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nodeCanvas.js
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nodeCanvas.js
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/* Copyright 2017 Mozilla Foundation
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
const Canvas = require('canvas')
const assert = require('assert')
function NodeCanvasFactory() { }
NodeCanvasFactory.prototype = {
create: function NodeCanvasFactory_create(width, height) {
assert(width > 0 && height > 0, 'Invalid canvas size')
const canvas = Canvas.createCanvas(width, height)
const context = canvas.getContext('2d')
return {
canvas: canvas,
context: context,
}
},
reset: function NodeCanvasFactory_reset(canvasAndContext, width, height) {
assert(canvasAndContext.canvas, 'Canvas is not specified')
assert(width > 0 && height > 0, 'Invalid canvas size')
canvasAndContext.canvas.width = width
canvasAndContext.canvas.height = height
},
destroy: function NodeCanvasFactory_destroy(canvasAndContext) {
assert(canvasAndContext.canvas, 'Canvas is not specified')
// Zeroing the width and height cause Firefox to release graphics
// resources immediately, which can greatly reduce memory consumption.
canvasAndContext.canvas.width = 0
canvasAndContext.canvas.height = 0
canvasAndContext.canvas = null
canvasAndContext.context = null
},
}
module.exports = NodeCanvasFactory