wallpapers/image: force reload wallpaper after target size changes

When the target size changes while the provider type is single image
or the current wallpaper is animated, the frontend is required to force
update the wallpaper.

wallpapers/image/imagepackage/contents/ui/main.qml

@@ -89,6 +89,7 @@ QQC2.StackView {
         }
         targetSize: root.sourceSize
 
+        onActualSizeChanged: Qt.callLater(loadImage);
         onColorSchemeChanged: loadImageImmediately();
     }
 

wallpapers/image/plugin/utils/mediaproxy.cpp

@@ -91,8 +91,13 @@ void MediaProxy::setTargetSize(const QSize &size)
     Q_EMIT targetSizeChanged(size);
 
     if (m_providerType == Provider::Type::Package) {
+        determineBackgroundType(); // In case file format changes after size changes
         updateModelImage();
     }
+    if (m_providerType == Provider::Type::Image || m_backgroundType == BackgroundType::Type::AnimatedImage) {
+        // When KPackage contains animated wallpapers, image provider is not used.
+        Q_EMIT actualSizeChanged();
+    }
 }
 
 Provider::Type MediaProxy::providerType() const

wallpapers/image/plugin/utils/mediaproxy.h

@@ -77,6 +77,13 @@ Q_SIGNALS:
 
     void targetSizeChanged(const QSize &size);
 
+    /**
+     * Emitted when the target size changes while the provider type is single image
+     * or the current wallpaper is animated.
+     * The frontend is required to force update the wallpaper.
+     */
+    void actualSizeChanged();
+
     /**
      * Emitted when system color scheme changes. The frontend is required to
      * reload the wallpaper even if the image path is not changed.