gpu-screen-recorder-ui/src/WindowUtils.cpp

#include "../include/WindowUtils.hpp"

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

#include <stdbool.h>
#include <stdio.h>
#include <string.h>

namespace gsr {
    static bool window_has_atom(Display *dpy, Window window, Atom atom) {
        Atom type;
        unsigned long len, bytes_left;
        int format;
        unsigned char *properties = NULL;
        if(XGetWindowProperty(dpy, window, atom, 0, 1024, False, AnyPropertyType, &type, &format, &len, &bytes_left, &properties) < Success)
            return false;

        if(properties)
            XFree(properties);

        return type != None;
    }

    static bool window_is_user_program(Display *dpy, Window window) {
        const Atom net_wm_state_atom = XInternAtom(dpy, "_NET_WM_STATE", False);
        const Atom wm_state_atom = XInternAtom(dpy, "WM_STATE", False);
        return window_has_atom(dpy, window, net_wm_state_atom) || window_has_atom(dpy, window, wm_state_atom);
    }

    static Window window_get_target_window_child(Display *display, Window window) {
        if(window == None)
            return None;

        if(window_is_user_program(display, window))
            return window;

        Window root;
        Window parent;
        Window *children = nullptr;
        unsigned int num_children = 0;
        if(!XQueryTree(display, window, &root, &parent, &children, &num_children) || !children)
            return None;

        Window found_window = None;
        for(int i = num_children - 1; i >= 0; --i) {
            if(children[i] && window_is_user_program(display, children[i])) {
                found_window = children[i];
                goto finished;
            }
        }

        for(int i = num_children - 1; i >= 0; --i) {
            if(children[i]) {
                Window win = window_get_target_window_child(display, children[i]);
                if(win) {
                    found_window = win;
                    goto finished;
                }
            }
        }

        finished:
        XFree(children);
        return found_window;
    }

    static Window get_window_at_cursor_position(Display *dpy) {
        Window root_window = None;
        Window window = None;
        int dummy_i;
        unsigned int dummy_u;
        XQueryPointer(dpy, DefaultRootWindow(dpy), &root_window, &window, &dummy_i, &dummy_i, &dummy_i, &dummy_i, &dummy_u);
        if(window)
            window = window_get_target_window_child(dpy, window);
        return window;
    }

    Window get_focused_window(Display *dpy, WindowCaptureType cap_type) {
        //const Atom net_active_window_atom = XInternAtom(dpy, "_NET_ACTIVE_WINDOW", False);
        Window focused_window = None;

        if(cap_type == WindowCaptureType::FOCUSED) {
            // Atom type = None;
            // int format = 0;
            // unsigned long num_items = 0;
            // unsigned long bytes_left = 0;
            // unsigned char *data = NULL;
            // XGetWindowProperty(dpy, DefaultRootWindow(dpy), net_active_window_atom, 0, 1, False, XA_WINDOW, &type, &format, &num_items, &bytes_left, &data);

            // if(type == XA_WINDOW && num_items == 1 && data)
            //     focused_window = *(Window*)data;

            // if(data)
            //     XFree(data);

            // if(focused_window)
            //     return focused_window;

            int revert_to = 0;
            XGetInputFocus(dpy, &focused_window, &revert_to);
            if(focused_window && focused_window != DefaultRootWindow(dpy) && window_is_user_program(dpy, focused_window))
                return focused_window;
        }

        focused_window = get_window_at_cursor_position(dpy);
        if(focused_window && focused_window != DefaultRootWindow(dpy))
            return focused_window;

        return None;
    }

    static char* get_window_title(Display *dpy, Window window) {
        const Atom net_wm_name_atom = XInternAtom(dpy, "_NET_WM_NAME", False);
        const Atom wm_name_atom = XInternAtom(dpy, "WM_NAME", False);
        const Atom utf8_string_atom = XInternAtom(dpy, "UTF8_STRING", False);

        Atom type = None;
        int format = 0;
        unsigned long num_items = 0;
        unsigned long bytes_left = 0;
        unsigned char *data = NULL;
        XGetWindowProperty(dpy, window, net_wm_name_atom, 0, 1024, False, utf8_string_atom, &type, &format, &num_items, &bytes_left, &data);

        if(type == utf8_string_atom && format == 8 && data)
            return (char*)data;

        type = None;
        format = 0;
        num_items = 0;
        bytes_left = 0;
        data = NULL;
        XGetWindowProperty(dpy, window, wm_name_atom, 0, 1024, False, 0, &type, &format, &num_items, &bytes_left, &data);

        if((type == XA_STRING || type == utf8_string_atom) && data)
            return (char*)data;

        return NULL;
    }

    static const char* strip(const char *str, int *len) {
        int str_len = strlen(str);
        for(int i = 0; i < str_len; ++i) {
            if(str[i] != ' ') {
                str += i;
                str_len -= i;
                break;
            }
        }

        for(int i = str_len - 1; i >= 0; --i) {
            if(str[i] != ' ') {
                str_len = i + 1;
                break;
            }
        }

        *len = str_len;
        return str;
    }

    static std::string string_string(const char *str) {
        int len = 0;
        str = strip(str, &len);
        return std::string(str, len);
    }

    std::string get_focused_window_name(Display *dpy, WindowCaptureType window_capture_type) {
        std::string result;
        const Window focused_window = get_focused_window(dpy, window_capture_type);
        if(focused_window == None)
            return result;

        // Window title is not always ideal (for example for a browser), but for games its pretty much required
        char *window_title = get_window_title(dpy, focused_window);
        if(window_title) {
            result = string_string(window_title);
            XFree(window_title);
            return result;
        }

        XClassHint class_hint = {nullptr, nullptr};
        XGetClassHint(dpy, focused_window, &class_hint);
        if(class_hint.res_class) {
            result = string_string(class_hint.res_class);
            return result;
        }

        return result;
    }
}