Document reference for working with bitmaps in Cocoa?

  • Hi all.

    I've been working with the NSBitmapImageRep class in order to create
    bitmaps from Raster/Sample data I am obtaining from an external source.

    I'm having problems getting the "alpha channel" to work correctly.

    If I exclude alpha, my bitMapData is just an array of bytes (unsigned
    char*) that contains the pixels samples in RGB format (three bytes
    per pixel.)

    But if I include an alpha byte in ARGB format, my bitmap no longer
    displays. Actually, it's all white, but when I draw it selected, with
    a blue background, my image shows up but only the Red colors show.

    So clearly, I'm not understanding how I'm supposed to format the
    bitMapData array when I want to include an alpha channel.

    I would appreciate any document references on this subject. I've read
    the API docs for NSImage, NSImageRep, and NSBitmapImageRep. I also
    have the Bunny Core Graphics book, but that's a much lower-level API
    and doesn't cover this topic.

    Thanks,

    Rob Ross, Lead Software Engineer
    E! Networks
    <rross...>
    ---------------------------------------------------
    "Beware of he who would deny you access to information, for in his
    heart he dreams himself your master." -- Commissioner Pravin Lal
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