Color Sampling of Images

Discussion in 'iOS Programming' started by Shinji-23, Dec 18, 2008.

  1. macrumors newbie

    Dec 18, 2008
    I was planning on using a non-displayed image for hit detection by getting the color of the image at the point corresponding to the touch. I can't seem to find anyway to do this in the iPhone SDK.

    Does anybody know of an equivalent of NSBitmapImageRep's colorAtX:y:?
  2. macrumors 604

    Jul 29, 2003
    Silicon Valley
    If you have a pointer to the raw bitmap, and know the bytes-per-row and bytes-per-pixel, then it's a couple multiplies and an add to get a pointer to the raw pixel data from an X,Y coordinate.

  3. thread starter macrumors newbie

    Dec 18, 2008
    How do you get at that? Would that be CGImageGetDataProvider(image.CGImage)? Even if it is, do I have to realize that it's a PNG backing and code up the PNG reading standard to get at my color?

    (And if it is, how do I get data out of the CGDataProviderRef?)
  4. macrumors 68030


    Sep 2, 2008

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