I want to find and cut out the painted area (painted means: not transparent.). Do you got any Ideas how to do that?
Data Informations:
unsigned char array* imageData; // (each entry = grey value of pixel)
int imageHeight;
int imageWidth;
int imageSize;
Example Code:

Qt Code: 
  1. QPixmap img(imageWidth , imageHeight);
  2. 	img.fill(Qt::transparent);
  3. 	QPainter paint(&img);
  4. 	paint.setCompositionMode(QPainter::CompositionMode_Source);
  5.  
  6. 	int currentPos;
  7.  
  8.  
  9. 	while(currentpos < imageDataSize)
  10. 	{
  11. 		int x = imageDataSize % imageWidth;
  12. 		int y = imageDataSize / imageWidth+1;
  13. 		int greyVal =  imageData[currentPos];
  14.  
  15. 		paint.setPen(QColor(greyVal,greyVal,greyVal);
  16. 		if(hmm < 160)
  17. 		{
  18. 			paint.drawPoint(x,y);
  19. 		} else {
  20. 			paint.save();
  21. 			paint.setOpacity(0.0);
  22. 			paint.setPen(QColor(255,255,255,255));
  23. 			paint.drawPoint(x,y);
  24. 			paint.restore();
  25.  
  26. 		}
  27. 		currentPos++;
  28. 	}
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