MarkdownEditor: guess image suffix when fetching images to local

src/utils/imageutils.cpp

@@ -0,0 +1,18 @@
+#include "imageutils.h"
+
+#include <QMimeDatabase>
+
+using namespace vnotex;
+
+QImage::Format ImageUtils::guessImageFormat(const QByteArray &p_data)
+{
+    auto image = QImage::fromData(p_data);
+    return image.format();
+}
+
+QString ImageUtils::guessImageSuffix(const QByteArray &p_data)
+{
+    QMimeDatabase mimeDb;
+    auto mimeType = mimeDb.mimeTypeForData(p_data);
+    return mimeType.preferredSuffix();
+}

src/utils/imageutils.h

@@ -0,0 +1,19 @@
+#ifndef IMAGEUTILS_H
+#define IMAGEUTILS_H
+
+#include <QImage>
+
+namespace vnotex
+{
+    class ImageUtils
+    {
+    public:
+        ImageUtils() = delete;
+
+        static QImage::Format guessImageFormat(const QByteArray &p_data);
+
+        static QString guessImageSuffix(const QByteArray &p_data);
+    };
+}
+
+#endif // IMAGEUTILS_H

src/utils/utils.pri

@@ -4,6 +4,7 @@ SOURCES += \
     $$PWD/contentmediautils.cpp \
     $$PWD/docsutils.cpp \
     $$PWD/htmlutils.cpp \
+    $$PWD/imageutils.cpp \
     $$PWD/pathutils.cpp \
     $$PWD/processutils.cpp \
     $$PWD/textutils.cpp \
@@ -19,6 +20,7 @@ HEADERS += \
     $$PWD/contentmediautils.h \
     $$PWD/docsutils.h \
     $$PWD/htmlutils.h \
+    $$PWD/imageutils.h \
     $$PWD/pathutils.h \
     $$PWD/processutils.h \
     $$PWD/textutils.h \

src/widgets/editors/markdowneditor.cpp

@@ -37,6 +37,7 @@
 #include <utils/widgetutils.h>
 #include <utils/textutils.h>
 #include <utils/webutils.h>
+#include <utils/imageutils.h>
 #include <core/exception.h>
 #include <core/markdowneditorconfig.h>
 #include <core/texteditorconfig.h>
@@ -1092,7 +1093,11 @@ void MarkdownEditor::fetchImagesToLocalAndReplace(QString &p_text)
             // Network path.
             QByteArray data = vte::Downloader::download(QUrl(imageUrl));
             if (!data.isEmpty()) {
-                tmpFile.reset(FileUtils::createTemporaryFile(info.suffix()));
+                auto suffix = info.suffix();
+                if (suffix.isEmpty()) {
+                    suffix = ImageUtils::guessImageSuffix(data);
+                }
+                tmpFile.reset(FileUtils::createTemporaryFile(suffix));
                 if (tmpFile->open() && tmpFile->write(data) > -1) {
                     srcImagePath = tmpFile->fileName();
                 }