XFetchName始终返回0

我试图写一个C代码来获取我的Linux系统中的活动窗口的标题,但函数XFetchName总是返回零,我也尝试了XGetWMName,相同的结果……
但是使用xprop,我可以看到“WM_NAME”属性中有一个字符串

谁能告诉我我的代码有什么问题？

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


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

      display = XOpenDisplay(NULL);
      XGetInputFocus(display, &focus, &revert);
      int ret = XFetchName(display, focus, &window_name);
      printf("ret = %d\n", ret);
      if (window_name) printf("Title = %s\n", window_name);
      return 0;
}

谢谢.

解决方法:

您可以尝试使用XGetWMName功能.虽然XGetWMName和XFetchName的描述都表示他们将返回WM_NAME属性,但似乎它们彼此不同.有时,它们会返回相同的名称.有时,只有XGetWMName返回名称.

您还可以使用xwininfo -root -tree获取所有窗口的名称,并与XFetchName和XGetWMName的结果进行比较.

此代码可以列出所有窗口并打印窗口ID和XFetchName和XGetWMName的结果.您可以使用窗口ID在xwininfo -root -tree的输出中查找.

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

void enum_windows(Display* display, Window window, int depth) {
  int i;

  XTextProperty text;
  XGetWMName(display, window, &text);
  char* name;
  XFetchName(display, window, &name);
  for (i = 0; i < depth; i++)
    printf("\t");
  printf("id=0x%x, XFetchName=\"%s\", XGetWMName=\"%s\"\n", window, name != NULL ? name : "(no name)", text.value);

  Window root, parent;
  Window* children;
  int n;
  XQueryTree(display, window, &root, &parent, &children, &n);
  if (children != NULL) {
    for (i = 0; i < n; i++) {
      enum_windows(display, children[i], depth + 1);
    }
    XFree(children);
  }
}

int main() {
  Display* display = XOpenDisplay(NULL);
  Window root = XDefaultRootWindow(display);
  enum_windows(display, root, 0);
}

这是一段输出,显示两个函数的结果可能不同.

id=0x2c7, XFetchName="(no name)", XGetWMName="(null)"
    id=0x400001, XFetchName="(no name)", XGetWMName="(null)"
    id=0x800036, XFetchName="(no name)", XGetWMName="(null)"
        id=0x1400001, XFetchName="(no name)", XGetWMName="c - XFetchName always returns 0 - Stack Overflow - Chromium"
    id=0x1000001, XFetchName="terminator", XGetWMName="terminator"
        id=0x1000002, XFetchName="(no name)", XGetWMName="(null)"
    id=0x1200001, XFetchName="chromium", XGetWMName="chromium"
        id=0x1200002, XFetchName="(no name)", XGetWMName="(null)"

这是xwininfo -root -tree输出的一部分,显示了这些窗口的名称.
xwininfo：窗口ID：0x2c7(根窗口)(没有名称)

  Root window id: 0x2c7 (the root window) (has no name)
  Parent window id: 0x0 (none)
     29 children:
     0x1200001 "chromium": ("chromium" "Chromium")  10x10+10+10  +10+10
        1 child:
        0x1200002 (has no name): ()  1x1+-1+-1  +9+9
     0x1000001 "terminator": ("terminator" "Terminator")  10x10+10+10  +10+10
        1 child:
        0x1000002 (has no name): ()  1x1+-1+-1  +9+9
     0x800036 (has no name): ()  1364x741+0+25  +0+25
        1 child:
        0x1400001 "c - XFetchName always returns 0 - Stack Overflow - Chromium": ("Chromium" "Chromium")  1364x741+0+0  +1+26
     0x400001 (has no name): ()  10x10+-20+-20  +-20+-20

标签：c-3,xlib,linux
来源： https://codeday.me/bug/20191008/1871749.html