Dear T.C.,
I did some more tests. I started the Xserver in various modes and tested
the
image display. Here are my findings.
Using 8 bpp depth 8 - no problems.
Using 16 bpp depth 16 - once the image is displayed, the form can be
moved around by grabbing the window title
bar. If the canvas is moved inside
the form, the image does not display correctly.
Using 24 bpp depth 24 - the image does not display at all even on
starting the program
Using 32 bpp depth 24 - Everything OK !
Hope this gives a clue.
Ravi Mehrotra
National Physical Laboratory
New Delhi, India
"T.C. Zhao" wrote:
>
> # To subscribers of the xforms list from "T.C. Zhao" <tc_zhao@yahoo.com> :
>
> Thank you for sending me the demo problem. At the moment,
> I can't seem to reproduce the problem. Moving and redrawing
> occur correctly. Maybe somewhere there is a race condition
> that does not shown on my machine. I'll look into it a bit more.
> BTW, my X server is 32bpp.
>
> --- Ravi Mehrotra <ravi@csnpl.ren.nic.in> wrote:
> > Dear T.C.,
> >
> > Thanks for the suggestion. I have tried it. The problem of the image
> > loaded in the canvas graying out once the canvas is moved persists.
> > I have written a small piece of code to test it out. I am sending as
> > attachments the code as file image.c and the ppm image as median.ppm.
> >
> >
> > Just to recap, I am using a Pentium II machine with Linux 2.2.6 and
> > XForms 0.89 with a depth of 16bpp. I am displaying a ppm format image
> > in
> > a canvas. The canvas is moved and picture redisplayed through a
> > canvas
> > handler trapping the Expose event. Upon moving the canvas, the image
> > grays outto a very faint one and loses all color. This does not
> > happen
> > if thewhole form is moved using the title bar of the window ( which
> > also
> > generates an Expose event). The problem occurs only on using depths
> > greater than 8 bpp.
> >
> > I did some further tests. I used another version of Linux 2.0.30 on a
> > Pentium Pro machine with XForms 0.88, Date: 1998/08/25. The problem
> > disappeared. The program compiled on this machine and run on the
> > earlier
> > Pentium II machine also shows no problems. The program compiled
> > under
> > XForms 0.89 shows the problem on both computers. Thus it seems that
> > the
> > problem is in the 0.89 version.
> >
> > I will appreciate any further help.
> >
> > Ravi Mehrotra
> > National Physical Laboratory
> > New Delhi, India
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