[copybara] Import robotpy examples (#8608)

GitOrigin-RevId: 9ba4bc3040fa7e772f5a594039e78fc6c43d114e

robotpyExamples/HttpCamera/vision.py

@@ -0,0 +1,71 @@
+#
+# Copyright (c) FIRST and other WPILib contributors.
+# Open Source Software; you can modify and/or share it under the terms of
+# the WPILib BSD license file in the root directory of this project.
+#
+
+"""
+This is a demo program showing the use of OpenCV to do vision processing. The image is acquired
+from an HTTP camera, then a rectangle is put on the image and sent to the dashboard. OpenCV has
+many methods for different types of processing.
+"""
+
+import numpy
+import cscore
+from cscore import CameraServer
+import cv2
+
+#
+# This code will work both on a RoboRIO and on other platforms. The exact mechanism
+# to run it differs depending on whether you’re on a RoboRIO or a coprocessor
+#
+# https://robotpy.readthedocs.io/en/stable/vision/code.html
+
+
+def main():
+    # Create an HTTP camera. The address will need to be modified to have the
+    # correct team number. The exact path will depend on the source.
+    camera = cscore.HttpCamera("HTTP Camera", "http://10.x.y.11/video/stream.mjpg")
+    # Start capturing images
+    CameraServer.startAutomaticCapture(camera)
+    # Set the resolution
+    camera.setResolution(640, 480)
+
+    # Get a CvSink. This will capture Mats from the camera
+    cvSink = CameraServer.getVideo()
+
+    # Setup a CvSource. This will send images back to the Dashboard
+    outputStream = CameraServer.putVideo("Rectangle", 640, 480)
+
+    # Mats are very memory expensive. Lets reuse this Mat.
+    mat = numpy.zeros((480, 640, 3), dtype="uint8")
+
+    # Declare the color of the rectangle
+    rectColor = (255, 255, 255)
+
+    # The camera code will be killed when the robot.py program exits. If you wish to perform cleanup,
+    # you should register an atexit handler. The child process will NOT be launched when running the robot code in
+    # simulation or unit testing mode
+
+    while True:
+        # Tell the CvSink to grab a frame from the camera and put it in the source mat.  If there is an error notify the
+        # output.
+
+        if cvSink.grabFrame(mat) == 0:
+            # Send the output the error.
+            outputStream.notifyError(cvSink.getError())
+
+            # skip the rest of the current iteration
+            continue
+
+        # Put a rectangle on the image
+        mat = cv2.rectangle(
+            img=mat,
+            pt1=(100, 100),
+            pt2=(400, 400),
+            color=rectColor,
+            lineType=5,
+        )
+
+        # Give the output stream a new image to display
+        outputStream.putFrame(mat)