I have had a very odd use case for some functionality on a recent job, and thought I would share some things that may be of use to people on here.
My task was to capture an image from a camera local to the gateway and display/use the image directly in ignition.
To do this I have used a few tools and methods.
- Install Automation Professionals Image Streamer Module Link
- Follow the instructions to install FFmpeg and OpenCV Link
- Install your USB webcam so that it works in Windows as normal.
- Open up Ignition and start some code:
Under Scripting -> Gateway Events I set up a Message Handler called Capture Image
import base64
from system import cv2
logger = system.util.getLogger("ImageLog")
# initialize the camera
cam = cv2.VideoCapture(0) # 0 -> index of camera
cvImg = cv2.Mat()
buffer = cv2.MatOfByte()
if not cam.isOpened():
logger.info("Error: Could not open camera.")
else:
s = cam.read(cvImg) #read image
if s: # frame captured without any errors
retval = cv2.imgcodecs.imencode('.jpg', cvImg,buffer) #encode the Mat from openCV as a jpeg
imageBytes = ''.join(map(lambda x: chr(x % 256), buffer.toArray())) #convert the image to a stream of bytes
jpg_as_text = base64.b64encode(imageBytes) #Encode the image as base64
b64Image = "data:image/jpeg;base64,%s"%jpg_as_text #Add the image metadata to the string
system.tag.writeBlocking(["[edge]New Tag"], [b64Image]) #Write the tag
logger.info("Image Captured")
cam.release() #Release camera from script
In the above script, you will see I have created a single tag [edge]New Tag
This is tag is a Memory Tag of type String and this will eventually hold a base64 image string. This is not an ideal way to store the image but its a proof of concept that works.
I am working in Perspective, so I have made a view with an Image and a Button on a page together.
In the view, I have bound the Image prop source to the tag with a Direct tag binding to [edge]New Tag
I have added an onClick event to the Button with the following script:
def runAction(self, event):
system.util.sendMessage("Edge","CaptureImage",payload={})
Now if you save the project and run the view, click the button and in a second or so you should see an image on the screen in the image container.
Enjoy.