73 lines
2.3 KiB
TypeScript
73 lines
2.3 KiB
TypeScript
/**
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* Copyright (c) 2017 The xterm.js authors. All rights reserved.
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* @license MIT
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*/
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import { ITerminal } from '../../Types';
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import { IColorSet } from '../Types';
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import { ICharAtlasConfig } from '../../shared/atlas/Types';
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import { generateCharAtlas } from '../../shared/atlas/CharAtlasGenerator';
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import { generateConfig, configEquals } from './CharAtlasUtils';
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interface ICharAtlasCacheEntry {
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bitmap: HTMLCanvasElement | Promise<ImageBitmap>;
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config: ICharAtlasConfig;
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ownedBy: ITerminal[];
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}
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let charAtlasCache: ICharAtlasCacheEntry[] = [];
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/**
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* Acquires a char atlas, either generating a new one or returning an existing
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* one that is in use by another terminal.
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* @param terminal The terminal.
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* @param colors The colors to use.
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*/
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export function acquireCharAtlas(terminal: ITerminal, colors: IColorSet, scaledCharWidth: number, scaledCharHeight: number): HTMLCanvasElement | Promise<ImageBitmap> {
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const newConfig = generateConfig(scaledCharWidth, scaledCharHeight, terminal, colors);
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// Check to see if the terminal already owns this config
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for (let i = 0; i < charAtlasCache.length; i++) {
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const entry = charAtlasCache[i];
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const ownedByIndex = entry.ownedBy.indexOf(terminal);
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if (ownedByIndex >= 0) {
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if (configEquals(entry.config, newConfig)) {
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return entry.bitmap;
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} else {
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// The configs differ, release the terminal from the entry
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if (entry.ownedBy.length === 1) {
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charAtlasCache.splice(i, 1);
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} else {
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entry.ownedBy.splice(ownedByIndex, 1);
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}
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break;
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}
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}
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}
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// Try match a char atlas from the cache
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for (let i = 0; i < charAtlasCache.length; i++) {
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const entry = charAtlasCache[i];
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if (configEquals(entry.config, newConfig)) {
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// Add the terminal to the cache entry and return
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entry.ownedBy.push(terminal);
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return entry.bitmap;
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}
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}
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const canvasFactory = (width: number, height: number) => {
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const canvas = document.createElement('canvas');
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canvas.width = width;
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canvas.height = height;
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return canvas;
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};
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const newEntry: ICharAtlasCacheEntry = {
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bitmap: generateCharAtlas(window, canvasFactory, newConfig),
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config: newConfig,
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ownedBy: [terminal]
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};
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charAtlasCache.push(newEntry);
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return newEntry.bitmap;
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}
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