Strange NSView redraw problem

• Subject: Strange NSView redraw problem
• From: "John Cassington" <email@hidden>
• Date: Sat, 30 Sep 2006 15:39:52 +1000
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Hello,
I have a nsview class which is used more than once at a time. the view
can be 'selected' in that its background color can change based on a
boolean value.

when i change the 'selection' from view to view, the nsbezierpath used
to draw the curved border around the view does not clear properly.

here are two example images:
before: http://img88.imageshack.us/img88/7259/beforemultipleredrawsvc7.png
after: http://img136.imageshack.us/img136/3713/aftermultipleredrawsrz9.png

i think this has something to do with anti-aliasing, but i am not sure.

i am using the following three lines to try and clear the view before a redraw:

NSEraseRect([self frame]);
[[NSColor clearColor] set];
NSRectFill([self frame]);

here is the whole code:

<<START CODE>>

	NSEraseRect([self frame]);
   [[NSColor clearColor] set];
   NSRectFill([self frame]);
	
	    NSColor *bgColor = [NSColor colorWithCalibratedWhite:0.25 alpha:0.85];
   NSRect bgRect = rect;
   int minX = NSMinX(bgRect);
   int midX = NSMidX(bgRect);
   int maxX = NSMaxX(bgRect);
   int minY = NSMinY(bgRect);
   int midY = NSMidY(bgRect);
   int maxY = NSMaxY(bgRect);
   float radius = 10.0; // correct value to duplicate Panther's App Switcher
   NSBezierPath *bgPath = [NSBezierPath bezierPath];

   // Bottom edge and bottom-right curve
   [bgPath moveToPoint:NSMakePoint(midX, minY)];
   [bgPath appendBezierPathWithArcFromPoint:NSMakePoint(maxX, minY)
                                    toPoint:NSMakePoint(maxX, midY)
                                     radius:radius];

   // Right edge and top-right curve
   [bgPath appendBezierPathWithArcFromPoint:NSMakePoint(maxX, maxY)
                                    toPoint:NSMakePoint(midX, maxY)
                                     radius:radius];

   // Top edge and top-left curve
   [bgPath appendBezierPathWithArcFromPoint:NSMakePoint(minX, maxY)
                                    toPoint:NSMakePoint(minX, midY)
                                     radius:radius];

   // Left edge and bottom-left curve
   [bgPath appendBezierPathWithArcFromPoint:bgRect.origin
                                    toPoint:NSMakePoint(midX, minY)
                                     radius:radius];
   [bgPath closePath];

   [bgColor set];
	if (isSelected) {
		[[NSColor colorWithCalibratedWhite:1.0 alpha:0.3] set];
	}
   [bgPath fill];
	
	[[NSColor colorWithCalibratedWhite:1.0 alpha:0.2] set];
	[bgPath setLineWidth:2.0];

	[bgPath setLineJoinStyle:NSRoundLineJoinStyle];
	[bgPath stroke];

	int i = 0;
	for (i=0;i<[imagesArray count];i++) {
		NSImage *thisIcon = [imagesArray objectAtIndex:i];
		[thisIcon drawAtPoint:NSMakePoint((64*i)+10,3)
fromRect:NSMakeRect(0,0,[thisIcon size].width,[thisIcon size].height)
operation:NSCompositeSourceOver fraction:1.0];
	}

<<END CODE>>

If anyone has any idea as to how i can make the corners of my view
draw properly,
it would be much appreciated.

Thanks,
John Cassington
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