Added x11 fallback (flameshot-org#4588)

Author: borgmanJeremy

flameshot.example.ini

@@ -107,6 +107,12 @@
 ;; (This option is not available on Windows)
 ;useJpgForClipboard=false
 ;
+;; [Deprecated] Use legacy Qt X11 screenshot method instead of freedesktop
+;; portal. Enable this if your WM has no xdg-desktop-portal (e.g. xmonad, i3).
+;; Only effective on X11; ignored on Wayland. (bool)
+;; (This option is only available on Linux)
+;useX11LegacyScreenshot=false
+;
 ;; Upload to imgur without confirmation (bool)
 ;uploadWithoutConfirmation=false
 ;

src/config/generalconf.cpp

@@ -56,6 +56,9 @@ GeneralConf::GeneralConf(QWidget* parent)
     initAntialiasingPinZoom();
     initUndoLimit();
     initInsecurePixelate();
+#if defined(Q_OS_LINUX)
+    initUseX11LegacyScreenshot();
+#endif
 #ifdef ENABLE_IMGUR
     initCopyAndCloseAfterUpload();
     initUploadWithoutConfirmation();
@@ -124,6 +127,9 @@ void GeneralConf::_updateComponents(bool allowEmptySavePath)
 #if defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
     m_showTray->setChecked(!config.disabledTrayIcon());
 #endif
+#if defined(Q_OS_LINUX)
+    m_useX11LegacyScreenshot->setChecked(config.useX11LegacyScreenshot());
+#endif
 }
 
 void GeneralConf::updateComponents()
@@ -909,3 +915,27 @@ void GeneralConf::setInsecurePixelate(bool checked)
 {
     ConfigHandler().setInsecurePixelate(checked);
 }
+
+#if defined(Q_OS_LINUX)
+void GeneralConf::initUseX11LegacyScreenshot()
+{
+    m_useX11LegacyScreenshot =
+      new QCheckBox(tr("Use legacy X11 screenshot method (deprecated)"), this);
+    m_useX11LegacyScreenshot->setToolTip(
+      tr("Bypass the freedesktop portal and use Qt's native X11 screen "
+         "capture. Enable this if your window manager lacks "
+         "xdg-desktop-portal (e.g. xmonad, i3). "
+         "Only effective on X11; ignored on Wayland."));
+    m_scrollAreaLayout->addWidget(m_useX11LegacyScreenshot);
+
+    connect(m_useX11LegacyScreenshot,
+            &QCheckBox::clicked,
+            this,
+            &GeneralConf::useX11LegacyScreenshotChanged);
+}
+
+void GeneralConf::useX11LegacyScreenshotChanged(bool checked)
+{
+    ConfigHandler().setUseX11LegacyScreenshot(checked);
+}
+#endif

src/config/generalconf.h

@@ -61,6 +61,9 @@ private slots:
     void setJpegQuality(int v);
     void setReverseArrow(bool checked);
     void setInsecurePixelate(bool checked);
+#if defined(Q_OS_LINUX)
+    void useX11LegacyScreenshotChanged(bool checked);
+#endif
 
 private:
     const QString chooseFolder(const QString& currentPath = "");
@@ -99,6 +102,9 @@ private slots:
     void initJpegQuality();
     void initReverseArrow();
     void initInsecurePixelate();
+#if defined(Q_OS_LINUX)
+    void initUseX11LegacyScreenshot();
+#endif
 
     void _updateComponents(bool allowEmptySavePath);
 
@@ -147,4 +153,7 @@ private slots:
     QSpinBox* m_jpegQuality;
     QCheckBox* m_reverseArrow;
     QCheckBox* m_insecurePixelate;
+#if defined(Q_OS_LINUX)
+    QCheckBox* m_useX11LegacyScreenshot;
+#endif
 };

src/utils/confighandler.cpp

@@ -140,6 +140,11 @@ static QMap<class QString, QSharedPointer<ValueHandler>>
     // Not visible on settings dialog
     OPTION("ignorePrntScrForcesSnipping" ,Bool               ( false         )),
 #endif
+#if defined(Q_OS_LINUX)
+    // Bypass freedesktop portal and use Qt's native X11
+    // screenshot method. Intended for WMs without xdg-desktop-portal.
+    OPTION("useX11LegacyScreenshot"      ,Bool               ( false         )),
+#endif
 };
 
 static QMap<QString, QSharedPointer<KeySequence>> recognizedShortcuts = {

src/utils/confighandler.h

@@ -145,6 +145,11 @@ class ConfigHandler : public QObject
                          setIgnorePrntScrForcesSnipping,
                          bool)
 #endif
+#if defined(Q_OS_LINUX)
+    CONFIG_GETTER_SETTER(useX11LegacyScreenshot,
+                         setUseX11LegacyScreenshot,
+                         bool)
+#endif
 
     // SPECIAL CASES
     bool startupLaunch();

src/utils/screengrabber.cpp

@@ -205,13 +205,25 @@ QPixmap ScreenGrabber::grabEntireDesktop(bool& ok, int preSelectedMonitor)
     screenshot.setDevicePixelRatio(currentScreen->devicePixelRatio());
     return screenshot;
 
-#elif defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
-    freeDesktopPortal(ok, screenshot);
-    if (!ok) {
-        AbstractLogger::error() << tr("Unable to capture screen");
-        return QPixmap();
+#elif defined(Q_OS_LINUX)
+    if (!m_info.waylandDetected() && ConfigHandler().useX11LegacyScreenshot()) {
+        qWarning() << "Using deprecated legacy X11 screenshot method. "
+                      "Consider installing xdg-desktop-portal for your "
+                      "desktop. Future versions of Flameshot may remove the "
+                      "option to use the legacy method.";
+        screenshot = x11LegacyScreenshot();
+        ok = !screenshot.isNull();
+        if (!ok) {
+            AbstractLogger::error() << tr("Unable to capture screen");
+            return QPixmap();
+        }
+    } else {
+        freeDesktopPortal(ok, screenshot);
+        if (!ok) {
+            AbstractLogger::error() << tr("Unable to capture screen");
+            return QPixmap();
+        }
     }
-
 #elif defined(Q_OS_WIN)
     screenshot = windowsScreenshot(wid);
 #endif
@@ -256,10 +268,21 @@ QPixmap ScreenGrabber::grabFullDesktop(bool& ok)
         painter.drawPixmap(offset, p);
     }
     painter.end();
-#elif defined(Q_OS_LINUX) || defined(Q_OS_UNIX)
-    freeDesktopPortal(ok, screenshot);
-    if (!ok) {
-        AbstractLogger::error() << tr("Unable to capture screen");
+#elif defined(Q_OS_LINUX)
+    if (!m_info.waylandDetected() && ConfigHandler().useX11LegacyScreenshot()) {
+        qWarning() << "Using deprecated legacy X11 screenshot method. "
+                      "Consider installing xdg-desktop-portal for your "
+                      "desktop.";
+        screenshot = x11LegacyScreenshot();
+        ok = !screenshot.isNull();
+        if (!ok) {
+            AbstractLogger::error() << tr("Unable to capture screen");
+        }
+    } else {
+        freeDesktopPortal(ok, screenshot);
+        if (!ok) {
+            AbstractLogger::error() << tr("Unable to capture screen");
+        }
     }
 #elif defined(Q_OS_WIN)
     screenshot = windowsScreenshot(0);
@@ -629,3 +652,44 @@ QPixmap ScreenGrabber::windowsScreenshot(int wid)
 
     return desktop;
 }
+
+QPixmap ScreenGrabber::x11LegacyScreenshot()
+{
+    const QList<QScreen*> screens = QGuiApplication::screens();
+
+    if (screens.isEmpty()) {
+        return QPixmap();
+    }
+
+    if (screens.size() == 1) {
+        QScreen* screen = screens.first();
+        QPixmap p = screen->grabWindow(0);
+        p.setDevicePixelRatio(screen->devicePixelRatio());
+        return p;
+    }
+
+    // Composite all screens using logical geometry.
+    // On i3 (tested) DPR is uniform so we don't need the per-screen
+    // physical pixel math that the Windows backend does. Not sure if this is
+    // true for other DE's like xmonad.
+    QRect totalGeom;
+    for (QScreen* s : screens) {
+        totalGeom = totalGeom.united(s->geometry());
+    }
+
+    qreal dpr = screens.first()->devicePixelRatio();
+    QPixmap desktop(qRound(totalGeom.width() * dpr),
+                    qRound(totalGeom.height() * dpr));
+    desktop.setDevicePixelRatio(dpr);
+    desktop.fill(Qt::black);
+
+    QPainter painter(&desktop);
+    for (QScreen* s : screens) {
+        QPixmap p = s->grabWindow(0);
+        QPoint offset = s->geometry().topLeft() - totalGeom.topLeft();
+        painter.drawPixmap(offset, p);
+    }
+    painter.end();
+
+    return desktop;
+}

src/utils/screengrabber.h

@@ -38,6 +38,7 @@ class ScreenGrabber : public QObject
     QWidget* createMonitorPreviews(const QPixmap& fullScreenshot);
     QPixmap cropToMonitor(const QPixmap& fullScreenshot, int monitorIndex);
     QPixmap windowsScreenshot(int wid);
+    QPixmap x11LegacyScreenshot();
 
     DesktopInfo m_info;
     QPixmap Screenshot;