Making a Screenshot in LibGDX by Pressing the Prt Scr Button

Question

By following this solution on Stack Overflow I have come up with the following Java class:

public final class Screenshot {

    private static byte[] pixels;
    private static Pixmap pixmap;

    public static void take() {
        pixels = ScreenUtils.getFrameBufferPixels(0, 0,
                Gdx.graphics.getBackBufferWidth(),
                Gdx.graphics.getBackBufferHeight(),
                true);

        pixmap = new Pixmap(Gdx.graphics.getBackBufferWidth(),
                Gdx.graphics.getBackBufferHeight(),
                Pixmap.Format.RGBA8888);

        BufferUtils.copy(pixels, 0, pixmap.getPixels(), pixels.length);
        PixmapIO.writePNG(Gdx.files.external("./screenshot_" + new Date().getTime() + ".png"), pixmap);

        pixmap.dispose();
        pixels = null;
    }
}

Calling Screenshot().take() will take the LibGDX render buffer and dump it in a PNG file. Exactly what I want.

My question is if there's a good way to 'capture' the print screen button. Is there a print screen keycode that I can use?

Use [key bindings](https://docs.oracle.com/javase/tutorial/uiswing/misc/keybinding.html) with this key code: http://stackoverflow.com/a/10793610/300257 — Gilbert Le Blanc, Feb 19 '16 at 17:52
@GilbertLeBlanc thank you for your comment! Could you please advice me on how to do this correctly with a code example as an answer? If you could do that for me, I can accept it as the answer. — Tim Visser, Feb 20 '16 at 18:55

score 3 · Accepted Answer · answered Feb 20 '16 at 22:54

It seems that in LibGDX you cannot.

The way you are checking the keyboard input is

    Gdx.input.isKeyPressed(key)

where key is object of class Keys which does not includes prtscr button.

What's more - the Keys objects are integers so I tried to find out what button code of prtsrc is by checking:

    uiStage.addListener(new ClickListener()
    {
        @Override
        public boolean keyDown(InputEvent event, int keycode)
        {
            System.out.println(keycode);
            return true;
        }
    });

and I got 0 on my computer. I have checked what 0 is in Keys class by printing

    System.out.println(Input.Keys.toString(42));

and the result was Unknown. I'm pretty surprised to be honest but it seems that LibGDX does not support PRINT_SCREEN button.

Probably there is a way to ommit LibGDX mechanism and use the platform specific function to check if prtsrc was clicked (internet says that it's ASCII code is 44) but the answer for LibGDX itself seems to be - there is no way to do it.

That is absolutely unplanned for... I now want to know if the missing implementation has some sort of reason behind it... I wonder... — Tim Visser, Feb 21 '16 at 01:18
What comes to my mind is that maybe because prtscr button is not available on e.g. android virtual keyboard or it can be differ on different devices - maybe it worths to ask libgdx production team - I believe they will explain — m.antkowicz, Feb 21 '16 at 01:49

Making a Screenshot in LibGDX by Pressing the Prt Scr Button

1 Answers1