gpu-screen-recorder-ui/src/GlobalHotkeysX11.cpp

#include "../include/GlobalHotkeysX11.hpp"
#define XK_MISCELLANY
#include <X11/keysymdef.h>

namespace gsr {
    static bool x_failed = false;
    static int xerror_grab_error(Display*, XErrorEvent*) {
        x_failed = true;
        return 0;
    }

    static unsigned int x11_get_numlock_mask(Display *dpy) {
        unsigned int numlockmask = 0;
        KeyCode numlock_keycode = XKeysymToKeycode(dpy, XK_Num_Lock);
        XModifierKeymap *modmap = XGetModifierMapping(dpy);
        if(modmap) {
            for(int i = 0; i < 8; ++i) {
                for(int j = 0; j < modmap->max_keypermod; ++j) {
                    if(modmap->modifiermap[i * modmap->max_keypermod + j] == numlock_keycode)
                        numlockmask = (1 << i);
                }
            }
            XFreeModifiermap(modmap);
        }
        return numlockmask;
    }

    GlobalHotkeysX11::GlobalHotkeysX11() {
        dpy = XOpenDisplay(NULL);
        if(!dpy)
            fprintf(stderr, "GlobalHotkeysX11 error: failed to connect to X11 server, global hotkeys wont be available\n");
    }

    GlobalHotkeysX11::~GlobalHotkeysX11() {
        if(dpy) {
            XCloseDisplay(dpy);
            dpy = nullptr;
        }
    }

    bool GlobalHotkeysX11::bind_key_press(Hotkey hotkey, const std::string &id, GlobalHotkeyCallback callback) {
        if(!dpy)
            return false;

        auto it = bound_keys_by_id.find(id);
        if(it != bound_keys_by_id.end())
            return false;

        x_failed = false;
        XErrorHandler prev_xerror = XSetErrorHandler(xerror_grab_error);

        unsigned int numlock_mask = x11_get_numlock_mask(dpy);
        unsigned int modifiers[] = { 0, LockMask, numlock_mask, numlock_mask|LockMask };
        for(int i = 0; i < 4; ++i) {
            XGrabKey(dpy, XKeysymToKeycode(dpy, hotkey.key), hotkey.modifiers | modifiers[i], DefaultRootWindow(dpy), False, GrabModeAsync, GrabModeAsync);
        }
        XSync(dpy, False);
        
        if(x_failed) {
            for(int i = 0; i < 4; ++i) {
                XUngrabKey(dpy, XKeysymToKeycode(dpy, hotkey.key), hotkey.modifiers | modifiers[i], DefaultRootWindow(dpy));
            }
            XSync(dpy, False);
            XSetErrorHandler(prev_xerror);
            return false;
        } else {
            XSetErrorHandler(prev_xerror);
            bound_keys_by_id[id] = { hotkey, std::move(callback) };
            return true;
        }
    }

    void GlobalHotkeysX11::unbind_key_press(const std::string &id) {
        if(!dpy)
            return;

        auto it = bound_keys_by_id.find(id);
        if(it == bound_keys_by_id.end())
            return;

        x_failed = false;
        XErrorHandler prev_xerror = XSetErrorHandler(xerror_grab_error);

        unsigned int numlock_mask = x11_get_numlock_mask(dpy);
        unsigned int modifiers[] = { 0, LockMask, numlock_mask, numlock_mask|LockMask };
        for(int i = 0; i < 4; ++i) {
            XUngrabKey(dpy, XKeysymToKeycode(dpy, it->second.hotkey.key), it->second.hotkey.modifiers | modifiers[i], DefaultRootWindow(dpy));
        }
        XSync(dpy, False);

        XSetErrorHandler(prev_xerror);
        bound_keys_by_id.erase(id);
    }

    void GlobalHotkeysX11::unbind_all_keys() {
        if(!dpy)
            return;

        x_failed = false;
        XErrorHandler prev_xerror = XSetErrorHandler(xerror_grab_error);

        unsigned int numlock_mask = x11_get_numlock_mask(dpy);
        unsigned int modifiers[] = { 0, LockMask, numlock_mask, numlock_mask|LockMask };
        for(auto it = bound_keys_by_id.begin(); it != bound_keys_by_id.end();) {
            for(int i = 0; i < 4; ++i) {
                XUngrabKey(dpy, XKeysymToKeycode(dpy, it->second.hotkey.key), it->second.hotkey.modifiers | modifiers[i], DefaultRootWindow(dpy));
            }
        }
        bound_keys_by_id.clear();
        XSync(dpy, False);

        XSetErrorHandler(prev_xerror);
    }

    void GlobalHotkeysX11::poll_events() {
        while(XPending(dpy)) {
            XNextEvent(dpy, &xev);
            if(xev.type == KeyPress) {
                const KeySym key_sym = XLookupKeysym(&xev.xkey, 0);
                call_hotkey_callback({ key_sym, xev.xkey.state });
            }
        }
    }

    static unsigned int key_state_without_locks(unsigned int key_state) {
        return key_state & ~(Mod2Mask|LockMask);
    }

    void GlobalHotkeysX11::call_hotkey_callback(Hotkey hotkey) const {
        for(const auto &[key, val] : bound_keys_by_id) {
            if(val.hotkey.key == hotkey.key && key_state_without_locks(val.hotkey.modifiers) == key_state_without_locks(hotkey.modifiers)) {
                val.callback(key);
                return;
            }
        }
    }
}