{
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    {
      "cell_type": "code",
      "execution_count": null,
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      },
      "outputs": [],
      "source": [
        "%gui qt"
      ]
    },
    {
      "cell_type": "markdown",
      "metadata": {},
      "source": [
        "\n# Update data using timer events in a background thread\n\nUpdate VisPy visualizations from timer events in a background QThread.\n"
      ]
    },
    {
      "cell_type": "code",
      "execution_count": null,
      "metadata": {
        "collapsed": false
      },
      "outputs": [],
      "source": [
        "import time\nfrom math import sin, pi\n\nimport numpy as np\nfrom PyQt5 import QtWidgets, QtCore\n\nfrom vispy.scene import SceneCanvas, visuals\nfrom vispy.app import use_app\n\nIMAGE_SHAPE = (600, 800)  # (height, width)\nCANVAS_SIZE = (800, 600)  # (width, height)\nNUM_LINE_POINTS = 200\n\nCOLORMAP_CHOICES = [\"viridis\", \"reds\", \"blues\"]\nLINE_COLOR_CHOICES = [\"black\", \"red\", \"blue\"]\n\n\nclass Controls(QtWidgets.QWidget):\n    def __init__(self, parent=None):\n        super().__init__(parent)\n        layout = QtWidgets.QVBoxLayout()\n        self.colormap_label = QtWidgets.QLabel(\"Image Colormap:\")\n        layout.addWidget(self.colormap_label)\n        self.colormap_chooser = QtWidgets.QComboBox()\n        self.colormap_chooser.addItems(COLORMAP_CHOICES)\n        layout.addWidget(self.colormap_chooser)\n\n        self.line_color_label = QtWidgets.QLabel(\"Line color:\")\n        layout.addWidget(self.line_color_label)\n        self.line_color_chooser = QtWidgets.QComboBox()\n        self.line_color_chooser.addItems(LINE_COLOR_CHOICES)\n        layout.addWidget(self.line_color_chooser)\n\n        layout.addStretch(1)\n        self.setLayout(layout)\n\n\nclass CanvasWrapper:\n    def __init__(self):\n        self.canvas = SceneCanvas(size=CANVAS_SIZE)\n        self.grid = self.canvas.central_widget.add_grid()\n\n        self.view_top = self.grid.add_view(0, 0, bgcolor='cyan')\n        image_data = _generate_random_image_data(IMAGE_SHAPE)\n        self.image = visuals.Image(\n            image_data,\n            texture_format=\"auto\",\n            cmap=COLORMAP_CHOICES[0],\n            parent=self.view_top.scene,\n        )\n        self.view_top.camera = \"panzoom\"\n        self.view_top.camera.set_range(x=(0, IMAGE_SHAPE[1]), y=(0, IMAGE_SHAPE[0]), margin=0)\n\n        self.view_bot = self.grid.add_view(1, 0, bgcolor='#c0c0c0')\n        line_data = _generate_random_line_positions(NUM_LINE_POINTS)\n        self.line = visuals.Line(line_data, parent=self.view_bot.scene, color=LINE_COLOR_CHOICES[0])\n        self.view_bot.camera = \"panzoom\"\n        self.view_bot.camera.set_range(x=(0, NUM_LINE_POINTS), y=(0, 1))\n\n    def set_image_colormap(self, cmap_name: str):\n        print(f\"Changing image colormap to {cmap_name}\")\n        self.image.cmap = cmap_name\n\n    def set_line_color(self, color):\n        print(f\"Changing line color to {color}\")\n        self.line.set_data(color=color)\n\n    def update_data(self, new_data_dict):\n        print(\"Updating data...\")\n        self.image.set_data(new_data_dict[\"image\"])\n        self.line.set_data(new_data_dict[\"line\"])\n\n\ndef _generate_random_image_data(shape, dtype=np.float32):\n    rng = np.random.default_rng()\n    data = rng.random(shape, dtype=dtype)\n    return data\n\n\ndef _generate_random_line_positions(num_points, dtype=np.float32):\n    rng = np.random.default_rng()\n    pos = np.empty((num_points, 2), dtype=np.float32)\n    pos[:, 0] = np.arange(num_points)\n    pos[:, 1] = rng.random((num_points,), dtype=dtype)\n    return pos\n\n\nclass MyMainWindow(QtWidgets.QMainWindow):\n    closing = QtCore.pyqtSignal()\n\n    def __init__(self, canvas_wrapper: CanvasWrapper, *args, **kwargs):\n        super().__init__(*args, **kwargs)\n\n        central_widget = QtWidgets.QWidget()\n        main_layout = QtWidgets.QHBoxLayout()\n\n        self._controls = Controls()\n        main_layout.addWidget(self._controls)\n        self._canvas_wrapper = canvas_wrapper\n        main_layout.addWidget(self._canvas_wrapper.canvas.native)\n\n        central_widget.setLayout(main_layout)\n        self.setCentralWidget(central_widget)\n\n        self._connect_controls()\n\n    def _connect_controls(self):\n        self._controls.colormap_chooser.currentTextChanged.connect(self._canvas_wrapper.set_image_colormap)\n        self._controls.line_color_chooser.currentTextChanged.connect(self._canvas_wrapper.set_line_color)\n\n    def closeEvent(self, event):\n        print(\"Closing main window!\")\n        self.closing.emit()\n        return super().closeEvent(event)\n\n\nclass DataSource(QtCore.QObject):\n    \"\"\"Object representing a complex data producer.\"\"\"\n    new_data = QtCore.pyqtSignal(dict)\n    finished = QtCore.pyqtSignal()\n\n    def __init__(self, num_iterations=1000, parent=None):\n        super().__init__(parent)\n        self._should_end = False\n        self._count = 0\n        self._num_iters = num_iterations\n        self._image_data = _generate_random_image_data(IMAGE_SHAPE)\n        self._line_data = _generate_random_line_positions(NUM_LINE_POINTS)\n\n    def run_data_creation(self):\n        if self._should_end or self._count >= self._num_iters:\n            print(\"Data source finishing\")\n            self.finished.emit()\n            return\n\n        time.sleep(1.0)\n        image_data = self._update_image_data(self._count)\n        line_data = self._update_line_data(self._count)\n        self._count += 1\n\n        data_dict = {\n            \"image\": image_data,\n            \"line\": line_data,\n        }\n        self.new_data.emit(data_dict)\n        QtCore.QTimer.singleShot(0, self.run_data_creation)\n\n    def _update_image_data(self, count):\n        img_count = count % IMAGE_SHAPE[1]\n        self._image_data[:, img_count] = img_count / IMAGE_SHAPE[1]\n        rdata_shape = (IMAGE_SHAPE[0], IMAGE_SHAPE[1] - img_count - 1)\n        self._image_data[:, img_count + 1:] = _generate_random_image_data(rdata_shape)\n        return self._image_data.copy()\n\n    def _update_line_data(self, count):\n        self._line_data[:, 1] = np.roll(self._line_data[:, 1], -1)\n        self._line_data[-1, 1] = abs(sin((count / self._num_iters) * 16 * pi))\n        return self._line_data\n\n    def stop_data(self):\n        print(\"Data source is quitting...\")\n        self._should_end = True\n\n\nif __name__ == \"__main__\":\n    app = use_app(\"pyqt5\")\n    app.create()\n\n    canvas_wrapper = CanvasWrapper()\n    win = MyMainWindow(canvas_wrapper)\n    data_thread = QtCore.QThread(parent=win)\n    data_source = DataSource()\n    data_source.moveToThread(data_thread)\n\n    # update the visualization when there is new data\n    data_source.new_data.connect(canvas_wrapper.update_data)\n    # start data generation when the thread is started\n    data_thread.started.connect(data_source.run_data_creation)\n    # if the data source finishes before the window is closed, kill the thread\n    # to clean up resources\n    data_source.finished.connect(data_thread.quit)\n    # if the window is closed, tell the data source to stop\n    win.closing.connect(data_source.stop_data)\n    # when the thread has ended, delete the data source from memory\n    data_thread.finished.connect(data_source.deleteLater)\n\n    win.show()\n    data_thread.start()\n    app.run()\n\n    print(\"Waiting for data source to close gracefully...\")\n    data_thread.quit()\n    data_thread.wait(5000)"
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    }
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