canvas.js

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/*
 * Copyright (c) 2015 Sylvain Peyrefitte
 *
 * This file is part of mstsc.js.
 *
 * mstsc.js is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
 
(function() {
    
    /**
     * decompress bitmap from RLE algorithm
     * @param   bitmap  {object} bitmap object of bitmap event of node-rdpjs
     */
    function decompress (bitmap) {
        var fName = null;
        switch (bitmap.bitsPerPixel) {
        case 15:
            fName = 'bitmap_decompress_15';
            break;
        case 16:
            fName = 'bitmap_decompress_16';
            break;
        case 24:
            fName = 'bitmap_decompress_24';
            break;
        case 32:
            fName = 'bitmap_decompress_32';
            break;
        default:
            throw 'invalid bitmap data format';
        }
        
        var input = new Uint8Array(bitmap.data);
        var inputPtr = Module._malloc(input.length);
        var inputHeap = new Uint8Array(Module.HEAPU8.buffer, inputPtr, input.length);
        inputHeap.set(input);
        
        var output_width = bitmap.destRight - bitmap.destLeft + 1;
        var output_height = bitmap.destBottom - bitmap.destTop + 1;
        var ouputSize = output_width * output_height * 4;
        var outputPtr = Module._malloc(ouputSize);
 
        var outputHeap = new Uint8Array(Module.HEAPU8.buffer, outputPtr, ouputSize);
 
        var res = Module.ccall(fName,
            'number',
            ['number', 'number', 'number', 'number', 'number', 'number', 'number', 'number'],
            [outputHeap.byteOffset, output_width, output_height, bitmap.width, bitmap.height, inputHeap.byteOffset, input.length]
        );
        
        var output = new Uint8ClampedArray(outputHeap.buffer, outputHeap.byteOffset, ouputSize);
        
        Module._free(inputPtr);
        Module._free(outputPtr);
        
        return { width : output_width, height : output_height, data : output };
    }
    
    /**
     * Un compress bitmap are reverse in y axis
     */
    function reverse (bitmap) {
        return { width : bitmap.width, height : bitmap.height, data : new Uint8ClampedArray(bitmap.data) };
    }
 
    /**
     * Canvas renderer
     * @param canvas {canvas} use for rendering
     */
    function Canvas(canvas) {
        this.canvas = canvas;
        this.ctx = canvas.getContext("2d");
    }
    
    Canvas.prototype = {
        /**
         * update canvas with new bitmap
         * @param bitmap {object}
         */
        update : function (bitmap) {
            var output = null;
            if (bitmap.isCompress) {
                output = decompress(bitmap);
            }
            else {
                output = reverse(bitmap);
            }
            
            // use image data to use asm.js
            var imageData = this.ctx.createImageData(output.width, output.height);
            imageData.data.set(output.data);
            this.ctx.putImageData(imageData, bitmap.destLeft, bitmap.destTop);
        }
    }
    
    /**
     * Module export
     */
    Mstsc.Canvas = {
        create : function (canvas) {
            return new Canvas(canvas);
        }
    }
})();