Don't call draw() twice when Qt canvas first appears. #9103
Conversation
Right now the resizeEvent triggered from within the paintEvent will itself trigger a second paintEvent. Adding a print to draw() shows that this patch ensures that draw() only gets called once the first time the canvas appears.
c67a944 to
46d3828
Compare
|
This seems reasonable, but I am not sure I understand why some code was moved into backend_qt5 and other code was simply moved around within backend_qt5agg? |
|
Whatever is independent of Agg (and would be used just as much by #8771) was moved out of backend_qt5agg into backend_qt5. |
|
Ok, that makes some sense, but with the way the code is right now, isn't the backend_qt5 completely broken now? Does |
|
It is up to whoever else wants to implement a qt5 backend to also update the dpi in their own reimplementation of the paintEvent handler (e.g. https://github.com/matplotlib/matplotlib/pull/8771/files#diff-24903670c280dbda97ed82b992060879). The pure qt5 backend cannot be used without a renderer. Its whole purpose is to be inherited by classes that will actually be coupled to a specific renderer. |
Right now the resizeEvent triggered from within the paintEvent will
itself trigger a second paintEvent. Adding a print to draw() shows that
this patch ensures that draw() only gets called once the first time the
canvas appears.
See http://doc.qt.io/qt-5/qwidget.html#resizeEvent http://doc.qt.io/qt-4.8/qwidget.html#resizeEvent for relevant docs.
PR Summary
PR Checklist