Add Processing example and fix typos in Python comments

Author: robertpoll

Processing/HelloWorld/HelloWorld.pde

@@ -0,0 +1,108 @@
+import processing.net.*;
+
+/*
+   Very simple example of how to use the Line-us API. The most important thing to
+   remember is to read the response after sending a command. The TCP buffer on
+   Line-us is small and it does not cope well with having to buffer more than
+   one message.
+
+   Good Luck!
+*/
+
+LineUs myLineUs;
+
+void setup() {
+  myLineUs = new LineUs(this);
+}
+
+void draw() {
+  
+  delay(1000);
+  
+  myLineUs.g01(900, 300, 0);
+  myLineUs.g01(900, -300, 0);
+  myLineUs.g01(900, -300, 1000);
+
+  myLineUs.g01(1200, 300, 0);
+  myLineUs.g01(1200, -300, 0);
+  myLineUs.g01(1200, -300, 1000);
+
+  myLineUs.g01(900, 0, 0);
+  myLineUs.g01(1200, 0, 0);
+  myLineUs.g01(1200, 0, 1000);
+
+  myLineUs.g01(1500, 150, 0);
+  myLineUs.g01(1500, -300, 0);
+  myLineUs.g01(1500, -300, 1000);
+
+  myLineUs.g01(1500, 250, 0);
+  myLineUs.g01(1500, 300, 0);
+  myLineUs.g01(1500, 300, 1000);
+  
+  delay(1000);
+  
+  exit();
+}
+
+//An example class to show how to use the Line-us API
+
+class LineUs {
+  
+  Client lineUs;
+  Boolean connected = false;
+  String helloMessage;
+  
+  LineUs(PApplet papp) {
+    lineUs = new Client(papp, "line-us.local", 1337);
+    connected = true;
+    helloMessage = readResponse();
+  }
+  
+  String getHelloString() {
+    if(connected) {
+      return helloMessage;
+    } else {
+      return("Not connected");
+    }
+  }
+  
+  //Close the connection to the Line-us
+  void disconnect() {
+    lineUs.stop();
+    connected = false;
+  }
+  
+  //Send a G01 (interpolated move), and wait for the response before returning
+  void g01(int x, int y, int z) {
+    String cmd = "G01 X";
+    cmd += str(x);
+    cmd += " Y";
+    cmd += str(y);
+    cmd += " Z";
+    cmd += str(z);
+    sendCommand(cmd);
+    readResponse();
+  }
+  
+  //Read from the socket one byte at a time until we get a null
+  String readResponse() {
+    String line = "";
+    int c;
+    while(true) {
+       c = lineUs.read();
+       if(c != 0 && c != -1) {
+         line += (char) c;
+       } else if(c == 0) {
+         break;
+       }
+    }
+    return line;
+  }
+  
+  //Send the command to Line-us
+  void sendCommand(String command) {
+    command += "\0";
+    lineUs.write(command);
+  }
+  
+}

Python/HelloWorld.py

@@ -23,7 +23,7 @@ def disconnect(self):
         self.__connected = False
 
     def g01(self, x, y, z):
-        """Send a G01 (interpolated move, and wait for the response before returning"""
+        """Send a G01 (interpolated move), and wait for the response before returning"""
         cmd = b'G01 X'
         cmd += str(x).encode()
         cmd += b' Y'
@@ -34,7 +34,7 @@ def g01(self, x, y, z):
         self.__read_response()
 
     def __read_response(self):
-        """Read form the socket one byte at a time until we get a null"""
+        """Read from the socket one byte at a time until we get a null"""
         line = b''
         while True:
             char = self.__line_us.recv(1)

README.md

@@ -11,6 +11,7 @@ Line-us can be controlled using a simple TCP sockets API. The commands are a sub
 - [Co-ordinate System](#co-ordinate-system)
 - [CAUTION for firmware 1.0.1 and lower](#caution-for-firmware-101-and-lower)
 - [Simple Python Example](#simple-python-example)
+- [Simple Processing Example](#simple-processing-example)
 
 ### Making a Connection
 The default name for Line-us is `line-us`, although it can be changed using the `M550` Gcode command or using the App. Line-us supports mDNS (Bonjour) so by default the hostname will be `line-us.local` and it listens on port 1337. The connection to Line-us can be tested with a telnet client by using the command `telnet line-us.local 1337`. On a successful connection Line-us will respond with a `hello` message followed by `KEY:value` pairs for `VERSION` (firmware version number) `NAME` (the name of the Line-us) and `SERIAL` (the serial number of the Line-us). The `hello` message (like all messages from Line-us) is terminated with `\r\n\0`. It is **very important that the full `hello` message is read from the socket including the `\0` before any commands are sent**.
@@ -33,3 +34,5 @@ It should not be possible to send a GCode that overstretches the arm, or causes
 ### Simple Python Example
 [Source code](Python/HelloWorld.py#L1) for a very simple example can be downloaded from [here](../../raw/master/Python/HelloWorld.py). The example works with Python 2.7 and Python 3, but Python 3 is preferred.
 
+### Simple Processing Example
+[Source code](Processing/HelloWorld/HelloWorld.pde#L1) for a very simple example can be downloaded from [here](../../raw/master/Processing/HelloWorld). The example works with with Processing 3.3.7 (Java).