Correctly handle empty paths in QgsImageCache

Author: nyalldawson

src/core/qgsimagecache.cpp

@@ -101,8 +101,13 @@ QgsImageCache::QgsImageCache( QObject *parent )
   connect( this, &QgsAbstractContentCacheBase::remoteContentFetched, this, &QgsImageCache::remoteImageFetched );
 }
 
-QImage QgsImageCache::pathAsImage( const QString &file, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache )
+QImage QgsImageCache::pathAsImage( const QString &f, const QSize size, const bool keepAspectRatio, const double opacity, bool &fitsInCache )
 {
+  const QString file = f.trimmed();
+
+  if ( file.isEmpty() )
+    return QImage();
+
   QMutexLocker locker( &mMutex );
 
   fitsInCache = true;
@@ -141,6 +146,9 @@ QImage QgsImageCache::pathAsImage( const QString &file, const QSize size, const
 
 QSize QgsImageCache::originalSize( const QString &path ) const
 {
+  if ( path.isEmpty() )
+    return QSize();
+
   // direct read if path is a file -- maybe more efficient than going the bytearray route? (untested!)
   if ( QFile::exists( path ) )
   {

tests/src/core/testqgsimagecache.cpp

@@ -53,6 +53,7 @@ class TestQgsImageCache : public QObject
     void size(); // check various size-specific handling
     void opacity(); // check non-opaque image rendering
     void base64();
+    void empty();
 
 };
 
@@ -254,6 +255,22 @@ void TestQgsImageCache::base64()
   QCOMPARE( size.height(), 60 );
 }
 
+void TestQgsImageCache::empty()
+{
+  QgsImageCache cache;
+  bool inCache = false;
+
+  QImage img = cache.pathAsImage( QString(), QSize( 200, 200 ), true, 1.0, inCache );
+  QVERIFY( img.isNull() );
+
+  QVERIFY( !cache.originalSize( QString() ).isValid() );
+
+  img = cache.pathAsImage( QStringLiteral( " " ), QSize( 200, 200 ), true, 1.0, inCache );
+  QVERIFY( img.isNull() );
+
+  QVERIFY( !cache.originalSize( QStringLiteral( " " ) ).isValid() );
+}
+
 bool TestQgsImageCache::imageCheck( const QString &testName, QImage &image, int mismatchCount )
 {
   //draw background