Add QgsTemporaryCursorOverride class

Temporarily sets a QApplication override cursor for the lifetime
of the object, then removes it

Makes it easier to ensure that the override is always removed
regardless of the exit path taken.

src/app/dwg/qgsdwgimportdialog.cpp

@@ -44,21 +44,7 @@
 #include "qgslogger.h"
 #include "qgsproperty.h"
 #include "qgslayertree.h"
-
-
-struct CursorOverride
-{
-  CursorOverride()
-  {
-    QApplication::setOverrideCursor( Qt::BusyCursor );
-  }
-
-  ~CursorOverride()
-  {
-    QApplication::restoreOverrideCursor();
-  }
-};
-
+#include "qgsguiutils.h"
 
 QgsDwgImportDialog::QgsDwgImportDialog( QWidget *parent, Qt::WindowFlags f )
   : QDialog( parent, f )
@@ -163,7 +149,7 @@ void QgsDwgImportDialog::pbLoadDatabase_clicked()
   if ( !QFileInfo::exists( leDatabase->text() ) )
     return;
 
-  CursorOverride waitCursor;
+  QgsTemporaryCursorOverride waitCursor( Qt::BusyCursor );
 
   bool lblVisible = false;
 
@@ -261,7 +247,7 @@ void QgsDwgImportDialog::pbBrowseDrawing_clicked()
 
 void QgsDwgImportDialog::pbImportDrawing_clicked()
 {
-  CursorOverride waitCursor;
+  QgsTemporaryCursorOverride waitCursor( Qt::BusyCursor );
 
   QgsDwgImporter importer( leDatabase->text(), mCrsSelector->crs() );
 
@@ -457,7 +443,7 @@ void QgsDwgImportDialog::pbDeselectAll_clicked()
 
 void QgsDwgImportDialog::buttonBox_accepted()
 {
-  CursorOverride waitCursor;
+  QgsTemporaryCursorOverride waitCursor( Qt::BusyCursor );
 
   QMap<QString, bool> layers;
   bool allLayers = true;

src/gui/qgsguiutils.cpp

@@ -21,6 +21,7 @@
 
 #include <QImageWriter>
 #include <QFontDialog>
+#include <QApplication>
 
 
 namespace QgsGuiUtils
@@ -235,3 +236,17 @@ namespace QgsGuiUtils
     return key;
   }
 }
+
+//
+// QgsTemporaryCursorOverride
+//
+
+QgsTemporaryCursorOverride::QgsTemporaryCursorOverride( const QCursor &cursor )
+{
+  QApplication::setOverrideCursor( cursor );
+}
+
+QgsTemporaryCursorOverride::~QgsTemporaryCursorOverride()
+{
+  QApplication::restoreOverrideCursor();
+}

src/gui/qgsguiutils.h

@@ -164,4 +164,26 @@ namespace QgsGuiUtils
   QString createWidgetKey( QWidget *widget, const QString &keyName = QString() );
 }
 
+/**
+ * Temporarily sets a cursor override for the QApplication for the lifetime of the object.
+ *
+ * When the object is deleted, the cursor override is removed.
+ *
+ * \ingroup gui
+ * \since QGIS 3.2
+ */
+class GUI_EXPORT QgsTemporaryCursorOverride
+{
+  public:
+
+    /**
+     * Constructor for QgsTemporaryCursorOverride. Sets the application override
+     * cursor to \a cursor.
+     */
+    QgsTemporaryCursorOverride( const QCursor &cursor );
+
+    ~QgsTemporaryCursorOverride();
+
+};
+
 #endif // QGSGUIUTILS_H