OK, Here's the deal. Although there is a byte for alpha in the z buffer
(imagedata) it seems to be ignored. The alpha data is only in the alphadata
property. You also must set the text property to empty before you set the new
image(imagedata) and alpha data(alphadata).
This example just does a crop in the middle of y and pastes the remaining top
and bottom together:
command CropMiddleOfImage pImageName, pMiddlePercentCrop
--
-- pImageName ==> LiveCode image control's name
-- pMiddlePercentCrop ==> 0 to 100
--
local tImageData, tWidth, tHeight, tTop, tBottom, tNewImageData, tAlphaData,
tNewAlphaData
lock screen
put the imagedata of image pImageName into tImageData
put the alphadata of image pImageName into tAlphaData
put the width of image pImageName into tWidth
put the height of image pImageName into tHeight
put pMiddlePercentCrop / 100 into pMiddlePercentCrop
put trunc((tHeight - (tHeight * pMiddlePercentCrop)) / 2) into tTop
put tTop into tBottom
if not (((tHeight - (tHeight * pMiddlePercentCrop)) / 2) is an integer) then
add 1 to tBottom
end if
put byte 1 to (tTop*4*tWidth) -1 of tImageData into tNewImageData
put byte (the number of bytes of tImageData - (tBottom*4*tWidth)) to -1 of
tImageData after tNewImageData
put byte 1 to (tTop*tWidth) -1 of tAlphaData into tNewAlphaData
put byte (the number of bytes of tAlphaData - (tBottom*tWidth)) to -1 of
tAlphaData after tNewAlphaData
set the height of image pImageName to tTop+tBottom
set the width of image pImageName to tWidth
set the text of image pImageName to empty
set the imagedata of image pImageName to tNewImageData
set the alphadata of image pImageName to tNewAlphaData
unlock screen
end CropMiddleOfImage pImageName
Ralph DiMola
IT Director
Evergreen Information Services
rdim...@evergreeninfo.net
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