Need a control to show a image and draw on it and scrollable

jronald

For example, as shown above, load a image and draw on it.
When the image is larger than the control, scrollbars are support.
Which control is most suitable?

Pl45m4

@jronald

QScrollArea + QLabel with QPixmap for the image

Or have a look at the Graphics View Framework:

https://doc.qt.io/qt-5/graphicsview.html

There are also some MS Paint-like examples using Graphics View or a plain widget as canvas to draw on:

https://doc.qt.io/qt-5/qtwidgets-widgets-scribble-example.html

(Mabye you can use this example as template since it almost does what you want to do)

jronald

@Pl45m4
I prefer a single control like QWidget, how to make it scrollable?
I've checked the Scribble Example, it doesn't support scrollbar.

Pl45m4

@jronald

There is no such single widget...
Qt is a programming framework, not plug and play :)
Something (or most of the times) you have to make your own widgets and implement your own behavior to get what you want.

I said you could use the scribble example as template, not "take it and you are done". Of course it might need some additional coding to get from it, what you expect.

If you have a canvas widget, where you can draw on, you can put it in a QScrollArea and voilà, it's scrollable...

Btw: You can make a custom and single QWidget from any other combination of QWidgets, so it can be used and "cloned" multiple times on your GUI.

jronald

@Pl45m4 said in Need a control to show a image and draw on it and scrollable:

If you have a canvas widget, where you can draw on, you can put it in a QScrollArea

Tried: https://forum.qt.io/topic/133473/no-scrollbars-when-put-qwidget-derived-class-object-in-qscrollarea
But scrollbars don't appear, what the problem?

Pl45m4

@jronald

Is the widget larger than the scrollable area? If not, there's no need for scrollBars. Only if the widget's height/width exceeds the area, the scrollBars appear.
So you probably need to make your widget bigger