Re: Manipulating large graphics

[Roland Smith <rsmith xs4all nl>]

On 08 Oct 2001 01:12:09 -0400
Havoc Pennington <hp@redhat.com> wrote:

> 
> Scott Gifford <sgifford@suspectclass.com> writes:
> > I'm working on an application that deals with extremely large graphics
> > --- it loads in images of forms and lets you type on them.  Right now
> > I'm just using a GdkPixbuf, and have run into some of its limitations.
> > A scanned 300dpi form that's 8.5x11 inches is 8.4 million pixels, and
> > with 24bit color, over 25MB of memory!  The viewed image is much
> > larger than the screen, and flickers when it is manipulated.  And I
> > have to convert PostScript and PDF files into PNGs to edit them.
> > 
> > I'm trying to find a straightforward way to reduce memory usage, to
> > allow zooming in and out, and to support PostScript and PDF image
> > formats.
> > 
> > Anybody got any pointers?  

You can do conversions on-the-fly by spawning (fork/exec) ghostscript or
'convert' from the imageMagick suite from your app.

> > The code and more information about the project is at:
> > 
> >     http://www.suspectclass.com/~sgifford/proforma/
> > 

Very nice app! 

Maybe you can show a shrunken image of the form (again made on-the-fly with
ImageMagick) where the user can click on a editable area to bring up a dialog
(with possibly en enlarged portion of the document?) where they can fill in a
value?

What if you use pixmaps with a lower colordepth? I'd suspect 8 bits would be
sufficient for most forms. Wouldn't that reduce the memory requirement?

Roland
-- 
R.F. Smith                         "I have made this letter longer than usual
r s m i t h @ x s 4 a l l . n l     because I lack the time to make it shorter"
http://www.xs4all.nl/~rsmith/                             -- Blaise Pascal

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