add load image from url

src/asset.cpp

@@ -150,6 +150,79 @@ bool Asset::create_dir(const std::string& path)
 #endif
 }
 
+static size_t curl_data_handler_asset(void* contents, size_t size, size_t nmemb, void* userp)
+{
+    auto buffer = reinterpret_cast<std::vector<uint8_t>*>(userp);
+    buffer->insert(buffer->end(), (char*)contents, (char*)contents + (size * nmemb));
+    return size * nmemb;
+}
+
+static int progress_callback_asset_download(void* clientp, curl_off_t dltotal,
+    curl_off_t dlnow, curl_off_t ultotal, curl_off_t ulnow)
+{
+    Asset* ass = static_cast<Asset*>(clientp);
+    if (ass->m_stop_async)
+    {
+        LOG("interrupt download of %s", ass->m_current_url.c_str());
+        return 1;
+    }
+    float p = dltotal > 0 ? (float)dlnow / (float)dltotal : 0.f;
+    bool cont = ass->on_progress(p);
+    return cont ? 0 : 1;
+}
+
+bool Asset::open_url(const std::string& url, std::function<bool(float)> progress /*= nullptr*/)
+{
+    CURL* curl = curl_easy_init();
+    if (curl)
+    {
+        close();
+        LOG("download %s", url.c_str());
+        m_current_url = url;
+        std::vector<uint8_t> data;
+        curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
+        curl_easy_setopt(curl, CURLOPT_WRITEDATA, &data);
+        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, curl_data_handler_asset);
+#ifdef __ANDROID__
+        curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 0L);
+#endif
+        if (progress)
+        {
+            on_progress = progress;
+            curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, progress_callback_asset_download);
+            curl_easy_setopt(curl, CURLOPT_XFERINFODATA, this);
+            curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0);
+        }
+        auto err = curl_easy_perform(curl);
+        curl_easy_cleanup(curl);
+        
+        if (err == CURLE_OK)
+        {
+            if (m_data)
+                delete m_data;
+            m_data = new uint8_t[data.size()];
+            std::copy(data.begin(), data.end(), m_data);
+            m_len = data.size();
+            return true;
+        }
+    }
+    return false;
+}
+
+std::future<bool>& Asset::open_url_async(const std::string& url, 
+    std::function<bool(float)> progress /*= nullptr*/, std::function<void(bool)> complete /*= nullptr*/)
+{
+    close_remote();
+    m_stop_async = false;
+    remote_future = std::async([this, url, progress, complete] {
+        bool ok = open_url(url, progress);
+        if (ok && complete)
+            complete(ok);
+        return ok;
+    });
+    return remote_future;
+}
+
 bool Asset::open(const char* path)
 {
     //LOG("Asset::open %s", path);
@@ -249,3 +322,18 @@ void Asset::close()
     m_fp = nullptr;
 #endif
 }
+
+void Asset::close_remote()
+{
+    if (remote_future.valid())
+    {
+        m_stop_async = true;
+        remote_future.get();
+    }
+}
+
+Asset::~Asset()
+{
+    close_remote();
+    close();
+}