Port method to determine whether page should be exported

src/core/layout/qgslayoutpagecollection.cpp

@@ -368,6 +368,28 @@ QList<QgsLayoutItem *> QgsLayoutPageCollection::itemsOnPage( int page ) const
   return itemList;
 }
 
+bool QgsLayoutPageCollection::shouldExportPage( int page ) const
+{
+  if ( page >= mPages.count() || page < 0 )
+  {
+    //page number out of range, of course we shouldn't export it - stop smoking crack!
+    return false;
+  }
+
+  //check all frame items on page
+  QList<QgsLayoutFrame *> frames;
+  itemsOnPage( frames, page );
+  for ( QgsLayoutFrame *frame : qgis::as_const( frames ) )
+  {
+    if ( frame->hidePageIfEmpty() && frame->isEmpty() )
+    {
+      //frame is set to hide page if empty, and frame is empty, so we don't want to export this page
+      return false;
+    }
+  }
+  return true;
+}
+
 void QgsLayoutPageCollection::addPage( QgsLayoutItemPage *page )
 {
   if ( !mBlockUndoCommands )

src/core/layout/qgslayoutpagecollection.h

@@ -98,6 +98,7 @@ class CORE_EXPORT QgsLayoutPageCollection : public QObject, public QgsLayoutSeri
     /**
      * Returns whether a given \a page index is empty, ie, it contains no items except for the background
      * paper item.
+     * \see shouldExportPage()
      */
     bool pageIsEmpty( int page ) const;
 

tests/src/core/testqgslayout.cpp

@@ -24,6 +24,8 @@
 #include "qgslayoutundostack.h"
 #include "qgslayoutitemlabel.h"
 #include "qgslayoutitempolyline.h"
+#include "qgslayoutitemhtml.h"
+#include "qgslayoutframe.h"
 
 class TestQgsLayout: public QObject
 {
@@ -47,6 +49,7 @@ class TestQgsLayout: public QObject
     void layoutItemByUuid();
     void undoRedoOccurred();
     void itemsOnPage(); //test fetching matching items on a set page
+    void shouldExportPage();
     void pageIsEmpty();
     void clear();
 
@@ -614,6 +617,50 @@ void TestQgsLayout::itemsOnPage()
   QCOMPARE( labels.length(), 0 );
 }
 
+void TestQgsLayout::shouldExportPage()
+{
+  QgsProject proj;
+  QgsLayout l( &proj );
+  QgsLayoutItemPage *page = new QgsLayoutItemPage( &l );
+  page->setPageSize( "A4" );
+  l.pageCollection()->addPage( page );
+  QgsLayoutItemPage *page2 = new QgsLayoutItemPage( &l );
+  page2->setPageSize( "A4" );
+  l.pageCollection()->addPage( page2 );
+
+  QgsLayoutItemHtml *htmlItem = new QgsLayoutItemHtml( &l );
+  //frame on page 1
+  QgsLayoutFrame *frame1 = new QgsLayoutFrame( &l, htmlItem );
+  frame1->attemptSetSceneRect( QRectF( 0, 0, 100, 100 ) );
+  //frame on page 2
+  QgsLayoutFrame *frame2 = new QgsLayoutFrame( &l, htmlItem );
+  frame2->attemptSetSceneRect( QRectF( 0, 320, 100, 100 ) );
+  frame2->setHidePageIfEmpty( true );
+  htmlItem->addFrame( frame1 );
+  htmlItem->addFrame( frame2 );
+  htmlItem->setContentMode( QgsLayoutItemHtml::ManualHtml );
+  //short content, so frame 2 should be empty
+  htmlItem->setHtml( QStringLiteral( "<p><i>Test manual <b>html</b></i></p>" ) );
+  htmlItem->loadHtml();
+
+  QVERIFY( l.pageCollection()->shouldExportPage( 0 ) );
+  QVERIFY( !l.pageCollection()->shouldExportPage( 1 ) );
+
+  //long content, so frame 2 should not be empty
+  htmlItem->setHtml( QStringLiteral( "<p style=\"height: 10000px\"><i>Test manual <b>html</b></i></p>" ) );
+  htmlItem->loadHtml();
+
+  QVERIFY( l.pageCollection()->shouldExportPage( 0 ) );
+  QVERIFY( l.pageCollection()->shouldExportPage( 1 ) );
+
+  //...and back again...
+  htmlItem->setHtml( QStringLiteral( "<p><i>Test manual <b>html</b></i></p>" ) );
+  htmlItem->loadHtml();
+
+  QVERIFY( l.pageCollection()->shouldExportPage( 0 ) );
+  QVERIFY( !l.pageCollection()->shouldExportPage( 1 ) );
+}
+
 void TestQgsLayout::pageIsEmpty()
 {
   QgsProject proj;