How to move everything in Graphics2D by x,y coordinates.

Question

I need to move already made BufferedImage by x,y coordinates and then draw another things on it with Graphics2D object. I tried to use this code to do that :

Graphics2D g = img.createGraphics();
g.translate(x, y);  

but it doesn't work. Is there any way to move everything in Graphics2D object and then draw on it or I have to use this code to do that:

BufferedImage temp = new BufferedImage(img.getWidth(),img.getHeight(),BufferedImage.TYPE_INT_ARGB);
Graphics2D g = temp.createGraphics();
g.drawImage(img,x, y,null);

Using this code and then drawing only few elements rather than making whole image from scratch isn't big leap in performance so I think making new BufferedImage then drawing image on it isn't best way. I would rather just create Graphics2D object from already made image and then just move it by a few pixels diagonally, but I couldn't find the way to do that.

Answer 1

From the Graphics2d docs when you use translate:

All coordinates used in subsequent rendering operations on this graphics context are relative to this new origin.

You are defining a transformation that affects future operations. After calling translate if you were to call a method on graphics like draw3DRect(0, 0, ... snipped ... ) the starting coordinates 0,0 would be translated by x,y.

I think your best bet might be to use the methods of BufferedImage to move all the pixels before you get the graphics object. You have getRgb and setRgb

A naive example of moving the pixels:

BufferedImage buffImg = ImageIO.read(img);
int width = buffImg.getWidth();
int horizontalOffset = 10;
int verticalOffset = 10;
int widthToMove = width - horizontalOffset;
int heightToMove = buffImg.getHeight() - verticalOffset;
int[] rgb = buffImg.getRGB(0, 0, widthToMove, heightToMove, null, 0, widthToMove);
buffImg.setRGB(horizontalOffset,verticalOffset,widthToMove, heightToMove,rgb, 0, widthToMove);

This still leaves you with some work to do because there is a strip at the top and to the left that you need to fill with background colour.

If it's going to be used on big images you might want to use a buffer int[] and pass it to getRGB in a loop, getting and setting in chunks.