_UNSET));
      assert.deepStrictEqual(wc.holey?.get('a'), undefined);
      assert.deepStrictEqual(wc.holey?.size, 0);
    });
    it('setFont with changed weight', () => {
      wc.setFont('monospace', 15, '100', 'bold');
      assert.deepStrictEqual(wc.flat[0], castf32(WidthCacheSettings.FLAT_UNSET));
      assert.deepStrictEqual(wc.holey?.get('a'), undefined);
      assert.deepStrictEqual(wc.holey?.size, 0);
    });
    it('setFont with changed weightBold', () => {
      wc.setFont('monospace', 15, 'normal', '900');
      assert.deepStrictEqual(wc.flat[0], castf32(WidthCacheSettings.FLAT_UNSET));
      assert.deepStrictEqual(wc.holey?.get('a'), undefined);
      assert.deepStrictEqual(wc.holey?.size, 0);
    });
    it('setFont with unchanged settings does not cache entries', () => {
      wc.setFont('monospace', 15, 'normal', 'bold');
      assert.deepStrictEqual(wc.flat[0], castf32(1.23));
      assert.deepStrictEqual(wc.holey?.get('a'), 2.34);
      assert.deepStrictEqual(wc.holey?.size, 1);
    });
  });
  describe('get', () => {
    it('store regular < WidthCacheSettings.FLAT_SIZE in flat', () => {
      for (let i = 0; i < WidthCacheSettings.FLAT_SIZE + 10; ++i) {
        const width = wc.get(String.fromCharCode(i), false, false);
        assert.deepStrictEqual(width, 5);
        if (i < WidthCacheSettings.FLAT_SIZE) {
          assert.deepStrictEqual(wc.flat[i], 5);
          assert.deepStrictEqual(wc.holey?.get(String.fromCharCode(i)), undefined);
        } else {
          assert.deepStrictEqual(wc.holey?.get(String.fromCharCode(i)), 5);
        }
      }
    });
    it('stores bold & italic in holey', () => {
      // bold
      let width = wc.get('b', true, false);
      assert.deepStrictEqual(width, 5);
      assert.deepStrictEqual(wc.holey?.get('bB'), 5);
      // italic
      width = wc.get('i', false, true);
      assert.deepStrictEqual(width, 5);
      assert.deepStrictEqual(wc.holey?.get('iI'), 5);
      // bold&italic
      width = wc.get('x', true, true);
      assert.deepStrictEqual(width, 5);
      assert.deepStrictEqual(wc.holey?.get('xBI'), 5);
    });
    it('can store any string', () => {
      // regular
      let width = wc.get('foo', false, false);
      assert.deepStrictEqual(width, 5);
      assert.deepStrictEqual(wc.holey?.get('foo'), 5);
      // bold&italic
      width = wc.get('bar&baz', true, true);
      assert.deepStrictEqual(width, 5);
      assert.deepStrictEqual(wc.holey?.get('bar&bazBI'), 5);
    });
  });
});