在X11窗口上移动窗口事件

Question

I currently have 2 X11 windows that I want to keep in sync. One overlays a transparent graphic while the other one shows video. I currently have the one that overlays graphic to be always on top of the one of the video, but I am having trouble making sure both windows are at the same places when moved. I am looking for a window move event in the X11 documentation, but I can't seem to find one.

In addition, in my event handle loop, I have tried to get the location of one of my windows and to move the other window to that location. This has failed whenever XGetWindowAttributes is called it always returns x=0 and y=0 even though the window is moved.

Window   win;
int nxvisuals = 0;
XVisualInfo visual_template;
XVisualInfo *visual_list;
XVisualInfo vinfo;
Visual *visual;
int depth;
Atom wm_state;
(void)wm_state;

x_display = XOpenDisplay ( NULL );   // open the standard display (the primary screen)

visual_template.screen = DefaultScreen(x_display);
visual_list = XGetVisualInfo(x_display, VisualScreenMask, &visual_template, &nxvisuals);

XMatchVisualInfo(x_display, XDefaultScreen(x_display), 32, TrueColor, &vinfo)

Window parent = XDefaultRootWindow(x_display);
XSync(x_display, True);
visual = vinfo.visual;
depth = vinfo.depth;

XSetWindowAttributes  swa;
swa.event_mask = ExposureMask | PointerMotionMask | KeyPressMask;
swa.colormap = XCreateColormap(x_display, XDefaultRootWindow(x_display), visual, AllocNone);
swa.background_pixel = 0;
swa.border_pixel = 0;

win = XCreateWindow (   // create a window with the provided parameters
          x_display, parent,
          0, 0, 1024, 576, 0,
          depth, InputOutput,
          visual, CWEventMask | CWBackPixel | CWColormap | CWBorderPixel,
          &swa );

XSync(x_display, True);

XSetWindowAttributes  xattr;

xattr.override_redirect = False;
XChangeWindowAttributes ( x_display, win, CWOverrideRedirect, &xattr );

XWMHints hints;
hints.input = True;
hints.flags = InputHint;
XSetWMHints(x_display, win, &hints);

XSizeHints *size_hints = XAllocSizeHints();
size_hints->flags = PMinSize | PMaxSize | PSize;
size_hints->min_width = 1024;
size_hints->max_width = 1024;
size_hints->min_height = 576;
size_hints->max_height = 576;
XSetNormalHints(x_display, win, size_hints);
XSetWMSizeHints(x_display,win , size_hints, PSize | PMinSize | PMaxSize);

XMapWindow ( x_display , win );                   // make the window visible on the screen
XStoreName ( x_display , win , "OpenGL" ); // give the window a name

/* Second window starts here */
int cnxvisuals = 0;
XVisualInfo cvisual_template;
XVisualInfo *cvisual_list;
XVisualInfo cvinfo;
Visual *cvisual;
int cdepth;

cvisual_template.screen = DefaultScreen(x_display);
cvisual_list = XGetVisualInfo(x_display, VisualScreenMask, &cvisual_template, &cnxvisuals);

XMatchVisualInfo(x_display, XDefaultScreen(x_display), 24, TrueColor, &cvinfo)

Window child = XDefaultRootWindow(x_display);
XSync(x_display, True);
cvisual = cvinfo.visual;
cdepth = cvinfo.depth;

XSetWindowAttributes  cswa;
cswa.event_mask = PointerMotionMask | KeyPressMask;
cswa.colormap = XCreateColormap(x_display, XDefaultRootWindow(x_display), cvisual, AllocNone);
cswa.background_pixel = 0;
cswa.border_pixel = 0;

child = XCreateWindow (   // create a window with the provided parameters
          x_display, parent,
          0, 0, 1024, 576, 0,
          cdepth, InputOutput,
          cvisual, CWEventMask | CWBackPixel | CWColormap | CWBorderPixel,
          &cswa );

XSync(x_display, True);

XSetWindowAttributes  xcattr;

xcattr.override_redirect = False;
XChangeWindowAttributes ( x_display, child, CWOverrideRedirect, &xcattr );

XWMHints chints;
chints.input = True;
chints.flags = InputHint;
XSetWMHints(x_display, child, &chints);

XSetNormalHints(x_display, child, size_hints);
XSetWMSizeHints(x_display,child , size_hints, PSize | PMinSize | PMaxSize);

XMapWindow ( x_display , child );                   // make the window visible on the screen
XStoreName ( x_display , child , "video" ); // give the window a name

XSelectInput(x_display, child, ExposureMask | FocusChangeMask);

int id = pthread_create(&x11loop, NULL,x11_handle_events,this);

Here is my handle events call

void* x11_handle_events(void *void_ptr)
{
    Renderer* renderer = static_cast<Renderer*>(void_ptr);
    renderer->stop = false;
    XEvent event;
    XWindowAttributes opengl_attrs;
    while(!renderer->stop)
    {
        XNextEvent(renderer->x_display, &event);
        switch(event.type)
        {
            case Expose:
            if (event.xexpose.window == renderer->child)
            {
                XRaiseWindow(renderer->x_display, renderer->win);
            }
            break;

            case FocusIn:
           if (event.xfocus.window == renderer->child)
            {
                XRaiseWindow(renderer->x_display, renderer->win);
            }
            break;

        }

        // Make sure both windows are in the same location
        XGetWindowAttributes(renderer->x_display, renderer->child, &opengl_attrs);
        XMoveWindow(renderer->x_display, renderer->win, opengl_attrs.x, opengl_attrs.y);
    }


    pthread_exit(0);
    return NULL;
}

Answer 1

The event you're looking for is ConfigureNotify

http://tronche.com/gui/x/xlib/events/window-state-change/configure.html

The X server can report ConfigureNotify events to clients wanting information about actual changes to a window's state, such as size, position, border, and stacking order. The X server generates this event type whenever one of the following configure window requests made by a client application actually completes:

snip

A window is moved by calling XMoveWindow().

The x and y members are set to the coordinates relative to the parent window's origin and indicate the position of the upper-left outside corner of the window. The width and height members are set to the inside size of the window, not including the border. The border_width member is set to the width of the window's border, in pixels.

The event mask is iirc StructureNotifyMask .

The window manager might disagree with your moving around though... but if it still doesn't work, leave a comment and we'll look deeper.