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Editorial Team
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Asked: 2026-06-14T00:07:10+00:00

I wish to overlay one CGImage over another. As an example the first CGImage

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I wish to overlay one CGImage over another.

As an example the first CGImage is 1024×768 and want to overlay a second 100×100 CGImage at a given location.

I have seen how to do this using NSImage but don’t really want to convert my CGImages to NSImage’s then do overlay then convert the result back to CGImage. I have also seen iOS versions of the code, but unsure how to go about it on Mac?

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1 Answer

  1. Editorial Team

    I’m mostly used to iOS, so I might be out of my depth here, but assuming you have a graphics context (sized like the larger of the two images), can’t you just draw the two CGImages on top of each other?

    CGImageRef img1024x768;
CGImageRef img100x100;

CGSize imgSize = CGSizeMake(CGImageGetWidth(img1024x768), CGImageGetHeight(img1024x768));

CGRect largeBounds = CGRectMake(0, 0, CGImageGetWidth(img1024x768), CGImageGetHeight(img1024x768));
CGContextDrawImage(ctx, largeBounds, img1024x768);

CGRect smallBounds = CGRectMake(0, 0, CGImageGetWidth(img100x100), CGImageGetHeight(img100x100));
CGContextDrawImage(ctx, smallBounds, img100x100);

    And then draw the result into a NSImage?

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