fabric/dist/src/filters/GLProbes/WebGLProbe.mjs

Object model for HTML5 canvas, and SVG-to-canvas parser. Backed by jsdom and node-canvas.

import { log } from '../../util/internals/console.mjs';
import { GLProbe } from './GLProbe.mjs';

/**
 * Lazy initialize WebGL constants
 */
class WebGLProbe extends GLProbe {
  /**
   * Tests if webgl supports certain precision
   * @param {WebGL} Canvas WebGL context to test on
   * @param {GLPrecision} Precision to test can be any of following
   * @returns {Boolean} Whether the user's browser WebGL supports given precision.
   */
  testPrecision(gl, precision) {
    const fragmentSource = "precision ".concat(precision, " float;\nvoid main(){}");
    const fragmentShader = gl.createShader(gl.FRAGMENT_SHADER);
    if (!fragmentShader) {
      return false;
    }
    gl.shaderSource(fragmentShader, fragmentSource);
    gl.compileShader(fragmentShader);
    return !!gl.getShaderParameter(fragmentShader, gl.COMPILE_STATUS);
  }

  /**
   * query browser for WebGL
   */
  queryWebGL(canvas) {
    const gl = canvas.getContext('webgl');
    if (gl) {
      this.maxTextureSize = gl.getParameter(gl.MAX_TEXTURE_SIZE);
      this.GLPrecision = ['highp', 'mediump', 'lowp'].find(precision => this.testPrecision(gl, precision));
      gl.getExtension('WEBGL_lose_context').loseContext();
      log('log', "WebGL: max texture size ".concat(this.maxTextureSize));
    }
  }
  isSupported(textureSize) {
    return !!this.maxTextureSize && this.maxTextureSize >= textureSize;
  }
}

export { WebGLProbe };
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