如何使用libxcb获取顶级窗口及其名称

Question

我有一个带有2个打开窗口的Linux桌面：一个终端和一个浏览器。我试图用libxcb获取那些窗口的名称。这是我在 httpps：///wwww.systutorials。 com/doc/linux/man/3-xcb_query_tree_reply/

这是我的代码：

#include <stdio.h>
#include <malloc.h>
#include <string.h>
#include <stdlib.h>
#include <xcb/xcb.h>

void get_children(xcb_connection_t* c, xcb_window_t window, xcb_window_t** children, int* count)
{
    *count = 0;
    *children = NULL;

    auto cookie = xcb_query_tree(c, window);
    auto reply = xcb_query_tree_reply(c, cookie, NULL);
    if (reply)
    {
        *count = xcb_query_tree_children_length(reply);
        *children = xcb_query_tree_children(reply);

        free(reply);
    }
}

void get_name(xcb_connection_t* c, xcb_window_t window, char** name, int* length)
{
    *length = 0;
    *name = NULL;

    auto cookie = xcb_get_property(c, 0, window, XCB_ATOM_WM_NAME, XCB_ATOM_STRING, 0, 0);
    auto reply = xcb_get_property_reply(c, cookie, NULL);
    if (reply)
    {
        *length = xcb_get_property_value_length(reply);
        *name = (char*)xcb_get_property_value(reply);

        free(reply);
    }
}

int main()
{
    auto c = xcb_connect(":0.0", NULL);
    auto screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;
    auto rootWindow = screen->root;

    int nChildren;
    xcb_window_t* children;
    get_children(c, screen->root, &children, &nChildren);
    for (int i = 0; i < nChildren; i++)
    {
        auto wid = children[i];

        int length;
        char* name;
        get_name(c, wid, &name, &length);
        printf("%u %d\n", wid, length);
    }

    return 0;
}

这是我的代码：返回40个Windows，其名称为0

20971989 0
20971802 0
20972112 0
20972308 0
... (truncated for brevity)

。 -l 。

我在做什么错？

Answer 1

我弄清楚了这个问题。我需要在XCB_GET_PROPERTY函数调用中添加长度。以下代码有效。

auto cookie = xcb_get_property(c, 0, window, XCB_ATOM_WM_NAME, XCB_ATOM_STRING, 0, 1000);