Great explanation, I wasn't aware of that. thank you Ken Tiemo > -----Ursprüngliche Nachricht----- > Von: use-livecode-boun...@lists.runrev.com [mailto:use-livecode- > boun...@lists.runrev.com] Im Auftrag von Ken Ray > Gesendet: Montag, 11. Juli 2011 15:29 > An: How to use LiveCode > Betreff: Re: AW: How to test if an image is empty? > > > Thanks Mark and Scott, > > "the text" ... hmm, not the first to think about with an image :) > > If it helps, Tiemo, you can use this: > > put "" into image 1 > > and > > if image 1 is empty then... > > The "text" property is implied in the same was as for fields ("put field 1 > into.." vs. "put the text of field 1 into..."). > > Here's a good way to think about images: there's a distinction between the > actual image binary data and what is used to show the user what the image > currently looks like (including scaling, rotation, rendering in various > quality levels, the "paintCompression", etc.). The binary data is the image's > *contents* (the 'text' of the image in this case), and what is shown to the > user is the 'imageData'+'maskData'+'alphaData' (which I'll just call "image > data"). If you empty out the image data, the binary data still exists - all > you've done is to say (in effect) "don't show this image to the user", or more > accurately: "show blank to the user". > > You can have binary data without image data but not the other way around; once > you set the image data of an image, the binary data is *created* to support > the image data you set. This can be very useful in keeping a scaled version of > an image in a stack without holding on to all the extra "weight" of the > original image. > > So for example, if you imported a 100K image that was 1000 x 1000 pixels and > then scaled it down to 100 x 100 (and set the lockLoc to true so it doesn't > "pop" back to its original size), the user would see 100 x 100 pixels of image > data, but the image would be storing 1000 x 1000 pixels of binary data. > However, if you created a new blank 100 x 100 image an then executed: > > set the imageData of img 2 to the imageData of img 1 > set the alphaData of img 2 to the alphaData of img 1 > set the maskData of img 2 to the maskData of img 1 > > the binary data for img 2 would only be what is necessary to support what the > user sees (100 x 100 pixels). It would look exactly like image 1, but would be > only 1% of the original number of pixels and would only take up 1K instead of > 100K. You could then delete image 1 and you'd have exactly what you started > with but storing a bunch less space. > > This is great for working with thumbnails of full-resolution images; of course > if you *need* to keep the full-res image around because the image might scale > *up* from 100x100 to 1000x1000 (or any size in between) then you want to work > with the full-res image and not make a "cheap copy", but you get the idea. > > I have a very old (but still mostly accurate) primer on imageData, alphaData, > and maskData here: > > http://www.sonsothunder.com/devres/revolution/tips/imag003.htm > > Hope this helps, > > Ken Ray > Sons of Thunder Software, Inc. > Email: k...@sonsothunder.com > Web Site: http://www.sonsothunder.com/ > > > > > Thanks for your quick response > > Tiemo > > > >> -----Ursprüngliche Nachricht----- > >> Von: use-livecode-boun...@lists.runrev.com [mailto:use-livecode- > >> boun...@lists.runrev.com] Im Auftrag von Scott Rossi > >> Gesendet: Montag, 11. Juli 2011 11:48 > >> An: LiveCode Mail List > >> Betreff: Re: How to test if an image is empty? > >> > >> Recently, Tiemo Hollmann TB wrote: > >> > >>> when I put empty into img "foo" the imagedata of img "foo" is still not > >>> empty, there are still any binary data in the image. > >>> > >>> I can't test if the imagedata of img "foo" is empty" nor can I test if > > the > >>> img "foo" is empty. How can I test if I have put empty into an image? > > Can I > >>> test it binary? > >> > >> To "truly" empty an image, I set the text property of the image to empty, > >> and also check that property to make sure it's empty. > >> > >> return (the text of img 1 is empty) > >> > >> Regards, > >> > >> Scott Rossi > >> Creative Director > >> Tactile Media, UX Design > >> > >> > >> > >> _______________________________________________ > >> 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 > > > > _______________________________________________ > 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
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