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Asked: 2026-06-15T05:57:20+00:00

Using drawInRect I’m getting inconsistent results Sometimes the images draw correctly, and sometimes the

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Using drawInRect I’m getting inconsistent results

Sometimes the images draw correctly, and sometimes the images look like they are half a pixel off:

enter image description here

On the top left, you’ll see that the cap image of the slider draws normal, then the fill has blurry edges, even though they are drawn with the same x, y …

// top cap
[topCap drawInRect:NSMakeRect(5, 5, 11, 7)
          fromRect:NSZeroRect
         operation:NSCompositeSourceOver
          fraction:1];

// background fill
[topFill drawInRect:NSMakeRect(5, 12, 11, (CGRectGetHeight(aRect) - 23))
           fromRect:NSZeroRect
          operation:NSCompositeSourceOver
           fraction:1];

Bottom left arrow, the same situation.

Center right arrow, similar situation. You can see the left cap image renders correctly, then the background fill (a 1px wide image) gets all blurry.

I’m wondering if it has something to do with stretching the image, because it seems the images that I’m trying to fill a rectangle with render poorly.

Thanks for any insight.

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1 Answer

  1. Editorial Team

    If you know why drawInRect distorts the image please leave an answer. Here is the way I found to get around this:

    For some areas I used colorWithPatternImage

    NSColor* backgroundFill = [NSColor colorWithPatternImage:backgroundImage];
[backgroundFill set];
NSRectFill(background);

    The problem I ran into with this is that the pattern origin is set to the window not the view, so sometimes the pattern would misalign.

    For several areas I used NSDrawThreePartImage which correctly tiled the image without distorting it. Even when I did not have 3 images, I just put the same image in 3 times.

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