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Smooth scrolling zoom in draw widget; how? [message #7837]

Thu, 09 January 1997 00:00

kak
Messages: 16
Registered: February 1995

Junior Member

I use a scrollable draw widget to display large images (up to 2048x2048)
at full resolution (viewport is 512x512 or 1024x1024 depending
on screen resolution).

The problem is: users want to zoom into images and keep the smooth
scrolling viewport for the expanded image . If I simply blow up my image
by the required factor, the size will quickly increase beyond
the computers memory.

I thought about keeping the original byte scaled image as byte array
or as pixmap. For each viewport scroll event I would calculate the
portion of the zoomed image to display from the current viewport
coordinates. Then I would take the respective subarray of the image
and extend it using rebin(subarr, view_port_x, view_port_y, /sample)
and finally display it in the viewport.

I doubt that this is efficient enough to provide the illusion of smooth
scrolling.
Has anybody a better idea?

Karl
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IPP, PO Box 1533 | Phone: +49-89-3299-1655 | E-Mail:
D-85740 Garching | FAX : +49-89-3299-1149 | krieger@ipp.mpg.de

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		Smooth scrolling zoom in draw widget; how? By: kak on Thu, 09 January 1997 00:00
		Re: SMOOTH By: pit on Fri, 20 June 1997 00:00

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