Graham Samuel wrote:
I suppose it's just finger trouble, but I'm having great difficulty
using import snapshot and export snapshot - the RunRev docs seem not
to be completely specific on this. For example, while apparently I can
take a snapshot of something that isn't open and isn't visible (the
docs say so!), I don't seem to be able to take a snapshot of an object
whose loc is outside the visible area. For example I have an image
which I've placed out of site at 2000,2000 based on a quite small
stack, say 800 by 600 pixels. I'm used to this technique for hiding
stuff from the user, and also for working with objects larger than the
visible area - in this case, I am doing both of these. Now I want to
tinker with the image. The statement
import snapshot from rect 1375,2592,1749,2625 of this stack
compiles OK but results in an execution error. Experiments seem to
show that a statement of the same form restricted to the bounds of the
stack's window work OK.
What I'm actually trying to do is to create a composite image at
screen resolution, by overlaying images on top of one another and then
taking a snapshot of the resultant screen area, but all without the
user seeing anything. My experiments appear to show that I can do it
while the various objects are visible (in the visible area) but not
otherwise. Can anyone explain how this could be done?
The rect option can be useful at times, but since v2.7 we've had a much
easier and more robust method of exporting images of objects by
specifying the object itself rather than a rect:
import snapshot from img "MyImage"
The object needn't be an image; it can be anything other than a stack
(referencing the card will work for those), even groups.
The big difference is how the image is generated:
Using the rect option cips a portion of the display buffer, so if your
image is out of bounds there won't be anything to get.
But using an object reference causes the engine to render the object
into a private buffer for you, much like it would do when rendering the
image on a card, and then hands that buffer back to you in the resulting
image.
In my experience using object references is reliable under a much wider
range of circumstances than using rects, even with objects on cards that
aren't open.
This extension to the snapshot syntax was a by-product of the massive
rendering overhaul Mark Waddingham did for v2.7, and one that's done
wonders here for making screenshots very easily.
--
Richard Gaskin
Fourth World
Revolution training and consulting: http://www.fourthworld.com
Webzine for Rev developers: http://www.revjournal.com
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