How do I limit mouse pointer movement in wxWidgets?

Question

Is there a way to limit mouse pointer movement to a specific area in wxWidgets? I know there is an API function ClipCursor() in Windows, but is there a method in wxWidgets for all platforms?

Answer 1

No. There is no such function in wx by all i know. Start up a timer (say 50ms) checking the global mouse position. If the mouse is outside the region, then set it into again.

If you want to restrict the mouse for some certain reason, for example to make some sort of game, then you can capture the mouse (see wxWindow::CaptureMouse). You will get mouse events even if the pointer is outside your window. Then you could react to mouse-motion events and do the check for the position there, without a timer. Downside of this is that the mouse won't be able to be used somewhere else for other programs since they won't receive events.

wxWidgets manual states that OSX guidelines forbid the programs to set the mouse pointer to a certain position programmatically. That might contribute to the reason there is not much support for such stuff in wx, especially since wx tries really hard to be compatible to everything possible.

Small sample. Click on the button to restrict the mouse to area 0,0,100,100. Click somewhere to release it.

#include <wx/wx.h>

namespace sample {

class MyWin : public wxFrame {
public:
    MyWin() 
        :wxFrame(0, wxID_ANY, wxT("haha title")) {
        mRestricted = wxRect(0, 0, 100, 100);
        mLast = mRestricted.GetTopLeft();
        wxButton * button = new wxButton(this, wxID_ANY, wxT("click this"));
    }

private:
    void OnClicked(wxCommandEvent& event) {
        if(!HasCapture()) {
            CaptureMouse();
            CheckPosition();
        }
    }

    void OnMotion(wxMouseEvent& event) {
        CheckPosition();
    }

    void OnLeft(wxMouseEvent& event) {
        if(HasCapture())
            ReleaseMouse();
    }

    void CheckPosition() {
        wxPoint pos = wxGetMousePosition();
        if(!mRestricted.Contains(pos)) {
            pos = ScreenToClient(mLast);
            WarpPointer(pos.x, pos.y);
        } else {
            mLast = pos;
        }
    }

    wxRect mRestricted;
    wxPoint mLast;
    DECLARE_EVENT_TABLE();
};

BEGIN_EVENT_TABLE(MyWin, wxFrame)
    EVT_BUTTON(wxID_ANY, MyWin::OnClicked)
    EVT_MOTION(MyWin::OnMotion)
    EVT_LEFT_DOWN(MyWin::OnLeft)
END_EVENT_TABLE()

class MyApp : public wxApp {
    virtual bool OnInit() {
        MyWin * win = new MyWin;
        win -> Show();
        SetTopWindow(win);
        return true;
    }
};

} /* sample:: */

IMPLEMENT_APP(sample::MyApp)