Add actions to switch grid display/snapping on/off

python/core/layout/qgslayoutcontext.sip

@@ -128,9 +128,16 @@ class QgsLayoutContext
     bool gridVisible() const;
 %Docstring
  Returns true if the page grid should be drawn.
+.. seealso:: setGridVisible()
  :rtype: bool
 %End
 
+    void setGridVisible( bool visible );
+%Docstring
+ Sets whether the page grid should be ``visible``.
+.. seealso:: gridVisible()
+%End
+
 };
 
 

python/core/layout/qgslayoutitem.sip

@@ -228,6 +228,11 @@ class QgsLayoutItem : QgsLayoutObject, QGraphicsRectItem
  recalculation of its position and size.
 %End
 
+    virtual void redraw();
+%Docstring
+ Triggers a redraw (update) of the item.
+%End
+
     virtual void refreshDataDefinedProperty( const QgsLayoutObject::DataDefinedProperty property = QgsLayoutObject::AllProperties );
 %Docstring
  Refreshes a data defined ``property`` for the item by reevaluating the property's value

python/core/layout/qgslayoutitempage.sip

@@ -80,6 +80,11 @@ class QgsLayoutItemPage : QgsLayoutItem
     virtual void attemptResize( const QgsLayoutSize &size );
 
 
+  public slots:
+
+    virtual void redraw();
+
+
   protected:
 
     virtual void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = 0 );

python/core/layout/qgslayoutpagecollection.sip

@@ -188,6 +188,13 @@ class QgsLayoutPageCollection : QObject
  :rtype: float
 %End
 
+  public slots:
+
+    void redraw();
+%Docstring
+ Triggers a redraw for all pages.
+%End
+
   signals:
 
     void changed();

src/app/layout/qgslayoutdesignerdialog.cpp

@@ -122,6 +122,9 @@ QgsLayoutDesignerDialog::QgsLayoutDesignerDialog( QWidget *parent, Qt::WindowFla
   mActionShowRulers->blockSignals( false );
   connect( mActionShowRulers, &QAction::triggered, this, &QgsLayoutDesignerDialog::showRulers );
 
+  connect( mActionShowGrid, &QAction::triggered, this, &QgsLayoutDesignerDialog::showGrid );
+  connect( mActionSnapGrid, &QAction::triggered, this, &QgsLayoutDesignerDialog::snapToGrid );
+
   mView = new QgsLayoutView();
   //mView->setMapCanvas( mQgis->mapCanvas() );
   mView->setContentsMargins( 0, 0, 0, 0 );
@@ -337,6 +340,17 @@ void QgsLayoutDesignerDialog::showRulers( bool visible )
   settings.setValue( QStringLiteral( "LayoutDesigner/showRulers" ), visible );
 }
 
+void QgsLayoutDesignerDialog::showGrid( bool visible )
+{
+  mLayout->context().setGridVisible( visible );
+  mLayout->pageCollection()->redraw();
+}
+
+void QgsLayoutDesignerDialog::snapToGrid( bool enabled )
+{
+  mLayout->snapper().setSnapToGrid( enabled );
+}
+
 void QgsLayoutDesignerDialog::closeEvent( QCloseEvent * )
 {
   emit aboutToClose();

src/app/layout/qgslayoutdesignerdialog.h

@@ -115,6 +115,16 @@ class QgsLayoutDesignerDialog: public QMainWindow, private Ui::QgsLayoutDesigner
      */
     void showRulers( bool visible );
 
+    /**
+     * Toggles whether the page grid should be \a visible.
+     */
+    void showGrid( bool visible );
+
+    /**
+     * Toggles whether snapping to the page grid is \a enabled.
+     */
+    void snapToGrid( bool enabled );
+
   signals:
 
     /**

src/core/layout/qgslayoutcontext.cpp

@@ -80,5 +80,10 @@ double QgsLayoutContext::dpi() const
 
 bool QgsLayoutContext::gridVisible() const
 {
-  return true;
+  return mGridVisible;
+}
+
+void QgsLayoutContext::setGridVisible( bool visible )
+{
+  mGridVisible = visible;
 }

src/core/layout/qgslayoutcontext.h

@@ -141,9 +141,16 @@ class CORE_EXPORT QgsLayoutContext
 
     /**
      * Returns true if the page grid should be drawn.
+     * \see setGridVisible()
      */
     bool gridVisible() const;
 
+    /**
+     * Sets whether the page grid should be \a visible.
+     * \see gridVisible()
+     */
+    void setGridVisible( bool visible );
+
   private:
 
     Flags mFlags = 0;
@@ -153,6 +160,8 @@ class CORE_EXPORT QgsLayoutContext
 
     QgsLayoutMeasurementConverter mMeasurementConverter;
 
+    bool mGridVisible = false;
+
 
 };
 

src/core/layout/qgslayoutitem.cpp

@@ -374,6 +374,11 @@ void QgsLayoutItem::refresh()
   refreshDataDefinedProperty();
 }
 
+void QgsLayoutItem::redraw()
+{
+  update();
+}
+
 void QgsLayoutItem::drawDebugRect( QPainter *painter )
 {
   if ( !painter )

src/core/layout/qgslayoutitem.h

@@ -235,6 +235,11 @@ class CORE_EXPORT QgsLayoutItem : public QgsLayoutObject, public QGraphicsRectIt
      */
     void refresh() override;
 
+    /**
+     * Triggers a redraw (update) of the item.
+     */
+    virtual void redraw();
+
     /**
      * Refreshes a data defined \a property for the item by reevaluating the property's value
      * and redrawing the item with this new value. If \a property is set to

src/core/layout/qgslayoutitempage.cpp

@@ -117,6 +117,12 @@ void QgsLayoutItemPage::attemptResize( const QgsLayoutSize &size )
   mGrid->setRect( 0, 0, rect().width(), rect().height() );
 }
 
+void QgsLayoutItemPage::redraw()
+{
+  QgsLayoutItem::redraw();
+  mGrid->update();
+}
+
 void QgsLayoutItemPage::draw( QgsRenderContext &context, const QStyleOptionGraphicsItem * )
 {
   if ( !context.painter() || !mLayout /*|| !mLayout->pagesVisible() */ )

src/core/layout/qgslayoutitempage.h

@@ -110,6 +110,10 @@ class CORE_EXPORT QgsLayoutItemPage : public QgsLayoutItem
 
     void attemptResize( const QgsLayoutSize &size ) override;
 
+  public slots:
+
+    void redraw() override;
+
   protected:
 
     void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = nullptr ) override;

src/core/layout/qgslayoutpagecollection.cpp

@@ -135,6 +135,14 @@ double QgsLayoutPageCollection::pageShadowWidth() const
   return spaceBetweenPages() / 2;
 }
 
+void QgsLayoutPageCollection::redraw()
+{
+  Q_FOREACH ( QgsLayoutItemPage *page, mPages )
+  {
+    page->redraw();
+  }
+}
+
 QgsLayout *QgsLayoutPageCollection::layout() const
 {
   return mLayout;

src/core/layout/qgslayoutpagecollection.h

@@ -191,6 +191,13 @@ class CORE_EXPORT QgsLayoutPageCollection : public QObject
      */
     double pageShadowWidth() const;
 
+  public slots:
+
+    /**
+     * Triggers a redraw for all pages.
+     */
+    void redraw();
+
   signals:
 
     /**

src/ui/layout/qgslayoutdesignerbase.ui

@@ -118,6 +118,9 @@
     <addaction name="mActionZoomAll"/>
     <addaction name="mActionZoomToWidth"/>
     <addaction name="separator"/>
+    <addaction name="mActionShowGrid"/>
+    <addaction name="mActionSnapGrid"/>
+    <addaction name="separator"/>
     <addaction name="mActionShowRulers"/>
     <addaction name="separator"/>
     <addaction name="mToolbarMenu"/>
@@ -307,6 +310,38 @@
     <string>Add Pages…</string>
    </property>
   </action>
+  <action name="mActionShowGrid">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="icon">
+    <iconset resource="../../../images/images.qrc">
+     <normaloff>:/images/themes/default/vector_grid.png</normaloff>:/images/themes/default/vector_grid.png</iconset>
+   </property>
+   <property name="text">
+    <string>Show &amp;Grid</string>
+   </property>
+   <property name="toolTip">
+    <string>Show grid</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+'</string>
+   </property>
+  </action>
+  <action name="mActionSnapGrid">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>S&amp;nap to Grid</string>
+   </property>
+   <property name="toolTip">
+    <string>Snap to grid</string>
+   </property>
+   <property name="shortcut">
+    <string>Ctrl+Shift+'</string>
+   </property>
+  </action>
  </widget>
  <resources>
   <include location="../../../images/images.qrc"/>