LibGDX - How to export a texture as a .png onto, say, the desktop

Question

I'm making a game in which I need to export a texture which the user has edited as a .png into a specified location. I'd like it if I could have the default saving window thing (like on other apps when you do cmd+s). If this isn't possible, is there any way in GDX to export a texture (as a .png) to the computer (and preferably not the assets folder)

Answer 1

One way of achieving this would be to save the portion of the screen where they've made their edits by taking a screen shot using the ScreenUtils.getFrameBufferPixmap method and then dumping the Pixmap data to a file using the PixmapIO class that can write PNGs from a Pixmap.

public class ScreenshotFactory {

private static int counter = 1;
public static void saveScreenshot(){
    try{
        FileHandle fh;
        do{
            fh = new FileHandle("screenshot" + counter++ + ".png");
        }while (fh.exists());
        Pixmap pixmap = getScreenshot(0, 0, Gdx.graphics.getWidth(), Gdx.graphics.getHeight(), false);
        PixmapIO.writePNG(fh, pixmap);
        pixmap.dispose();
    }catch (Exception e){           
    }
}

private static Pixmap getScreenshot(int x, int y, int w, int h, boolean yDown){
    final Pixmap pixmap = ScreenUtils.getFrameBufferPixmap(x, y, w, h);

    if (yDown) {
        // Flip the pixmap upside down
        ByteBuffer pixels = pixmap.getPixels();
        int numBytes = w * h * 4;
        byte[] lines = new byte[numBytes];
        int numBytesPerLine = w * 4;
        for (int i = 0; i < h; i++) {
            pixels.position((h - i - 1) * numBytesPerLine);
            pixels.get(lines, i * numBytesPerLine, numBytesPerLine);
        }
        pixels.clear();
        pixels.put(lines);
        pixels.clear();
    }

    return pixmap;
}
}

The snippet above is snagged from Take a Screenshot for libGDX on github. It should be easy to modify it to take only a portion of the screen or to change it to work on a Pixmap grabbed from another FrameBuffer.