Allow showing larger images and show error if too big

Author: svetter

src/viewer/ascent_viewer.cpp

@@ -490,9 +490,30 @@ void AscentViewer::changeToPhoto(int photoIndex, bool saveDescriptionFirst)
 	}
 	else {
 		QString filepath = photos.at(currentPhotoIndex).filepath;
+		QImageReader::setAllocationLimit(512);
+
+		// Set up error message capturing
+		imageLoadErrorMessage.clear();
+		qInstallMessageHandler([] (QtMsgType type, const QMessageLogContext& context, const QString& msg) {
+			Q_UNUSED(type);
+			Q_UNUSED(context);
+			if (!msg.startsWith("QImageIOHandler: ")) return;
+			QString trimmedMessage = msg;
+			trimmedMessage.remove("QImageIOHandler: ");
+			AscentViewer::imageErrorMessageOccurred(trimmedMessage);
+		});
+
 		QImageReader reader = QImageReader(filepath);
 		reader.setAutoTransform(true);
 		QImage image = reader.read();
+
+		// Fetch printed error message
+		qInstallMessageHandler(nullptr);
+		QString extraErrorMessage = imageLoadErrorMessage;
+		imageLoadErrorMessage.clear();
+		if (!extraErrorMessage.isEmpty()) {
+			extraErrorMessage = tr("\nMore details: %1.").arg(extraErrorMessage);
+		}
 
 		if (!image.isNull()) {	// Image loaded
 			// Prepare image frame to show image
@@ -504,8 +525,9 @@ void AscentViewer::changeToPhoto(int photoIndex, bool saveDescriptionFirst)
 			QString labelText = tr(
 				"This image file cannot be shown:\n%1"
 				"\nReason: %2."
+				"%3"
 				"\n\nYou can remove the image, replace the file, or mass relocate image files in the whole database.")
-				.arg(filepath, reader.errorString());	// Error string is already translated
+				.arg(filepath, reader.errorString(), extraErrorMessage);	// Error string is already translated
 			imageErrorLabel->setText(labelText);
 
 			// Show image error box
@@ -1011,6 +1033,20 @@ void AscentViewer::handle_filesDropped(QStringList filepaths)
 
 
 
+/**
+ * Globally accessible static function for receiving error messages from QImageReader.
+ * 
+ * This function is used because qInstallMessageHandler() does not allow capturing in lambdas.
+ * 
+ * @param message	The error message with its prefix already removed.
+ */
+void AscentViewer::imageErrorMessageOccurred(const QString& message)
+{
+	imageLoadErrorMessage = message;
+}
+
+
+
 /**
  * Spawns the info area context menu at the given position and controls the enabled state of its
  * actions.

src/viewer/ascent_viewer.h

@@ -99,6 +99,10 @@ class AscentViewer : public QDialog, public Ui_AscentViewer {
 	/** Context menu action for editing the current ascent's trip. */
 	QAction* editTripAction;
 
+private:
+	/** Temporary global static variable for error messages printed when loading images. */
+	inline static QString imageLoadErrorMessage = QString();
+	
 public:
 	AscentViewer(MainWindow* parent, Database* db, const ItemTypesHandler* typesHandler, ViewRowIndex viewRowIndex);
 	virtual ~AscentViewer();
@@ -172,6 +176,9 @@ private slots:
 	// Files dropped on image frame
 	void handle_filesDropped(QStringList filepaths);
 
+	// Error message capture
+	static void imageErrorMessageOccurred(const QString& message);
+	
 private:
 	// Helpers
 	void popupInfoContextMenu(QPoint pos);