Add java, cpp, and python examples

deps/examples/python-multiCameraServer/README.txt

@@ -0,0 +1,17 @@
+=======================
+Building locally on rPi
+=======================
+
+1) Copy multiCameraServer.py and runCamera to /home/pi
+2) Run "./runInteractive" in /home/pi or "sudo svc -t /service/camera" to
+   restart service.
+
+
+===================
+Building on desktop
+===================
+
+1) Copy multiCameraServer.py and runCamera to /home/pi on the Pi
+2) On the Pi, run "./runInteractive" in /home/pi or
+   "sudo svc -t /service/camera" to restart service.
+

deps/examples/python-multiCameraServer/multiCameraServer.py

@@ -0,0 +1,154 @@
+#!/usr/bin/env python3
+#----------------------------------------------------------------------------
+# Copyright (c) 2018 FIRST. All Rights Reserved.
+# Open Source Software - may be modified and shared by FRC teams. The code
+# must be accompanied by the FIRST BSD license file in the root directory of
+# the project.
+#----------------------------------------------------------------------------
+
+import json
+import time
+import sys
+
+from cscore import CameraServer, VideoSource
+from networktables import NetworkTablesInstance
+
+#   JSON format:
+#   {
+#       "team": <team number>,
+#       "ntmode": <"client" or "server", "client" if unspecified>
+#       "cameras": [
+#           {
+#               "name": <camera name>
+#               "path": <path, e.g. "/dev/video0">
+#               "pixel format": <"MJPEG", "YUYV", etc>   // optional
+#               "width": <video mode width>              // optional
+#               "height": <video mode height>            // optional
+#               "fps": <video mode fps>                  // optional
+#               "brightness": <percentage brightness>    // optional
+#               "white balance": <"auto", "hold", value> // optional
+#               "exposure": <"auto", "hold", value>      // optional
+#               "properties": [                          // optional
+#                   {
+#                       "name": <property name>
+#                       "value": <property value>
+#                   }
+#               ]
+#           }
+#       ]
+#   }
+
+configFile = "/boot/frc.json"
+
+class CameraConfig: pass
+
+team = None
+server = False
+cameras = []
+
+"""Report parse error."""
+def parseError(str):
+    print("config error in '" + configFile + "': " + str, file=sys.stderr)
+
+"""Read single camera configuration."""
+def readCameraConfig(config):
+    cam = CameraConfig()
+
+    # name
+    try:
+        cam.name = config["name"]
+    except KeyError:
+        parseError("could not read camera name")
+        return False
+
+    # path
+    try:
+        cam.path = config["path"]
+    except KeyError:
+        parseError("camera '{}': could not read path".format(cam.name))
+        return False
+
+    cam.config = config
+
+    cameras.append(cam)
+    return True
+
+"""Read configuration file."""
+def readConfig():
+    global team
+    global server
+
+    # parse file
+    try:
+        with open(configFile, "rt") as f:
+            j = json.load(f)
+    except OSError as err:
+        print("could not open '{}': {}".format(configFile, err), file=sys.stderr)
+        return False
+
+    # top level must be an object
+    if not isinstance(j, dict):
+        parseError("must be JSON object")
+        return False
+
+    # team number
+    try:
+        team = j["team"]
+    except KeyError:
+        parseError("could not read team number")
+        return False
+
+    # ntmode (optional)
+    if "ntmode" in j:
+        str = j["ntmode"]
+        if str.lower() == "client":
+            server = False
+        elif str.lower() == "server":
+            server = True
+        else:
+            parseError("could not understand ntmode value '{}'".format(str))
+
+    # cameras
+    try:
+        cameras = j["cameras"]
+    except KeyError:
+        parseError("could not read cameras")
+        return False
+    for camera in cameras:
+        if not readCameraConfig(camera):
+            return False
+
+    return True
+
+"""Start running the camera."""
+def startCamera(config):
+    print("Starting camera '{}' on {}".format(config.name, config.path))
+    camera = CameraServer.getInstance() \
+        .startAutomaticCapture(name=config.name, path=config.path)
+
+    camera.setConfigJson(json.dumps(config.config))
+
+if __name__ == "__main__":
+    if len(sys.argv) >= 2:
+        configFile = sys.argv[1]
+
+    # read configuration
+    if not readConfig():
+        sys.exit(1)
+
+    # start NetworkTables
+    ntinst = NetworkTablesInstance.getDefault()
+    if server:
+        print("Setting up NetworkTables server")
+        ntinst.startServer()
+    else:
+        print("Setting up NetworkTables client for team {}".format(team))
+        ntinst.startClientTeam(team)
+
+    # start cameras
+    for camera in cameras:
+        startCamera(camera)
+
+    # loop forever
+    while True:
+        time.sleep(10)

deps/examples/python-multiCameraServer/runCamera

@@ -0,0 +1,4 @@
+#!/bin/sh
+echo "Waiting 5 seconds..."
+sleep 5
+exec ./multiCameraServer.py