I have a complex layout of widgets in widgets in widgets in a QMainWindow. In one of them I have an image, it sits in the corner. What I would like to achieve is following: if the image is activated (e.g. clicked upon), it should be enlarged, so it might overlap other widgets, or parts of other widgets. The problem is, I still would like it to remain in the layout, but in a way that everything else remains in its original size and position.
I was thinking about having an empty but similar size widget as a "placeholder", and have the actual resizable widget float on top of it. My problem is, that it does not guarantee that it stays in its position if the main window is resized, maximized, etc. Is there a better or more efficient way to do it?
One way to do it, if the widgets to be overlapped are in the same layout than the one you want to enlarge, and the policies for that widget allow it, is just .setVisible(false) in the other widgets. The widget that remains visible should resize to cover all the available area!
If I can't find a better solution, I think I'll do the following:
The MainWindow will have no layout, just two QWidgets on top of each other. The bottom one will contain all the layouts and everything else, while the upper one will have a transparent background and the resizable widget, maybe supported with a number of spacers.
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I have multiple widgets inside of a main window. Each widget and the main window all exist in layouts. In the case where there are two widgets next two each other is there a way to have one expand before the other expands/shrinks? I need both widgets to be expandable, but one is more important than the other. So, when the widgets shrink I need the widget on the left to shrink before the widget on the right shrinks.
This can be easily achieved by setting a non-zero stretch on the widgets, and ensuring that they report proper maximum sizes. The stretch on the more important widget can be, say, 10x that of the less important widget. That way, the less important widget will grow very little unless the more important one is at full width.
In Qt, how can I have a widget which automatically sizes itself according to the size of it's children?
For example, if I have a QGroupBox which contains a QHBoxLayout which contains some QPushButtons, I would like the QGroupBox to automatically calculate it's size so that it is no bigger and no smaller than necessary to fit all of the QPushButtons.
Ideally I would like to be able to do this in Qt Designer so that I can create a .ui file which already knows how to size the QGroupBox, however I am also opening to deriving from a class inside a .ui file and doing the resizing manually.
I have tried placing the QGroupBox inside it's own layout (with and without a spacer) but this just resizes the QGroupBox to the smallest possible size so that none of the children are visible.
There are two things to pay attention to:
Set the size policies appropriately on the children in the groupbox. You literally need to think what the buttons can do - most likely, you do not want the buttons to either grow or shrink, so setting both of their size policies to Fixed is the right thing to do. You could, possibly, let the buttons expand horizontally, so the horizontal policy of MinimumExpanding is an option.
Set the size constraint on the layout in the groupbox to act according to your objective:
ui->groupbox->layout()->setConstraint(QLayout::SetMinAndMaxSize);
Of course, the groupbox will be inside of some layout in its parent window, but that doesn't matter.
You'll probably have the most luck by sub classing QGroupBox and overriding sizeHint or other sizing functions to loop through children and calculate the minimum bounding rectangle. Depending on how dynamic the group box is, managing connections to new widgets might be a small challenge.
I have a Qt application which has a window based on a QWdiget. Inside my window I have two QVBoxLayouts and one QHBoxLayout with controls underneath the first two Vertical layouts. When my window is resized, the QVBoxLayout move apart and the QHBoxLayout underneath also moves away. I want to prevent this from happening, what is the best way to do this?
All these layouts are inside a QGridLayout.
If I understand your question correctly, you have a window's layout like this :
The layouts is going to resize depending on the size of the objects in them. To solve your problem, you should set the alignment of your layouts within the grid layout using setAlignment method.
by the way, if nothing works, you can always write your own layout manager.
I am having a problem redrawing a QWidget window after its size has been adjusted. I have tried update(), repaint(), adjustSize(), but all seem to suffer from the same thing: only part of the window is redrawn, resulting in the window frame on the bottom and right sides to not show. The window is also not resized entirely.
Just in case it makes a difference, the window is in a QMdiArea.
Thanks.
// ... some subwidget resizing and moving.
calibrationWindowUIs[activeWindow].layoutWidget2->move(QPoint(oldXLeft, 30 + height + 21));
calibrationWindowUIs[activeWindow].layoutWidget1->move(QPoint(oldXRight, 30 + height + 21));
// Set window size.
calibrationWindows[activeWindow]->setMinimumSize(calibrationWindowUIs[activeWindow].tabWidget->geometry().width() + 40, calibrationWindowUIs[activeWindow].tabWidget->geometry().height() + 40);
calibrationWindows[activeWindow]->update();
Note: I'm new to Qt; perhaps I'm doing something wrong with layouts?
Edit: I may have not given enough information. Alright, to be quite honest, I still have to delve deeper into layouts and related material. What I had tried to do here was to use Qt Designer in order to design the window. I've done what perhaps amounts to a stupid mistake: I didn't use an overall parent layout for the entire window, but hacked it with a couple of smaller layouts that I therefore have to move about and resize individually. See the Qt Designer screen (the red rectangles are the sole layouts): .
What is happening is that in the frame to the right, I am playing a video clip that can be of various resolutions. I want the frame to resize depending on this resolution, which also means that the buttons and window have to move/resize accordingly. That is where the window resize comes in. I'm sure there is a more elegant solution than what I am doing here, but I am trying to handle several other scenarios here and hence the lack of quality of code.
The result is that when I load a clip, the window attempts to resize, but does so badly; the following is the result:
If the window is dragged, it 'pops' into its correct size; in the meantime, however, it just looks ugly.
A couple further questions: do you use the Qt Designer to design your UIs? I found that programmatically you can achieve much better control of your interfaces. One thing which I could not do in the designer was to have a layout parented by the main widget, i.e. the equivalent of having the following bit of code:
QVBoxLayout* layout = new QVBoxLayout;
this->setLayout(layout);
A layout placed in the designer always seems to create this 'layoutWidget' subwidget, which the layout you placed is then parented to. Any way around that?
We use a mix of designer and code to create layouts, the Qt layout system can be very unintuitive at times. But I would probably not layout a full series of tabs in one designer ui file, i would make each tab each own widget and then assemble them either through code or in the designer by promoting to custom classes. This gives you better separation of responsibilities, by putting all the functionality of all the tabs into one file you almost guarantee a large unwieldy class.
When a widget has child widgets in designer you can assign a layout to it by adding it from the context menu. Make sure nothing is selected and click on the background of the widget in which you want to create a layout, select the layout and all of the widgets children will be assigned the layout.
What does help is creating hierarchies of layouts. Looking at your first screenshot, i would probably use a vertical layout with spacers on top and bottom for the items on the right, an horizontal layout with spacers left and right for the button bar and a grid layout for all the items together. Without the spacers your items will extend when the window grows. The spacers will let you control the behavior under resizing better.
you are calling setMinimumSize(). That's fine, but you should also call resize()
How do you change the behavior of a QListWidget so that it resizes its height instead of choosing a (seemingly arbitrary) height and adding scrollbars? See screenshot:
The QListView's should fill up as much space horizontally as they can (creating as many "columns," if you will.) Then they wrap and make as many rows as necessary to fit all the items. These calculations should be adjusted as the window is resized. This is all working fine.
However, what I want to happen is that instead of the height staying the same, the QListView should grow or shrink vertically and never need any scrollbars. The scrolling, if necessary, will be handled on the parent QWidget that hosts all of the labels and lists. It seems like once the height of the QListWidget is established (not sure where its default is coming from), it never changes. It is too big in some cases (see second "Test" list above) and too small in others (see first "blank maps" list above.)
The layout above is nothing surprising: two QLabel's and two QListWidget's in a QVBoxLayout. Here are the properties I have set on the QListWidget's:
setMovement(QListView::Static);
setResizeMode(QListView::Adjust);
setViewMode(QListView::IconMode);
setIconSize(QSize(128, 128));
(I already tried setting the horizontal and vertical scrollbar policies, but that just turns the scrollbars off, clipping the content. Not what I want.)
Maybe you could this without using QListWidget. The Qt's examples contain a new layout class, QFlowLayout, which could be useful. With the following kind of widget hierarchy you could get multiple groups with labels and they all would be inside one QScrollArea.
QScrollBox
QVBoxLayout
QLabel "Blank maps"
QWidget
QFlowLayout
your own widgets showing map images and labels
QLabel "Text"
QWidget
QFlowLayout
your own widgets
The problem is that this kind of solution would create much more widgets than QListWidget based solution. So if you have hundreds of items in your list, this might not be the best solution.
There is a protected member function called contentsSize() in QListView. It is used to calculate the required minimum(), maximum(), and pageStep() for the scrollbars (as mentioned here).
Can you subclass the QListView class and make use of that information? I suggest you recalculate the size of your widget in the same function where you add contents to it. While somewhat lacking elegance, this appears to be a pretty reliable solution.