fix: stackoverflow on image fallback chain (#1028)

Author: aurelleb

vicinae/src/ui/image/image.cpp

@@ -94,8 +94,9 @@ void ImageWidget::setObjectFit(ObjectFit fit) {
   update();
 }
 
-void ImageWidget::setUrl(const ImageURL &url) {
+void ImageWidget::setUrl(ImageURL url) {
   if (url == m_source) { return; }
+  m_isFallback = false;
   m_source = url;
   setUrlImpl(url);
 }
@@ -115,7 +116,7 @@ const ImageURL &ImageWidget::url() const { return m_source; }
 
 void ImageWidget::refreshTheme(const ThemeFile &theme) { setUrlImpl(m_source); }
 
-void ImageWidget::setUrlImpl(const ImageURL &url) {
+void ImageWidget::setUrlImpl(ImageURL url) {
   auto &theme = ThemeService::instance().theme();
   auto type = url.type();
 
@@ -174,7 +175,7 @@ void ImageWidget::setUrlImpl(const ImageURL &url) {
     m_loader.reset(new EmojiImageLoader(url.name()));
   }
 
-  if (!m_loader) { return handleLoadingError("No loader"); }
+  if (!m_loader) { handleLoadingError("No loader"); }
 
   if (m_loader) {
     connect(m_loader.get(), &AbstractImageLoader::dataUpdated, this,
@@ -192,8 +193,15 @@ QSize ImageWidget::sizeHint() const {
 }
 
 void ImageWidget::handleLoadingError(const QString &reason) {
-  if (auto fallback = m_source.fallback()) { return setUrlImpl(*fallback); }
-  return setUrlImpl(ImageURL::builtin("question-mark-circle"));
+  if (!m_isFallback) {
+    if (auto fallback = m_source.fallback()) {
+      m_isFallback = true;
+      setUrlImpl(*fallback);
+      return;
+    }
+  }
+
+  setUrlImpl(ImageURL::builtin("question-mark-circle"));
 }
 
 void ImageWidget::resizeEvent(QResizeEvent *event) {

vicinae/src/ui/image/image.hpp

@@ -53,7 +53,7 @@ class ImageWidget : public QWidget {
   void setAlignment(Qt::Alignment alignment);
   void setObjectFit(ObjectFit fit);
   const ImageURL &url() const;
-  void setUrl(const ImageURL &url);
+  void setUrl(ImageURL url);
   void setData(const QPixmap &pixmap);
   ImageWidget(QWidget *parent = nullptr);
   ~ImageWidget();
@@ -65,18 +65,18 @@ class ImageWidget : public QWidget {
   void showEvent(QShowEvent *event) override;
   void handleDataUpdated(const QPixmap &data, bool cachable);
   QSize sizeHint() const override;
-  void setUrlImpl(const ImageURL &url);
+  void setUrlImpl(ImageURL url);
   void refreshTheme(const ThemeFile &theme);
   QString sizedCacheKey(const QString &key, const QSize &size) const;
 
   QObjectUniquePtr<AbstractImageLoader> m_loader;
   QPixmap m_data;
   ImageURL m_source;
-  QString m_fallback;
   int m_renderCount = 0;
   uint8_t m_token = 0;
   ObjectFit m_fit = ObjectFit::Contain;
   QFlags<Qt::AlignmentFlag> m_alignment = Qt::AlignCenter;
   std::optional<ColorLike> m_backgroundColor;
   int m_borderRadius = 4;
+  bool m_isFallback = false;
 };