Add some rendering checks for layout items

src/core/layout/qgslayoutitem.cpp

@@ -36,7 +36,14 @@ void QgsLayoutItem::paint( QPainter *painter, const QStyleOptionGraphicsItem *it
   painter->save();
   preparePainter( painter );
 
-  draw( painter, itemStyle, pWidget );
+  if ( shouldDrawDebugRect() )
+  {
+    drawDebugRect( painter );
+  }
+  else
+  {
+    draw( painter, itemStyle, pWidget );
+  }
 
   painter->restore();
 }
@@ -62,4 +69,20 @@ void QgsLayoutItem::preparePainter( QPainter *painter )
   {
     return;
   }
+
+  painter->setRenderHint( QPainter::Antialiasing, shouldDrawAntialiased() );
+}
+
+bool QgsLayoutItem::shouldDrawAntialiased() const
+{
+  if ( !mLayout )
+  {
+    return true;
+  }
+  return mLayout->context().testFlag( QgsLayoutContext::FlagAntialiasing ) && !mLayout->context().testFlag( QgsLayoutContext::FlagDebug );
+}
+
+bool QgsLayoutItem::shouldDrawDebugRect() const
+{
+  return mLayout && mLayout->context().testFlag( QgsLayoutContext::FlagDebug );
 }

src/core/layout/qgslayoutitem.h

@@ -66,6 +66,8 @@ class CORE_EXPORT QgsLayoutItem : public QgsLayoutObject, public QGraphicsRectIt
 
     //! Prepares a painter by setting rendering flags
     void preparePainter( QPainter *painter );
+    bool shouldDrawAntialiased() const;
+    bool shouldDrawDebugRect() const;
 
     friend class TestQgsLayoutItem;
 };

tests/src/core/testqgslayoutitem.cpp

@@ -37,6 +37,11 @@ class TestQgsLayoutItem: public QObject
     void cleanup();// will be called after every testfunction.
     void creation(); //test creation of QgsLayoutItem
     void registry();
+    void shouldDrawDebug();
+    void shouldDrawAntialiased();
+    void preparePainter();
+    void debugRect();
+    void draw();
 
   private:
 
@@ -160,13 +165,98 @@ void TestQgsLayoutItem::registry()
   QVERIFY( !reg2.populate() );
 }
 
+void TestQgsLayoutItem::shouldDrawDebug()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+  TestItem *item = new TestItem( &l );
+  l.context().setFlag( QgsLayoutContext::FlagDebug, true );
+  QVERIFY( item->shouldDrawDebugRect() );
+  l.context().setFlag( QgsLayoutContext::FlagDebug, false );
+  QVERIFY( !item->shouldDrawDebugRect() );
+  delete item;
+}
+
+void TestQgsLayoutItem::shouldDrawAntialiased()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+  TestItem *item = new TestItem( &l );
+  l.context().setFlag( QgsLayoutContext::FlagAntialiasing, false );
+  QVERIFY( !item->shouldDrawAntialiased() );
+  l.context().setFlag( QgsLayoutContext::FlagAntialiasing, true );
+  QVERIFY( item->shouldDrawAntialiased() );
+  delete item;
+}
+
+void TestQgsLayoutItem::preparePainter()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+  TestItem *item = new TestItem( &l );
+  //test with no painter
+  item->preparePainter( nullptr );
+
+  //test antialiasing correctly set for painter
+  QImage image( QSize( 100, 100 ), QImage::Format_ARGB32 );
+  QPainter painter;
+  painter.begin( &image );
+  l.context().setFlag( QgsLayoutContext::FlagAntialiasing, false );
+  item->preparePainter( &painter );
+  QVERIFY( !( painter.renderHints() & QPainter::Antialiasing ) );
+  l.context().setFlag( QgsLayoutContext::FlagAntialiasing, true );
+  item->preparePainter( &painter );
+  QVERIFY( painter.renderHints() & QPainter::Antialiasing );
+  delete item;
+}
+
+void TestQgsLayoutItem::debugRect()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+  TestItem *item = new TestItem( &l );
+  l.addItem( item );
+  item->setPos( 100, 100 );
+  item->setRect( 0, 0, 200, 200 );
+  l.setSceneRect( 0, 0, 400, 400 );
+  l.context().setFlag( QgsLayoutContext::FlagDebug, true );
+  QImage image( l.sceneRect().size().toSize(), QImage::Format_ARGB32 );
+  image.fill( 0 );
+  QPainter painter( &image );
+  l.render( &painter );
+  painter.end();
+
+  bool result = renderCheck( "layoutitem_debugrect", image, 0 );
+  QVERIFY( result );
+}
+
+void TestQgsLayoutItem::draw()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+  TestItem *item = new TestItem( &l );
+  l.addItem( item );
+  item->setPos( 100, 100 );
+  item->setRect( 0, 0, 200, 200 );
+  l.setSceneRect( 0, 0, 400, 400 );
+  l.context().setFlag( QgsLayoutContext::FlagAntialiasing, false ); //disable antialiasing to limit cross platform differences
+  QImage image( l.sceneRect().size().toSize(), QImage::Format_ARGB32 );
+  image.fill( 0 );
+  QPainter painter( &image );
+  l.render( &painter );
+  painter.end();
+  bool result = renderCheck( "layoutitem_draw", image, 0 );
+  QVERIFY( result );
+}
+
 bool TestQgsLayoutItem::renderCheck( QString testName, QImage &image, int mismatchCount )
 {
   mReport += "<h2>" + testName + "</h2>\n";
   QString myTmpDir = QDir::tempPath() + QDir::separator();
   QString myFileName = myTmpDir + testName + ".png";
   image.save( myFileName, "PNG" );
   QgsRenderChecker myChecker;
+  myChecker.setControlPathPrefix( "layouts" );
   myChecker.setControlName( "expected_" + testName );
   myChecker.setRenderedImage( myFileName );
   bool myResultFlag = myChecker.compareImages( testName, mismatchCount );