Making an Image Translucent Using AlphaData |
|
imageData
and
maskData
. If you don’t, take a look at tip
imag003 - Understanding ImageData, MaskData and AlphaData before
continuing.
The following is an example of making an image 50% transparent using the alphaData
property
of an image. It is similar to setting the ink
of an image to blend
and then
setting the blendLevel
, but is useful to show how to manipulate the alphaData
of an image.
This can be shortened further because you’re using every pixel of the image, so you don’t need to know the height and width of the image. Here’s the shorter version (thanks, Sarah!):on mouseUp put the imageData of image 1 into iData put the width of image 1 into tW put the height of image 1 into tH put empty into aData repeat with i = 1 to tH -- iterate each row repeat with j = 1 to tW -- iterate each column -- Set every pixel to be 50% transparent (1/2 of 255 = 128) put binaryEncode("C",128) after aData end repeat end repeat set the alphaData of image 1 to aData set the imageData of image 1 to iData end mouseUp
on mouseUp put the imageData of image 1 into iData put empty into aData repeat for each char X in the alphaData of image 1 -- See Note below -- Set every pixel to be 50% transparent (1/2 of 255 = 128) put binaryEncode("C",128) after aData end repeat set the alphaData of image 1 to aData set the imageData of image 1 to iData end mouseUp
Note: Using this approach provides
a way to iterate over the pixels using a repeat for each looping
construct (which is much faster than a repeat with loop). Both
the maskData of image and the alphaData of image
will return a number of characters (a "length") that is the total number of pixels in the image
(for a refresher on this, see
imag003 - Understanding ImageData, MaskData and AlphaData.)
So, since I could use either |
Have fun!
Posted 7/2/2002 by Ken Ray
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