My QTabWidget has 2 tabs on launch.
Tab 1 is the one that's opened upon launch.
Tab 2 contains some widgets of which I take the QSize to later draw similar elements in newly opened tabs.
The problem is that currently the size of the elements is 640x480 (apparently the default value), if tab 2 was not shown yet. Once tab 2 is selected, the elements are "drawn" and get their sizes depending on resolutio, window size etc.
How can I force the drawing of the elements in the background without opening tab 2, so that I can obtain the sizes the elements would have if the tab was opened? repaint and update do not do that.
My current workaround is to launch with tab 2 open and switch to tab 1 in main.cpp between myWindow.show() and myApp.exec() but that seems a bit dirty.
For performance reasons, a QWidget's size() method is not guaranteed to return its expected value until after the QWidget has actually been laid out and shown.
If you need to know in advance what a QWidget's size would be, you can call its sizeHint() method instead, and that will force the calculation to be performed right away, so that the correct size can be returned even if it hasn't already been computed.
according to Document resizeEvent was never called when the widget is not visible and also paintEvent. this is a normal routine for decrease processing effort and reduce the rendering process. if you want to know when a tab1 resized, reimplement(override) resizeEvent and say to tab2 must be resized.
Related
Currently if I make a window in GTK3
For example 300x300
And I put a button at the bottom, right hand corner, I can not shrink my window
Size because this button is preventing me is there a function in gtk3 that can allow me to ignore all widgets, and resize to anything even 0x0
And this is the user doing this with the window resize, drag and click
And is there a way where I can set this resize limit myself, and not have this dependent on whats in my window
If you initially use set_size_request() to set the window to 300x300, then it won't shrink below that. To allow users to shrink below an initial value, use set_default_size(). I seem to have read that the minimum size of a widget is 1x1, which seems logical, as, at 0x0 you wouldn't be able to resize it anymore. If you want less than 1x1, you can use hide() and just hide the contents.
But if you have any widgets inside the window, then the minimum size is determined by the widgets! (Called the 'natural size')
To allow a window smaller that than the one determined by the widgets, you can maybe use a Gtk.ScrolledWindow.
Also, recall that the outer border is drawn by the window manager, NOT by Gtk. However, you can disable the outer border by using set_decorated(). Not that this may not work - depending if the window manager respects this (not Gtk's fault).
I use QSplitter to place some widgets side by side.
Being a user, I can resize those widgets just dragging a splitter.
Being a programmer, I don't know how to specify exactly what width and what height do I want at the moment.
That's my original state (adjusted by different stretches).
I tried to use setFixedSize(), but after that call the user can't resize widgets by itself anymore (and that's definitely correct behavior, because the size gets 'fixed').
If I use resize(), it has almost no effect. The widget is resized, but (!) incorrectly and (!) when I start dragging again the widget gets its initial state.
Is there any way to resize that left widget in code correctly? I don't want to have fixed size but resize() doesn't work properly, as you can see. So what should I do?
QSplitter hast its method QSplitter::setSizes(QList<int>) where each entry in the list is the size of the widget in pixels, from left to right or top to bottom respectively. The method does not require you to know the exact width, it still works with guessed sizes.
I use this functionality for instance to store the user defined sizes (obtained by QSplitter::sizes()) in a QSettings instance on the program shutdown and reapply them when the software is started again. If they are not set for some reason I just set the overall width divided by the number of widgets in the splitter and it works fine enough as an initial state.
I am programming a game and I have a tab widget which takes up the majority of the window. I want to use the extra space in the tab bar for buttons. I have the tab widget in a grid layout. To accomplish this, I use the code below in order to remove and add back the button widgets to the desired areas (the solution to someone else's question).
ui->centralLayout->removeWidget(ui->exitButton);
ui->centralLayout->removeWidget(ui->ResizeButton);
ui->centralLayout->addWidget(ui->ResizeButton,0,4, Qt::AlignTop|Qt::AlignRight);
ui->centralLayout->addWidget(ui->exitButton,0,4, Qt::AlignTop|Qt::AlignRight);
This does not work for me; however, because I would like the second widget-- the resize button-- to be just to the left of the exit button. What is occurring is that it instead overlaps the exit button. I simply need to move it 21 pixels to the left and have no idea how!
I tried putting both buttons in a frame and then removing and adding the frame the way I did the buttons. Unfortunately the same functions I used do not exist for the qt frame object.
Here are some pictures of my window.
https://docs.google.com/document/d/17w5USWQcCtb6OdcRShdcYcRjXTcdVpmdrG5TWLX71y8/edit?usp=sharing
you are using void QGridLayout::addWidget(QWidget * widget, int row, int column, Qt::Alignment alignment = 0) overload.
2-nd and 3-rd parameters are row and column of a grid. And you put 2 widgets in the same cell so they are overlaping each other.
I solved my problem. Earlier when I was trying to add them to a frame and reposition it I could not but using a widget as the container for my buttons let me place them the way I was earlier attempting to individually place the buttons.
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 an instance of QDialog, populated by widgets using code generated by uic. The dialog contains a few labels laid out vertically, and I am popping the dialog from time to time to show some text in these labels. The text can be multi-line and its length is not pre-determined. I set the vertical size policy to fixed, so the user can't drag it (doesn't make sense), but I also want the dialog to change its size before being shown to accomodate for the current size of the labels.
To this end, I was calling QWidget::adjustSize() on the QDialog before displaying it, but it doesn't work as expected. When the dialog is shown, it seems to retain the (wrong) size from the previous displaying, but when I click the mouse in the (disabled) vertical resize mode, the dialog suddenly "snaps" to the (correct) adjusted size.
Is there any way to make my dialog appear correctly?
EDIT: I tied rubenvb's advice, and ended up with this:
QSizePolicy free(QSizePolicy::MinimumExpanding, QSizePolicy::MinimumExpanding);
QSizePolicy fixed(QSizePolicy::MinimumExpanding, QSizePolicy::Fixed);
dialog->setSizePolicy(free);
dialog->adjustSize();
dialog->setSizePolicy(fixed);
dialog->show();
Unfortunately, that didn't seem to change anything.
This isn't the answer you're hoping for, and it may not apply to what you're trying to do, however, the only way that I was able to adjust the dimensions of a QWidget at run-time was by handling the object's resizeEvent(..) method. This allowed me to calc the size of items based upon the font being used, number of lines, available space, etc., and then adjust their size accordingly before passing the 'event' on to the base resizeEvent(..) method.
My approach used a single QWidget container within a window, below a header, above a footer status area, and to the right of a column of menu buttons. The widget container, inside the resizeEvent() call, would look at the objects it was going to display, calculate the font heights being used, and then resize some items according to their dimensions (because of how the style sheet selected fonts and colors, etc) and then adjust the sub-widget dimensions before allowing the container widget to get the resizeEvent() message.
So I wasn't so interested in setting a window size, but I think the container QWidget might work the same way? I was more interested in setting the dimensions to some asthetically pleasing size, depending upon the dimensions of the display.
Hope you find that helpful.
Do everything in the right order:
Dialog is not shown. Dialog is resizeable.
Calculate new size, set new size.
Set dialog to not-resizeable.
Show Dialog.
Hide dialog, go to step one.