/
BaseCharAtlas.ts
56 lines (49 loc) · 1.66 KB
/
BaseCharAtlas.ts
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/**
* Copyright (c) 2017 The xterm.js authors. All rights reserved.
* @license MIT
*/
import { IGlyphIdentifier } from './Types';
import { IDisposable } from 'xterm';
export default abstract class BaseCharAtlas implements IDisposable {
private _didWarmUp: boolean = false;
public dispose(): void { }
/**
* Perform any work needed to warm the cache before it can be used. May be called multiple times.
* Implement _doWarmUp instead if you only want to get called once.
*/
public warmUp(): void {
if (!this._didWarmUp) {
this._doWarmUp();
this._didWarmUp = true;
}
}
/**
* Perform any work needed to warm the cache before it can be used. Used by the default
* implementation of warmUp(), and will only be called once.
*/
protected _doWarmUp(): void { }
/**
* Called when we start drawing a new frame.
*
* TODO: We rely on this getting called by TextRenderLayer. This should really be called by
* Renderer instead, but we need to make Renderer the source-of-truth for the char atlas, instead
* of BaseRenderLayer.
*/
public beginFrame(): void { }
/**
* May be called before warmUp finishes, however it is okay for the implementation to
* do nothing and return false in that case.
*
* @param ctx Where to draw the character onto.
* @param glyph Information about what to draw
* @param x The position on the context to start drawing at
* @param y The position on the context to start drawing at
* @returns The success state. True if we drew the character.
*/
public abstract draw(
ctx: CanvasRenderingContext2D,
glyph: IGlyphIdentifier,
x: number,
y: number
): boolean;
}