Add method to clear page collections for layouts

Author: nyalldawson

python/core/layout/qgslayoutpagecollection.sip

@@ -144,6 +144,8 @@ class QgsLayoutPageCollection : QObject, QgsLayoutSerializableObject
  the first page in the collection.
 
  Calling deletePage() automatically triggers a reflow() of pages.
+
+.. seealso:: clear()
 %End
 
     void deletePage( QgsLayoutItemPage *page );
@@ -152,6 +154,14 @@ class QgsLayoutPageCollection : QObject, QgsLayoutSerializableObject
  from the collection's layout().
 
  Calling deletePage() automatically triggers a reflow() of pages.
+
+.. seealso:: clear()
+%End
+
+    void clear();
+%Docstring
+ Removes all pages from the collection.
+.. seealso:: deletePage()
 %End
 
     QgsLayoutItemPage *takePage( QgsLayoutItemPage *page ) /TransferBack/;

src/core/layout/qgslayoutpagecollection.cpp

@@ -454,6 +454,26 @@ void QgsLayoutPageCollection::deletePage( QgsLayoutItemPage *page )
   }
 }
 
+void QgsLayoutPageCollection::clear()
+{
+  if ( !mBlockUndoCommands )
+  {
+    mLayout->undoStack()->beginMacro( tr( "Remove Pages" ) );
+    mLayout->undoStack()->beginCommand( this, tr( "Remove Pages" ) );
+  }
+  for ( int i = mPages.count() - 1;  i >= 0; --i )
+  {
+    emit pageAboutToBeRemoved( i );
+    mPages.takeAt( i )->deleteLater();
+  }
+  reflow();
+  if ( !mBlockUndoCommands )
+  {
+    mLayout->undoStack()->endCommand();
+    mLayout->undoStack()->endMacro();
+  }
+}
+
 QgsLayoutItemPage *QgsLayoutPageCollection::takePage( QgsLayoutItemPage *page )
 {
   mPages.removeAll( page );

src/core/layout/qgslayoutpagecollection.h

@@ -153,6 +153,8 @@ class CORE_EXPORT QgsLayoutPageCollection : public QObject, public QgsLayoutSeri
      * the first page in the collection.
      *
      * Calling deletePage() automatically triggers a reflow() of pages.
+     *
+     * \see clear()
      */
     void deletePage( int pageNumber );
 
@@ -161,9 +163,17 @@ class CORE_EXPORT QgsLayoutPageCollection : public QObject, public QgsLayoutSeri
      * from the collection's layout().
      *
      * Calling deletePage() automatically triggers a reflow() of pages.
+     *
+     * \see clear()
      */
     void deletePage( QgsLayoutItemPage *page );
 
+    /**
+     * Removes all pages from the collection.
+     * \see deletePage()
+     */
+    void clear();
+
     /**
      * Takes a \a page from the collection, returning ownership of the page to the caller.
      */

tests/src/python/test_qgslayoutpagecollection.py

@@ -187,6 +187,36 @@ def testDeletePages(self):
         self.assertEqual(len(page_about_to_be_removed_spy), 2)
         self.assertEqual(page_about_to_be_removed_spy[-1][0], 0)
 
+    def testClear(self):
+        """
+        Test clearing the collection
+        """
+        p = QgsProject()
+        l = QgsLayout(p)
+        collection = l.pageCollection()
+
+        collection.clear()
+
+        # add a page
+        page = QgsLayoutItemPage(l)
+        page.setPageSize('A4')
+        collection.addPage(page)
+        # add a second page
+        page2 = QgsLayoutItemPage(l)
+        page2.setPageSize('A5')
+        collection.addPage(page2)
+
+        page_about_to_be_removed_spy = QSignalSpy(collection.pageAboutToBeRemoved)
+
+        # clear
+        collection.clear()
+        self.assertEqual(collection.pageCount(), 0)
+        self.assertEqual(len(page_about_to_be_removed_spy), 2)
+
+        QCoreApplication.sendPostedEvents(None, QEvent.DeferredDelete)
+        self.assertTrue(sip.isdeleted(page))
+        self.assertTrue(sip.isdeleted(page2))
+
     def testExtendByNewPage(self):
         """
         Test extend by adding new page