Auto enable snapping when using the trim/extent tool

src/app/qgsmaptooltrimextendfeature.cpp

@@ -387,8 +387,25 @@ void QgsMapToolTrimExtendFeature::reset()
   mVlayer = nullptr;
   mLimitLayer = nullptr;
 }
+void QgsMapToolTrimExtendFeature::activate()
+{
+  QgsMapTool::activate();
+
+  // Save the original snapping configuration
+  mOriginalSnappingConfig = mCanvas->snappingUtils()->config();
+
+  // Enable Snapping & Snapping on Segment
+  QgsSnappingConfig snappingConfig = mOriginalSnappingConfig;
+  snappingConfig.setEnabled( true );
+  Qgis::SnappingTypes flags = snappingConfig.typeFlag();
+  flags |= Qgis::SnappingType::Segment;
+  snappingConfig.setTypeFlag( flags );
+  mCanvas->snappingUtils()->setConfig( snappingConfig );
+}
 void QgsMapToolTrimExtendFeature::deactivate()
 {
   reset();
+  // Restore the original snapping configuration
+  mCanvas->snappingUtils()->setConfig( mOriginalSnappingConfig );
   QgsMapTool::deactivate();
 }

src/app/qgsmaptooltrimextendfeature.h

@@ -19,6 +19,7 @@
 #include "qgsmaptooledit.h"
 #include "qgis_app.h"
 #include "qgsrubberband.h"
+#include "qgssnappingconfig.h"
 
 class APP_EXPORT QgsMapToolTrimExtendFeature : public QgsMapToolEdit
 {
@@ -35,6 +36,9 @@ class APP_EXPORT QgsMapToolTrimExtendFeature : public QgsMapToolEdit
 
     void keyPressEvent( QKeyEvent *e ) override;
 
+    //! called when map tool is being activated
+    void activate() override;
+
     //! called when map tool is being deactivated
     void deactivate() override;
 
@@ -81,6 +85,9 @@ class APP_EXPORT QgsMapToolTrimExtendFeature : public QgsMapToolEdit
     };
     //! The first step (0): choose the limit. The second step (1): choose the segment to trim/extend
     Step mStep = StepLimit;
+
+    //! Snapping config that will be restored on deactivation
+    QgsSnappingConfig mOriginalSnappingConfig;
 };
 
 #endif // QGSMAPTOOLTRIMEXTENDFEATURE_H