[layouts] Add method to get overview item extent as a vector layer

nyalldawson · nyalldawson · commit 6eb49feddc7e · 2019-01-03T04:53:28.000+10:00
The layer contains a single feature representing the linked map
extent, and set to render using the overview's symbol
diff --git a/python/core/auto_generated/layout/qgslayoutitemmapoverview.sip.in b/python/core/auto_generated/layout/qgslayoutitemmapoverview.sip.in
@@ -127,6 +127,7 @@ Constructor for QgsLayoutItemMapOverview.
 :param name: friendly display name for overview
 :param map: QgsLayoutItemMap the overview is attached to
 %End
+    ~QgsLayoutItemMapOverview();
 
     virtual void draw( QPainter *painter );
 
@@ -216,6 +217,17 @@ Sets whether the extent of the map is forced to center on the overview
 %Docstring
 Reconnects signals for overview map, so that overview correctly follows changes to source
 map's extent.
+%End
+
+    QgsVectorLayer *asMapLayer();
+%Docstring
+Returns a vector layer to render as part of the QgsLayoutItemMap render, containing
+a feature representing the overview extent (and with an appropriate renderer set matching
+the overview's frameSymbol() ).
+
+Ownership of the layer remain with the overview item.
+
+.. versionadded:: 3.6
 %End
 
   public slots:
diff --git a/src/core/layout/qgslayoutitemmapoverview.cpp b/src/core/layout/qgslayoutitemmapoverview.cpp
@@ -26,22 +26,29 @@
 #include "qgsreadwritecontext.h"
 #include "qgslayoututils.h"
 #include "qgsexception.h"
+#include "qgsvectorlayer.h"
+#include "qgssinglesymbolrenderer.h"
 
 #include <QPainter>
 
 QgsLayoutItemMapOverview::QgsLayoutItemMapOverview( const QString &name, QgsLayoutItemMap *map )
   : QgsLayoutItemMapItem( name, map )
+  , mExtentLayer( qgis::make_unique< QgsVectorLayer >( QStringLiteral( "Polygon?crs=EPSG:4326" ), QStringLiteral( "overview" ), QStringLiteral( "memory" ) ) )
 {
   createDefaultFrameSymbol();
 }
 
+QgsLayoutItemMapOverview::~QgsLayoutItemMapOverview() = default;
+
 void QgsLayoutItemMapOverview::createDefaultFrameSymbol()
 {
   QgsStringMap properties;
   properties.insert( QStringLiteral( "color" ), QStringLiteral( "255,0,0,75" ) );
   properties.insert( QStringLiteral( "style" ), QStringLiteral( "solid" ) );
   properties.insert( QStringLiteral( "style_border" ), QStringLiteral( "no" ) );
   mFrameSymbol.reset( QgsFillSymbol::createSimple( properties ) );
+
+  mExtentLayer->setRenderer( new QgsSingleSymbolRenderer( mFrameSymbol->clone() ) );
 }
 
 void QgsLayoutItemMapOverview::draw( QPainter *painter )
@@ -245,6 +252,62 @@ void QgsLayoutItemMapOverview::connectSignals()
   }
 }
 
+QgsVectorLayer *QgsLayoutItemMapOverview::asMapLayer()
+{
+  if ( !mEnabled || !mFrameMap || !mMap || !mMap->layout() )
+  {
+    return nullptr;
+  }
+
+  const QgsLayoutItemMap *overviewFrameMap = linkedMap();
+  if ( !overviewFrameMap )
+  {
+    return nullptr;
+  }
+
+  //get polygon for other overview frame map's extent (use visibleExtentPolygon as it accounts for map rotation)
+  QPolygonF otherExtent = overviewFrameMap->visibleExtentPolygon();
+  QgsGeometry g = QgsGeometry::fromQPolygonF( otherExtent );
+
+  if ( overviewFrameMap->crs() != mMap->crs() )
+  {
+    // reproject extent
+    QgsCoordinateTransform ct( overviewFrameMap->crs(),
+                               mMap->crs(), mLayout->project() );
+    g = g.densifyByCount( 20 );
+    try
+    {
+      g.transform( ct );
+    }
+    catch ( QgsCsException & )
+    {
+    }
+  }
+
+  //get current map's extent as a QPolygonF
+  QPolygonF thisExtent = mMap->visibleExtentPolygon();
+  QgsGeometry thisGeom = QgsGeometry::fromQPolygonF( thisExtent );
+  //intersect the two
+  QgsGeometry intersectExtent = thisGeom.intersection( g );
+
+  mExtentLayer->setBlendMode( mBlendMode );
+
+  static_cast< QgsSingleSymbolRenderer * >( mExtentLayer->renderer() )->setSymbol( mFrameSymbol->clone() );
+  mExtentLayer->dataProvider()->truncate();
+  mExtentLayer->setCrs( mMap->crs() );
+
+  if ( mInverted )
+  {
+    intersectExtent = thisGeom.difference( intersectExtent );
+  }
+
+  QgsFeature f;
+  f.setGeometry( intersectExtent );
+  mExtentLayer->dataProvider()->addFeature( f );
+
+  return mExtentLayer.get();
+}
+
 void QgsLayoutItemMapOverview::setFrameSymbol( QgsFillSymbol *symbol )
 {
   mFrameSymbol.reset( symbol );
diff --git a/src/core/layout/qgslayoutitemmapoverview.h b/src/core/layout/qgslayoutitemmapoverview.h
@@ -128,6 +128,7 @@ class CORE_EXPORT QgsLayoutItemMapOverview : public QgsLayoutItemMapItem
      * \param map QgsLayoutItemMap the overview is attached to
      */
     QgsLayoutItemMapOverview( const QString &name, QgsLayoutItemMap *map );
+    ~QgsLayoutItemMapOverview() override;
 
     void draw( QPainter *painter ) override;
     bool writeXml( QDomElement &elem, QDomDocument &doc, const QgsReadWriteContext &context ) const override;
@@ -211,6 +212,17 @@ class CORE_EXPORT QgsLayoutItemMapOverview : public QgsLayoutItemMapItem
      */
     void connectSignals();
 
+    /**
+     * Returns a vector layer to render as part of the QgsLayoutItemMap render, containing
+     * a feature representing the overview extent (and with an appropriate renderer set matching
+     * the overview's frameSymbol() ).
+     *
+     * Ownership of the layer remain with the overview item.
+     *
+     * \since QGIS 3.6
+     */
+    QgsVectorLayer *asMapLayer();
+
   public slots:
 
     /**
@@ -237,6 +249,8 @@ class CORE_EXPORT QgsLayoutItemMapOverview : public QgsLayoutItemMapItem
     //! True if map is centered on overview
     bool mCentered = false;
 
+    std::unique_ptr< QgsVectorLayer > mExtentLayer;
+
     //! Creates default overview symbol
     void createDefaultFrameSymbol();
 
diff --git a/tests/src/python/test_qgslayoutmapoverview.py b/tests/src/python/test_qgslayoutmapoverview.py
@@ -25,7 +25,10 @@
                        QgsVectorLayer,
                        QgsLayout,
                        QgsProject,
-                       QgsMultiBandColorRenderer)
+                       QgsMultiBandColorRenderer,
+                       QgsFillSymbol,
+                       QgsSingleSymbolRenderer,
+                       QgsCoordinateReferenceSystem)
 
 from qgis.testing import start_app, unittest
 from utilities import unitTestDataPath
@@ -95,7 +98,7 @@ def testOverviewMap(self):
         myTestResult, myMessage = checker.testLayout()
         self.report += checker.report()
         self.layout.removeLayoutItem(overviewMap)
-        assert myTestResult, myMessage
+        self.assertTrue(myTestResult, myMessage)
 
     def testOverviewMapBlend(self):
         overviewMap = QgsLayoutItemMap(self.layout)
@@ -115,7 +118,7 @@ def testOverviewMapBlend(self):
         myTestResult, myMessage = checker.testLayout()
         self.report += checker.report()
         self.layout.removeLayoutItem(overviewMap)
-        assert myTestResult, myMessage
+        self.assertTrue(myTestResult, myMessage)
 
     def testOverviewMapInvert(self):
         overviewMap = QgsLayoutItemMap(self.layout)
@@ -135,7 +138,7 @@ def testOverviewMapInvert(self):
         myTestResult, myMessage = checker.testLayout()
         self.report += checker.report()
         self.layout.removeLayoutItem(overviewMap)
-        assert myTestResult, myMessage
+        self.assertTrue(myTestResult, myMessage)
 
     def testOverviewMapCenter(self):
         overviewMap = QgsLayoutItemMap(self.layout)
@@ -156,7 +159,63 @@ def testOverviewMapCenter(self):
         myTestResult, myMessage = checker.testLayout()
         self.report += checker.report()
         self.layout.removeLayoutItem(overviewMap)
-        assert myTestResult, myMessage
+        self.assertTrue(myTestResult, myMessage)
+
+    def testAsMapLayer(self):
+        l = QgsLayout(QgsProject.instance())
+        l.initializeDefaults()
+        map = QgsLayoutItemMap(l)
+        map.attemptSetSceneRect(QRectF(20, 20, 200, 100))
+        l.addLayoutItem(map)
+
+        overviewMap = QgsLayoutItemMap(l)
+        overviewMap.attemptSetSceneRect(QRectF(20, 130, 70, 70))
+        l.addLayoutItem(overviewMap)
+        # zoom in
+        myRectangle = QgsRectangle(96, -152, 160, -120)
+        map.setExtent(myRectangle)
+        myRectangle2 = QgsRectangle(0, -256, 256, 0)
+        overviewMap.setExtent(myRectangle2)
+        overviewMap.overview().setLinkedMap(map)
+
+        layer = overviewMap.overview().asMapLayer()
+        self.assertIsNotNone(layer)
+        self.assertTrue(layer.isValid())
+        self.assertEqual([f.geometry().asWkt() for f in layer.getFeatures()], ['Polygon ((96 -120, 160 -120, 160 -152, 96 -152, 96 -120))'])
+
+        # check that layer has correct renderer
+        fill_symbol = QgsFillSymbol.createSimple({'color': '#00ff00', 'outline_color': '#ff0000', 'outline_width': '10'})
+        overviewMap.overview().setFrameSymbol(fill_symbol)
+        layer = overviewMap.overview().asMapLayer()
+        self.assertIsInstance(layer.renderer(), QgsSingleSymbolRenderer)
+        self.assertEqual(layer.renderer().symbol().symbolLayer(0).properties()['color'], '0,255,0,255')
+        self.assertEqual(layer.renderer().symbol().symbolLayer(0).properties()['outline_color'], '255,0,0,255')
+
+        # test layer blend mode
+        self.assertEqual(layer.blendMode(), QPainter.CompositionMode_SourceOver)
+        overviewMap.overview().setBlendMode(QPainter.CompositionMode_Clear)
+        layer = overviewMap.overview().asMapLayer()
+        self.assertEqual(layer.blendMode(), QPainter.CompositionMode_Clear)
+
+        # should have no effect
+        overviewMap.setMapRotation(45)
+        layer = overviewMap.overview().asMapLayer()
+        self.assertEqual([f.geometry().asWkt() for f in layer.getFeatures()], ['Polygon ((96 -120, 160 -120, 160 -152, 96 -152, 96 -120))'])
+
+        map.setMapRotation(15)
+        layer = overviewMap.overview().asMapLayer()
+        self.assertEqual([f.geometry().asWkt(0) for f in layer.getFeatures()], ['Polygon ((93 -129, 155 -112, 163 -143, 101 -160, 93 -129))'])
+
+        # with reprojection
+        map.setCrs(QgsCoordinateReferenceSystem('EPSG:3875'))
+        layer = overviewMap.overview().asMapLayer()
+        self.assertEqual([f.geometry().asWkt(0) for f in layer.getFeatures()], ['Polygon ((93 -129, 96 -128, 99 -127, 102 -126, 105 -126, 108 -125, 111 -124, 114 -123, 116 -123, 119 -122, 122 -121, 125 -120, 128 -119, 131 -119, 134 -118, 137 -117, 140 -116, 143 -115, 146 -115, 149 -114, 152 -113, 155 -112, 155 -114, 156 -115, 156 -117, 156 -118, 157 -120, 157 -121, 158 -123, 158 -124, 158 -126, 159 -127, 159 -128, 160 -130, 160 -131, 160 -133, 161 -134, 161 -136, 161 -137, 162 -139, 162 -140, 163 -142, 163 -143, 160 -144, 157 -145, 154 -146, 151 -146, 148 -147, 145 -148, 142 -149, 140 -149, 137 -150, 134 -151, 131 -152, 128 -153, 125 -153, 122 -154, 119 -155, 116 -156, 113 -157, 110 -157, 107 -158, 104 -159, 101 -160, 101 -158, 100 -157, 100 -155, 100 -154, 99 -152, 99 -151, 98 -149, 98 -148, 98 -146, 97 -145, 97 -144, 96 -142, 96 -141, 96 -139, 95 -138, 95 -136, 95 -135, 94 -133, 94 -132, 93 -130, 93 -129))'])
+
+        map.setCrs(overviewMap.crs())
+        # with invert
+        overviewMap.overview().setInverted(True)
+        layer = overviewMap.overview().asMapLayer()
+        self.assertEqual([f.geometry().asWkt(0) for f in layer.getFeatures()], ['Polygon ((-53 -128, 128 53, 309 -128, 128 -309, -53 -128),(93 -129, 101 -160, 163 -143, 155 -112, 93 -129))'])
 
 
 if __name__ == '__main__':
