Question

I try to draw a sequence of pattern images (different repeated patterns in one view).

So what I did is this, in a loop:

CGContextRef context = UIGraphicsGetCurrentContext();

// clip to the drawing rectangle to draw the pattern for this portion of the view
CGContextClipToRect(context, drawingRect);

// the first call here works fine... but for the next nothing will be drawn
CGContextDrawTiledImage(context, CGRectMake(0, 0, 2, 31), [img CGImage]);

I think that after I’ve clipped the context to draw the pattern in the specific rectangle, I cut out a snippet from the big canvas and the next time, my canvas is gone. can’t cut out another snippet. So I must reset that clipping somehow in order to be able to draw another pattern again somewhere else?

Edit: In the documentation I found this:

CGContextClip: “… Therefore, to
re-enlarge the paintable area by
restoring the clipping path to a prior
state, you must save the graphics
state before you clip and restore the
graphics state after you’ve completed
any clipped drawing. …”

Well then, how to store the graphics state before clipping and how to restore it?

Answer 1

The functions you are looking for are:

CGContextSaveGState(context);

and

CGContextRestoreGState(context);