With Qt 4.8, I have :
a main window (QMainWindow);
a central widget setCentralWidget(x), x beeing a QLabel that contains an image;
another widget "B": a QLabel that contains an image
My problem is that the widget B is hidden under the central widget. How could I raise the widget B in the foreground ?
I know that B is hidden under the central widget because sometimes when B is placed on the left, and the image of the central widget is small enough, I can see a part of B.
You can use B.raise() in order to increase z-index of B widget.
Raises this widget to the top of the parent widget's stack.
After this call the widget will be visually in front of any overlapping sibling widgets.
You could also attach "B" as a child of the central widget, or a child of widget X. This should then show on top.
QWidget B = new QWidget(x);
Alternatively, use a layout and add that to the central widget, with widgets x and B added to the layout. For example: -
QHBoxLayout* pLayout = new QHBoxLayout();
pLayout->addWidget(B);
pLayout->addWidget(x);
pMainWindow->setCentralWidget(pLayout);
Related
Qt 5.5.0
In my application, I have a QGraphicsView as the main widget and a QDockWidget for properties.
The goal is for the user to select an item in the graphics view and, depending on the item, present the appropriate properties for that item.
I achieve this by having a properties manager widget with a layout containing each of the properties widgets. I have signals and slots hooked up for getting the currently selected item, and then show() the widget I need and hide() the rest.
This works great! However, when selecting different items, the dock shrinks or grows based on the shown widget. It is very jarring, and rather annoying. The thing is though, that when the user manually resizes the dock, it maintains that size. I want the maintained size to be default rather than this autosizing behaviour.
Things I've tried:
I've tried changing the sizePolicy() of the dock and the mainwindow: No effect.
I've set a minimum size for my properties manager which does indeed prevent the dock from shrinking when a smaller set of properties is shown. However, I still want the user to be able to shrink the dock to a smaller size if they wish, and this method prevents that...
Conclusion:
Is there a flag or something that is set when the user resizes the dock that tells it to maintain that size? If so, is there a way to manually set it?
I haven't tried subclassing QDockWidget or QMainWindow yet. Is there a method(s) that I can override to achieve the correct behaviour?
Thanks for any help!
All that was necessary was to call
setSizePolicy(QSizePolicy::Preferred, QSizePolicy::Expanding);
in the constructor of my properties manager widget (the central widget of the QDockWidget)
I also overloaded the sizeHint() function to return a respectable default size.
First, create your dock widget:
QDockWidget *dock = new QDockWidget;
Now set size policy to dock's widget.
If dock is vertical:
dock->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Expanding);
If dock is horizontal:
dock->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Ignored);
Set your widget to dock:
QWidget *myWidget = new QWidget;
dock->setWidget(myWidget);
Now set size policy to dock's widget.
If dock is vertical:
dock->widget()->setSizePolicy(QSizePolicy::Ignored, QSizePolicy::Expanding);
If dock is horizontal:
dock->widget()->setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Ignored);
Finally, add dock to main window:
If dock is vertical:
mainWindow->addDockWidget(Qt::LeftDockWidgetArea, dock);
mainWindow->resizeDocks({dock}, {0}, Qt::Horizontal);
If dock is horizontal:
mainWindow->addDockWidget(Qt::TopDockWidgetArea, dock);
mainWindow->resizeDocks({dock}, {0}, Qt::Vertical);
I have two widgets (both QFrames), none of them have any title bar associated with them (which I achieve through setWindowFlags(Qt::FramelessWindowHint)). One of them is a main widget, and the other a sidebar sort of widget, which is supposed to stick to it at its right boundary (its height being approximately 1/4th of the main widget).
I cannot keep them both in a transparent QFrame with static positioning, since the main widget is draggable through its top (since title bar is missing on it, I do it manually by intercepting mousepress/mousemove events and moving it accordingly). The custom drag on the main widget works fine, but when I try to move the sidebar along with, a very obvious visual delay shows up between the two, there are momentary gaps visible between the two while dragging the main widget to the left, or momentary overlapping between the two when dragging the main widget to the right (the sidebar is not draggable, no drag logic is implemented for it).
How do I 'glue' these two widgets together, such that they move together all the time without any delay? I browsed the Qt docs, it may be possible that QDockWidget can help here, but I could not understand how. The main widget here is not a QMainWindow.
Platform - OS X Yosemite, Qt 5.3.1, 32 bit.
You should definitely use QDockWidget here.
Make your "main widget" derive from QMainWindow rather than QFrame (it may not be "obvious" as QMainWindow does not derive from QFrame, but it should not be such a big deal).
Then, encapsulate your second widget within a QDockWidget and dock it in the main widget like that:
// secondWidget being your QFrame based widget
// mainWidget being your "main widget"
QDockWidget* dockingBar = new QDockWidget("My bar", mainWidget );
dockingBar->setWidget( secondWidget );
// dock on left side, change first parameter to dock somewhere else:
mainWidget->addDockWidget( Qt::LeftDockWidgetArea, dockingBar );
An alternative is to create a third widget that would become your top-level widget and use a QLayout to insert your two QFrames in this new one:
QWidget* newTopLevelWidget = new QWidget();
// QHBoxLayout to have mainWidget on the left hand side of secondWidget
// Replace by QVBoxLayout to have mainWidget on top of secondWidget
QLayout* layout = new QHBoxLayout( newTopLevelWidget );
layout->addWidget( mainWidget );
layout->addWidget( secondWidget );
I have a QWidget that I want to include within a scroll-area so that when the designated QWidget size is exceeded vertically, the user can scroll up and down to see more.
QWidget renameWidget;
QScrollArea scrollarea.
How do I go about doing this? I set the widget inside the scroll-area on the UI editor but it didn't work.
Any ideas?
Thanks.
Think of QScrollArea as another layout. Add the scroll area to your main widget and put everything else inside it with setWidget().
QScrollArea is QWidget, so you can even use it as a top level widget:
QScrollArea *scrollArea = new QScrollArea();
scrollArea->resize(250, 250);
QWidget *widget = new QWidget(scrollArea);
widget->setBackgroundRole(QPalette::Dark);
widget->resize(200, 200);
scrollArea->setWidget(widget);
scrollArea->show();
QScrollArea provides a scrolling view onto another widget. It is used to display the contents of a child widget within a frame. If the widget exceeds the size of the frame, the view can provide scroll bars so that the entire area of the child widget can be viewed.
An example:
QScrollArea *scrollArea = new QScrollArea(this);
scrollArea->setBackgroundRole(QPalette::Dark);
scrollArea->setWidget(renameWidget);
I have a simple qt application with a QTabWidget inside the main window. I also have a few QPushButton(s) and QRadioButton(s).
What I want is that when I resize the window either manually or by maximizing/minimizing it should resize the containers in the same way.
In other words, what I want is equivalent of DockStyle.Fill in qt C++
How can I do that ?
In Qt you have to use Layouts:
The Qt layout system provides a simple and powerful way of automatically arranging child widgets within a widget to ensure that
they make good use of the available space.
In short, all components in a layout will be relocated to new places after the window, to which the layout belongs, is resized.
If you are using deisgner:
1. Click the empty space of a widget to select itself(or a main Window, I use just a base widget here for demonstration), and the layout option will be hightlighted:
2. Choose a desired layout
Here is what object monitor looks like after a QVBoxLayout is used:
If your widget doesn't use layout, it will look like this:
What we have done here is to make the base widget/mainWindow equip a main layout. You can see that the buttons are automatically aligned, when you resize the widget, those component will be relocated according to the layout:
Perhaps you will find it nettlesome of those expanding space, so the next move is to add a Spacer to the layout; so when layout is resized, only the spacer will stretch.
(Another option is to make your widgets expandable, see ** at the end of this post)
3. Besides, you can add a layout into another to create a nested layout
For example, first I choose A and B (by pressing Ctrl) and use QVBoxLayout. This additional layout is not base layout and hence highlighted by red rectangle.
Then I choose C and the layout which contains A & B, and use QHBoxLayout on them,
Finally I use another QVBoxLayout as my main layout on the base widget, just like what we did previously.
And the object monitor:
If you like the special feeling of hitting keyboard and always handcraft the code:
For the last example:
QWidget *Form = new QWidget;
QPushButton *pushButton_A = new QPushButton("A");
QPushButton *pushButton_B = new QPushButton("B");
QPushButton *pushButton_C = new QPushButton("C");
QVBoxLayout *verticalLayout = new QVBoxLayout;
QHBoxLayout *horizontalLayout = new QHBoxLayout;
QVBoxLayout *mainLayout = new QVBoxLayout;
verticalLayout->addWidget(pushButton_A);
verticalLayout->addWidget(pushButton_B);
horizontalLayout->addWidget(pushButton_C);
horizontalLayout->addLayout(verticalLayout);
mainLayout->addLayout(horizontalLayout);
Form->setLayout(mainLayout);
Form->show();
In your case
Here is an example of layout:
Notice that QMainWidget has a centralwidget as a base widget. Besides, each tab of QTabWidget has it's own base widget (tab and tab_2 in the picture) which adopts another base layout.
*Don't forget to add Spacer in layouts to shape them as you like.
** You can set size policy on each widget (QTabWidget, QPushButton etc) to make them horizontally/vertically expandable or fixed, this cooperates with the layout strategy. For example, in the very begin example if we set
button A to be vertically fixed, horizontally expanding
button B to be vertically expanding, horizontally expanding
button C to be vertically expanding, horizontally fixed
It will look like this when resizing:
you need to look into how to use layouts in your application
http://qt-project.org/doc/qt-4.8/layout.html
As a quick and simple first try, in the Designer you can right-click on the main window, and choose "layout" from the drop-down menu. Here you can pick the grid layout, for instance.
I have a QMainWindow whose central widget has been set to a QGraphicsView viewing a black scene (for test purposes). Note that in the code below, I use my class derived from QGraphicsView, called CQtGlView, which reimplements only the resizeEvent function.
Regardless of whether I add the view directly,
CQtMainWindow::CQtMainWindow() {
m_glView = new CQtGlView();
setCentralWidget(m_glView);
}
or stick it in a layout with margins of 0 in a dummy widget,
CQtMainWindow::CQtMainWindow() {
m_glView = new CQtGlView();
QWidget* dummy = new QWidget();
QHBoxLayout* l = new QHBoxLayout();
l->setContentsMargins(0,0,0,0);
l->addWidget(m_glView);
dummy->setLayout(l);
setCentralWidget(dummy);
}
I get an unwanted grey border around the widget.
The screenshot below illustrates the problem, visible between my scene and the windows aero border.
This would not be a problem if my application did not allow switching to full screen. The border is very obvious once the rest of the screen is black.
It's possible this area represents the DockWidgetAreas around the outside of the central widget.
Is there anything I can do to solve this other than not use QMainWindow? (Undesirable due to my use of menuBar, tool bars, and statusBar.)
It turns out that QGraphicsView derives from QFrame, where I assumed it was only a QWidget.
The solution to this problem was to call setFrameStyle(QFrame::NoFrame); in the constructor of my QGraphicsView subclass. Or if it was not a subclass,
m_glView->setFrameStyle(QFrame::NoFrame);
Have you tried setFrameShape(QFrame::NoFrame) on the QGraphicsView?