Problem with QScrollview and QPainter

[Sarma]

That would be better. Iam sending you again two files and the complete code. These are the files that iam sending:

small.txt (that contains the small file for which small.gif is sent).
large.txt ( that contains the large file for which large.gif is sent) and
source.cpp ( where the code has been written).

Note: The "/tmp/parsetext.txt " in the code at any time contains the file for which graph has to be generated. And sir, I have not changed the code as you said previously (reading the file in another method). I have tried that but I faced the same problem of over-writing for large files. Kindly take time to see this and help me in what ever way possible.

Thanks alot for your co-operation.
with regards,
sarma.

[wysota]

Ok, I think I might have found your problem. As far as I remember there exists a maximum size of a widget under X11. I don't remember the exact size, but it's probably around 64k (or less) and I see you are trying to obtain greater heights which probably causes an overflow of some variable resulting in y values being y = kount1 % maxheight.

So having found the bug is one thing, but working it around is another. In your case, you can either switch to Qt4 (which, afair has a workaround for this) or make a fake scrollview. Instead of having a very big viewport, have a regular widget which will change its contents according to scrollbar values. Meaning you'll have to implement paintEvent in such a way, that is renders only a part of your chart which should currently be visible. You could also check if QCanvasView has the same limitations.

A side effect will be that your widget should redraw much faster.

[Sarma]

Sir,
What you said might be correct. But Iam a novice in QtProgramming. So I don't know how to fix this problem . I shall be greatful to you if you help me in this regard.This is the only problem that Iam having since 3 weeks. Presently Iam trying it with QCanvasView.

Thanks alot,
Sarma.