How to read graphs
let's say that i want to make a program thar allows you to draw lines
how do i read the coordinates of the drawn graph (lines)
Have a look at the documentation of Qt's graphics view framework and at how the scene manages the coordinate system and puting the graphic items onto the scene at a specific position.
What do you mean by "read the coordinates"? Do you want to move your mouse over the graphics view and to show somewhere the current coordinates under the mouse cursor? In this case you'll need to map curser's coordinates to view's and to scene's coordinates and to show these values somewhere.
"move mouse over the graphics view and to show somewhere the current coordinates under the mouse cursor" that would be good too i will need this one too.
what i want is that somebody draws anything with the mouse curser
i mean anything like a face, circle or even a simple line and i have to read the coordinates into let's say a container.