LibWeb: Until an image has loaded or failed, don't occupy layout size

This patch makes images have an implicit zero intrinsic size before
they have either loaded or failed to load. This is tracked by the
ImageLoader object.

This fixes a long-standing issue with images occupying empty 150x150
rectangles of space.

Libraries/LibWeb/Layout/LayoutImage.cpp

@@ -54,20 +54,27 @@ int LayoutImage::preferred_height() const
 
 void LayoutImage::layout(LayoutMode layout_mode)
 {
-    if (m_image_loader.width()) {
+    if (!m_image_loader.has_loaded_or_failed()) {
         set_has_intrinsic_width(true);
-        set_intrinsic_width(m_image_loader.width());
-    }
-    if (m_image_loader.height()) {
         set_has_intrinsic_height(true);
-        set_intrinsic_height(m_image_loader.height());
+        set_intrinsic_width(0);
-    }
+        set_intrinsic_height(0);
-
-    if (m_image_loader.width() && m_image_loader.height()) {
-        set_has_intrinsic_ratio(true);
-        set_intrinsic_ratio((float)m_image_loader.width() / (float)m_image_loader.height());
     } else {
-        set_has_intrinsic_ratio(false);
+        if (m_image_loader.width()) {
+            set_has_intrinsic_width(true);
+            set_intrinsic_width(m_image_loader.width());
+        }
+        if (m_image_loader.height()) {
+            set_has_intrinsic_height(true);
+            set_intrinsic_height(m_image_loader.height());
+        }
+
+        if (m_image_loader.width() && m_image_loader.height()) {
+            set_has_intrinsic_ratio(true);
+            set_intrinsic_ratio((float)m_image_loader.width() / (float)m_image_loader.height());
+        } else {
+            set_has_intrinsic_ratio(false);
+        }
     }
 
     if (renders_as_alt_text()) {

Libraries/LibWeb/Loader/ImageLoader.cpp

@@ -39,6 +39,7 @@ ImageLoader::ImageLoader()
 
 void ImageLoader::load(const URL& url)
 {
+    m_loading_state = LoadingState::Loading;
     LoadRequest request;
     request.set_url(url);
     set_resource(ResourceLoader::the().load_resource(Resource::Type::Image, request));
@@ -62,11 +63,14 @@ void ImageLoader::resource_did_load()
     ASSERT(resource());
 
     if (!resource()->mime_type().starts_with("image/")) {
+        m_loading_state = LoadingState::Failed;
         if (on_fail)
             on_fail();
         return;
     }
 
+    m_loading_state = LoadingState::Loaded;
+
 #ifdef IMAGE_LOADER_DEBUG
     if (!resource()->has_encoded_data()) {
         dbg() << "ImageLoader: Resource did load, no encoded data. URL: " << resource()->url();
@@ -118,6 +122,7 @@ void ImageLoader::animate()
 void ImageLoader::resource_did_fail()
 {
     dbg() << "ImageLoader: Resource did fail. URL: " << resource()->url();
+    m_loading_state = LoadingState::Failed;
     if (on_fail)
         on_fail();
 }

Libraries/LibWeb/Loader/ImageLoader.h

@@ -42,6 +42,8 @@ public:
 
     bool has_image() const;
 
+    bool has_loaded_or_failed() const { return m_loading_state != LoadingState::Loading; }
+
     void set_visible_in_viewport(bool) const;
 
     unsigned width() const;
@@ -59,10 +61,18 @@ private:
 
     void animate();
 
+    enum class LoadingState {
+        None,
+        Loading,
+        Loaded,
+        Failed,
+    };
+
     mutable bool m_visible_in_viewport { false };
 
     size_t m_current_frame_index { 0 };
     size_t m_loops_completed { 0 };
+    LoadingState m_loading_state { LoadingState::Loading };
     NonnullRefPtr<Core::Timer> m_timer;
 };