New utility class QgsTemporaryCursorRestoreOverride

This class temporarily removes ALL cursor overrides for the
QApplication for the lifetime of the object, and restores them
(in the same order) upon object destruction.

Author: nyalldawson

src/gui/qgsguiutils.cpp

@@ -272,3 +272,31 @@ void QgsTemporaryCursorOverride::release()
   mHasOverride = false;
   QApplication::restoreOverrideCursor();
 }
+
+
+//
+// QgsTemporaryCursorRestoreOverride
+//
+
+QgsTemporaryCursorRestoreOverride::QgsTemporaryCursorRestoreOverride()
+{
+  while ( QApplication::overrideCursor() )
+  {
+    mCursors.emplace_back( QCursor( *QApplication::overrideCursor() ) );
+    QApplication::restoreOverrideCursor();
+  }
+}
+
+QgsTemporaryCursorRestoreOverride::~QgsTemporaryCursorRestoreOverride()
+{
+  restore();
+}
+
+void QgsTemporaryCursorRestoreOverride::restore()
+{
+  for ( auto it = mCursors.rbegin(); it != mCursors.rend(); ++it )
+  {
+    QApplication::setOverrideCursor( *it );
+  }
+  mCursors.clear();
+}

src/gui/qgsguiutils.h

@@ -206,4 +206,35 @@ class GUI_EXPORT QgsTemporaryCursorOverride
 
 };
 
+/**
+ * Temporarily removes all cursor overrides for the QApplication for the lifetime of the object.
+ *
+ * When the object is deleted, all stacked cursor overrides are restored.
+ *
+ * \ingroup gui
+ * \since QGIS 3.8
+ */
+class GUI_EXPORT QgsTemporaryCursorRestoreOverride
+{
+  public:
+
+    /**
+     * Constructor for QgsTemporaryCursorRestoreOverride. Removes all application override
+     * cursors.
+     */
+    QgsTemporaryCursorRestoreOverride();
+
+    ~QgsTemporaryCursorRestoreOverride();
+
+    /**
+     * Restores the cursor override early (i.e. before this object is destroyed).
+     */
+    void restore();
+
+  private:
+
+    std::vector< QCursor > mCursors;
+
+};
+
 #endif // QGSGUIUTILS_H