Implement sending content from progmem

make the example editor run from progmem

src/ESPAsyncWebServer.h

@@ -209,6 +209,8 @@ class AsyncWebServerRequest {
     void send(Stream &stream, String contentType, size_t len);
     void send(String contentType, size_t len, AwsResponseFiller callback);
     void sendChunked(String contentType, AwsResponseFiller callback);
+    void send_P(int code, String contentType, const uint8_t * content, size_t len);
+    void send_P(int code, String contentType, PGM_P content);
 
     AsyncWebServerResponse *beginResponse(int code, String contentType=String(), String content=String());
     AsyncWebServerResponse *beginResponse(FS &fs, String path, String contentType=String(), bool download=false);
@@ -217,6 +219,8 @@ class AsyncWebServerRequest {
     AsyncWebServerResponse *beginResponse(String contentType, size_t len, AwsResponseFiller callback);
     AsyncWebServerResponse *beginChunkedResponse(String contentType, AwsResponseFiller callback);
     AsyncResponseStream *beginResponseStream(String contentType, size_t bufferSize=1460);
+    AsyncWebServerResponse *beginResponse_P(int code, String contentType, const uint8_t * content, size_t len);
+    AsyncWebServerResponse *beginResponse_P(int code, String contentType, PGM_P content);
 
     int headers();                     // get header count
     bool hasHeader(String name);

src/WebRequest.cpp

@@ -673,6 +673,14 @@ AsyncResponseStream * AsyncWebServerRequest::beginResponseStream(String contentT
   return new AsyncResponseStream(contentType, bufferSize);
 }
 
+AsyncWebServerResponse * AsyncWebServerRequest::beginResponse_P(int code, String contentType, const uint8_t * content, size_t len){
+  return new AsyncProgmemResponse(code, contentType, content, len);
+}
+
+AsyncWebServerResponse * AsyncWebServerRequest::beginResponse_P(int code, String contentType, PGM_P content){
+  return beginResponse_P(code, contentType, (const uint8_t *)content, strlen_P(content));
+}
+
 void AsyncWebServerRequest::send(int code, String contentType, String content){
   send(beginResponse(code, contentType, content));
 }
@@ -701,6 +709,14 @@ void AsyncWebServerRequest::sendChunked(String contentType, AwsResponseFiller ca
   send(beginChunkedResponse(contentType, callback));
 }
 
+void AsyncWebServerRequest::send_P(int code, String contentType, const uint8_t * content, size_t len){
+  send(beginResponse_P(code, contentType, content, len));
+}
+
+void AsyncWebServerRequest::send_P(int code, String contentType, PGM_P content){
+  send(beginResponse_P(code, contentType, content));
+}
+
 void AsyncWebServerRequest::redirect(String url){
   AsyncWebServerResponse * response = beginResponse(302);
   response->addHeader("Location",url);

src/WebResponseImpl.h

@@ -81,6 +81,15 @@ class AsyncChunkedResponse: public AsyncAbstractResponse {
     size_t _fillBuffer(uint8_t *buf, size_t maxLen);
 };
 
+class AsyncProgmemResponse: public AsyncAbstractResponse {
+  private:
+    const uint8_t * _content;
+  public:
+    AsyncProgmemResponse(int code, String contentType, const uint8_t * content, size_t len);
+    bool _sourceValid(){ return true; }
+    size_t _fillBuffer(uint8_t *buf, size_t maxLen);
+};
+
 class cbuf;
 
 class AsyncResponseStream: public AsyncAbstractResponse, public Print {

src/WebResponses.cpp

@@ -471,6 +471,27 @@ size_t AsyncChunkedResponse::_fillBuffer(uint8_t *data, size_t len){
   return _content(data, len, _sentLength);
 }
 
+/*
+ * Progmem Response
+ * */
+
+AsyncProgmemResponse::AsyncProgmemResponse(int code, String contentType, const uint8_t * content, size_t len){
+  _code = code;
+  _content = content;
+  _contentType = contentType;
+  _contentLength = len;
+}
+
+size_t AsyncProgmemResponse::_fillBuffer(uint8_t *data, size_t len){
+  size_t left = _contentLength - _sentLength;
+    if (left > len) {
+      memcpy_P(data, _content + _sentLength, len);
+      return len;
+    }
+    memcpy_P(data, _content + _sentLength, left);
+    return left;
+}
+
 
 /*
  * Response Stream (You can print/write/printf to it, up to the contentLen bytes)