add load image from url

src/asset.h

@@ -13,13 +13,23 @@ public:
     static std::string absolute(const std::string& path);
     static bool is_asset(const std::string& path);
     static bool create_dir(const std::string& path);
+
+    bool m_stop_async = false;
+    std::function<bool(float)> on_progress;
+    std::future<bool> remote_future;
+
     std::string m_current_path;
+    std::string m_current_url;
     FILE* m_fp = nullptr;
     int m_len = 0;
     uint8_t* m_data = nullptr;
     bool open(const char* path);
+    bool open_url(const std::string& url, std::function<bool(float)> progress = nullptr);
+    std::future<bool>& open_url_async(const std::string& url, std::function<bool(float)> progress = nullptr,
+        std::function<void(bool)> complete = nullptr);
     uint8_t* read_all();
     void close();
-    ~Asset() { close(); }
+    void close_remote();
+    ~Asset();
 };