dragonbones-runtime/.cache/egret-core-5.1.0/src/egret/native/rendering/canvas/NativeCanvasRenderBuffer.ts

the tools to build dragonbones file for diffrent framework

//////////////////////////////////////////////////////////////////////////////////////
//
//  Copyright (c) 2014-present, Egret Technology.
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//  modification, are permitted provided that the following conditions are met:
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namespace egret.native {

    /**
     * 创建一个canvas。
     */
    function createCanvas(width?:number, height?:number):NativeCanvas {
        let result = new NativeCanvas();
        if (!isNaN(width) && !isNaN(height)) {
            result.width = width;
            result.height = height;
        }
        return result;
    }

    let sharedCanvas:NativeCanvas;

    /**
     * @private
     * NativeCanvas2D渲染器
     */
    export class NativeCanvasRenderBuffer implements sys.RenderBuffer {

        public constructor(width?:number, height?:number) {
            this.surface = createCanvas(width, height);
            this.context = this.surface.getContext("2d");
            //保证rootCanvas是第一个创建的canvas
        }

        /**
         * 渲染上下文
         */
        public context:any;
        /**
         * 呈现最终绘图结果的画布
         */
        public surface:NativeCanvas;

        /**
         * 渲染缓冲的宽度，以像素为单位。
         * @readOnly
         */
        public get width():number {
            return this.surface.width;
        }

        /**
         * 渲染缓冲的高度，以像素为单位。
         * @readOnly
         */
        public get height():number {
            return this.surface.height;
        }

        /**
         * 改变渲染缓冲的大小并清空缓冲区
         * @param width 改变后的宽
         * @param height 改变后的高
         * @param useMaxSize 若传入true，则将改变后的尺寸与已有尺寸对比，保留较大的尺寸。
         */
        public resize(width:number, height:number, useMaxSize?:boolean):void {
            //resize 之前要提交下绘制命令
            if($supportCmdBatch) {
                $cmdManager.flush();
            }
            let surface = this.surface;
            surface.width = width;
            surface.height = height;
            this.clear();
        }

        /**
         * 获取指定区域的像素
         */
        public getPixels(x:number, y:number, width:number = 1, height:number = 1):number[] {
            return this.context.getImageData(x, y, width, height).data;
        }

        /**
         * 转换成base64字符串，如果图片（或者包含的图片）跨域，则返回null
         * @param type 转换的类型，如: "image/png","image/jpeg"
         */
        public toDataURL(type?:string, encoderOptions?:number):string {
            return this.surface.toDataURL(type, encoderOptions);
        }

        /**
         * 清空缓冲区数据
         */
        public clear():void {
            let width = this.surface.width;
            let height = this.surface.height;
            if(width > 0 && height > 0) {
                this.context.setTransform(1, 0, 0, 1, 0, 0);
                this.context.clearRect(0, 0, width, height);
            }
        }

        /**
         * 销毁绘制对象
         */
        public destroy():void {
            this.surface.width = this.surface.height = 1;
        }
    }
}