Programmer's Reference

Reading bitmaps from files

Bitmaps can be read from files by sending the readBitmapFile:widthReturn:heightReturn:bitmapReturn:xHotReturn:yHotReturn: message to any CgDrawable. Parameters passed to the method include the file name and ReturnParameter objects for the width, height, the actual bitmap, and the x and y hot spot location. The value of any ReturnParameter object can be accessed by sending it the value message.

| error wReturn hReturn bReturn xReturn yReturn bitmap |
error := CgWindow default
    readBitmapFile: 'brick'
    widthReturn: (wReturn := ReturnParameter new)
    heightReturn: (hReturn := ReturnParameter new)
    bitmapReturn: (bReturn := ReturnParameter new)
    xHotReturn: (xReturn := ReturnParameter new)
    yHotReturn: (yReturn := ReturnParameter new).
 
error = 0
    ifTrue: [
        Transcript cr; show: 'File read successful. ',
            'Bitmap width: ', wReturn value printString,
            ', height: ', hReturn value printString,
            ', hotspot: ', (xReturn value @ yReturn value) printString.
        bitmap := bReturn value.
        bitmap freePixmap]
    ifFalse: [Transcript nextPutAll: 'File read error: ',
      error printString; cr].


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