On 03/29/2016 10:47 AM, David Heremans wrote:
Hello,
I seem to have a 'visibility problem' with my application.
I have a QGraphicsscene that represents a piece of A4 paper at 300DPI
(approx. 3300 by 2500 scene coordinates). On this scene I have a simple
street map and some symbols. I draw the lines in black with thickness
ranging between 1 to 10 and when printed on paper this all looks fine.
However when I draw these in a much smaller qgraphicsview I have to
zoom out quite a lot. As this happens the thin lines start to get
lighter and lighter up until the point that you can not see them any more.
Is there a way to avoid this from happening?
I know that if I draw them with size 0 then the lines will always be one
pixel wide on screen but then the printed version is not as nice. And
then they also will always be the same thickness even when zoomed in to
100%.
It really is a problem because some of the symbols become invisible this
way when you are editing the map.
Any body here has any hints on how to handle this situation?
I Use a global variable to track the current operation
For example, am I drawing to drawing to the screen or printing.
Then I override the graphics item paint() function and just
do what needs to be done for the current context. You could
suppress painting all together. You could change the pen/brush.
Set a minimum line width based on zoom factor (I have not actually
done that, but I assume it is possible.)
regards,
David H
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