imagedata and alpha byte
Correcting my previous post. You don't have to set the imageData explicitly. I was confused by vanishing images. Apparently if you want to set all of the imageData to numToByte(0) or numToByte(256) the image vanishes. The workaround is to set it to 1 or 255 respectively. This is in LC 9 GM Kind regards Bernd Here is the corrected script --- on mouseUp local tAlphaData, tTransparent, tOpaque local tCollect, tLength -- not needed here but if you want to modify existing AD put the alphaData of image 1 into tAlphaData put numToByte(1) into tTransparent -- dont set to 0 or image vanishes put numToByte(255) into tOpaque -- dont set to 256 or image vanishes put the width of image 1 * the height of image 1 into tLength repeat tLength --put tTransparent after tCollect put tOpaque after tCollect end repeat set the alphaData of image 1 to tCollect end mouseUp - ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: imagedata and alpha byte
Hi, please do not use numToChar in version 7.0 and up for image manipulation, use numToByte or byteToNum NumToChar is deprecated. It might work but is horribly slow. along the lines of Mike's example -- on mouseUp local tAlphaData, tTransparent, tHalfTransparent local tImgData, tCollect, tLength put the imageData of image 1 into tImgData -- not needed here but if you want to modify existing AD put the alphaData of image 1 into tAlphaData put numToByte(0) into tTransparent put numToByte(127) into tHalfTransparent put the width of image 1 * the height of image 1 into tLength repeat tLength -- put tTransparent after tCollect put tHalfTransparent after tCollect end repeat -- in LC 9 you have to set imagedata again explicitly set the imageData of image 1 to tImgData set the alphaData of image 1 to tCollect end mouseUp Kind regards Bernd ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: imagedata and alpha byte
Already assuming that you know which pixel you wish to modify, (like if you want to modify pixel 25 in pixel row 3, that would be pixel 75.. I think..) you would need to do something like the following.. --first, put the current alphadata into a variable. put the alphadata of img "myImg" into tAlpha -- then modify the alphadata for the pixel in question put numtochar(0) into char 75 of tAlpha -- 0 is transparent, 255 is completely opaque -- change all necessary pixels here then -- set the image to the new alphadata set the alphadata of img "myImg" to tAlpha On Wed, May 9, 2018 at 11:59 AM, jbv via use-livecode < use-livecode@lists.runrev.com> wrote: > On Wed, May 9, 2018 7:51 pm, Richmond Mathewson via use-livecode wrote: > > The inevitable question has to be why you are doing that in such a > > fiddly sort of way. > > > > Richmond. > > > > It would be too long to explain, but in short some users of a client > app will modify pixels of images that will then be exported as PNG to > a server and then displayed in a website. > I have successfully modified the alpha channel of images with php for > years, and am just wondering why this doesn't work in LC... > > > ___ > use-livecode mailing list > use-livecode@lists.runrev.com > Please visit this url to subscribe, unsubscribe and manage your > subscription preferences: > http://lists.runrev.com/mailman/listinfo/use-livecode > ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: imagedata and alpha byte
On Wed, May 9, 2018 7:51 pm, Richmond Mathewson via use-livecode wrote: > The inevitable question has to be why you are doing that in such a > fiddly sort of way. > > Richmond. > It would be too long to explain, but in short some users of a client app will modify pixels of images that will then be exported as PNG to a server and then displayed in a website. I have successfully modified the alpha channel of images with php for years, and am just wondering why this doesn't work in LC... ___ use-livecode mailing list use-livecode@lists.runrev.com Please visit this url to subscribe, unsubscribe and manage your subscription preferences: http://lists.runrev.com/mailman/listinfo/use-livecode
Re: imagedata and alpha byte
The inevitable question has to be why you are doing that in such a
fiddly sort of way.
Richmond.
On 9/5/2018 8:49 pm, jbv via use-livecode wrote:
Hi list,
Still struggling with imagedata, I am trying to modify the transparency
of an image by manipulating pixel by pixel the alpha byte.
I tried with numToChar(0) and binaryEncode("B*","") but to no
avail...
OTOH manipulating the RVB channel works fine.
Any idea on how modify the alpha channel of the imagedata of a image,
and then exporting the image as PNG with the modified transparency ?
Thanks in advance.
jbv
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imagedata and alpha byte
Hi list,
Still struggling with imagedata, I am trying to modify the transparency
of an image by manipulating pixel by pixel the alpha byte.
I tried with numToChar(0) and binaryEncode("B*","") but to no
avail...
OTOH manipulating the RVB channel works fine.
Any idea on how modify the alpha channel of the imagedata of a image,
and then exporting the image as PNG with the modified transparency ?
Thanks in advance.
jbv
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