[win] Show task manager progress in windows task bar

Hooks the task manager progress reports up to a Windows taskbar button
progress bar. This lets you easily see when a background task has
finished running!

Author: nyalldawson

src/app/CMakeLists.txt

@@ -479,6 +479,8 @@ QT5_WRAP_CPP(QGIS_APP_MOC_SRCS ${QGIS_APP_MOC_HDRS})
 SET (QGIS_APPMAIN_SRCS main.cpp)
 
 IF (WIN32)
+  FIND_PACKAGE(Qt5WinExtras)
+
   IF (MSVC)
     SET (QGIS_APPMAIN_SRCS ${QGIS_APPMAIN_SRCS} ${CMAKE_CURRENT_SOURCE_DIR}/qgis_win32.rc)
   ELSE(MSVC)
@@ -640,7 +642,7 @@ ENDIF (ANDROID)
 IF(WIN32)
   ADD_DEFINITIONS(-DQWT_DLL)
   TARGET_LINK_LIBRARIES(${QGIS_APP_NAME} DbgHelp)
-  TARGET_LINK_LIBRARIES(qgis_app DbgHelp)
+  TARGET_LINK_LIBRARIES(qgis_app DbgHelp Qt5::WinExtras )
 ENDIF(WIN32)
 
 IF (APPLE)

src/app/qgisapp.cpp

@@ -74,11 +74,17 @@
 #include <qgsapplication.h>
 #include <qgscomposition.h>
 #include <qgslayerstylingwidget.h>
+#include "qgstaskmanager.h"
 
 #include <QNetworkReply>
 #include <QNetworkProxy>
 #include <QAuthenticator>
 
+#ifdef Q_OS_WIN
+#include <QWinTaskbarButton>
+#include <QWinTaskbarProgress>
+#endif
+
 //
 // Mac OS X Includes
 // Must include before GEOS 3 due to unqualified use of 'Point'
@@ -1101,6 +1107,20 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
   mActionTouch = nullptr;
 #endif
 
+
+#ifdef Q_OS_WIN
+  QWinTaskbarButton* taskButton = new QWinTaskbarButton( this );
+  taskButton->setWindow( windowHandle() );
+
+  QWinTaskbarProgress* taskProgress = taskButton->progress();
+  taskProgress->setVisible( false );
+  connect( QgsApplication::taskManager(), &QgsTaskManager::taskAdded, taskProgress, [taskProgress] { taskProgress->setMaximum( 0 ); taskProgress->show(); }
+         );
+  connect( QgsApplication::taskManager(), &QgsTaskManager::finalTaskProgressChanged, taskProgress, [taskProgress]( double val ) { taskProgress->setMaximum( 100 );taskProgress->show(); taskProgress->setValue( val ); }
+         );
+  connect( QgsApplication::taskManager(), &QgsTaskManager::allTasksFinished, taskProgress, &QWinTaskbarProgress::hide );
+#endif
+
   // supposedly all actions have been added, now register them to the shortcut manager
   QgsShortcutsManager::instance()->registerAllChildren( this );