Add Cura.NetworkMJPGImage widget

cura/PrinterOutput/NetworkMJPGImage.py

@@ -0,0 +1,153 @@
+# Copyright (c) 2018 Aldo Hoeben / fieldOfView
+# NetworkMJPGImage is released under the terms of the LGPLv3 or higher.
+
+from PyQt5.QtCore import QUrl, pyqtProperty, pyqtSignal, pyqtSlot, QRect
+from PyQt5.QtGui import QImage
+from PyQt5.QtQuick import QQuickPaintedItem
+from PyQt5.QtNetwork import QNetworkRequest, QNetworkReply, QNetworkAccessManager
+
+from UM.Logger import Logger
+
+#
+# A QQuickPaintedItem that progressively downloads a network mjpeg stream,
+# picks it apart in individual jpeg frames, and paints it.
+#
+class NetworkMJPGImage(QQuickPaintedItem):
+
+    def __init__(self, *args, **kwargs) -> None:
+        super().__init__(*args, **kwargs)
+
+        self._stream_buffer = b""
+        self._stream_buffer_start_index = -1
+        self._network_manager = None
+        self._image_request = None
+        self._image_reply = None
+        self._image = QImage()
+        self._image_rect = QRect()
+
+        self._source_url = QUrl()
+        self._started = False
+
+        self._mirror = False
+
+        self.setAntialiasing(True)
+
+    ##  Ensure that close gets called when object is destroyed
+    def __del__(self) -> None:
+        self.stop()
+
+
+    def paint(self, painter: "QPainter") -> None:
+        if self._mirror:
+            painter.drawImage(self.contentsBoundingRect(), self._image.mirrored())
+            return
+
+        painter.drawImage(self.contentsBoundingRect(), self._image)
+
+
+    def setSourceURL(self, source_url: "QUrl") -> None:
+        self._source_url = source_url
+        self.sourceURLChanged.emit()
+        if self._started:
+            self.start()
+
+    def getSourceURL(self) -> "QUrl":
+        return self._source_url
+
+    sourceURLChanged = pyqtSignal()
+    source = pyqtProperty(QUrl, fget = getSourceURL, fset = setSourceURL, notify = sourceURLChanged)
+
+    def setMirror(self, mirror: bool) -> None:
+        if mirror == self._mirror:
+            return
+        self._mirror = mirror
+        self.mirrorChanged.emit()
+        self.update()
+
+    def getMirror(self) -> bool:
+        return self._mirror
+
+    mirrorChanged = pyqtSignal()
+    mirror = pyqtProperty(bool, fget = getMirror, fset = setMirror, notify = mirrorChanged)
+
+    imageSizeChanged = pyqtSignal()
+
+    @pyqtProperty(int, notify = imageSizeChanged)
+    def imageWidth(self) -> int:
+        return self._image.width()
+
+    @pyqtProperty(int, notify = imageSizeChanged)
+    def imageHeight(self) -> int:
+        return self._image.height()
+
+
+    @pyqtSlot()
+    def start(self) -> None:
+        self.stop()  # Ensure that previous requests (if any) are stopped.
+
+        if not self._source_url:
+            Logger.log("w", "Unable to start camera stream without target!")
+            return
+        self._started = True
+
+        self._image_request = QNetworkRequest(self._source_url)
+        if self._network_manager is None:
+            self._network_manager = QNetworkAccessManager()
+
+        self._image_reply = self._network_manager.get(self._image_request)
+        self._image_reply.downloadProgress.connect(self._onStreamDownloadProgress)
+
+    @pyqtSlot()
+    def stop(self) -> None:
+        self._stream_buffer = b""
+        self._stream_buffer_start_index = -1
+
+        if self._image_reply:
+            try:
+                try:
+                    self._image_reply.downloadProgress.disconnect(self._onStreamDownloadProgress)
+                except Exception:
+                    pass
+
+                if not self._image_reply.isFinished():
+                    self._image_reply.close()
+            except Exception as e:  # RuntimeError
+                pass  # It can happen that the wrapped c++ object is already deleted.
+
+            self._image_reply = None
+            self._image_request = None
+
+        self._network_manager = None
+
+        self._started = False
+
+
+    def _onStreamDownloadProgress(self, bytes_received: int, bytes_total: int) -> None:
+        # An MJPG stream is (for our purpose) a stream of concatenated JPG images.
+        # JPG images start with the marker 0xFFD8, and end with 0xFFD9
+        if self._image_reply is None:
+            return
+        self._stream_buffer += self._image_reply.readAll()
+
+        if len(self._stream_buffer) > 2000000:  # No single camera frame should be 2 Mb or larger
+            Logger.log("w", "MJPEG buffer exceeds reasonable size. Restarting stream...")
+            self.stop()  # resets stream buffer and start index
+            self.start()
+            return
+
+        if self._stream_buffer_start_index == -1:
+            self._stream_buffer_start_index = self._stream_buffer.indexOf(b'\xff\xd8')
+        stream_buffer_end_index = self._stream_buffer.lastIndexOf(b'\xff\xd9')
+        # If this happens to be more than a single frame, then so be it; the JPG decoder will
+        # ignore the extra data. We do it like this in order not to get a buildup of frames
+
+        if self._stream_buffer_start_index != -1 and stream_buffer_end_index != -1:
+            jpg_data = self._stream_buffer[self._stream_buffer_start_index:stream_buffer_end_index + 2]
+            self._stream_buffer = self._stream_buffer[stream_buffer_end_index + 2:]
+            self._stream_buffer_start_index = -1
+            self._image.loadFromData(jpg_data)
+
+            if self._image.rect() != self._image_rect:
+                self.imageSizeChanged.emit()
+
+            self.update()