Images aren't handled properly

I'm using parts of gordon for parsing a swf and noticed that it doesn't handle images very well. Below is some adjusted code that handled everything (so far) except lossless pix15 and jpeg4 because i can't seem to create test scenarios. I figured since gordon has helped so much on my project it was only fit to return the favor.
        if(colorData) {
            var colorTableSize = obj.colorTableSize || 0,
                withAlpha = obj.withAlpha,
                bpp = (withAlpha || (obj.format == 5) ? 4 : 3),
                cmIdx = colorTableSize * bpp,
                pxIdx = 0,
                canvas = this.doc.createElement("canvas"),
                ctx = canvas.getContext("2d"),
                imgData = ctx.createImageData(width, height),
                pad = colorTableSize ? ((width + 3) & ~3) - width : 0;

            canvas.width = width;
            canvas.height = height;

            // If colorTableSize, then image is Colormapped
            // If no colorTableSize, then image is Direct

            // Without Alpha
            // (BitmapFormat 3) Colormapped Images are stored RGB, canvas uses RGBA
            // (BitmapFormat 4) Direct Images 15bit are UB[1] res, UB[5] red, UB[5] green, UB[5] blue
            // (BitmapFormat 5) Direct Images 24bit are UI8 res, UI8 red, UI8 green, UI8 blue

            // With Alpha
            // (BitmapFormat 3) Colormapped Images are stored RGBA, canvas uses RGBA
            // (BitmapFormat 5) Direct Images 32bit are stored ARGB, canvas uses RGBA
            if(obj.format == 4) colorData = new Flashbug.BytearrayString(colorData.join(''));

            for (var y = 0; y < height; y++) {
                for (var x = 0; x < width; x++) {
                    var idx = (colorTableSize ? colorData[cmIdx++] : cmIdx++) * bpp, r, g, b, a;
                    if(withAlpha) {
                        r = colorTableSize ? colorData[idx] : colorData[idx + 1];
                        g = colorTableSize ? colorData[idx + 1] : colorData[idx + 2];
                        b = colorTableSize ? colorData[idx + 2] : colorData[idx + 3];
                        a = colorTableSize ? colorData[idx + 3] : colorData[idx];
                    } else {
                        if(obj.format == 3) {
                            r = colorData[idx];
                            g = colorData[idx + 1];
                            b = colorData[idx + 2];
                        } else if(obj.format == 4) {
                            // Untested
                            colorData.readUB(1); // Reserved
                            r = colorData.readUB(5);
                            g = colorData.readUB(5);
                            b = colorData.readUB(5);
                        } else if(obj.format == 5) {
                            //colorData[idx]; // Reserved
                            r = colorData[idx + 1];
                            g = colorData[idx + 2];
                            b = colorData[idx + 3];
                        }
                        a = 255;
                    }

                    // BUG: Corrupted color data? (zlib?)
                    // had an image that wasn't the correct data size
                    // colorData.length = 65529
                    // imgData.data.length = 65536
                    // delta 7px
                    if(a) {
                        imgData.data[pxIdx] = r || 0; //R
                        imgData.data[pxIdx + 1] = g || 0; //G
                        imgData.data[pxIdx + 2] = b || 0; //B
                        imgData.data[pxIdx + 3] = a; //A
                    }
                    pxIdx += 4;
                }
                cmIdx += pad;
            }

            ctx.putImageData(imgData, 0, 0);
            uri = canvas.toDataURL();

            param.value.data = atob(uri.split(',')[1]);
        } else {
            uri = "data:image/jpeg;base64," + btoa(obj.data);

            // Moved to the image onload becuase of drawImage blowing up in Firefox
            /*if (obj.alphaData) {
                var img = new Image(),
                    canvas = this.doc.createElement("canvas"),
                    ctx = canvas.getContext("2d"),
                    len = width * height,
                    data = obj.alphaData;
                img.src = uri;
                canvas.width = width;
                canvas.height = height;

                //Component returned failure code: 0x80040111 (NS_ERROR_NOT_AVAILABLE) [nsIDOMCanvasRenderingContext2D.drawImage]
                ctx.drawImage(img, 0, 0); // <----- 

                var imgData = ctx.getImageData(0, 0, width, height),
                    pxIdx = 0;

                for (var i = 0; i < len; i++) {
                    imgData.data[pxIdx + 3] = data[i];
                    pxIdx += 4;
                }
                ctx.putImageData(imgData, 0, 0);
                uri = canvas.toDataURL();
            }*/
        }

        ///////////////// in image onload ///////////////////
        var canvas = this.doc.createElement("canvas"),
            ctx = canvas.getContext("2d"),
            len = w * h;
        canvas.width = w;
        canvas.height = h;

        ctx.drawImage(img, 0, 0);

        var imgData = ctx.getImageData(0, 0, w, h),
            pxIdx = 0;
            var counter = 0;
        for (var i = 0; i < len; i++) {
            var a = obj.alphaData[i];
            // BUG: Corrupted Alpha data? (zlib?)
            // had an image that wasn't the correct data size
            // alphaData.length = 141143
            // imgData.data.length = 141198
            // delta 55px
            if(a != undefined) imgData.data[pxIdx + 3] = a;
            pxIdx += 4;
        }

        ctx.putImageData(imgData, 0, 0);
        obj.hasAlpha = true; // Used a flag so when the image calls onload again, it won't mix in the alpha twice
        img.src = canvas.toDataURL();
tbtlr / gordon

Images aren't handled properly #14
