Scrolling QGraphicsView programmatically

Answer 1

I haven't done this myself but this is from the QGraphicsView documentation

... When the scene is larger than the scroll bars' values, you can choose to use translate() to navigate the scene instead.

By using scroll you are moving the widget, translate should achieve what you are looking for, moving the contents of the QGraphicsScene underneath the view

Answer 2

You can set the QGraphicsScene's area that will be displayed by the QGraphicsView with the method QGraphicsView::setSceneRect(). So when you press the button and move the mouse, you can change the center of the displayed part of the scene and achieve your goal.

Answer 3

My addition to translate() method. It works great unless you scale the scene. If you do this, you'll notice, that the image is not in sync with your mouse movements. That's when mapToScene() comes to help. You should map your points from mouse events to scene coordinates. Then the mapped difference goes to translate(), viola - your scene follows your mouse with a great precision.

For example:

QPointF tmp2 = mapToScene(event->pos());
QPointF tmp = tmp2-mapToScene(previous_point);
translate(tmp.x(),tmp.y());