Context and the drawing of NSImages
Context and the drawing of NSImages
- Subject: Context and the drawing of NSImages
- From: Brant Sears <email@hidden>
- Date: Wed, 13 Aug 2008 13:30:22 -0400
Hi. I've run into some behavior that I don't understand.
I'm trying to draw a series of NSImages programatically and then
cache them into an NSArray.
The problem I'm having is that some of the operations I'm doing on
one image seem to have an effect on some subsequent images in the
series.
The way I'm creating the images is by initializing a new NSImage
object, calling lockFocus on it, doing the drawing, calling
unlockFocus, then returning the image and adding it to my array.
The call that seems to be the problem is [[NSView focusView]
setBoundsOrigin:]. It appears from the results I'm getting that these
changes seem to "reset" when the instance of NSImageCacheView
changes. It seems to be the case that the focusView and the NSImage
object are not the same thing. I tried calling recache on the image
after I create it which had no effect.
What I am doing wrong? How can I control the resetting of the
graphics context? I'm intending to draw images that involve several
operations on the context. This is just a simplified example.
Thanks.
// this is the code that makes the images and adds them to the array.
for (i=0;i<kNumberOfImages;++i) {
NSImage * myImage = [self imageForIndex:i];
if (myImage) {
[imgArray addObject: myImage];
}
}
// this is the method that makes the image.
- (NSImage*)imageForIndex:(int)index
{
float w = 128;
float h = 128;
[NSGraphicsContext saveGraphicsState];
NSImage *myImage = [[NSImage alloc] initWithSize:NSMakeSize(w, h)];
[myImage lockFocus];
NSLog([[NSView focusView] description]);
NSColor * myColors[] = {
[NSColor redColor]
,[NSColor greenColor]
,[NSColor blueColor]
,[NSColor cyanColor]
,[NSColor yellowColor]
,[NSColor magentaColor]
,[NSColor orangeColor]
,[NSColor purpleColor]
};
int numColors = sizeof(myColors) / sizeof(NSColor);
while (index >= numColors)
index -= numColors;
[myColors[index] set];
NSRectFill(NSMakeRect(0,0,w,h));
NSPoint myPoint = NSMakePoint(-1 * (w/2), -1 * (h/2));
[[NSView focusView] setBoundsOrigin:myPoint];
[[NSColor blackColor]set];
NSRect circleRect = NSMakeRect(-20,-20,40,40);
NSBezierPath * circlePath = [NSBezierPath bezierPathWithOvalInRect:
circleRect];
[circlePath fill];
[myImage unlockFocus];
[NSGraphicsContext restoreGraphicsState];
return myImage;
}
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