Save QWidget as image

Qt library is an excellent GUI library for C++ programmers developed by Nokia and now is an open source project. Often, we may use QPainter to draw strings, lines or images on a QWidget. We can override the QWidget's paintEvent() method when we want to use QPianter object to draw something on a QWidget.

If we want to save the items drawn on QWidget as image for later reference, what can we do? We can save a QWidget as an image. Here is the code for achieving this:

QPixmap pixmap(this->size());

this->render(&pixmap);

pixmap.save("test.png");

Quite simple, right? Yes, these are all the codes you need. Here this refers to any QWidget pointer, it has a size() method which returns the size of the QWidget, the pixmap will use this value to create the image with the same size. Later, we need to use the render() method to render the contents of widget to the QPixmap object. Finally, we need to save the rendered contents to an image.

The following table shows the image file format supported by QPixmap.