Add user-friendly warnings when built without webkit and opening layouts with html items

src/app/qgisapp.cpp

@@ -1734,6 +1734,9 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipBadLayers
   QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutNorthArrowValidityCheck() );
   QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutOverviewValidityCheck() );
   QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutPictureSourceValidityCheck() );
+#ifndef WITH_QTWEBKIT
+  QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutHtmlItemValidityCheck() );
+#endif
 
   mSplash->showMessage( tr( "Initializing file filters" ), Qt::AlignHCenter | Qt::AlignBottom, splashTextColor );
   qApp->processEvents();

src/core/layout/qgslayoutitemhtml.cpp

@@ -39,6 +39,7 @@
 #include <QNetworkReply>
 #include <QThread>
 #include <QUrl>
+#include <QAbstractTextDocumentLayout>
 
 // clazy:excludeall=lambda-in-connect
 
@@ -335,8 +336,10 @@ QSizeF QgsLayoutItemHtml::totalSize() const
   return mSize;
 }
 
-void QgsLayoutItemHtml::render( QgsLayoutItemRenderContext &context, const QRectF &renderExtent, const int )
+void QgsLayoutItemHtml::render( QgsLayoutItemRenderContext &context, const QRectF &renderExtent, const int frameIndex )
 {
+#ifdef WITH_QTWEBKIT
+  Q_UNUSED( frameIndex )
   if ( !mWebPage )
     return;
 
@@ -346,6 +349,38 @@ void QgsLayoutItemHtml::render( QgsLayoutItemRenderContext &context, const QRect
   painter->scale( context.renderContext().scaleFactor() / mHtmlUnitsToLayoutUnits, context.renderContext().scaleFactor() / mHtmlUnitsToLayoutUnits );
   painter->translate( 0.0, -renderExtent.top() * mHtmlUnitsToLayoutUnits );
   mWebPage->mainFrame()->render( painter, QRegion( renderExtent.left(), renderExtent.top() * mHtmlUnitsToLayoutUnits, renderExtent.width() * mHtmlUnitsToLayoutUnits, renderExtent.height() * mHtmlUnitsToLayoutUnits ) );
+#else
+  Q_UNUSED( renderExtent )
+  if ( mLayout->renderContext().isPreviewRender() )
+  {
+    if ( QgsLayoutFrame *currentFrame = frame( frameIndex ) )
+    {
+      QPainter *painter = context.renderContext().painter();
+
+      // painter is scaled to dots, so scale back to layout units
+      const QRectF painterRect = QRectF( currentFrame->rect().left() * context.renderContext().scaleFactor(),
+                                         currentFrame->rect().top() * context.renderContext().scaleFactor(),
+                                         currentFrame->rect().width() * context.renderContext().scaleFactor(),
+                                         currentFrame->rect().height() * context.renderContext().scaleFactor()
+                                       );
+
+      painter->setBrush( QBrush( QColor( 255, 125, 125, 125 ) ) );
+      painter->setPen( Qt::NoPen );
+      painter->drawRect( painterRect );
+      painter->setBrush( Qt::NoBrush );
+
+      painter->setPen( QColor( 200, 0, 0, 255 ) );
+      QTextDocument td;
+      td.setTextWidth( painterRect.width() );
+      td.setHtml( QStringLiteral( "<span style=\"color: rgb(200,0,0);\"><b>%1</b><br>%2</span>" ).arg(
+                    tr( "WebKit not available!" ),
+                    tr( "The item cannot be rendered because this QGIS install was built without WebKit support." ) ) );
+      painter->setClipRect( painterRect );
+      QAbstractTextDocumentLayout::PaintContext ctx;
+      td.documentLayout()->draw( painter, ctx );
+    }
+  }
+#endif
 }
 
 double QgsLayoutItemHtml::htmlUnitsToLayoutUnits()

src/gui/layout/qgslayoutvaliditychecks.cpp

@@ -19,6 +19,9 @@
 #include "qgslayoutitemscalebar.h"
 #include "qgslayoutitemmap.h"
 #include "qgslayoutitempicture.h"
+#ifndef WITH_QTWEBKIT
+#include "qgslayoutmultiframe.h"
+#endif
 #include "qgslayout.h"
 #include "qgssettings.h"
 #include <QUrl>
@@ -245,3 +248,55 @@ QList<QgsValidityCheckResult> QgsLayoutPictureSourceValidityCheck::runCheck( con
 {
   return mResults;
 }
+
+#ifndef WITH_QTWEBKIT
+//
+// QgsLayoutHtmlItemValidityCheck
+//
+
+QgsLayoutHtmlItemValidityCheck *QgsLayoutHtmlItemValidityCheck::create() const
+{
+  return new QgsLayoutHtmlItemValidityCheck();
+}
+
+QString QgsLayoutHtmlItemValidityCheck::id() const
+{
+  return QStringLiteral( "layout_html_item_check" );
+}
+
+int QgsLayoutHtmlItemValidityCheck::checkType() const
+{
+  return static_cast< int >( QgsAbstractValidityCheck::Type::LayoutCheck );
+}
+
+bool QgsLayoutHtmlItemValidityCheck::prepareCheck( const QgsValidityCheckContext *context, QgsFeedback * )
+{
+  if ( context->type() != QgsValidityCheckContext::TypeLayoutContext )
+    return false;
+
+  const QgsLayoutValidityCheckContext *layoutContext = static_cast< const QgsLayoutValidityCheckContext * >( context );
+  if ( !layoutContext )
+    return false;
+
+  const QList<QgsLayoutMultiFrame *> multiFrames = layoutContext->layout->multiFrames();
+  for ( QgsLayoutMultiFrame *multiFrame : std::as_const( multiFrames ) )
+  {
+    if ( multiFrame->type() == QgsLayoutItemRegistry::LayoutHtml && multiFrame->frameCount() > 0 )
+    {
+      QgsValidityCheckResult res;
+      res.type = QgsValidityCheckResult::Warning;
+      res.title = QObject::tr( "HTML item cannot be rendered" );
+      res.detailedDescription = QObject::tr( "HTML items cannot be rendered because this QGIS install was built without WebKit support. These items will be missing from the export." );
+      mResults.append( res );
+      break;
+    }
+  }
+
+  return true;
+}
+
+QList<QgsValidityCheckResult> QgsLayoutHtmlItemValidityCheck::runCheck( const QgsValidityCheckContext *, QgsFeedback * )
+{
+  return mResults;
+}
+#endif

src/gui/layout/qgslayoutvaliditychecks.h

@@ -110,4 +110,27 @@ class GUI_EXPORT QgsLayoutPictureSourceValidityCheck : public QgsAbstractValidit
     QList<QgsValidityCheckResult> mResults;
 };
 
+#ifndef WITH_QTWEBKIT
+/**
+ * \ingroup gui
+ * \brief Layout HTML item validity check
+ *
+ * \note This class is not a part of public API
+ * \since QGIS 3.40
+ */
+class GUI_EXPORT QgsLayoutHtmlItemValidityCheck : public QgsAbstractValidityCheck
+{
+  public:
+    //! constructor
+    QgsLayoutHtmlItemValidityCheck *create() const override;
+    QString id() const override;
+    int checkType() const override;
+    bool prepareCheck( const QgsValidityCheckContext *context, QgsFeedback *feedback ) override;
+    QList< QgsValidityCheckResult > runCheck( const QgsValidityCheckContext *context, QgsFeedback *feedback ) override;
+
+  private:
+    QList<QgsValidityCheckResult> mResults;
+};
+#endif
+
 #endif // QGSLAYOUTVALIDITYCHECKS_H