[layouts] Show an explicit warning when exporting a layout which contains a broken image

python/core/auto_generated/layout/qgslayoutitempicture.sip.in

@@ -79,6 +79,8 @@ this value. The path can either be a local path or a remote (http) path.
 :return: path for the source image
 
 .. seealso:: :py:func:`setPicturePath`
+
+.. seealso:: :py:func:`evaluatedPath`
 %End
 
     double pictureRotation() const;
@@ -252,6 +254,24 @@ Returns the current picture mode (image format).
     virtual void finalizeRestoreFromXml();
 
 
+    bool isMissingImage() const;
+%Docstring
+Returns true if the source image is missing and the picture
+cannot be rendered.
+
+.. versionadded:: 3.6
+%End
+
+    QString evaluatedPath() const;
+%Docstring
+Returns the current evaluated picture path, which includes
+the result of data defined path overrides.
+
+.. seealso:: :py:func:`picturePath`
+
+.. versionadded:: 3.6
+%End
+
   public slots:
 
     void setPictureRotation( double rotation );

src/app/layout/qgslayoutvaliditychecks.cpp

@@ -18,6 +18,7 @@
 #include "qgsvaliditycheckcontext.h"
 #include "qgslayoutitemscalebar.h"
 #include "qgslayoutitemmap.h"
+#include "qgslayoutitempicture.h"
 #include "qgslayout.h"
 
 //
@@ -126,3 +127,61 @@ QList<QgsValidityCheckResult> QgsLayoutOverviewValidityCheck::runCheck( const Qg
 {
   return mResults;
 }
+
+
+
+//
+// QgsLayoutPictureSourceValidityCheck
+//
+
+QgsLayoutPictureSourceValidityCheck *QgsLayoutPictureSourceValidityCheck::create() const
+{
+  return new QgsLayoutPictureSourceValidityCheck();
+}
+
+QString QgsLayoutPictureSourceValidityCheck::id() const
+{
+  return QStringLiteral( "layout_picture_source_check" );
+}
+
+int QgsLayoutPictureSourceValidityCheck::checkType() const
+{
+  return QgsAbstractValidityCheck::TypeLayoutCheck;
+}
+
+bool QgsLayoutPictureSourceValidityCheck::prepareCheck( const QgsValidityCheckContext *context, QgsFeedback * )
+{
+  if ( context->type() != QgsValidityCheckContext::TypeLayoutContext )
+    return false;
+
+  const QgsLayoutValidityCheckContext *layoutContext = static_cast< const QgsLayoutValidityCheckContext * >( context );
+  if ( !layoutContext )
+    return false;
+
+  QList< QgsLayoutItemPicture * > pictureItems;
+  layoutContext->layout->layoutItems( pictureItems );
+  for ( QgsLayoutItemPicture *picture : qgis::as_const( pictureItems ) )
+  {
+    if ( picture->isMissingImage() )
+    {
+      QgsValidityCheckResult res;
+      res.type = QgsValidityCheckResult::Warning;
+      res.title = QObject::tr( "Picture source is missing or corrupt" );
+      const QString name = picture->displayName().toHtmlEscaped();
+
+      const QUrl picUrl = QUrl::fromUserInput( picture->evaluatedPath() );
+      const bool isLocalFile = picUrl.isLocalFile();
+
+      res.detailedDescription = QObject::tr( "The source for picture “%1” could not be loaded or is corrupt:<p>%2" ).arg( name,
+                                isLocalFile ? QDir::toNativeSeparators( picture->evaluatedPath() ) : picture->evaluatedPath() );
+      mResults.append( res );
+    }
+  }
+
+  return true;
+}
+
+QList<QgsValidityCheckResult> QgsLayoutPictureSourceValidityCheck::runCheck( const QgsValidityCheckContext *, QgsFeedback * )
+{
+  return mResults;
+}

src/app/layout/qgslayoutvaliditychecks.h

@@ -44,3 +44,18 @@ class APP_EXPORT QgsLayoutOverviewValidityCheck : public QgsAbstractValidityChec
   private:
     QList<QgsValidityCheckResult> mResults;
 };
+
+class APP_EXPORT QgsLayoutPictureSourceValidityCheck : public QgsAbstractValidityCheck
+{
+  public:
+
+    QgsLayoutPictureSourceValidityCheck *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;
+};
+

src/app/qgisapp.cpp

@@ -1244,6 +1244,7 @@ QgisApp::QgisApp( QSplashScreen *splash, bool restorePlugins, bool skipVersionCh
 
   QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutScaleBarValidityCheck() );
   QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutOverviewValidityCheck() );
+  QgsApplication::validityCheckRegistry()->addCheck( new QgsLayoutPictureSourceValidityCheck() );
 
   mSplash->showMessage( tr( "Initializing file filters" ), Qt::AlignHCenter | Qt::AlignBottom );
   qApp->processEvents();

src/core/layout/qgslayoutitempicture.cpp

@@ -485,6 +485,8 @@ void QgsLayoutItemPicture::updateMapRotation()
 
 void QgsLayoutItemPicture::loadPicture( const QString &path )
 {
+  mIsMissingImage = false;
+  mEvaluatedPath = path;
   if ( path.startsWith( QLatin1String( "http" ) ) )
   {
     //remote location
@@ -503,6 +505,7 @@ void QgsLayoutItemPicture::loadPicture( const QString &path )
   {
     //trying to load an invalid file or bad expression, show cross picture
     mMode = FormatSVG;
+    mIsMissingImage = true;
     QString badFile( QStringLiteral( ":/images/composer/missing_image.svg" ) );
     mSVG.load( badFile );
     if ( mSVG.isValid() )
@@ -569,6 +572,16 @@ QSizeF QgsLayoutItemPicture::pictureSize()
   }
 }
 
+bool QgsLayoutItemPicture::isMissingImage() const
+{
+  return mIsMissingImage;
+}
+
+QString QgsLayoutItemPicture::evaluatedPath() const
+{
+  return mEvaluatedPath;
+}
+
 void QgsLayoutItemPicture::shapeChanged()
 {
   if ( mMode == FormatSVG && !mLoadingSvg )

src/core/layout/qgslayoutitempicture.h

@@ -94,6 +94,7 @@ class CORE_EXPORT QgsLayoutItemPicture: public QgsLayoutItem
      * this value. The path can either be a local path or a remote (http) path.
      * \returns path for the source image
      * \see setPicturePath()
+     * \see evaluatedPath()
      */
     QString picturePath() const;
 
@@ -230,6 +231,23 @@ class CORE_EXPORT QgsLayoutItemPicture: public QgsLayoutItem
 
     void finalizeRestoreFromXml() override;
 
+    /**
+     * Returns true if the source image is missing and the picture
+     * cannot be rendered.
+     *
+     * \since QGIS 3.6
+     */
+    bool isMissingImage() const;
+
+    /**
+     * Returns the current evaluated picture path, which includes
+     * the result of data defined path overrides.
+     *
+     * \see picturePath()
+     * \since QGIS 3.6
+     */
+    QString evaluatedPath() const;
+
   public slots:
 
     /**
@@ -318,6 +336,8 @@ class CORE_EXPORT QgsLayoutItemPicture: public QgsLayoutItem
     bool mHasExpressionError = false;
     bool mLoaded = false;
     bool mLoadingSvg = false;
+    bool mIsMissingImage = false;
+    QString mEvaluatedPath;
 
     //! Loads an image file into the picture item and redraws the item
     void loadPicture( const QString &path );

tests/src/app/testqgsapplayoutvaliditychecks.cpp

@@ -26,6 +26,7 @@
 #include "qgslayout.h"
 #include "qgslayoutitemscalebar.h"
 #include "qgslayoutitemmap.h"
+#include "qgslayoutitempicture.h"
 #include "qgsabstractvaliditycheck.h"
 #include "qgsvaliditycheckcontext.h"
 #include "layout/qgslayoutvaliditychecks.h"
@@ -46,6 +47,7 @@ class TestQgsLayoutValidityChecks : public QObject
 
     void testScaleBarValidity();
     void testOverviewValidity();
+    void testPictureValidity();
 
   private:
     QString mTestDataDir;
@@ -158,6 +160,63 @@ void TestQgsLayoutValidityChecks::testOverviewValidity()
   QCOMPARE( res.at( 1 ).type, QgsValidityCheckResult::Warning );
 }
 
+void TestQgsLayoutValidityChecks::testPictureValidity()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+
+  QgsLayoutItemPicture *picture = new QgsLayoutItemPicture( &l );
+  l.addItem( picture );
+
+  QgsLayoutValidityCheckContext context( &l );
+  QgsFeedback f;
+
+  // invalid picture source
+  picture->setPicturePath( QStringLiteral( "blaaaaaaaaaaaaaaaaah" ) );
+  QgsLayoutPictureSourceValidityCheck check;
+  QVERIFY( check.prepareCheck( &context, &f ) );
+  QList< QgsValidityCheckResult > res = check.runCheck( &context, &f );
+  QCOMPARE( res.size(), 1 );
+  QCOMPARE( res.at( 0 ).type, QgsValidityCheckResult::Warning );
+
+  QgsLayoutPictureSourceValidityCheck check2;
+  picture->setPicturePath( QString() );
+  QVERIFY( check2.prepareCheck( &context, &f ) );
+  res = check2.runCheck( &context, &f );
+  QCOMPARE( res.size(), 0 );
+
+  QgsLayoutPictureSourceValidityCheck check3;
+  picture->setPicturePath( QStringLiteral( TEST_DATA_DIR ) + "/sample_svg.svg" );
+  QVERIFY( check3.prepareCheck( &context, &f ) );
+  res = check3.runCheck( &context, &f );
+  QCOMPARE( res.size(), 0 );
+
+  QgsLayoutItemPicture *picture2 = new QgsLayoutItemPicture( &l );
+  l.addItem( picture2 );
+  picture2->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty::fromExpression( QStringLiteral( "'d:/bad' || 'robot'" ) ) );
+  l.refresh();
+
+  QgsLayoutPictureSourceValidityCheck check4;
+  QVERIFY( check4.prepareCheck( &context, &f ) );
+  res = check4.runCheck( &context, &f );
+  QCOMPARE( res.size(), 1 );
+  QCOMPARE( res.at( 0 ).type, QgsValidityCheckResult::Warning );
+
+  picture2->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty::fromExpression( QStringLiteral( "''" ) ) );
+  l.refresh();
+  QgsLayoutPictureSourceValidityCheck check5;
+  QVERIFY( check5.prepareCheck( &context, &f ) );
+  res = check5.runCheck( &context, &f );
+  QCOMPARE( res.size(), 0 );
+
+  picture2->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty::fromExpression( QStringLiteral( "'%1'" ).arg( QStringLiteral( TEST_DATA_DIR ) + "/sam' || 'ple_svg.svg" ) ) );
+  l.refresh();
+  QgsLayoutPictureSourceValidityCheck check6;
+  QVERIFY( check6.prepareCheck( &context, &f ) );
+  res = check6.runCheck( &context, &f );
+  QCOMPARE( res.size(), 0 );
+}
+
 
 
 QGSTEST_MAIN( TestQgsLayoutValidityChecks )

tests/src/core/testqgslayoutpicture.cpp

@@ -60,6 +60,7 @@ class TestQgsLayoutPicture : public QObject
 
     void pictureExpression();
     void pictureInvalidExpression();
+    void valid();
 
 
   private:
@@ -422,5 +423,32 @@ void TestQgsLayoutPicture::pictureInvalidExpression()
   mPicture->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty() );
 }
 
+void TestQgsLayoutPicture::valid()
+{
+  QgsProject p;
+  QgsLayout l( &p );
+
+  QgsLayoutItemPicture *picture = new QgsLayoutItemPicture( &l );
+  l.addItem( picture );
+
+  picture->setPicturePath( mPngImage );
+  QVERIFY( !picture->isMissingImage() );
+  QCOMPARE( picture->evaluatedPath(), mPngImage );
+
+  picture->setPicturePath( QStringLiteral( "bad" ) );
+  QVERIFY( picture->isMissingImage() );
+  QCOMPARE( picture->evaluatedPath(), QStringLiteral( "bad" ) );
+
+  picture->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty::fromExpression( QStringLiteral( "'%1'" ).arg( mSvgImage ) ) );
+  picture->refreshPicture();
+  QVERIFY( !picture->isMissingImage() );
+  QCOMPARE( picture->evaluatedPath(), mSvgImage );
+
+  picture->dataDefinedProperties().setProperty( QgsLayoutObject::PictureSource, QgsProperty::fromExpression( QStringLiteral( "'bad'" ) ) );
+  picture->refreshPicture();
+  QVERIFY( picture->isMissingImage() );
+  QCOMPARE( picture->evaluatedPath(), QStringLiteral( "bad" ) );
+}
+
 QGSTEST_MAIN( TestQgsLayoutPicture )
 #include "testqgslayoutpicture.moc"