Xlib:XGetWindowAttributes总是返回1x1?

你说得对-你看到的是一扇儿童窗户。尤其是GTK应用程序,在“real”窗口下创建一个子窗口,该窗口始终为1x1,并且当应用程序具有焦点时,该子窗口始终获得焦点。如果您只是使用GNOME终端运行程序,那么您将始终看到一个GTK应用程序具有焦点(终端)。

如果您以这样一种方式运行您的程序,即非GTK程序碰巧具有焦点,则不会发生这种情况,但您仍然可以找到具有焦点的子窗口,而不是顶层窗口。(其中一种方法是跑 sleep 在你这样的程序之前: sleep 4; ./my_program -这给了你一个改变焦点的机会。)

我想是为了找到顶层的窗户 XQueryTree

这对我有效:

#include <X11/Xlib.h>
#include <stdio.h>
#include <stdlib.h>

/*
Returns the parent window of "window" (i.e. the ancestor of window
that is a direct child of the root, or window itself if it is a direct child).
If window is the root window, returns window.
*/
Window get_toplevel_parent(Display * display, Window window)
{
     Window parent;
     Window root;
     Window * children;
     unsigned int num_children;

     while (1) {
         if (0 == XQueryTree(display, window, &root,
                   &parent, &children, &num_children)) {
             fprintf(stderr, "XQueryTree error\n");
             abort(); //change to whatever error handling you prefer
         }
         if (children) { //must test for null
             XFree(children);
         }
         if (window == root || parent == root) {
             return window;
         }
         else {
             window = parent;
         }
     }
}

int main(int argc, char *argv[])
{
    Display *display;
    Window focus, toplevel_parent_of_focus;
    XWindowAttributes attr;
    int revert;

    display = XOpenDisplay(NULL);
    XGetInputFocus(display, &focus, &revert);
    toplevel_parent_of_focus = get_toplevel_parent(display, focus);
    XGetWindowAttributes(display, toplevel_parent_of_focus, &attr);
    printf("[0x%x] %d x %d\n", (unsigned)toplevel_parent_of_focus, 
       attr.width, attr.height);

    return 0;
}