Merge pull request #7711 from m-kuhn/mapToolSnapToGrid

Snap to grid for maptools [FEATURE]

python/gui/auto_generated/qgsmapmouseevent.sip.in

@@ -117,6 +117,15 @@ The unsnapped, real mouse cursor position in pixel coordinates.
 Alias to pos()
 
 :return: Mouse position in pixel coordinates
+%End
+
+    void snapToGrid( double precision, const QgsCoordinateReferenceSystem &crs );
+%Docstring
+Snaps the mapPoint to a grid with the given ``precision``.
+The snapping will be done in the specified ``crs``. If this crs is
+different from the mapCanvas crs, it will be reprojected on the fly.
+
+.. versionadded:: 3.4
 %End
 
 };

python/gui/auto_generated/qgsmaptooladvanceddigitizing.sip.in

@@ -149,6 +149,22 @@ canvasMoveEvent is triggered and it's not hidden by the cad's
 construction mode.
 
 :param e: Mouse events prepared by the cad system
+%End
+
+    bool snapToLayerGridEnabled() const;
+%Docstring
+Enables or disables snap to grid of mouse events.
+The snapping will occur in the layer's CRS.
+
+.. versionadded:: 3.4
+%End
+
+    void setSnapToLayerGridEnabled( bool snapToLayerGridEnabled );
+%Docstring
+Enables or disables snap to grid of mouse events.
+The snapping will occur in the layer's CRS.
+
+.. versionadded:: 3.4
 %End
 
 };

python/gui/auto_generated/qgssnaptogridcanvasitem.sip.in

@@ -0,0 +1,92 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgssnaptogridcanvasitem.h                                    *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+
+class QgsSnapToGridCanvasItem : QObject, QgsMapCanvasItem
+{
+%Docstring
+
+Shows a grid on the map canvas given a spatial resolution.
+
+.. versionadded:: 3.4
+%End
+
+%TypeHeaderCode
+#include "qgssnaptogridcanvasitem.h"
+%End
+  public:
+
+    QgsSnapToGridCanvasItem( QgsMapCanvas *mapCanvas /TransferThis/ );
+%Docstring
+Will automatically be added to the ``mapCanvas``.
+%End
+
+    virtual void paint( QPainter *painter );
+
+
+    QgsPointXY point() const;
+%Docstring
+A point that will be highlighted on the map canvas.
+The point needs to be in map coordinates. The closest point on the
+grid will be highlighted.
+%End
+
+    void setPoint( const QgsPointXY &point );
+%Docstring
+A point that will be highlighted on the map canvas.
+The point needs to be in map coordinates. The closest point on the
+grid will be highlighted.
+%End
+
+    double precision() const;
+%Docstring
+The resolution of the grid in map units.
+If a crs has been specified it will be in CRS units.
+%End
+
+    void setPrecision( double precision );
+%Docstring
+The resolution of the grid in map units.
+If a crs has been specified it will be in CRS units.
+%End
+
+    QgsCoordinateReferenceSystem crs() const;
+%Docstring
+The CRS in which the grid should be calculated.
+By default will be an invalid QgsCoordinateReferenceSystem and
+as such equal to the CRS of the map canvas.
+%End
+
+    void setCrs( const QgsCoordinateReferenceSystem &crs );
+%Docstring
+The CRS in which the grid should be calculated.
+By default will be an invalid QgsCoordinateReferenceSystem and
+as such equal to the CRS of the map canvas.
+%End
+
+    bool enabled() const;
+%Docstring
+Enable this item. It will be hidden if disabled.
+%End
+
+    void setEnabled( bool enabled );
+%Docstring
+Enable this item. It will be hidden if disabled.
+%End
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/gui/qgssnaptogridcanvasitem.h                                    *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

python/gui/gui_auto.sip

@@ -193,6 +193,7 @@
 %Include auto_generated/qgssearchquerybuilder.sip
 %Include auto_generated/qgsshortcutsmanager.sip
 %Include auto_generated/qgsslider.sip
+%Include auto_generated/qgssnaptogridcanvasitem.sip
 %Include auto_generated/qgsstatusbar.sip
 %Include auto_generated/qgssublayersdialog.sip
 %Include auto_generated/qgssubstitutionlistwidget.sip

src/app/qgsmaptoolsplitfeatures.cpp

@@ -27,6 +27,7 @@ QgsMapToolSplitFeatures::QgsMapToolSplitFeatures( QgsMapCanvas *canvas )
   : QgsMapToolCapture( canvas, QgisApp::instance()->cadDockWidget(), QgsMapToolCapture::CaptureLine )
 {
   mToolName = tr( "Split features" );
+  setSnapToLayerGridEnabled( false );
 }
 
 void QgsMapToolSplitFeatures::cadCanvasReleaseEvent( QgsMapMouseEvent *e )

src/app/qgsmaptoolsplitparts.cpp

@@ -27,6 +27,7 @@ QgsMapToolSplitParts::QgsMapToolSplitParts( QgsMapCanvas *canvas )
   : QgsMapToolCapture( canvas, QgisApp::instance()->cadDockWidget(), QgsMapToolCapture::CaptureLine )
 {
   mToolName = tr( "Split parts" );
+  setSnapToLayerGridEnabled( false );
 }
 
 void QgsMapToolSplitParts::cadCanvasReleaseEvent( QgsMapMouseEvent *e )

src/core/qgsvectorlayereditutils.cpp

@@ -47,7 +47,7 @@ bool QgsVectorLayerEditUtils::insertVertex( double x, double y, QgsFeatureId atF
 
   geometry.insertVertex( x, y, beforeVertex );
 
-  mLayer->editBuffer()->changeGeometry( atFeatureId, geometry );
+  mLayer->changeGeometry( atFeatureId, geometry );
   return true;
 }
 
@@ -64,7 +64,7 @@ bool QgsVectorLayerEditUtils::insertVertex( const QgsPoint &point, QgsFeatureId
 
   geometry.insertVertex( point, beforeVertex );
 
-  mLayer->editBuffer()->changeGeometry( atFeatureId, geometry );
+  mLayer->changeGeometry( atFeatureId, geometry );
   return true;
 }
 
@@ -87,7 +87,7 @@ bool QgsVectorLayerEditUtils::moveVertex( const QgsPoint &p, QgsFeatureId atFeat
 
   geometry.moveVertex( p, atVertex );
 
-  mLayer->editBuffer()->changeGeometry( atFeatureId, geometry );
+  mLayer->changeGeometry( atFeatureId, geometry );
   return true;
 }
 
@@ -112,7 +112,7 @@ QgsVectorLayer::EditResult QgsVectorLayerEditUtils::deleteVertex( QgsFeatureId f
     geometry.set( nullptr );
   }
 
-  mLayer->editBuffer()->changeGeometry( featureId, geometry );
+  mLayer->changeGeometry( featureId, geometry );
   return !geometry.isNull() ? QgsVectorLayer::Success : QgsVectorLayer::EmptyGeometry;
 }
 
@@ -159,7 +159,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::addRing( QgsCurve *ring, c
     if ( addRingReturnCode == 0 )
       if ( addRingReturnCode == QgsGeometry::Success )
       {
-        mLayer->editBuffer()->changeGeometry( f.id(), g );
+        mLayer->changeGeometry( f.id(), g );
         if ( modifiedFeatureId )
           *modifiedFeatureId = f.id();
 
@@ -212,7 +212,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::addPart( const QgsPointSeq
       //convert back to single part if required by layer
       geometry.convertToSingleType();
     }
-    mLayer->editBuffer()->changeGeometry( featureId, geometry );
+    mLayer->changeGeometry( featureId, geometry );
   }
   return errorCode;
 }
@@ -247,7 +247,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::addPart( QgsCurve *ring, Q
       //convert back to single part if required by layer
       geometry.convertToSingleType();
     }
-    mLayer->editBuffer()->changeGeometry( featureId, geometry );
+    mLayer->changeGeometry( featureId, geometry );
   }
   return errorCode;
 }
@@ -267,7 +267,7 @@ int QgsVectorLayerEditUtils::translateFeature( QgsFeatureId featureId, double dx
   int errorCode = geometry.translate( dx, dy );
   if ( errorCode == 0 )
   {
-    mLayer->editBuffer()->changeGeometry( featureId, geometry );
+    mLayer->changeGeometry( featureId, geometry );
   }
   return errorCode;
 }
@@ -348,13 +348,13 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::splitFeatures( const QVect
     if ( splitFunctionReturn == QgsGeometry::OperationResult::Success )
     {
       //change this geometry
-      mLayer->editBuffer()->changeGeometry( feat.id(), featureGeom );
+      mLayer->changeGeometry( feat.id(), featureGeom );
 
       //insert new features
       for ( int i = 0; i < newGeometries.size(); ++i )
       {
         QgsFeature f = QgsVectorLayerUtils::createFeature( mLayer, newGeometries.at( i ), feat.attributes().toMap() );
-        mLayer->editBuffer()->addFeature( f );
+        mLayer->addFeature( f );
       }
 
       if ( topologicalEditing )
@@ -470,7 +470,7 @@ QgsGeometry::OperationResult QgsVectorLayerEditUtils::splitParts( const QVector<
 
       if ( !addPartRet )
       {
-        mLayer->editBuffer()->changeGeometry( feat.id(), featureGeom );
+        mLayer->changeGeometry( feat.id(), featureGeom );
       }
 
       if ( topologicalEditing )

src/gui/CMakeLists.txt

@@ -358,6 +358,7 @@ SET(QGIS_GUI_SRCS
   qgsshortcutsmanager.cpp
   qgsslider.cpp
   qgssnapindicator.cpp
+  qgssnaptogridcanvasitem.cpp
   qgssublayersdialog.cpp
   qgssubstitutionlistwidget.cpp
   qgssqlcomposerdialog.cpp
@@ -527,6 +528,7 @@ SET(QGIS_GUI_MOC_HDRS
   qgssearchquerybuilder.h
   qgsshortcutsmanager.h
   qgsslider.h
+  qgssnaptogridcanvasitem.h
   qgssqlcomposerdialog.h
   qgsstatusbar.h
   qgssublayersdialog.h

src/gui/qgsmapmouseevent.cpp

@@ -71,6 +71,30 @@ void QgsMapMouseEvent::setMapPoint( const QgsPointXY &point )
   mPixelPoint = mapToPixelCoordinates( point );
 }
 
+void QgsMapMouseEvent::snapToGrid( double precision, const QgsCoordinateReferenceSystem &crs )
+{
+  if ( precision <= 0 )
+    return;
+
+  try
+  {
+    QgsCoordinateTransform ct( mMapCanvas->mapSettings().destinationCrs(), crs, mMapCanvas->mapSettings().transformContext() );
+
+    QgsPointXY pt = ct.transform( mMapPoint );
+
+    pt.setX( std::round( pt.x() / precision ) * precision );
+    pt.setY( std::round( pt.y() / precision ) * precision );
+
+    pt = ct.transform( pt, QgsCoordinateTransform::ReverseTransform );
+
+    setMapPoint( pt );
+  }
+  catch ( QgsCsException &e )
+  {
+    Q_UNUSED( e )
+  }
+}
+
 QPoint QgsMapMouseEvent::mapToPixelCoordinates( const QgsPointXY &point )
 {
   double x = point.x(), y = point.y();

src/gui/qgsmapmouseevent.h

@@ -126,6 +126,15 @@ class GUI_EXPORT QgsMapMouseEvent : public QMouseEvent
      */
     QPoint originalPixelPoint() const { return pos(); }
 
+    /**
+     * Snaps the mapPoint to a grid with the given \a precision.
+     * The snapping will be done in the specified \a crs. If this crs is
+     * different from the mapCanvas crs, it will be reprojected on the fly.
+     *
+     * \since QGIS 3.4
+     */
+    void snapToGrid( double precision, const QgsCoordinateReferenceSystem &crs );
+
   private:
 
     QPoint mapToPixelCoordinates( const QgsPointXY &point );