QgsLayoutItemPolygon can provide a clip path

qgis · Jul 28, 2020 · aa0b36b · aa0b36b
1 parent 2b28395
commit aa0b36b
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Showing 5 changed files with 79 additions and 6 deletions.
diff --git a/python/core/auto_generated/layout/qgslayoutitempolygon.sip.in b/python/core/auto_generated/layout/qgslayoutitempolygon.sip.in
@@ -9,7 +9,6 @@
 
 
 
-
 class QgsLayoutItemPolygon: QgsLayoutNodesItem
 {
 %Docstring
@@ -49,6 +48,10 @@ The caller takes responsibility for deleting the returned object.
 
     virtual bool accept( QgsStyleEntityVisitorInterface *visitor ) const;
 
+    virtual QgsLayoutItem::Flags itemFlags() const;
+
+    virtual QgsGeometry clipPath() const;
+
 
     QgsFillSymbol *symbol();
 %Docstring

diff --git a/src/core/layout/qgslayoutitemnodeitem.cpp b/src/core/layout/qgslayoutitemnodeitem.cpp
@@ -28,6 +28,7 @@ void QgsLayoutNodesItem::setNodes( const QPolygonF &nodes )
 {
   mPolygon = nodes;
   updateSceneRect();
+  emit clipPathChanged();
 }
 
 QRectF QgsLayoutNodesItem::boundingRect() const
@@ -156,6 +157,7 @@ bool QgsLayoutNodesItem::addNode( QPointF pt,
   {
     rc = _addNode( idx, start, maxDistance );
     updateSceneRect();
+    emit clipPathChanged();
   }
 
   return rc;
@@ -246,7 +248,10 @@ bool QgsLayoutNodesItem::removeNode( const int index )
 {
   bool rc = _removeNode( index );
   if ( rc )
+  {
     updateSceneRect();
+    emit clipPathChanged();
+  }
   return rc;
 }
 
@@ -259,7 +264,7 @@ bool QgsLayoutNodesItem::moveNode( const int index, QPointF pt )
     QPointF nodeItem = mapFromScene( pt );
     mPolygon.replace( index, nodeItem );
     updateSceneRect();
-
+    emit clipPathChanged();
     rc = true;
   }
 
@@ -287,6 +292,7 @@ bool QgsLayoutNodesItem::readPropertiesFromElement( const QDomElement &itemElem,
   }
 
   emit changed();
+  emit clipPathChanged();
   return true;
 }
 
@@ -305,6 +311,7 @@ void QgsLayoutNodesItem::rescaleToFitBoundingBox()
   QTransform trans;
   trans = trans.scale( ratioX, ratioY );
   mPolygon = trans.map( mPolygon );
+  emit clipPathChanged();
 }
 
 bool QgsLayoutNodesItem::setSelectedNode( const int index )

diff --git a/src/core/layout/qgslayoutitempolygon.cpp b/src/core/layout/qgslayoutitempolygon.cpp
@@ -111,6 +111,22 @@ bool QgsLayoutItemPolygon::accept( QgsStyleEntityVisitorInterface *visitor ) con
   return true;
 }
 
+QgsLayoutItem::Flags QgsLayoutItemPolygon::itemFlags() const
+{
+  QgsLayoutItem::Flags flags = QgsLayoutNodesItem::itemFlags();
+  flags |= QgsLayoutItem::FlagProvidesClipPath;
+  return flags;
+}
+
+QgsGeometry QgsLayoutItemPolygon::clipPath() const
+{
+  QPolygonF path = mapToScene( mPolygon );
+  // ensure polygon is closed
+  if ( path.at( 0 ) != path.constLast() )
+    path << path.at( 0 );
+  return QgsGeometry::fromQPolygonF( path );
+}
+
 void QgsLayoutItemPolygon::_draw( QgsLayoutItemRenderContext &context, const QStyleOptionGraphicsItem * )
 {
   //setup painter scaling to dots so that raster symbology is drawn to scale

diff --git a/src/core/layout/qgslayoutitempolygon.h b/src/core/layout/qgslayoutitempolygon.h
@@ -26,7 +26,6 @@
  * Layout item for node based polygon shapes.
  * \since QGIS 3.0
  */
-
 class CORE_EXPORT QgsLayoutItemPolygon: public QgsLayoutNodesItem
 {
     Q_OBJECT
@@ -55,6 +54,8 @@ class CORE_EXPORT QgsLayoutItemPolygon: public QgsLayoutNodesItem
     QIcon icon() const override;
     QString displayName() const override;
     bool accept( QgsStyleEntityVisitorInterface *visitor ) const override;
+    QgsLayoutItem::Flags itemFlags() const override;
+    QgsGeometry clipPath() const override;
 
     /**
      * Returns the fill symbol used to draw the shape.

diff --git a/tests/src/python/test_qgslayoutpolygon.py b/tests/src/python/test_qgslayoutpolygon.py
@@ -12,16 +12,20 @@
 
 import qgis  # NOQA
 
-from qgis.PyQt.QtGui import QPolygonF
-from qgis.PyQt.QtCore import QPointF
+from qgis.PyQt.QtGui import QPolygonF, QPainter, QImage
+from qgis.PyQt.QtCore import QPointF, QRectF
 from qgis.PyQt.QtXml import QDomDocument
+from qgis.PyQt.QtTest import QSignalSpy
 
 from qgis.core import (QgsLayoutItemPolygon,
                        QgsLayoutItemRegistry,
                        QgsLayout,
                        QgsFillSymbol,
                        QgsProject,
-                       QgsReadWriteContext)
+                       QgsReadWriteContext,
+                       QgsLayoutItem,
+                       QgsLayoutItemRenderContext,
+                       QgsLayoutUtils)
 from qgis.testing import (start_app,
                           unittest
                           )
@@ -317,6 +321,48 @@ def testBounds(self):
         self.assertEqual(bounds.top(), -3.0)
         self.assertEqual(bounds.bottom(), 93.0)
 
+    def testClipPath(self):
+        pr = QgsProject()
+        l = QgsLayout(pr)
+
+        p = QPolygonF()
+        p.append(QPointF(50.0, 30.0))
+        p.append(QPointF(100.0, 10.0))
+        p.append(QPointF(200.0, 100.0))
+        shape = QgsLayoutItemPolygon(p, l)
+
+        # must be a closed polygon, in scene coordinates!
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((50 30, 100 10, 200 100, 50 30))')
+        self.assertTrue(int(shape.itemFlags() & QgsLayoutItem.FlagProvidesClipPath))
+
+        spy = QSignalSpy(shape.clipPathChanged)
+        self.assertTrue(shape.addNode(QPointF(150, 110), False))
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((50 30, 100 10, 200 100, 150 110, 50 30))')
+        self.assertEqual(len(spy), 1)
+
+        shape.removeNode(3)
+        self.assertEqual(len(spy), 2)
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((50 30, 100 10, 200 100, 50 30))')
+
+        shape.moveNode(2, QPointF(180, 100))
+        self.assertEqual(len(spy), 3)
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((50 30, 100 10, 180 100, 50 30))')
+
+        shape.setNodes(p)
+        self.assertEqual(len(spy), 4)
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((100 40, 150 20, 250 110, 100 40))')
+
+        shape.attemptSetSceneRect(QRectF(30, 10, 100, 200))
+        self.assertEqual(shape.clipPath().asWkt(), 'Polygon ((30 30, 80 10, 180 100, 30 30))')
+        # bit gross - this needs fixing in the item. It shouldn't rely on a draw operation to update the
+        # path as a result of a move/resize
+        im = QImage()
+        p = QPainter(im)
+        rc = QgsLayoutUtils.createRenderContextForLayout(l, p)
+        shape.draw(QgsLayoutItemRenderContext(rc))
+        p.end()
+        self.assertEqual(len(spy), 5)
+
 
 if __name__ == '__main__':
     unittest.main()