Draw a line follow mouse

[Dandan]

Hi, I'm a newbie. I need draw a line with follow mouse in graphic view (or anything) and function save and clear. But mouse event can't active, or wrong. I mistake ui element
I need help .
Thank you

[ValentinMichelet]

Hi,

Do you want the line to be drawn when one mouse button is pressed, or whenever the mouse move?
Can you be more specific about the exact behavior you try to achieve?

Meanwhile, you can consult these links:
http://stackoverflow.com/questions/24672146/qpainter-draw-line
http://zetcode.com/gui/qt4/painting/

Also, could you post your code so we can check what might go wrong?