v1.4.0 to reduce String usage

### Major Releases v1.4.0

1. Reduce usage of Arduino String with std::string
2. Optimize library code and examples by using **reference-passing instead of value-passing**.
3. Fix bug related to String in library and examples
4. Update `Packages' Patches`

Author: khoih-prog

README.md

@@ -1252,7 +1252,7 @@ void handleRoot()
 {
   digitalWrite(led, 1);
 
-#define BUFFER_SIZE     400
+#define BUFFER_SIZE     512
 
   char temp[BUFFER_SIZE];
   int sec = millis() / 1000;
@@ -1305,29 +1305,54 @@ void handleNotFound()
   digitalWrite(led, 0);
 }
 
+#define ORIGINAL_STR_LEN        2048
+
 void drawGraph()
 {
-  String out;
-  out.reserve(3000);
+  static String out;
+  static uint16_t previousStrLen = ORIGINAL_STR_LEN;
+
+  if (out.length() == 0)
+  {
+    ET_LOGWARN1(F("String Len = 0, extend to"), ORIGINAL_STR_LEN);
+    out.reserve(ORIGINAL_STR_LEN);
+  }
+
+  out = F( "<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" width=\"310\" height=\"150\">\n" \
+           "<rect width=\"310\" height=\"150\" fill=\"rgb(250, 230, 210)\" stroke-width=\"3\" stroke=\"rgb(0, 0, 0)\" />\n" \
+           "<g stroke=\"blue\">\n");
+
   char temp[70];
-  out += "<svg xmlns=\"http://www.w3.org/2000/svg\" version=\"1.1\" width=\"310\" height=\"150\">\n";
-  out += "<rect width=\"310\" height=\"150\" fill=\"rgb(250, 230, 210)\" stroke-width=\"1\" stroke=\"rgb(0, 0, 0)\" />\n";
-  out += "<g stroke=\"black\">\n";
+  
   int y = rand() % 130;
 
   for (int x = 10; x < 300; x += 10)
   {
     int y2 = rand() % 130;
-    sprintf(temp, "<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" stroke-width=\"1\" />\n", x, 140 - y, x + 10, 140 - y2);
+    sprintf(temp, "<line x1=\"%d\" y1=\"%d\" x2=\"%d\" y2=\"%d\" stroke-width=\"2\" />\n", x, 140 - y, x + 10, 140 - y2);
     out += temp;
     y = y2;
   }
-  out += "</g>\n</svg>\n";
+  
+  out += F("</g>\n</svg>\n");
+
+  ET_LOGDEBUG1(F("String Len = "), out.length());
+
+  if (out.length() > previousStrLen)
+  {
+    ET_LOGERROR3(F("String Len > "), previousStrLen, F(", extend to"), out.length() + 48);
 
-  server.send(200, "image/svg+xml", out);
+    previousStrLen = out.length() + 48;
+    
+    out.reserve(previousStrLen);
+  }
+  else
+  {
+    server.send(200, "image/svg+xml", out);
+  }
 }
 
-void setup(void)
+void setup()
 {
   pinMode(led, OUTPUT);
   digitalWrite(led, 0);
@@ -1389,9 +1414,42 @@ void setup(void)
   Serial.println(Ethernet.localIP());
 }
 
-void loop(void)
+
+void heartBeatPrint()
+{
+  static int num = 1;
+
+  Serial.print(F("."));
+
+  if (num == 80)
+  {
+    Serial.println();
+    num = 1;
+  }
+  else if (num++ % 10 == 0)
+  {
+    Serial.print(F(" "));
+  }
+}
+
+void check_status()
+{
+  static unsigned long checkstatus_timeout = 0;
+
+#define STATUS_CHECK_INTERVAL     10000L
+
+  // Send status report every STATUS_REPORT_INTERVAL (60) seconds: we don't need to send updates frequently if there is no status change.
+  if ((millis() > checkstatus_timeout) || (checkstatus_timeout == 0))
+  {
+    heartBeatPrint();
+    checkstatus_timeout = millis() + STATUS_CHECK_INTERVAL;
+  }
+}
+
+void loop()
 {
   server.handleClient();
+  check_status();
 }
 ```
 
@@ -1415,8 +1473,8 @@ void loop(void)
 // If USE_BUILTIN_ETHERNET == false and USE_UIP_ETHERNET == false => 
 // either use W5x00 with EthernetXYZ library
 // or ENC28J60 with EthernetENC library
-//#define USE_BUILTIN_ETHERNET    true
-#define USE_BUILTIN_ETHERNET    false
+#define USE_BUILTIN_ETHERNET    true
+//#define USE_BUILTIN_ETHERNET    false
 
 //#define USE_UIP_ETHERNET        true
 #define USE_UIP_ETHERNET        false
@@ -1432,9 +1490,9 @@ void loop(void)
   #define USE_ETHERNET          false //true
   #define USE_ETHERNET2         false //true
   #define USE_ETHERNET3         false //true
-  #define USE_ETHERNET_LARGE    false
+  #define USE_ETHERNET_LARGE    true
   #define USE_ETHERNET_ESP8266  false //true
-  #define USE_ETHERNET_ENC      true
+  #define USE_ETHERNET_ENC      false
   #define USE_CUSTOM_ETHERNET   false
 #endif