As far as i know the two ways to get mouse position are using libgpm or reading /dev/input/mice file. But the latter just returns a relative position from the last position. So my question is how can i get the absolute mouse position though reading /dev/input/mice or other way.
And i want to implement this function by C or C++. Any information will be appreciate.
First, a mouse device is probably sending only relative movements, so there is no way to get the absolute position (just try to raise the mouse with your hand and put it elsewhere), except by integrating the movement.
And almost all Linux GUI environments are above X11, so it is the X11 server (usually the Xorg process) which deals with the mouse (it is the only process actually reading /dev/input/mice)
You'll then need to make an X11 client application. See this & that question. But you'll be much better in using some existing toolkit library, like Qt or GTK; see e.g. QMouseEvent & QWidget::mouseMoveEvent in Qt, and GtkWidget "motion-notify-event" signal in Gtk (and many other functions).
See also this question
Related
I think I understand the reasoning behind Wayland preventing windows from being manually positioned but there are a couple of instances in my Qt 5.15.2 application where I really need to have either some or absolute control over the position:
In the first instance the window is a pop-up. I'm using a QMainWindow so I can have it borderless with rounded corners, a coloured background and a transparency. I need it to pop-up when I hover over a certain element on my QGraphicsScene but want to ensure that when it appears it is close to the QGraphicsScene element in question but does not obscure it. Using a call to QMainWindow::move was perfect pre-Wayland and works fine on Windows too.
In the second instance my application has a number of windows which the user may open and close over time. The first time each one opens I don't care too much where it is positioned but if the user moves it before closing it then the next time the user opens it I want it to reappear where the user previously left it. Again, using the move() method of the various things that inherit from QWidget was perfect pre-Wayland.
Does anyone know of any work-arounds that would solve either of these problems under Qt on Wayland? It seems to me that neither is a particularly uncommon requirement and if Wayland won't let me set a specific position it might have a way of achieving something similar (e.g. a way of telling the compositor to position something near something else without obscuring it) and hopefully that maps onto something in the Qt API.
I searched, but most posts are just telling me what I already have, so below is basically my code right now:
DIKeyboard->Acquire();
DIMouse->Acquire();
DIMouse->GetDeviceState(sizeof(DIMOUSESTATE), &mouseCurrState);
DIKeyboard->GetDeviceState(sizeof(keyboardState),(LPVOID)&keyboardState);
MousePos.x += mouseCurrState.lX;
MousePos.y += mouseCurrState.lY;
Any post telling me how to get absolute position just says to use those last two lines. But my program is windowed, and the mouse can start anywhere on the screen.
i.e. If my mouse happens to be in the centre of my screen, that becomes position 0,0. I basically just want the top left of my window (not my screen) to be my 0,0 mouse coordinates, but am having a hard time finding anything relevant.
Thanks for any help! :)
Following the discussion in the comments, you'll have to decide which method works best for you. Unfortunately, having never worked with DirectInput, I do not know the ins-and-outs of it.
However, Window Messages work best for RTS-style controls, where a cursor is drawn to screen. This is due to the fact that this respects user settings, such as mouse acceleration and mouse speed, whereas DirectInput only uses the driver settings (so not the control panel settings). The user will expect the mouse to feel the same, especially in windowed mode.
DirectInput works better for FPS-style controls, when there is no cursor drawn, as window messages give you only the cursor coordinates, and not offset values. This means that once you are at the edge of the screen, window messages will no longer allow you to detect the mouse being moved further (actually, I am not 100% sure on this, so if someone could verify, please feel free to comment).
For keyboard, I would definitely suggest window messages, because DirectInput offers no advantages, and WM input is easier to use, and quite powerful (the WM_KEYDOWN messages contains a lot of useful data), and it'll allow you (via TranslateMessage) to get good text input, adjusted to locale, etc.).
Solving your problem with DirectInput:
You could probably use GetCursorPos followed by ScreenToClient to initialise your MousePos structure. I'm guessing you'll need to redo this every time you lose mouse input and reacquire it.
Hybrid solution (for RTS like controls):
It might be possible to use a hybrid solution for the mouse if you desire RTS-like controls. If this is the case, I suggest, though I have not tested this, to use WM for the movement of the mouse, which avoids the need for workaround mentioned above, and only use DirectInput to detect additional mouse buttons.
Now one thing I think you should do in such a hybrid approach is not directly use the button when you detect it via DirectInput, but rather post a custom application message to your own message queue (using PostMessage and WM_APP) with the relevant information. I suggest this because using WM you do not get the real-time state of the mouse & keyboard, but rather the state at the time of the message. Posting a message that the button was pressed allows you to handle the extra buttons in the same state-dependent manner (I don't know how noticeable this 'lag' effect is). It also makes the entire input handling very uniform, as every bit of input with this enters as a window message.
I'm trying to figure out how to create a graphical interface, in X11, which exists outside of a window manager's/desktop environment's standard window frame. For example, when Thunderbird finds new mail, it shows a special alert in the lower right hand corner of the screen which is shown without any frame (no close/minimize buttons, etc.).
I'm specifically interested in doing this in QT with C++, but if someone knows a solution with a different graphical library, that would be helpful too.
For QT pass Qt::FramelessWindowHint as a window flag when you construct your top level widget.
See here for more info:
http://doc.qt.nokia.com/main-snapshot/qt.html#WindowType-enum
You can do this with X as well although I haven't done so in a long time.
http://www.xfree86.org/current/XCreateWindow.3.html
With GTK you would use gtk_window_set_decorated(), which would probably be Gtk::Widget->set_decorated() (I think, I don't use gtkmm).
http://developer.gnome.org/gtkmm/unstable/classGtk_1_1Window.html#a67adb1d8051a38e0e5272f141bb8778c
How can I retrieve the top window of which the cursor is on top of in the X11 server?
The window doesn't have to be ”active” (selected, open, whatever), it just has to have the cursor floating on top of it.
Thanks in advance.
You can use XQueryPointer() to get the mouse position. Then get a window list using XQueryTree(). XQueryTree() returns the window list in proper z-order so you can just loop through all the windows until you find one whose bounding box is under the pointer, XGetWindowAttributes() will give you everything you need to figure out the bounding box. I'm not sure what you would do with shaped windows though.
I haven't work with X11 for a few years so this might be a rather clunky approach but it should work. I also don't have my O'Reilly X11 books anymore, you'll want to get your hands on book one of that series if you're going to work with low level X11 stuff; I think the whole series is available for free online these days.
I haven't programmed X11 for over a decade, so forgive me if I get this wrong.
I believe you can register for mouse movement events on your windows. If you handle such event by storing the window handle in some variable or other, and then handling the event so it doesn't percolate down the tree, then at the time you want to identify the window you can just query the variable.
However this will only work when the mouse is over a window you have registered a suitable event handler for, so you won't know about windows belonging to other applications - unless there is a way to register for events on other people's windows which may be possible.
The advantage over the other answer is that you don't have to traverse the whole tree. The disadvantage is that you need to handle a great many mouse movement events, and it may not work to find other people's windows.
I believe there may also be mouse enter and mouse leave events too which would reduce the amount of processing required.
I have a problem about a simple mpi program.This program have some 3D points and these points are moving during the program. I created an simple code by implemented c++ and then I tried to add an simple gui. I used gnuplot library and I have a problem. When I call the gui function the gui is created and it is disappeared at the same time. I mean, point object have x,y,z coordinate and I have an array that includes point objects. I want to create them as gui. Can you help me about this problem?
Thanks for any help..
what about Qt? You could use the Qt Graphics View Framework to simulate the 3D-environment - it even supports coordinate transformation (ok, it was originally designed for 2d scope). It supports OpenGL and maybe you are able to simulate the 3D points by drawing dots and setting their positions using simple cosinus and tangens mathematics.
Don't get afraid of the many functions and classes Qt offers - it's very easy and fast to learn - just check out the simple tutorials and after that you right can start your gui!
...and if you are used to Qt, you'll never want to miss it :)
Could it be that the plot is up correctly but that then your program ends? Ie everything's correct, the window goes up, but the next thing that happens is that the program is done, and the window gets destroyed? Try putting in a couple lines that wait for a keypress right after you throw up the window. Then, the window will stay until you press a key (and then the program will end).