ofUrlFileLoader progress function

libs/openFrameworks/utils/ofURLFileLoader.cpp

@@ -299,6 +299,21 @@ size_t readBody_cb(void * ptr, size_t size, size_t nmemb, void * userdata) {
 	}
 	return 0; /* no more data left to deliver */
 }
+int progress_cb(void* ptr, curl_off_t dltotal, curl_off_t dlnow, curl_off_t ultotal, curl_off_t ulnow) {
+	auto & request = *static_cast<ofHttpRequest*>(ptr);
+	if (request.progressCallback) {
+		float progress = 0.0f;
+		if (request.method == ofHttpRequest::GET && dltotal > 0) {
+			progress = (float)dlnow / (float)dltotal;
+			// note: we may want to support upload and download for POST
+		} else if ((request.method == ofHttpRequest::PUT || request.method == ofHttpRequest::POST) && ultotal > 0) {
+			progress = (float)ulnow / (float)ultotal;
+		}
+
+		request.progressCallback(request, progress);
+	}
+	return 0;
+}
 }
 
 ofHttpResponse ofURLFileLoaderImpl::handleRequest(const ofHttpRequest & request) {
@@ -412,6 +427,13 @@ ofHttpResponse ofURLFileLoaderImpl::handleRequest(const ofHttpRequest & request)
 	// start request and receive response
 	ofHttpResponse response(request, 0, "");
 	CURLcode err = CURLE_OK;
+
+	if (request.progressCallback) {
+		curl_easy_setopt(curl.get(), CURLOPT_XFERINFOFUNCTION, progress_cb);
+		curl_easy_setopt(curl.get(), CURLOPT_XFERINFODATA, &request);
+		curl_easy_setopt(curl.get(), CURLOPT_NOPROGRESS, 0L);
+	}
+
 	if (request.saveTo) {
 		ofFile saveTo(request.name, ofFile::WriteOnly, true);
 		curl_easy_setopt(curl.get(), CURLOPT_WRITEDATA, &saveTo);

libs/openFrameworks/utils/ofURLFileLoader.h

@@ -23,6 +23,7 @@ class ofHttpRequest {
 	std::string body; ///< POST body data
 	std::string contentType; ///< POST data mime type
 	std::function<void(const ofHttpResponse &)> done;
+	std::function<void(const ofHttpRequest &, float)> progressCallback = nullptr; ///< pass a function for progress of download
 	size_t timeoutSeconds = 0;
 	bool headerOnly = false;