flameshot/external/QHotkey/qhotkey_x11.cpp

#include "qhotkey.h"
#include "qhotkey_p.h"
#include <QDebug>
#include <QThreadStorage>
#include <QTimer>
#include <QX11Info>
#include <X11/Xlib.h>
#include <xcb/xcb.h>

// compability to pre Qt 5.8
#ifndef Q_FALLTHROUGH
#define Q_FALLTHROUGH() (void)0
#endif

class QHotkeyPrivateX11 : public QHotkeyPrivate
{
public:
    // QAbstractNativeEventFilter interface
    bool nativeEventFilter(const QByteArray& eventType,
                           void* message,
                           long* result) Q_DECL_OVERRIDE;

protected:
    // QHotkeyPrivate interface
    quint32 nativeKeycode(Qt::Key keycode, bool& ok) Q_DECL_OVERRIDE;
    quint32 nativeModifiers(Qt::KeyboardModifiers modifiers,
                            bool& ok) Q_DECL_OVERRIDE;
    static QString getX11String(Qt::Key keycode);
    bool registerShortcut(QHotkey::NativeShortcut shortcut) Q_DECL_OVERRIDE;
    bool unregisterShortcut(QHotkey::NativeShortcut shortcut) Q_DECL_OVERRIDE;

private:
    static const QVector<quint32> specialModifiers;
    static const quint32 validModsMask;
    xcb_key_press_event_t prevHandledEvent;
    xcb_key_press_event_t prevEvent;

    static QString formatX11Error(Display* display, int errorCode);

    class HotkeyErrorHandler
    {
    public:
        HotkeyErrorHandler();
        ~HotkeyErrorHandler();

        static bool hasError;
        static QString errorString;

    private:
        XErrorHandler prevHandler;

        static int handleError(Display* display, XErrorEvent* error);
    };
};
NATIVE_INSTANCE(QHotkeyPrivateX11)

bool QHotkeyPrivate::isPlatformSupported()
{
    return QX11Info::isPlatformX11();
}

const QVector<quint32> QHotkeyPrivateX11::specialModifiers = { 0,
                                                               Mod2Mask,
                                                               LockMask,
                                                               (Mod2Mask |
                                                                LockMask) };
const quint32 QHotkeyPrivateX11::validModsMask =
  ShiftMask | ControlMask | Mod1Mask | Mod4Mask;

bool QHotkeyPrivateX11::nativeEventFilter(const QByteArray& eventType,
                                          void* message,
                                          long* result)
{
    Q_UNUSED(eventType)
    Q_UNUSED(result)

    auto* genericEvent = static_cast<xcb_generic_event_t*>(message);
    if (genericEvent->response_type == XCB_KEY_PRESS) {
        xcb_key_press_event_t keyEvent =
          *static_cast<xcb_key_press_event_t*>(message);
        this->prevEvent = keyEvent;
        if (this->prevHandledEvent.response_type == XCB_KEY_RELEASE) {
            if (this->prevHandledEvent.time == keyEvent.time)
                return false;
        }
        this->activateShortcut(
          { keyEvent.detail,
            keyEvent.state & QHotkeyPrivateX11::validModsMask });
    } else if (genericEvent->response_type == XCB_KEY_RELEASE) {
        xcb_key_release_event_t keyEvent =
          *static_cast<xcb_key_release_event_t*>(message);
        this->prevEvent = keyEvent;
        QTimer::singleShot(50, [this, keyEvent] {
            if (this->prevEvent.time == keyEvent.time &&
                this->prevEvent.response_type == keyEvent.response_type &&
                this->prevEvent.detail == keyEvent.detail) {
                this->releaseShortcut(
                  { keyEvent.detail,
                    keyEvent.state & QHotkeyPrivateX11::validModsMask });
            }
        });
        this->prevHandledEvent = keyEvent;
    }

    return false;
}

QString QHotkeyPrivateX11::getX11String(Qt::Key keycode)
{
    switch (keycode) {

        case Qt::Key_MediaLast:
        case Qt::Key_MediaPrevious:
            return QStringLiteral("XF86AudioPrev");
        case Qt::Key_MediaNext:
            return QStringLiteral("XF86AudioNext");
        case Qt::Key_MediaPause:
        case Qt::Key_MediaPlay:
        case Qt::Key_MediaTogglePlayPause:
            return QStringLiteral("XF86AudioPlay");
        case Qt::Key_MediaRecord:
            return QStringLiteral("XF86AudioRecord");
        case Qt::Key_MediaStop:
            return QStringLiteral("XF86AudioStop");
        default:
            return QKeySequence(keycode).toString(QKeySequence::NativeText);
    }
}

quint32 QHotkeyPrivateX11::nativeKeycode(Qt::Key keycode, bool& ok)
{
    QString keyString = getX11String(keycode);

    KeySym keysym = XStringToKeysym(keyString.toLatin1().constData());
    if (keysym == NoSymbol) {
        // not found -> just use the key
        if (keycode <= 0xFFFF)
            keysym = keycode;
        else
            return 0;
    }

    if (QX11Info::isPlatformX11()) {
        auto res = XKeysymToKeycode(QX11Info::display(), keysym);
        if (res != 0)
            ok = true;
        return res;
    }
    return 0;
}

quint32 QHotkeyPrivateX11::nativeModifiers(Qt::KeyboardModifiers modifiers,
                                           bool& ok)
{
    quint32 nMods = 0;
    if (modifiers & Qt::ShiftModifier)
        nMods |= ShiftMask;
    if (modifiers & Qt::ControlModifier)
        nMods |= ControlMask;
    if (modifiers & Qt::AltModifier)
        nMods |= Mod1Mask;
    if (modifiers & Qt::MetaModifier)
        nMods |= Mod4Mask;
    ok = true;
    return nMods;
}

bool QHotkeyPrivateX11::registerShortcut(QHotkey::NativeShortcut shortcut)
{
    Display* display = QX11Info::display();
    if (!display || !QX11Info::isPlatformX11())
        return false;

    HotkeyErrorHandler errorHandler;
    for (quint32 specialMod : QHotkeyPrivateX11::specialModifiers) {
        XGrabKey(display,
                 shortcut.key,
                 shortcut.modifier | specialMod,
                 DefaultRootWindow(display),
                 True,
                 GrabModeAsync,
                 GrabModeAsync);
    }
    XSync(display, False);

    if (errorHandler.hasError) {
        error = errorHandler.errorString;
        this->unregisterShortcut(shortcut);
        return false;
    }
    return true;
}

bool QHotkeyPrivateX11::unregisterShortcut(QHotkey::NativeShortcut shortcut)
{
    Display* display = QX11Info::display();
    if (!display)
        return false;

    HotkeyErrorHandler errorHandler;
    for (quint32 specialMod : QHotkeyPrivateX11::specialModifiers) {
        XUngrabKey(display,
                   shortcut.key,
                   shortcut.modifier | specialMod,
                   XDefaultRootWindow(display));
    }
    XSync(display, False);

    if (HotkeyErrorHandler::hasError) {
        error = HotkeyErrorHandler::errorString;
        return false;
    }
    return true;
}

QString QHotkeyPrivateX11::formatX11Error(Display* display, int errorCode)
{
    char errStr[256];
    XGetErrorText(display, errorCode, errStr, 256);
    return QString::fromLatin1(errStr);
}

// ---------- QHotkeyPrivateX11::HotkeyErrorHandler implementation ----------

bool QHotkeyPrivateX11::HotkeyErrorHandler::hasError = false;
QString QHotkeyPrivateX11::HotkeyErrorHandler::errorString;

QHotkeyPrivateX11::HotkeyErrorHandler::HotkeyErrorHandler()
{
    prevHandler = XSetErrorHandler(&HotkeyErrorHandler::handleError);
}

QHotkeyPrivateX11::HotkeyErrorHandler::~HotkeyErrorHandler()
{
    XSetErrorHandler(prevHandler);
    hasError = false;
    errorString.clear();
}

int QHotkeyPrivateX11::HotkeyErrorHandler::handleError(Display* display,
                                                       XErrorEvent* error)
{
    switch (error->error_code) {
        case BadAccess:
        case BadValue:
        case BadWindow:
            if (error->request_code == 33 || // grab key
                error->request_code == 34) { // ungrab key
                hasError = true;
                errorString =
                  QHotkeyPrivateX11::formatX11Error(display, error->error_code);
                return 1;
            }
            Q_FALLTHROUGH();
            // fall through
        default:
            return 0;
    }
}