Allow removing last point while measuring via del/backspace keys (fix #10176)

src/app/qgsmeasuredialog.cpp

@@ -89,6 +89,7 @@ void QgsMeasureDialog::restart()
 
 void QgsMeasureDialog::mouseMove( QgsPoint &point )
 {
+  mLastMousePoint = point;
   // show current distance/area while moving the point
   // by creating a temporary copy of point array
   // and adding moving point at the end
@@ -145,6 +146,43 @@ void QgsMeasureDialog::addPoint( QgsPoint &p )
   QgsDebugMsg( "Exiting" );
 }
 
+void QgsMeasureDialog::removeLastPoint()
+{
+  int numPoints = mTool->points().size();
+  if ( mMeasureArea )
+  {
+    if ( numPoints > 1 )
+    {
+      QList<QgsPoint> tmpPoints = mTool->points();
+      tmpPoints.append( mLastMousePoint );
+      double area = mDa.measurePolygon( tmpPoints );
+      editTotal->setText( formatArea( area ) );
+    }
+    else
+    {
+      editTotal->setText( formatArea( 0 ) );
+    }
+  }
+  else if ( !mMeasureArea && numPoints >= 1 )
+  {
+    //remove final row
+    delete mTable->takeTopLevelItem( mTable->topLevelItemCount() - 1 );
+
+    QgsPoint p1( mTool->points().last() );
+    double d = mDa.measureLine( p1, mLastMousePoint );
+
+    mTotal = mDa.measureLine( mTool->points() );
+    editTotal->setText( formatDistance( mTotal + d ) );
+
+    QGis::UnitType displayUnits;
+    // Meters or feet?
+    convertMeasurement( d, displayUnits, false );
+
+    QTreeWidgetItem *item = mTable->topLevelItem( mTable->topLevelItemCount() - 1 );
+    item->setText( 0, QLocale::system().toString( d, 'f', mDecimalPlaces ) );
+  }
+}
+
 void QgsMeasureDialog::on_buttonBox_rejected( void )
 {
   restart();

src/app/qgsmeasuredialog.h

@@ -47,6 +47,9 @@ class APP_EXPORT QgsMeasureDialog : public QDialog, private Ui::QgsMeasureBase
     //! Mose move
     void mouseMove( QgsPoint &point );
 
+    //! Remove last point
+    void removeLastPoint();
+
   public slots:
     //! Reject
     void on_buttonBox_rejected( void );
@@ -96,6 +99,8 @@ class APP_EXPORT QgsMeasureDialog : public QDialog, private Ui::QgsMeasureBase
 
     //! pointer to measure tool which owns this dialog
     QgsMeasureTool* mTool;
+
+    QgsPoint mLastMousePoint;
 };
 
 #endif

src/app/qgsmeasuretool.cpp

@@ -167,12 +167,54 @@ void QgsMeasureTool::canvasReleaseEvent( QMouseEvent * e )
     mDone = false;
   }
 
-  // we allways add the clicked point to the measuring feature
+  // we always add the clicked point to the measuring feature
   addPoint( point );
   mDialog->show();
 
 }
 
+void QgsMeasureTool::undo()
+{
+  if ( mRubberBand )
+  {
+    if ( mPoints.size() < 1 )
+    {
+      return;
+    }
+
+    if ( mPoints.size() == 1 )
+    {
+      //removing first point, so restart everything
+      restart();
+      mDialog->restart();
+    }
+    else
+    {
+      //remove second last point from line band, and last point from points band
+      mRubberBand->removePoint( -2, true );
+      mRubberBandPoints->removePoint( -1, true );
+      mPoints.removeLast();
+
+      mDialog->removeLastPoint();
+    }
+
+  }
+}
+
+void QgsMeasureTool::keyPressEvent( QKeyEvent* e )
+{
+  if (( e->key() == Qt::Key_Backspace || e->key() == Qt::Key_Delete ) )
+  {
+    if ( !mDone )
+    {
+      undo();
+    }
+
+    // Override default shortcut management in MapCanvas
+    e->ignore();
+  }
+}
+
 
 void QgsMeasureTool::addPoint( QgsPoint &point )
 {

src/app/qgsmeasuretool.h

@@ -70,6 +70,8 @@ class APP_EXPORT QgsMeasureTool : public QgsMapTool
     //! called when map tool is being deactivated
     virtual void deactivate();
 
+    virtual void keyPressEvent( QKeyEvent* e );
+
   public slots:
     //! updates the projections we're using
     void updateSettings();
@@ -102,6 +104,8 @@ class APP_EXPORT QgsMeasureTool : public QgsMapTool
     //@param p (pixel) coordinate
     QgsPoint snapPoint( const QPoint& p );
 
+    /**Removes the last vertex from mRubberBand*/
+    void undo();
 };
 
 #endif