Port shape items to layouts

python/core/core_auto.sip

@@ -383,6 +383,7 @@
 %Include layout/qgslayoutitem.sip
 %Include layout/qgslayoutitemmap.sip
 %Include layout/qgslayoutitemregistry.sip
+%Include layout/qgslayoutitemshape.sip
 %Include layout/qgslayoutobject.sip
 %Include symbology-ng/qgscptcityarchive.sip
 %Include symbology-ng/qgssvgcache.sip

python/core/layout/qgslayoutitemregistry.sip

@@ -101,6 +101,9 @@ class QgsLayoutItemRegistry : QObject
 
       // known
       LayoutPage,
+      LayoutRectangle,
+      LayoutEllipse,
+      LayoutTriangle,
 
       // item
       PluginItem,

python/core/layout/qgslayoutitemshape.sip

@@ -0,0 +1,156 @@
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/layout/qgslayoutitemshape.h                                 *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/
+
+
+
+class QgsLayoutItemShape : QgsLayoutItem
+{
+%Docstring
+ Base class for layout items which are basic shapes (e.g. rectangles, ellipses).
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutitemshape.h"
+%End
+  public:
+
+    void setSymbol( QgsFillSymbol *symbol );
+%Docstring
+ Sets the fill ``symbol`` used to draw the shape. Ownership is not transferred
+ and a clone of the symbol is made.
+.. seealso:: symbol()
+%End
+
+    QgsFillSymbol *symbol();
+%Docstring
+ Returns the fill symbol used to draw the shape.
+.. seealso:: setSymbol()
+ :rtype: QgsFillSymbol
+%End
+
+  protected:
+
+    explicit QgsLayoutItemShape( QgsLayout *layout );
+%Docstring
+ Constructor for QgsLayoutItemShape, with the specified parent ``layout``.
+%End
+
+};
+
+
+class QgsLayoutItemRectangularShape : QgsLayoutItemShape
+{
+%Docstring
+ A rectangular shape item for layouts.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutitemshape.h"
+%End
+  public:
+
+    explicit QgsLayoutItemRectangularShape( QgsLayout *layout );
+%Docstring
+ Constructor for QgsLayoutItemRectangularShape, with the specified parent ``layout``.
+%End
+    virtual int type() const;
+
+    static QgsLayoutItemRectangularShape *create( QgsLayout *layout, const QVariantMap &settings ) /Factory/;
+%Docstring
+ :rtype: QgsLayoutItemRectangularShape
+%End
+
+    void setCornerRadius( QgsLayoutMeasurement radius );
+%Docstring
+ Sets the corner ``radius`` for rounded rectangle corners.
+.. seealso:: cornerRadius()
+%End
+
+    QgsLayoutMeasurement cornerRadius() const;
+%Docstring
+ Returns the corner radius for rounded rectangle corners.
+.. seealso:: setCornerRadius()
+ :rtype: QgsLayoutMeasurement
+%End
+
+  protected:
+
+    virtual void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = 0 );
+
+
+};
+
+class QgsLayoutItemEllipseShape : QgsLayoutItemShape
+{
+%Docstring
+ A ellipse shape item for layouts.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutitemshape.h"
+%End
+  public:
+
+    explicit QgsLayoutItemEllipseShape( QgsLayout *layout );
+%Docstring
+ Constructor for QgsLayoutItemEllipseShape, with the specified parent ``layout``.
+%End
+    virtual int type() const;
+
+    static QgsLayoutItemEllipseShape *create( QgsLayout *layout, const QVariantMap &settings ) /Factory/;
+%Docstring
+ :rtype: QgsLayoutItemEllipseShape
+%End
+
+  protected:
+
+    virtual void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = 0 );
+
+
+};
+
+class QgsLayoutItemTriangleShape : QgsLayoutItemShape
+{
+%Docstring
+ A triangle shape item for layouts.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutitemshape.h"
+%End
+  public:
+
+    explicit QgsLayoutItemTriangleShape( QgsLayout *layout );
+%Docstring
+ Constructor for QgsLayoutItemTriangleShape, with the specified parent ``layout``.
+%End
+    virtual int type() const;
+
+    static QgsLayoutItemTriangleShape *create( QgsLayout *layout, const QVariantMap &settings ) /Factory/;
+%Docstring
+ :rtype: QgsLayoutItemTriangleShape
+%End
+
+  protected:
+
+    virtual void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = 0 );
+
+
+};
+
+/************************************************************************
+ * This file has been generated automatically from                      *
+ *                                                                      *
+ * src/core/layout/qgslayoutitemshape.h                                 *
+ *                                                                      *
+ * Do not edit manually ! Edit header and run scripts/sipify.pl again   *
+ ************************************************************************/

python/gui/layout/qgslayoutviewrubberband.sip

@@ -179,6 +179,36 @@ class QgsLayoutViewEllipticalRubberBand : QgsLayoutViewRubberBand
     virtual QRectF finish( QPointF position = QPointF(), Qt::KeyboardModifiers modifiers = 0 );
 
 
+};
+
+class QgsLayoutViewTriangleRubberBand : QgsLayoutViewRubberBand
+{
+%Docstring
+ QgsLayoutViewTriangleRubberBand is triangular rubber band for use within QgsLayoutView widgets.
+.. versionadded:: 3.0
+%End
+
+%TypeHeaderCode
+#include "qgslayoutviewrubberband.h"
+%End
+  public:
+
+    QgsLayoutViewTriangleRubberBand( QgsLayoutView *view = 0 );
+%Docstring
+ Constructor for QgsLayoutViewTriangleRubberBand.
+%End
+    virtual QgsLayoutViewTriangleRubberBand *create( QgsLayoutView *view ) const /Factory/;
+
+
+    ~QgsLayoutViewTriangleRubberBand();
+
+    virtual void start( QPointF position, Qt::KeyboardModifiers modifiers );
+
+    virtual void update( QPointF position, Qt::KeyboardModifiers modifiers );
+
+    virtual QRectF finish( QPointF position = QPointF(), Qt::KeyboardModifiers modifiers = 0 );
+
+
 };
 /************************************************************************
  * This file has been generated automatically from                      *

src/core/CMakeLists.txt

@@ -354,6 +354,7 @@ SET(QGIS_CORE_SRCS
   layout/qgslayoutitem.cpp
   layout/qgslayoutitemmap.cpp
   layout/qgslayoutitemregistry.cpp
+  layout/qgslayoutitemshape.cpp
   layout/qgslayoutmeasurement.cpp
   layout/qgslayoutmeasurementconverter.cpp
   layout/qgslayoutobject.cpp
@@ -677,6 +678,7 @@ SET(QGIS_CORE_MOC_HDRS
   layout/qgslayoutitem.h
   layout/qgslayoutitemmap.h
   layout/qgslayoutitemregistry.h
+  layout/qgslayoutitemshape.h
   layout/qgslayoutobject.h
 
   symbology-ng/qgscptcityarchive.h

src/core/layout/qgslayoutitemregistry.cpp

@@ -15,6 +15,7 @@
  ***************************************************************************/
 
 #include "qgslayoutitemregistry.h"
+#include "qgslayoutitemshape.h"
 #include "qgsgloweffect.h"
 #include "qgseffectstack.h"
 #include <QPainter>
@@ -41,6 +42,10 @@ bool QgsLayoutItemRegistry::populate()
   };
 
   addLayoutItemType( new QgsLayoutItemMetadata( 101, QStringLiteral( "temp type" ), QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddLabel.svg" ) ), createTemporaryItem ) );
+  addLayoutItemType( new QgsLayoutItemMetadata( LayoutRectangle, QStringLiteral( "Rectangle" ), QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicRectangle.svg" ) ), QgsLayoutItemRectangularShape::create ) );
+  addLayoutItemType( new QgsLayoutItemMetadata( LayoutEllipse, QStringLiteral( "Ellipse" ), QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicCircle.svg" ) ), QgsLayoutItemEllipseShape::create ) );
+  addLayoutItemType( new QgsLayoutItemMetadata( LayoutTriangle, QStringLiteral( "Triangle" ), QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicTriangle.svg" ) ), QgsLayoutItemTriangleShape::create ) );
+
   return true;
 }
 

src/core/layout/qgslayoutitemregistry.h

@@ -183,6 +183,9 @@ class CORE_EXPORT QgsLayoutItemRegistry : public QObject
 
       // known item types
       LayoutPage, //!< Page items
+      LayoutRectangle, //!< Rectangular shape item
+      LayoutEllipse, //!< Ellipse shape item
+      LayoutTriangle, //!< Triangle shape item
 
       // item types provided by plugins
       PluginItem, //!< Starting point for plugin item types

src/core/layout/qgslayoutitemshape.cpp

@@ -0,0 +1,173 @@
+/***************************************************************************
+                              qgslayoutitemshape.cpp
+                             -----------------------
+    begin                : July 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************/
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#include "qgslayoutitemshape.h"
+#include "qgslayout.h"
+#include "qgslayoututils.h"
+
+#include <QPainter>
+
+QgsLayoutItemShape::QgsLayoutItemShape( QgsLayout *layout )
+  : QgsLayoutItem( layout )
+{
+  QgsStringMap properties;
+  properties.insert( QStringLiteral( "color" ), QStringLiteral( "white" ) );
+  properties.insert( QStringLiteral( "style" ), QStringLiteral( "solid" ) );
+  properties.insert( QStringLiteral( "style_border" ), QStringLiteral( "solid" ) );
+  properties.insert( QStringLiteral( "color_border" ), QStringLiteral( "black" ) );
+  properties.insert( QStringLiteral( "width_border" ), QStringLiteral( "0.3" ) );
+  properties.insert( QStringLiteral( "joinstyle" ), QStringLiteral( "miter" ) );
+  mShapeStyleSymbol.reset( QgsFillSymbol::createSimple( properties ) );
+}
+
+void QgsLayoutItemShape::setSymbol( QgsFillSymbol *symbol )
+{
+  if ( !symbol )
+    return;
+
+  mShapeStyleSymbol.reset( symbol->clone() );
+}
+
+//
+// QgsLayoutItemRectangularShape
+//
+
+QgsLayoutItemRectangularShape::QgsLayoutItemRectangularShape( QgsLayout *layout )
+  : QgsLayoutItemShape( layout )
+  , mCornerRadius( 0.0 )
+{
+
+}
+
+QgsLayoutItemRectangularShape *QgsLayoutItemRectangularShape::create( QgsLayout *layout, const QVariantMap &settings )
+{
+  Q_UNUSED( settings );
+  return new QgsLayoutItemRectangularShape( layout );
+}
+
+void QgsLayoutItemRectangularShape::draw( QgsRenderContext &context, const QStyleOptionGraphicsItem * )
+{
+  QPainter *painter = context.painter();
+  painter->setPen( Qt::NoPen );
+  painter->setBrush( Qt::NoBrush );
+
+  double scale = context.convertToPainterUnits( 1, QgsUnitTypes::RenderMillimeters );
+
+  QPolygonF shapePolygon;
+  if ( mCornerRadius.length() > 0 )
+  {
+    //shapes with curves must be enlarged before conversion to QPolygonF, or
+    //the curves are approximated too much and appear jaggy
+    QTransform t = QTransform::fromScale( 100, 100 );
+    //inverse transform used to scale created polygons back to expected size
+    QTransform ti = t.inverted();
+
+    QPainterPath roundedRectPath;
+    double radius = mLayout->convertToLayoutUnits( mCornerRadius ) * scale;
+    roundedRectPath.addRoundedRect( QRectF( 0, 0, rect().width() * scale, rect().height() * scale ), radius, radius );
+    QPolygonF roundedPoly = roundedRectPath.toFillPolygon( t );
+    shapePolygon = ti.map( roundedPoly );
+  }
+  else
+  {
+    shapePolygon = QPolygonF( QRectF( 0, 0, rect().width() * scale, rect().height() * scale ) );
+  }
+
+  QList<QPolygonF> rings; //empty list
+
+  symbol()->startRender( context );
+  symbol()->renderPolygon( shapePolygon, &rings, nullptr, context );
+  symbol()->stopRender( context );
+}
+
+
+//
+// QgsLayoutItemEllipseShape
+//
+
+QgsLayoutItemEllipseShape::QgsLayoutItemEllipseShape( QgsLayout *layout )
+  : QgsLayoutItemShape( layout )
+{
+
+}
+
+QgsLayoutItemEllipseShape *QgsLayoutItemEllipseShape::create( QgsLayout *layout, const QVariantMap &settings )
+{
+  Q_UNUSED( settings );
+  return new QgsLayoutItemEllipseShape( layout );
+}
+
+void QgsLayoutItemEllipseShape::draw( QgsRenderContext &context, const QStyleOptionGraphicsItem * )
+{
+  QPainter *painter = context.painter();
+  painter->setPen( Qt::NoPen );
+  painter->setBrush( Qt::NoBrush );
+
+  double scale = context.convertToPainterUnits( 1, QgsUnitTypes::RenderMillimeters );
+
+  //shapes with curves must be enlarged before conversion to QPolygonF, or
+  //the curves are approximated too much and appear jaggy
+  QTransform t = QTransform::fromScale( 100, 100 );
+  //inverse transform used to scale created polygons back to expected size
+  QTransform ti = t.inverted();
+
+  //create an ellipse
+  QPainterPath ellipsePath;
+  ellipsePath.addEllipse( QRectF( 0, 0, rect().width() * scale, rect().height() * scale ) );
+  QPolygonF ellipsePoly = ellipsePath.toFillPolygon( t );
+  QPolygonF shapePolygon = ti.map( ellipsePoly );
+
+  QList<QPolygonF> rings; //empty list
+
+  symbol()->startRender( context );
+  symbol()->renderPolygon( shapePolygon, &rings, nullptr, context );
+  symbol()->stopRender( context );
+}
+
+//
+// QgsLayoutItemTriangleShape
+//
+
+QgsLayoutItemTriangleShape::QgsLayoutItemTriangleShape( QgsLayout *layout )
+  : QgsLayoutItemShape( layout )
+{
+
+}
+
+QgsLayoutItemTriangleShape *QgsLayoutItemTriangleShape::create( QgsLayout *layout, const QVariantMap &settings )
+{
+  Q_UNUSED( settings );
+  return new QgsLayoutItemTriangleShape( layout );
+}
+
+void QgsLayoutItemTriangleShape::draw( QgsRenderContext &context, const QStyleOptionGraphicsItem * )
+{
+  QPainter *painter = context.painter();
+  painter->setPen( Qt::NoPen );
+  painter->setBrush( Qt::NoBrush );
+
+  double scale = context.convertToPainterUnits( 1, QgsUnitTypes::RenderMillimeters );
+  QPolygonF shapePolygon = QPolygonF() << QPointF( 0, rect().height() * scale )
+                           << QPointF( rect().width() * scale, rect().height() * scale )
+                           << QPointF( rect().width() / 2.0 * scale, 0 )
+                           << QPointF( 0, rect().height() * scale );
+
+  QList<QPolygonF> rings; //empty list
+
+  symbol()->startRender( context );
+  symbol()->renderPolygon( shapePolygon, &rings, nullptr, context );
+  symbol()->stopRender( context );
+}

src/core/layout/qgslayoutitemshape.h

@@ -0,0 +1,158 @@
+/***************************************************************************
+                              qgslayoutitemshape.h
+                             ---------------------
+    begin                : July 2017
+    copyright            : (C) 2017 by Nyall Dawson
+    email                : nyall dot dawson at gmail dot com
+ ***************************************************************************/
+/***************************************************************************
+ *                                                                         *
+ *   This program is free software; you can redistribute it and/or modify  *
+ *   it under the terms of the GNU General Public License as published by  *
+ *   the Free Software Foundation; either version 2 of the License, or     *
+ *   (at your option) any later version.                                   *
+ *                                                                         *
+ ***************************************************************************/
+
+#ifndef QGSLAYOUTITEMSHAPE_H
+#define QGSLAYOUTITEMSHAPE_H
+
+#include "qgis_core.h"
+#include "qgslayoutitem.h"
+#include "qgslayoutitemregistry.h"
+#include "qgssymbol.h"
+#include "qgslayoutmeasurement.h"
+
+/**
+ * \ingroup core
+ * \class QgsLayoutItemShape
+ * \brief Base class for layout items which are basic shapes (e.g. rectangles, ellipses).
+ * \since QGIS 3.0
+ */
+class CORE_EXPORT QgsLayoutItemShape : public QgsLayoutItem
+{
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Sets the fill \a symbol used to draw the shape. Ownership is not transferred
+     * and a clone of the symbol is made.
+     * \see symbol()
+     */
+    void setSymbol( QgsFillSymbol *symbol );
+
+    /**
+     * Returns the fill symbol used to draw the shape.
+     * \see setSymbol()
+     */
+    QgsFillSymbol *symbol() { return mShapeStyleSymbol.get(); }
+
+  protected:
+
+    /**
+     * Constructor for QgsLayoutItemShape, with the specified parent \a layout.
+     */
+    explicit QgsLayoutItemShape( QgsLayout *layout );
+
+  private:
+    std::unique_ptr< QgsFillSymbol > mShapeStyleSymbol;
+};
+
+
+/**
+ * \ingroup core
+ * \class QgsLayoutItemRectangularShape
+ * \brief A rectangular shape item for layouts.
+ * \since QGIS 3.0
+ */
+class CORE_EXPORT QgsLayoutItemRectangularShape : public QgsLayoutItemShape
+{
+
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Constructor for QgsLayoutItemRectangularShape, with the specified parent \a layout.
+     */
+    explicit QgsLayoutItemRectangularShape( QgsLayout *layout );
+    virtual int type() const override { return QgsLayoutItemRegistry::LayoutRectangle; }
+
+    static QgsLayoutItemRectangularShape *create( QgsLayout *layout, const QVariantMap &settings ) SIP_FACTORY;
+
+    /**
+     * Sets the corner \a radius for rounded rectangle corners.
+     * \see cornerRadius()
+     */
+    void setCornerRadius( QgsLayoutMeasurement radius ) { mCornerRadius = radius; }
+
+    /**
+     * Returns the corner radius for rounded rectangle corners.
+     * \see setCornerRadius()
+     */
+    QgsLayoutMeasurement cornerRadius() const { return mCornerRadius; }
+
+  protected:
+
+    void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = nullptr ) override;
+
+  private:
+    QgsLayoutMeasurement mCornerRadius;
+};
+
+/**
+ * \ingroup core
+ * \class QgsLayoutItemEllipseShape
+ * \brief A ellipse shape item for layouts.
+ * \since QGIS 3.0
+ */
+class CORE_EXPORT QgsLayoutItemEllipseShape : public QgsLayoutItemShape
+{
+
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Constructor for QgsLayoutItemEllipseShape, with the specified parent \a layout.
+     */
+    explicit QgsLayoutItemEllipseShape( QgsLayout *layout );
+    virtual int type() const override { return QgsLayoutItemRegistry::LayoutEllipse; }
+
+    static QgsLayoutItemEllipseShape *create( QgsLayout *layout, const QVariantMap &settings ) SIP_FACTORY;
+
+  protected:
+
+    void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = nullptr ) override;
+
+};
+
+/**
+ * \ingroup core
+ * \class QgsLayoutItemTriangleShape
+ * \brief A triangle shape item for layouts.
+ * \since QGIS 3.0
+ */
+class CORE_EXPORT QgsLayoutItemTriangleShape : public QgsLayoutItemShape
+{
+
+    Q_OBJECT
+
+  public:
+
+    /**
+     * Constructor for QgsLayoutItemTriangleShape, with the specified parent \a layout.
+     */
+    explicit QgsLayoutItemTriangleShape( QgsLayout *layout );
+    virtual int type() const override { return QgsLayoutItemRegistry::LayoutTriangle; }
+
+    static QgsLayoutItemTriangleShape *create( QgsLayout *layout, const QVariantMap &settings ) SIP_FACTORY;
+
+  protected:
+
+    void draw( QgsRenderContext &context, const QStyleOptionGraphicsItem *itemStyle = nullptr ) override;
+
+};
+
+#endif //QGSLAYOUTITEMSHAPE_H

src/gui/layout/qgslayoutitemguiregistry.cpp

@@ -16,6 +16,7 @@
 
 #include "qgslayoutitemguiregistry.h"
 #include "qgslayoutviewrubberband.h"
+#include "qgslayoutitemregistry.h"
 #include <QPainter>
 
 
@@ -40,13 +41,23 @@ bool QgsLayoutItemGuiRegistry::populate()
   if ( !mMetadata.isEmpty() )
     return false;
 
-  // add temporary item to register
   auto createRubberBand = ( []( QgsLayoutView * view )->QgsLayoutViewRubberBand *
   {
     return new QgsLayoutViewRectangularRubberBand( view );
   } );
+  auto createEllipseBand = ( []( QgsLayoutView * view )->QgsLayoutViewRubberBand *
+  {
+    return new QgsLayoutViewEllipticalRubberBand( view );
+  } );
+  auto createTriangleBand = ( []( QgsLayoutView * view )->QgsLayoutViewRubberBand *
+  {
+    return new QgsLayoutViewTriangleRubberBand( view );
+  } );
 
   addLayoutItemGuiMetadata( new QgsLayoutItemGuiMetadata( 101, QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddLabel.svg" ) ), nullptr, createRubberBand ) );
+  addLayoutItemGuiMetadata( new QgsLayoutItemGuiMetadata( QgsLayoutItemRegistry::LayoutRectangle, QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicRectangle.svg" ) ), nullptr, createRubberBand ) );
+  addLayoutItemGuiMetadata( new QgsLayoutItemGuiMetadata( QgsLayoutItemRegistry::LayoutEllipse, QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicCircle.svg" ) ), nullptr, createEllipseBand ) );
+  addLayoutItemGuiMetadata( new QgsLayoutItemGuiMetadata( QgsLayoutItemRegistry::LayoutTriangle, QgsApplication::getThemeIcon( QStringLiteral( "/mActionAddBasicTriangle.svg" ) ), nullptr, createTriangleBand ) );
   return true;
 }
 

src/gui/layout/qgslayoutviewrubberband.cpp

@@ -19,6 +19,7 @@
 #include "qgslayoutview.h"
 #include <QGraphicsRectItem>
 #include <QGraphicsEllipseItem>
+#include <QGraphicsPolygonItem>
 
 QgsLayoutViewRubberBand::QgsLayoutViewRubberBand( QgsLayoutView *view )
   : mView( view )
@@ -248,3 +249,78 @@ QRectF QgsLayoutViewEllipticalRubberBand::finish( QPointF position, Qt::Keyboard
   }
   return updateRect( mRubberBandStartPos, position, constrainSquare, fromCenter );
 }
+
+//
+// QgsLayoutViewTriangleRubberBand
+//
+
+QgsLayoutViewTriangleRubberBand::QgsLayoutViewTriangleRubberBand( QgsLayoutView *view )
+  : QgsLayoutViewRubberBand( view )
+{
+
+}
+
+QgsLayoutViewTriangleRubberBand *QgsLayoutViewTriangleRubberBand::create( QgsLayoutView *view ) const
+{
+  return new QgsLayoutViewTriangleRubberBand( view );
+}
+
+QgsLayoutViewTriangleRubberBand::~QgsLayoutViewTriangleRubberBand()
+{
+  if ( mRubberBandItem )
+  {
+    layout()->removeItem( mRubberBandItem );
+    delete mRubberBandItem;
+  }
+}
+
+void QgsLayoutViewTriangleRubberBand::start( QPointF position, Qt::KeyboardModifiers )
+{
+  QTransform t;
+  mRubberBandItem = new QGraphicsPolygonItem();
+  mRubberBandItem->setBrush( brush() );
+  mRubberBandItem->setPen( pen() );
+  mRubberBandStartPos = position;
+  t.translate( position.x(), position.y() );
+  mRubberBandItem->setTransform( t );
+  mRubberBandItem->setZValue( QgsLayout::ZMapTool );
+  layout()->addItem( mRubberBandItem );
+  layout()->update();
+}
+
+void QgsLayoutViewTriangleRubberBand::update( QPointF position, Qt::KeyboardModifiers modifiers )
+{
+  if ( !mRubberBandItem )
+  {
+    return;
+  }
+
+  bool constrainSquare = modifiers & Qt::ShiftModifier;
+  bool fromCenter = modifiers & Qt::AltModifier;
+
+  QRectF newRect = updateRect( mRubberBandStartPos, position, constrainSquare, fromCenter );
+
+  QPolygonF shapePolygon = QPolygonF() << QPointF( 0, newRect.height() )
+                           << QPointF( newRect.width(), newRect.height() )
+                           << QPointF( newRect.width() / 2.0, 0 )
+                           << QPointF( 0, newRect.height() );
+
+  mRubberBandItem->setPolygon( shapePolygon );
+  QTransform t;
+  t.translate( newRect.x(), newRect.y() );
+  mRubberBandItem->setTransform( t );
+}
+
+QRectF QgsLayoutViewTriangleRubberBand::finish( QPointF position, Qt::KeyboardModifiers modifiers )
+{
+  bool constrainSquare = modifiers & Qt::ShiftModifier;
+  bool fromCenter = modifiers & Qt::AltModifier;
+
+  if ( mRubberBandItem )
+  {
+    layout()->removeItem( mRubberBandItem );
+    delete mRubberBandItem;
+    mRubberBandItem = nullptr;
+  }
+  return updateRect( mRubberBandStartPos, position, constrainSquare, fromCenter );
+}

src/gui/layout/qgslayoutviewrubberband.h

@@ -26,6 +26,7 @@
 class QgsLayoutView;
 class QGraphicsRectItem;
 class QGraphicsEllipseItem;
+class QGraphicsPolygonItem;
 class QgsLayout;
 
 /**
@@ -199,5 +200,36 @@ class GUI_EXPORT QgsLayoutViewEllipticalRubberBand : public QgsLayoutViewRubberB
     //! Start of rubber band creation
     QPointF mRubberBandStartPos;
 
+};
+
+/**
+ * \ingroup gui
+ * QgsLayoutViewTriangleRubberBand is triangular rubber band for use within QgsLayoutView widgets.
+ * \since QGIS 3.0
+ */
+class GUI_EXPORT QgsLayoutViewTriangleRubberBand : public QgsLayoutViewRubberBand
+{
+  public:
+
+    /**
+     * Constructor for QgsLayoutViewTriangleRubberBand.
+     */
+    QgsLayoutViewTriangleRubberBand( QgsLayoutView *view = nullptr );
+    QgsLayoutViewTriangleRubberBand *create( QgsLayoutView *view ) const override SIP_FACTORY;
+
+    ~QgsLayoutViewTriangleRubberBand();
+
+    void start( QPointF position, Qt::KeyboardModifiers modifiers ) override;
+    void update( QPointF position, Qt::KeyboardModifiers modifiers ) override;
+    QRectF finish( QPointF position = QPointF(), Qt::KeyboardModifiers modifiers = 0 ) override;
+
+  private:
+
+    //! Rubber band item
+    QGraphicsPolygonItem *mRubberBandItem = nullptr;
+
+    //! Start of rubber band creation
+    QPointF mRubberBandStartPos;
+
 };
 #endif // QGSLAYOUTVIEWRUBBERBAND_H