Notify failures when loading the sprite JSON and image

include/mbgl/util/exception.hpp

@@ -26,6 +26,11 @@ struct SourceLoadingException : Exception {
     inline SourceLoadingException(const std::string &msg) : Exception(msg) {}
 };
 
+struct SpriteLoadingException : Exception {
+    inline SpriteLoadingException(const char *msg) : Exception(msg) {}
+    inline SpriteLoadingException(const std::string &msg) : Exception(msg) {}
+};
+
 }
 }
 

src/mbgl/map/resource_loader.cpp

@@ -126,6 +126,10 @@ void ResourceLoader::onSpriteLoaded() {
     emitTileDataChanged();
 }
 
+void ResourceLoader::onSpriteLoadingFailed(std::exception_ptr error) {
+    emitResourceLoadingFailed(error);
+}
+
 void ResourceLoader::emitTileDataChanged() {
     assert(Environment::currentlyOn(ThreadType::Map));
 

src/mbgl/map/resource_loader.hpp

@@ -71,6 +71,7 @@ public:
 
     // Sprite::Observer implementation.
     void onSpriteLoaded() override;
+    void onSpriteLoadingFailed(std::exception_ptr error) override;
 
 private:
     void emitTileDataChanged();

src/mbgl/map/sprite.cpp

@@ -1,17 +1,20 @@
 #include <mbgl/map/sprite.hpp>
-#include <mbgl/util/raster.hpp>
-#include <mbgl/platform/log.hpp>
 
-#include <string>
-#include <mbgl/platform/platform.hpp>
 #include <mbgl/map/environment.hpp>
+#include <mbgl/platform/log.hpp>
+#include <mbgl/platform/platform.hpp>
 #include <mbgl/storage/resource.hpp>
 #include <mbgl/storage/response.hpp>
-#include <mbgl/util/uv_detail.hpp>
+#include <mbgl/util/exception.hpp>
+#include <mbgl/util/raster.hpp>
 #include <mbgl/util/std.hpp>
+#include <mbgl/util/uv_detail.hpp>
 
 #include <rapidjson/document.h>
 
+#include <string>
+#include <sstream>
+
 using namespace mbgl;
 
 SpritePosition::SpritePosition(uint16_t x_, uint16_t y_, uint16_t width_, uint16_t height_, float pixelRatio_, bool sdf_)
@@ -39,25 +42,31 @@ Sprite::Sprite(const std::string& baseUrl, float pixelRatio_)
     std::string spriteURL(baseUrl + (pixelRatio_ > 1 ? "@2x" : "") + ".png");
     std::string jsonURL(baseUrl + (pixelRatio_ > 1 ? "@2x" : "") + ".json");
 
-    jsonRequest = env.request({ Resource::Kind::JSON, jsonURL }, [this](const Response &res) {
+    jsonRequest = env.request({ Resource::Kind::JSON, jsonURL }, [this, jsonURL](const Response &res) {
         jsonRequest = nullptr;
         if (res.status == Response::Successful) {
             body = res.data;
             parseJSON();
         } else {
-            Log::Warning(Event::Sprite, "Failed to load sprite info: %s", res.message.c_str());
+            std::stringstream message;
+            message <<  "Failed to load [" << jsonURL << "]: " << res.message;
+            emitSpriteLoadingFailed(message.str());
+            return;
         }
         loadedJSON = true;
         emitSpriteLoadedIfComplete();
     });
 
-    spriteRequest = env.request({ Resource::Kind::Image, spriteURL }, [this](const Response &res) {
+    spriteRequest = env.request({ Resource::Kind::Image, spriteURL }, [this, spriteURL](const Response &res) {
         spriteRequest = nullptr;
         if (res.status == Response::Successful) {
             image = res.data;
             parseImage();
         } else {
-            Log::Warning(Event::Sprite, "Failed to load sprite image: %s", res.message.c_str());
+            std::stringstream message;
+            message <<  "Failed to load [" << spriteURL << "]: " << res.message;
+            emitSpriteLoadingFailed(message.str());
+            return;
         }
         loadedImage = true;
         emitSpriteLoadedIfComplete();
@@ -80,6 +89,15 @@ void Sprite::emitSpriteLoadedIfComplete() {
     }
 }
 
+void Sprite::emitSpriteLoadingFailed(const std::string& message) {
+    if (!observer) {
+        return;
+    }
+
+    auto error = std::make_exception_ptr(util::SpriteLoadingException(message));
+    observer->onSpriteLoadingFailed(error);
+}
+
 bool Sprite::isLoaded() const {
     return loadedImage && loadedJSON;
 }

src/mbgl/map/sprite.hpp

@@ -39,6 +39,7 @@ public:
         virtual ~Observer() = default;
 
         virtual void onSpriteLoaded() = 0;
+        virtual void onSpriteLoadingFailed(std::exception_ptr error) = 0;
     };
 
     Sprite(const std::string& baseUrl, float pixelRatio);
@@ -56,6 +57,7 @@ public:
     void setObserver(Observer* observer);
 private:
     void emitSpriteLoadedIfComplete();
+    void emitSpriteLoadingFailed(const std::string& message);
 
     void parseJSON();
     void parseImage();