On 12/17/2015 11:16 AM, Jason H wrote:
My very first Qt app is large and a little sloppy in
that the QWidget::update() function is being called
*someplace* where it should not, This is causing
unnecessary repaints.
Is there one place I can put a break to find the calls
which actually cause a repaint (and not the calls
which are made when a repaint is already pending).
Or, can you recommend a better way to diagnose
this problem. (The whole thing needs to be rewritten
now that I am older and wiser, but not just yet.)
Why do you think they are unnecessary?
Which update() is being called? There's like 4 overloads. Also, realize that Qt
will optimize out unneeded updates, or combine multiple into one. I find that
Qt is very good about not doing more than needed. It's better to track the
paintEvent()s.
I do not think there is a Qt issue here.
I'm sure it is me that is calling update when I should not.
I know they are unnecessary because my app responds with multiple
screen refreshes (paints) from a single user action. And for me those
paints can be expensive.
It is possible to investigate this using gdb with the
following, but not easy.
--------------- gdb commands.
file my_app
set logging redirect
set logging on temp.dat
set height 0
break QWidget::update
commands
where
continue
end
run
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