An example to show you how to use Qt's Graphics View framework to implement a plot-like application.

• How to use QGraphicsScene to draw background and foreground.
• How to group items.
• How to resize scene acoording to main window size.
• How to fit view to the items in scene.
• How to pan graphics view.
• How to support multi-level zoom in operation.
• How to draw text on foreground of scene and the text won't be scaled acoording to view's transformation.

NOTE To do multi-level zoom in. Use left button to drag the rect you want to zoom. After zoom in several times, click right button to zoom out one level. Use reset button reset the zoom level.

• Open src/qplot.pro by Qt Creator.
• Press build button.
• Run!

NOTE this program is built with Qt 5.4. However, it should be compatible with Qt4 and Qt5.