Question

I’ve tried this in Flash and openFrameworks but had the same problem in both…

I’m building up a canvas made of 1000s of images, then I am exporting the final image as a jpg

I’d like to export it as a 6 megapixel jpg or something similar, however my screen resolution is much lower than that, and the export only ever comes out at my screen size..

Is there any way to get around this?

Thanks….

Answer 1

That’s easy. You create a BitmapData object of the desired size, then draw everything you need in the manner you need over that bitmapdata, then encode that bitmapdata with JPEGEncoder and pwn. An example:

public function saveAsPNG():void {
        if (frameset[0] == null) return;
        var fr:FileReference = new FileReference();
        var totalHeight:int = Math.ceil(Math.sqrt(totalFrames));
        var iter:int = totalHeight;
        if (iter * (iter - 1) >= totalFrames) totalHeight--;
        var totalWidth:int = iter * baseRect.width;
        totalHeight *= baseRect.height;
        var dp:Point = new Point();
        var bigBitmap:BitmapData = new BitmapData(totalWidth, totalHeight, true, 0);
        for (var i:int = 0; i < totalFrames; i++) {
            var j:int = Math.floor(i / iter);
            var k:int = i - j * iter;
            dp.x = k * baseRect.width;
            dp.y = j * baseRect.height;
            bigBitmap.copyPixels(frameset[i], baseRect, dp); // semi-square bitmap as a result
        }
        fr.save(PNGEncoder.encode(bigBitmap));
    }

This takes a sequence of BitmapDatas named “frameset” and slaps it over a single BitmapData named “bigBitmap”, which is then exported as PNG – I use this format as I need detailed transparency. Since the source objects are of BitmapData type, there is no BitmapData.draw() involved, but BitmapData.copyPixels() instead.