Add methods to determine visible pages in a view

Author: nyalldawson

python/core/layout/qgslayout.sip

@@ -228,6 +228,7 @@ class QgsLayout : QGraphicsScene, QgsExpressionContextGenerator
  :rtype: QgsLayoutPageCollection
 %End
 
+
     QRectF layoutBounds( bool ignorePages = false, double margin = 0.0 ) const;
 %Docstring
  Calculates the bounds of all non-gui items in the layout. Ignores snap lines, mouse handles

python/core/layout/qgslayoutpagecollection.sip

@@ -66,6 +66,22 @@ class QgsLayoutPageCollection : QObject
  :rtype: int
 %End
 
+    QList< QgsLayoutItemPage * > visiblePages( QRectF region ) const;
+%Docstring
+ Returns a list of the pages which are visible within the specified
+ ``region`` (in layout coordinates).
+.. seealso:: visiblePageNumbers()
+ :rtype: list of QgsLayoutItemPage
+%End
+
+    QList< int > visiblePageNumbers( QRectF region ) const;
+%Docstring
+ Returns a list of the page numbers which are visible within the specified
+ ``region`` (in layout coordinates).
+.. seealso:: visiblePages()
+ :rtype: list of int
+%End
+
     void addPage( QgsLayoutItemPage *page /Transfer/ );
 %Docstring
  Adds a ``page`` to the collection. Ownership of the ``page`` is transferred

python/gui/layout/qgslayoutview.sip

@@ -37,6 +37,7 @@ class QgsLayoutView: QGraphicsView
  :rtype: QgsLayout
 %End
 
+
     void setCurrentLayout( QgsLayout *layout /KeepReference/ );
 %Docstring
  Sets the current ``layout`` to edit in the view.
@@ -112,6 +113,20 @@ class QgsLayoutView: QGraphicsView
  :rtype: int
 %End
 
+    QList< QgsLayoutItemPage * > visiblePages() const;
+%Docstring
+ Returns a list of page items which are currently visible in the view.
+.. seealso:: visiblePageNumbers()
+ :rtype: list of QgsLayoutItemPage
+%End
+
+    QList< int > visiblePageNumbers() const;
+%Docstring
+ Returns a list of page numbers for pages which are currently visible in the view.
+.. seealso:: visiblePages()
+ :rtype: list of int
+%End
+
   public slots:
 
     void zoomFull();

src/core/layout/qgslayout.cpp

@@ -135,6 +135,11 @@ QgsLayoutPageCollection *QgsLayout::pageCollection()
   return mPageCollection.get();
 }
 
+const QgsLayoutPageCollection *QgsLayout::pageCollection() const
+{
+  return mPageCollection.get();
+}
+
 QRectF QgsLayout::layoutBounds( bool ignorePages, double margin ) const
 {
   //start with an empty rectangle

src/core/layout/qgslayout.h

@@ -262,6 +262,12 @@ class CORE_EXPORT QgsLayout : public QGraphicsScene, public QgsExpressionContext
      */
     QgsLayoutPageCollection *pageCollection();
 
+    /**
+     * Returns a pointer to the layout's page collection, which stores and manages
+     * page items in the layout.
+     */
+    SIP_SKIP const QgsLayoutPageCollection *pageCollection() const;
+
     /**
      * Calculates the bounds of all non-gui items in the layout. Ignores snap lines, mouse handles
      * and other cosmetic items.

src/core/layout/qgslayoutpagecollection.cpp

@@ -168,6 +168,30 @@ int QgsLayoutPageCollection::pageNumber( QgsLayoutItemPage *page ) const
   return mPages.indexOf( page );
 }
 
+QList<QgsLayoutItemPage *> QgsLayoutPageCollection::visiblePages( QRectF region ) const
+{
+  QList<QgsLayoutItemPage *> pages;
+  Q_FOREACH ( QgsLayoutItemPage *page, mPages )
+  {
+    if ( page->mapToScene( page->rect() ).boundingRect().intersects( region ) )
+      pages << page;
+  }
+  return pages;
+}
+
+QList<int> QgsLayoutPageCollection::visiblePageNumbers( QRectF region ) const
+{
+  QList< int > pages;
+  int p = 0;
+  Q_FOREACH ( QgsLayoutItemPage *page, mPages )
+  {
+    if ( page->mapToScene( page->rect() ).boundingRect().intersects( region ) )
+      pages << p;
+    p++;
+  }
+  return pages;
+}
+
 void QgsLayoutPageCollection::addPage( QgsLayoutItemPage *page )
 {
   mPages.append( page );

src/core/layout/qgslayoutpagecollection.h

@@ -79,6 +79,20 @@ class CORE_EXPORT QgsLayoutPageCollection : public QObject
      */
     int pageNumber( QgsLayoutItemPage *page ) const;
 
+    /**
+     * Returns a list of the pages which are visible within the specified
+     * \a region (in layout coordinates).
+     * \see visiblePageNumbers()
+     */
+    QList< QgsLayoutItemPage * > visiblePages( QRectF region ) const;
+
+    /**
+     * Returns a list of the page numbers which are visible within the specified
+     * \a region (in layout coordinates).
+     * \see visiblePages()
+     */
+    QList< int > visiblePageNumbers( QRectF region ) const;
+
     /**
      * Adds a \a page to the collection. Ownership of the \a page is transferred
      * to the collection, and the page will automatically be added to the collection's

src/gui/layout/qgslayoutview.cpp

@@ -57,6 +57,11 @@ QgsLayout *QgsLayoutView::currentLayout()
   return qobject_cast<QgsLayout *>( scene() );
 }
 
+const QgsLayout *QgsLayoutView::currentLayout() const
+{
+  return qobject_cast<const QgsLayout *>( scene() );
+}
+
 void QgsLayoutView::setCurrentLayout( QgsLayout *layout )
 {
   setScene( layout );
@@ -163,6 +168,22 @@ QgsLayoutViewMenuProvider *QgsLayoutView::menuProvider() const
   return mMenuProvider.get();
 }
 
+QList<QgsLayoutItemPage *> QgsLayoutView::visiblePages() const
+{
+  //get current visible part of scene
+  QRect viewportRect( 0, 0, viewport()->width(), viewport()->height() );
+  QRectF visibleRect = mapToScene( viewportRect ).boundingRect();
+  return currentLayout()->pageCollection()->visiblePages( visibleRect );
+}
+
+QList<int> QgsLayoutView::visiblePageNumbers() const
+{
+  //get current visible part of scene
+  QRect viewportRect( 0, 0, viewport()->width(), viewport()->height() );
+  QRectF visibleRect = mapToScene( viewportRect ).boundingRect();
+  return currentLayout()->pageCollection()->visiblePageNumbers( visibleRect );
+}
+
 void QgsLayoutView::zoomFull()
 {
   fitInView( scene()->sceneRect(), Qt::KeepAspectRatio );

src/gui/layout/qgslayoutview.h

@@ -20,6 +20,7 @@
 #include "qgis.h"
 #include "qgsprevieweffect.h" // for QgsPreviewEffect::PreviewMode
 #include "qgis_gui.h"
+#include "qgslayoutitempage.h"
 #include <QPointer>
 #include <QGraphicsView>
 #include <QGraphicsRectItem>
@@ -65,6 +66,13 @@ class GUI_EXPORT QgsLayoutView: public QGraphicsView
      */
     QgsLayout *currentLayout();
 
+    /**
+     * Returns the current layout associated with the view.
+     * \see setCurrentLayout()
+     * \see layoutSet()
+     */
+    SIP_SKIP const QgsLayout *currentLayout() const;
+
     /**
      * Sets the current \a layout to edit in the view.
      * \see currentLayout()
@@ -137,6 +145,18 @@ class GUI_EXPORT QgsLayoutView: public QGraphicsView
      */
     int currentPage() const { return mCurrentPage; }
 
+    /**
+     * Returns a list of page items which are currently visible in the view.
+     * \see visiblePageNumbers()
+     */
+    QList< QgsLayoutItemPage * > visiblePages() const;
+
+    /**
+     * Returns a list of page numbers for pages which are currently visible in the view.
+     * \see visiblePages()
+     */
+    QList< int > visiblePageNumbers() const;
+
   public slots:
 
     /**

tests/src/python/test_qgslayoutpagecollection.py

@@ -25,7 +25,8 @@
                        QgsLayoutPageCollection,
                        QgsSimpleFillSymbolLayer,
                        QgsFillSymbol)
-from qgis.PyQt.QtCore import Qt, QCoreApplication, QEvent, QPointF
+from qgis.PyQt.QtCore import Qt, QCoreApplication, QEvent, QPointF, QRectF
+
 from qgis.testing import start_app, unittest
 
 start_app()
@@ -378,6 +379,44 @@ def testPageAtPoint(self):
         self.assertEqual(collection.pageAtPoint(QPointF(10, 500)), page2)
         self.assertFalse(collection.pageAtPoint(QPointF(10, 600)))
 
+    def testVisiblePages(self):
+        p = QgsProject()
+        l = QgsLayout(p)
+        collection = l.pageCollection()
+
+        self.assertFalse(collection.visiblePages(QRectF(0, 0, 10, 10)))
+        self.assertFalse(collection.visiblePageNumbers(QRectF(0, 0, 10, 10)))
+
+        # add a page
+        page = QgsLayoutItemPage(l)
+        page.setPageSize('A4')
+        collection.addPage(page)
+
+        self.assertFalse(collection.visiblePages(QRectF(-10, -10, 5, 5)))
+        self.assertFalse(collection.visiblePageNumbers(QRectF(-10, -10, 5, 5)))
+        self.assertEqual(collection.visiblePages(QRectF(-10, -10, 15, 15)), [page])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(-10, -10, 15, 15)), [0])
+        self.assertEqual(collection.visiblePages(QRectF(200, 200, 115, 115)), [page])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(200, 200, 115, 115)), [0])
+
+        page2 = QgsLayoutItemPage(l)
+        page2.setPageSize('A5')
+        collection.addPage(page2)
+
+        self.assertFalse(collection.visiblePages(QRectF(-10, -10, 5, 5)))
+        self.assertFalse(collection.visiblePageNumbers(QRectF(-10, -10, 5, 5)))
+        self.assertEqual(collection.visiblePages(QRectF(-10, -10, 15, 15)), [page])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(-10, -10, 15, 15)), [0])
+        self.assertEqual(collection.visiblePages(QRectF(200, 200, 115, 115)), [page])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(200, 200, 115, 115)), [0])
+
+        self.assertEqual(collection.visiblePages(QRectF(200, 200, 115, 615)), [page])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(200, 200, 115, 115)), [0])
+        self.assertEqual(collection.visiblePages(QRectF(100, 200, 115, 615)), [page, page2])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(100, 200, 115, 115)), [0, 1])
+        self.assertEqual(collection.visiblePages(QRectF(100, 310, 115, 615)), [page2])
+        self.assertEqual(collection.visiblePageNumbers(QRectF(100, 310, 115, 115)), [1])
+
 
 if __name__ == '__main__':
     unittest.main()