The Documentation for QWidget says this:
mouseReleaseEvent() is called when a mouse button is released. A
widget receives mouse release events when it has received the
corresponding mouse press event. This means that if the user presses
the mouse inside your widget, then drags the mouse somewhere else
before releasing the mouse button, your widget receives the release
event. There is one exception: if a popup menu appears while the mouse
button is held down, this popup immediately steals the mouse events.
It also says this:
If you create new widgets in the mousePressEvent() the
mouseReleaseEvent() may not end up where you expect, depending on the
underlying window system (or X11 window manager), the widgets'
location and maybe more
In my programme, the is a context where the user can change the current visible widget by pressing Enter. If they click and hold on a toolbar button and press enter while the mouse is still pressed, they can send the mouse release event to the now hidden widget. This is a problem as the actions in the toolbar of the now hidden page, relate to a state which has been deinitialised when the active widget was changed.
The desired behaviour would be for the changing of active widget to somehow 'cancel' or 'release' the old widget's claim to the coming mouse release event even though it (or one of its children) received the corresponding mouse press event, and for the action in the toolbar not to be triggered.
Is there any way to do this? Or does anyone have any guidance on what I might be looking for?
Thanks
One options is by creating eventFilter function (either in widget itself (if your own) or parent widget), installing it with installEventFilter and then checking for mouse release event type and only accept the event if widget's isVisible() returns true.
Another option (in case you have your own Qt based widget class) is to override mouseReleaseEvent and do the same visibility check in there.
Related
I want to check if the mouse button is clicked or released on my window in order to change the cursor. For now I have the signals, connected to the main window, but the problem is that , when I hover my mouse cursor over the button or GLArea, the events I linked to the window do not work, so the cursor does not change. By the way, all buttons in my application have their own signals, so, to change the cursor state I should duplicate the function below for all widgets, which does not seem good.
window->signal_button_release_event().connect(sigc::bind(sigc::ptr_fun(&MouseBtnReleased), window));
window->signal_button_press_event().connect(sigc::bind(sigc::ptr_fun(&MouseBtnClicked), window));
I have a c++ Win32 application with a node-based GUI where I create a dynamic combobox with CreateWindowEx when the user presses a certain key within the GUI. I want the user to be able to click outside of the combobox Rect in order to make the combobox disappear.
To do this, I'm currently destroying the combobox inside a WM_KILLFOCUS notification of its DlgProc (so any click outside of it destroys it). However, it seems that the WM_KILLFOCUS notification is sent anytime one of its child windows gains focus. For example, if I click in the combobox's edit text region, the combobox itself loses focus since that child gains focus. Given my setup, this causes the combobox to be removed when clicking within it's Rect.
How can I prevent this behavior? Basically I want to be able to detect when anything other than the combobox or its child windows gains focus, rather than simply detecting if the combobox itself loses focus.
You can determine, whether focus moves to a different control from inside the WM_KILLFOCUS handler. This message receives
[a] handle to the window that receives the keyboard focus.
through its wParam argument.
Use the CB_GETCOMBOBOXINFO message to retrieve a COMBOBOXINFO structure, that contains window handles to all contributing windows (hwndCombo, hwndItem, and hwndList). Comparing the wParam value to all of those window handles allows you to determine, whether focus moves inside the combo box or outside.
While this answers the question that was asked, the real solution would be to handle the CBN_KILLFOCUS notification instead. It is sent to the control parent when the combo box loses keyboard focus, ignoring focus change events internal to the combo box control.
I have a modeless CDialog that contains controls, some CButtons and a CScrollbar. The CDialog is parented off of an edit box that I want to keep focus at all times. The problem is that whenever the user uses the controls, clicking a button or on the scrollbar, the control steals focus from the edit box, causing both the parent window to draw without focus (grayed-out header bar), and causing the control to take all the keyboard input. Is there a way for the controls to respond to mouse actions but not steal focus?
The controls and the dialog are all created with WS_CHILD. The controls are parented off the dialog, and the dialog is parented off of the edit box.
I've tried setting focus back after the controls are used, but that causes the parent window to flicker as it loses and then regains focus. Basically I want something that works like a combo box, where the scroll bar can be clicked or dragged around, but keyboard input still goes to the dialog itself, not just the scroll bar, and the whole thing never loses focus.
I haven't done anything like this for a long time, so I'm sure there are a million little details, but I think the starting point is to override the handling of WM_MOUSEACTIVATE.
I am a little confused about child-parent relationship you described.
Can you explain what do you mean by:
The CDialog is parented off of an edit box that I want to keep focus at all times
Any window hosting other windows inside of the client area is a parent of those windows. It is impossible to create window without WS_CHILD that is contained by other window.
Therefore all dialog’s controls are children of this dialog. It is also possible that child window hosts another child window.
CDialog is just an MFC representation of a dialog window; the same applies to other controls. For example CButton is an MFC class that wraps handle of the window’s window that is predefined as window button control.
Dialog never has focus unless is empty (does not have any controls). If dialog contains even one control, this control always has focus.
What focus means is that any given window receives mouse and keyboard messages. Only one control can have focus at any given time. In order for scroll bar to process mouse click or keyboard to move slider, scroll bar must have focus; therefore some other control must give it up.
Combo box drop box (I think this is what you are referring to) is not a child of the dialog. It is a popup window that for the duration has keyboard focus and captures mouse. When it drops down, dialog is deactivated and once dropdown hides, dialog state is changed back to active hence focus never changes, it returns to the control that had focus when dialog was deactivated.
What you are trying to do is probably possible but it would require a lot of coding. Probably hooking messages would do the job but I think it would be going against the stream.
I need to detect if the mouse pointer leaves my custom widget even if a mouse button is pressed.
According to this post, Qt does not cause a leaveEvent in case a button is pressed, at least not in version 4.4. I am working with 4.7.3, but still do not get a leaveEvent in the described case. I also tried with the various drag-related events, but no luck. Does anyone have an idea how to deal with this?
Actually there is an even better option than using the mouse events of the parent widget: You can implement the mouseMoveEvent function of the child widget and get the QMouseEvent::pos() position which is relative to the top left corner of the widget. That means, if you know the size of the widget (use for example QWidget::rect()), you can compute within the widget if the mouse pointer is still on the widget or not without having to change the parent widget.
Well, I did something similar to #gregseth.
Write your own MouseLeaveEvent that is invoked from MouseMoveEvent
when the mouse's position is outside of the widget's boundary.
As Qt's documentation says "Mouse move events will occur only when a mouse button is pressed down"
I got the same problem. The only workaround I found is to manage the mouseMove event of the parent widget, and to check if the position of the cursor is inside or outside the boundaries of the widget you want the event on.
I'm trying to create a popup menu like control that contains custom widgets. I need to capture the mouse, but I need to have the children in the widget still get their mouse messages. It appears the grabMouse sends events only to the widget that grabbed the mouse, not its children.
The popup is simply a series of buttons (using a QGridLayout). The control should work that the user presses the right-mouse button, the popup appears, they move to an item and release the mouse button. Optimally it would work exactly like a QMenu popup but with custom widgets and a custom layout.
How can I achieve this?
It appears that simply specifying attribute Qt::Popup is enough to get the fundamental behaviour required.
Installing an event filter on all children is also necessary. All mouse events, enter/leave/hover events must be captured. QT has a defect with grabMouse so that won't work -- the filter must be used to get expected behaviour.