I am having what appears to be the same problem as asked in this (unanswered) question: Qt resizeGL problem
I am testing a new QGLWidget for a larger application. The resizeGL method is wired up to change the glViewport and repaint the OpenGL view. My QGLWidget is not part of a layout and is simply being created displayed as follows:
boost::shared_ptr<StandardCustomWidgetBuilder>
builder(new StandardCustomWidgetBuilder());
WaterfallDirector<StandardCustomWidgetBuilder, DataSource> director(builder);
director.construct();
std::unique_ptr<CustomWidget> widget = builder->getWidget();
widget->show();
On my computer, this defaults to creating a 640x480 window and calls resizeGL upon initialization. Whenever I resize the window, resizeGL is never called.
In my attempts to remedy this I have attempted creating a separate QWidget that has a QVBoxLayout containing only the CustomWidget. This created a very small window, so I fixed my sizeHint and sizePolicy for CustomWidget, though this still had no affect on having resizeGL called. At this point I'm not sure precisely how to proceed.
I resolved my problem with some help from my co-worker. As it turns out, I had implemented the event method and forgot to call the QGLWidget::event method inside it. The widget now correctly resizes.
If you haven't done so already, I would suggest checking the size hints and size policies of all widgets concerned.
For example, the following will make sure your widget uses available space when the window grows:
widget->setSizePolcy( QSizePolicy::MinimumExpanding,
QSizePolicy::MinimumExpanding );
I don't think that the default size policy for QGLWidget makes it want to expand, so I'm thinking it's just possible that this needs changing.
Related
We have big QT project where painting procedure often doesn't follow the rule that it should be done in overridden paintEvent method. As result we have warnings about it: Painter not active etc... But all work fine and at first glance I don't see any problems. Could you explain should I worry about it or not? What is the price of the incorrect use of this functionality?
Paint event is sended to the window when it is should be updated, eg when it is shown or something else. For example if widget is covered by another window, and this windows is moved away, then widget should be updated. Common way is to paint on the pixmap and draw this pixmap on the widget in the paint event handler. Or you can update/repaint each time you need to repaint it.
You can use QPainter to draw on pixmap, printer and so on whenever you want, but to draw on windget it must be done in paintEvent.
I found mistake - it is happened when invalid pixmap(I have created pixmap with size 0x0) is used. I have add check on it and now all are okey.
My paintEvent has access to a pointer whose value changes from time to time and what gets painted depends on these values. With basic debugging I'm sure that this function is being called but the window does not get updated. The new stuff only appears on the window when it loses focus to another application.
If this is about performance I can set a static variable in the paintEvent to check if the pointer has been updated or not to avoid unnecessary repaints. It would be nice if Qt would just paint when I told it to.
I was hoping someone could help me out or point me in the direction of the right documentation. Thanks.
you must call update() method to repaint your widget.
I have an application with a QMainWindow that should ideally have a QGLWidget centered on it, with spaces left around the outside for toolbars and other top/side widgets.
Unfortunately, no matter what size or geometry the QGLWidget is set to, it appears enormous and takes up the entire main window!
Basically, the setup is as follows: CreateWindow() is called in main(), which constructs the main window and calls a function Init(), which constructs the GLWidget. So, within Init(), which is a member of my adapted main window class, I essentially have:
GLScene = new MyQGLWidget(this);
setCentralWidget(GLScene);
Now, to make the GLScene conform to its desired size and position, I first tried setting its geometry within the GLWidget (a.k.a. my class derived directly from GLWidget) constructor:
MyQGLWidget::MyQGLWidget(QWidget* parent){
....
setGeometry(210, 40, 600, 400); //the main window is of course bigger and should fit this nicely
....
}
This, however, didn't work at all and still made it take up the entire main window. Instead, I tried putting the setGeometry call into Init(). I tried it both right before and right after setCentralWidget(); neither option worked. Nor did flat-out removing the setCentralWidget call (in fact, this made the GLWidget disappear).
Since this clearly isn't working properly, what is the correct way to scale the GLWidget? Or is it just a matter of how things are ordered that I need to look into more deeply?
You need to add a layout to it. I have exactly the same thing ( a widget derived from QGLWidget) whose parent calls the resize function. This solved all my issues and made it to where I can change its size at runtime.
I am writing an application using Qt and would like to have a "Metro Style" interface. Everything is finished except I don't know how to make the widget appear and disappear. For instance, in WPF you can animate (UIElement.RenderTransform).(TranslateTransform.Y) so that Y becomes zero or negative. How can I move the QWidget in a QGridLayout so that it can hide?
Example:
After doing some research I figured out a way to do this. Instead of letting Qt do the layout I simply handled it myself via move and set width/height functions. Overriding resizeEvent made it so I could update the values in case the window was resized. Additionally I used setMask to ensure that the widget did not leak over to unwanted locations in the UI.
I want to render the video from my webcam into QWidget. I've set QWidget, as a parent to IVideoWindow. Here is the code:
m_iVideoWindow->put_Owner((OAHWND)widget_->winId());
m_iVideoWindow->put_WindowStyle(WS_CHILD | WS_CLIPCHILDREN);
m_iVideoWindow->put_Left(0);
m_iVideoWindow->put_Top(0);
widget_->setChild(m_iVideoWindow);
Also i've reimplemented QWidget's resize event, and so when it's resizing it also resizes the IVideoWindow. Everything works good, when the widget is not set to the QLayout. When is - it becomes blank. That is the problem.
I think when Qt draws its widgets, it doesn't redraw them unless it knows they need to be updated. I'm also unsure as to whether it passes on whatever redraw stuff windows requires, to the window you've assigned as a child of the widget.
When I embed my own windows in a Qt widget, I use http://qt.nokia.com/products/appdev/add-on-products/catalog/4/Windows/qtwinmigrate/, but that may not solve your problem, as I still have to use a QTimer to force an update of my window.