Check if a QImage is empty

Jerome96

Hey guys

I am programming kind of a tileset creator for my 2D game. So I want to add a new picture from my hard disk which is bigger than the actual tilesize, then split it up into tiles.
I got that thing working, but when I use an image, it can happen that I have some tiles which are fully empty (because I didn't draw something on this part of the picture but can't leave this part away).

So I asked my self, how is it possible to check if a QImage is completly empty? So every pixel of it is transparent?

I hope you can help me.
Thank you anyway :)

zaps166

This can help for little-endian CPUs and "QImage::Format_ARGB32":

quint32 *pixels = (quint32 *)img.bits();
int imgSize = img.width() * img.height();
bool isTransparent = true;
for (int i = 0; i < imgSize; ++i)
{
	if (((pixels[i] >> 24) & 0xFF) != 0)
	{
		isTransparent = false;
		break;
	}
}

It checks that pixel is 100% transparent or not.