Refactored MLX90640 plugin and HTTP route to work with direct BytesIO - it improves performance over using temporary files or base64-encoded responses

platypush/backend/http/app/routes/plugins/camera/ir/mlx90640.py

@@ -1,11 +1,12 @@
-import base64
 import os
 import tempfile
 
 from flask import Response, request, Blueprint, send_from_directory
 
+from platypush import Config
 from platypush.backend.http.app import template_folder
 from platypush.backend.http.app.utils import authenticate, send_request
+from platypush.plugins.camera.ir.mlx90640 import CameraIrMlx90640Plugin
 
 camera_ir_mlx90640 = Blueprint('camera.ir.mlx90640', __name__, template_folder=template_folder)
 
@@ -15,15 +16,21 @@ __routes__ = [
 ]
 
 
-def get_feed(**args):
+def get_feed(**_):
-    try:
+    camera_conf = Config.get('camera.mlx90640') or {}
+    camera = CameraIrMlx90640Plugin(**camera_conf)
+
+    with camera:
         while True:
-            frame = send_request(action='camera.ir.mlx90640.capture', **args).output[0]
+            output = camera.get_stream()
-            frame = base64.decodebytes(frame.encode())
+
-            yield (b'--frame\r\n'
+            with output.ready:
-                   b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n')
+                output.ready.wait()
-    finally:
+                frame = output.frame
-        send_request(action='camera.ir.mlx90640.stop')
+
+            if frame and len(frame):
+                yield (b'--frame\r\n'
+                       b'Content-Type: image/jpeg\r\n\r\n' + frame + b'\r\n')
 
 
 @camera_ir_mlx90640.route('/camera/ir/mlx90640/frame', methods=['GET'])

platypush/plugins/camera/ir/mlx90640/__init__.py

@@ -2,12 +2,14 @@ import base64
 import io
 import os
 import subprocess
+import threading
 import time
 
-from platypush.plugins import Plugin, action
+from platypush.plugins import action
+from platypush.plugins.camera import CameraPlugin, StreamingOutput
 
 
-class CameraIrMlx90640Plugin(Plugin):
+class CameraIrMlx90640Plugin(CameraPlugin):
     """
     Plugin to interact with a `ML90640 <https://shop.pimoroni.com/products/mlx90640-thermal-camera-breakout>`_
     infrared thermal camera.
@@ -35,13 +37,15 @@ class CameraIrMlx90640Plugin(Plugin):
     _img_size = (32, 24)
     _rotate_values = {}
 
-    def __init__(self, fps=16, skip_frames=2, scale_factor=1, rotate=0, rawrgb_path=None, **kwargs):
+    def __init__(self, fps=16, skip_frames=2, scale_factor=1, rotate=0, grayscale=False, rawrgb_path=None, **kwargs):
         """
         :param fps: Frames per seconds (default: 16)
         :param skip_frames: Number of frames to be skipped on sensor initialization/warmup (default: 2)
         :param scale_factor: The camera outputs 24x32 pixels artifacts. Use scale_factor to scale them up to a larger
             image (default: 1)
         :param rotate: Rotation angle in degrees (default: 0)
+        :param grayscale: Save the image as grayscale - black pixels will be colder, white pixels warmer
+            (default: False = use false colors)
         :param rawrgb_path: Specify it if the rawrgb executable compiled from
             https://github.com/pimoroni/mlx90640-library is in another folder than
             `<directory of this file>/lib/examples`.
@@ -68,6 +72,7 @@ class CameraIrMlx90640Plugin(Plugin):
         self.skip_frames = skip_frames
         self.scale_factor = scale_factor
         self.rawrgb_path = rawrgb_path
+        self.grayscale = grayscale
         self._capture_proc = None
 
     def _is_capture_proc_running(self):
@@ -81,9 +86,40 @@ class CameraIrMlx90640Plugin(Plugin):
 
         return self._capture_proc
 
+    def _raw_capture(self):
+        from PIL import Image
+
+        camera = self._get_capture_proc(fps=self.fps)
+        size = self._img_size
+
+        while self._is_capture_proc_running():
+            frame = camera.stdout.read(size[0] * size[1] * 3)
+            image = Image.frombytes('RGB', size, frame)
+            self._output.write(frame)
+
+            if self.grayscale:
+                image = self._convert_to_grayscale(image)
+            if self.scale_factor != 1:
+                size = tuple(i * self.scale_factor for i in size)
+                image = image.resize(size, Image.ANTIALIAS)
+            if self.rotate:
+                image = image.transpose(self.rotate)
+
+            temp = io.BytesIO()
+            image.save(temp, format='jpg')
+            self._output.write(temp.getvalue())
+
+    def __enter__(self):
+        self._output = StreamingOutput(raw=False)
+        self._capturing_thread = threading.Thread(target=self._raw_capture)
+        self._capturing_thread.start()
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        self.stop()
+
     # noinspection PyShadowingBuiltins
     @action
-    def capture(self, output_file=None, frames=1, grayscale=False, fps=None, skip_frames=None, scale_factor=None,
+    def capture(self, output_file=None, frames=1, grayscale=None, fps=None, skip_frames=None, scale_factor=None,
                 rotate=None, format='jpeg'):
         """
         Capture one or multiple frames and return them as raw RGB
@@ -97,8 +133,7 @@ class CameraIrMlx90640Plugin(Plugin):
             `stop` is called.
         :type frames: int
 
-        :param grayscale: Save the image as grayscale - black pixels will be colder, white pixels warmer
+        :param grayscale: Override the default ``grayscale`` parameter.
-            (default: False)
         :type grayscale: bool
 
         :param fps: If set it overrides the fps parameter specified on the object (default: None)
@@ -126,9 +161,10 @@ class CameraIrMlx90640Plugin(Plugin):
         skip_frames = self.skip_frames if skip_frames is None else skip_frames
         scale_factor = self.scale_factor if scale_factor is None else scale_factor
         rotate = self._rotate_values.get(self.rotate if rotate is None else rotate, 0)
+        grayscale = self.grayscale if grayscale is None else grayscale
 
         size = self._img_size
-        sleep_time = 1.0 / self.fps
+        sleep_time = 1.0 / fps
         captured_frames = []
         n_captured_frames = 0
         files = set()