[effects] Show a notification when a screenshot got saved to file

Summary:
Inform the user about the path to where a screenshot got saved through a
notification. This is helpful on the one hand that the user sees that
the screenshot got saved and from a security perspective that the user
is informed when a screenshot is taken through the dbus interface. It
doesn't prevent non-authorized screenshot taking, but at least the user
is informed about it.

Reviewers: #kwin, #plasma, #vdg

Subscribers: plasma-devel, kwin

Tags: #kwin

Differential Revision: https://phabricator.kde.org/D3376

effects/CMakeLists.txt

@@ -20,6 +20,7 @@ set(kwin_effect_KDE_LIBS
     KF5::Plasma # screenedge effect
     KF5::IconThemes
     KF5::Service
+    KF5::Notifications # screenshot effect
 )
 
 set(kwin_effect_QT_LIBS

effects/screenshot/screenshot.cpp

@@ -30,6 +30,9 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>.
 #include <QMatrix4x4>
 #include <xcb/xcb_image.h>
 
+#include <KLocalizedString>
+#include <KNotification>
+
 namespace KWin
 {
 
@@ -240,6 +243,10 @@ QString ScreenShotEffect::saveTempImage(const QImage &img)
     }
     img.save(&temp);
     temp.close();
+    KNotification::event(KNotification::Notification,
+                        i18nc("Notification caption that a screenshot got saved to file", "Screenshot"),
+                        i18nc("Notification with path to screenshot file", "Screenshot saved to %1", temp.fileName()),
+                        QStringLiteral("spectacle"));
     return temp.fileName();
 }