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# -*- coding: utf-8 -*-
# vispy: gallery 10:120:10
# -----------------------------------------------------------------------------
# Copyright (c) Vispy Development Team. All Rights Reserved.
# Distributed under the (new) BSD License. See LICENSE.txt for more info.
# -----------------------------------------------------------------------------
"""
Update data using a loop in a background thread
===============================================
Update VisPy visualizations from a background QThread.
"""
import time
from math import sin, pi
import numpy as np
from PyQt5 import QtWidgets, QtCore
from vispy.scene import SceneCanvas, visuals
from vispy.app import use_app
IMAGE_SHAPE = (600, 800) # (height, width)
CANVAS_SIZE = (800, 600) # (width, height)
NUM_LINE_POINTS = 200
COLORMAP_CHOICES = ["viridis", "reds", "blues"]
LINE_COLOR_CHOICES = ["black", "red", "blue"]
class Controls(QtWidgets.QWidget):
def __init__(self, parent=None):
super().__init__(parent)
layout = QtWidgets.QVBoxLayout()
self.colormap_label = QtWidgets.QLabel("Image Colormap:")
layout.addWidget(self.colormap_label)
self.colormap_chooser = QtWidgets.QComboBox()
self.colormap_chooser.addItems(COLORMAP_CHOICES)
layout.addWidget(self.colormap_chooser)
self.line_color_label = QtWidgets.QLabel("Line color:")
layout.addWidget(self.line_color_label)
self.line_color_chooser = QtWidgets.QComboBox()
self.line_color_chooser.addItems(LINE_COLOR_CHOICES)
layout.addWidget(self.line_color_chooser)
layout.addStretch(1)
self.setLayout(layout)
class CanvasWrapper:
def __init__(self):
self.canvas = SceneCanvas(size=CANVAS_SIZE)
self.grid = self.canvas.central_widget.add_grid()
self.view_top = self.grid.add_view(0, 0, bgcolor='cyan')
image_data = _generate_random_image_data(IMAGE_SHAPE)
self.image = visuals.Image(
image_data,
texture_format="auto",
cmap=COLORMAP_CHOICES[0],
parent=self.view_top.scene,
)
self.view_top.camera = "panzoom"
self.view_top.camera.set_range(x=(0, IMAGE_SHAPE[1]), y=(0, IMAGE_SHAPE[0]), margin=0)
self.view_bot = self.grid.add_view(1, 0, bgcolor='#c0c0c0')
line_data = _generate_random_line_positions(NUM_LINE_POINTS)
self.line = visuals.Line(line_data, parent=self.view_bot.scene, color=LINE_COLOR_CHOICES[0])
self.view_bot.camera = "panzoom"
self.view_bot.camera.set_range(x=(0, NUM_LINE_POINTS), y=(0, 1))
def set_image_colormap(self, cmap_name: str):
print(f"Changing image colormap to {cmap_name}")
self.image.cmap = cmap_name
def set_line_color(self, color):
print(f"Changing line color to {color}")
self.line.set_data(color=color)
def update_data(self, new_data_dict):
print("Updating data...")
self.image.set_data(new_data_dict["image"])
self.line.set_data(new_data_dict["line"])
def _generate_random_image_data(shape, dtype=np.float32):
rng = np.random.default_rng()
data = rng.random(shape, dtype=dtype)
return data
def _generate_random_line_positions(num_points, dtype=np.float32):
rng = np.random.default_rng()
pos = np.empty((num_points, 2), dtype=np.float32)
pos[:, 0] = np.arange(num_points)
pos[:, 1] = rng.random((num_points,), dtype=dtype)
return pos
class MyMainWindow(QtWidgets.QMainWindow):
closing = QtCore.pyqtSignal()
def __init__(self, canvas_wrapper: CanvasWrapper, *args, **kwargs):
super().__init__(*args, **kwargs)
central_widget = QtWidgets.QWidget()
main_layout = QtWidgets.QHBoxLayout()
self._controls = Controls()
main_layout.addWidget(self._controls)
self._canvas_wrapper = canvas_wrapper
main_layout.addWidget(self._canvas_wrapper.canvas.native)
central_widget.setLayout(main_layout)
self.setCentralWidget(central_widget)
self._connect_controls()
def _connect_controls(self):
self._controls.colormap_chooser.currentTextChanged.connect(self._canvas_wrapper.set_image_colormap)
self._controls.line_color_chooser.currentTextChanged.connect(self._canvas_wrapper.set_line_color)
def closeEvent(self, event):
print("Closing main window!")
self.closing.emit()
return super().closeEvent(event)
class DataSource(QtCore.QObject):
"""Object representing a complex data producer."""
new_data = QtCore.pyqtSignal(dict)
finished = QtCore.pyqtSignal()
def __init__(self, num_iterations=1000, parent=None):
super().__init__(parent)
self._should_end = False
self._num_iters = num_iterations
self._image_data = _generate_random_image_data(IMAGE_SHAPE)
self._line_data = _generate_random_line_positions(NUM_LINE_POINTS)
def run_data_creation(self):
print("Run data creation is starting")
for count in range(self._num_iters):
if self._should_end:
print("Data source saw that it was told to stop")
break
time.sleep(1.0)
# Uncomment to mimic a long-running computation
# time.sleep(3)
image_data = self._update_image_data(count)
line_data = self._update_line_data(count)
data_dict = {
"image": image_data,
"line": line_data,
}
self.new_data.emit(data_dict)
print("Data source finishing")
self.finished.emit()
def _update_image_data(self, count):
img_count = count % IMAGE_SHAPE[1]
self._image_data[:, img_count] = img_count / IMAGE_SHAPE[1]
rdata_shape = (IMAGE_SHAPE[0], IMAGE_SHAPE[1] - img_count - 1)
self._image_data[:, img_count + 1:] = _generate_random_image_data(rdata_shape)
return self._image_data.copy()
def _update_line_data(self, count):
self._line_data[:, 1] = np.roll(self._line_data[:, 1], -1)
self._line_data[-1, 1] = abs(sin((count / self._num_iters) * 16 * pi))
return self._line_data
def stop_data(self):
print("Data source is quitting...")
self._should_end = True
if __name__ == "__main__":
app = use_app("pyqt5")
app.create()
canvas_wrapper = CanvasWrapper()
win = MyMainWindow(canvas_wrapper)
data_thread = QtCore.QThread(parent=win)
data_source = DataSource()
data_source.moveToThread(data_thread)
# update the visualization when there is new data
data_source.new_data.connect(canvas_wrapper.update_data)
# start data generation when the thread is started
data_thread.started.connect(data_source.run_data_creation)
# if the data source finishes before the window is closed, kill the thread
data_source.finished.connect(data_thread.quit, QtCore.Qt.DirectConnection)
# if the window is closed, tell the data source to stop
win.closing.connect(data_source.stop_data, QtCore.Qt.DirectConnection)
# when the thread has ended, delete the data source from memory
data_thread.finished.connect(data_source.deleteLater)
win.show()
data_thread.start()
app.run()
print("Waiting for data source to close gracefully...")
data_thread.wait(5000)
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