PyQtGraph – ROI 改变图像视图的信号

在本文中，我们将看到如何在PyQTGaph中触发图像视图对象的 ROI 变化信号。 PyQtGraph是Python的图形和用户界面库，提供设计和科学应用程序中常用的功能。它的主要目标是提供用于显示数据（绘图、视频等）的快速交互式图形。用于显示和分析图像数据的小部件。实现许多功能，例如显示 2D 和 3D 图像数据。对于 3D 数据，会显示一个 z 轴滑块，允许用户选择要显示的帧。显示具有定义暗/亮级别的可移动区域的图像数据的直方图，可编辑渐变提供颜色查找表，也可以使用向左/向右箭头键以及pgup、pgdn、home和end移动帧滑块。当图像视图的 ROI 发生变化时，会发出此信号。

我们可以在下面给出的命令的帮助下创建一个图像视图对象：

# creating a pyqtgraph image view object
imv = pg.ImageView()

为了触发这个信号，我们必须改变图像视图类，下面是类的语法：

# Image View class
class ImageView(pg.ImageView):

    # constructor which inherit original
    # ImageView
    def __init__(self, *args, **kwargs):
        pg.ImageView.__init__(self, *args, **kwargs)

    # roi changed method
    def roiChanged(self):

        # printing message
        print("ROI Changed")

下面是实现：

Python3

# importing Qt widgets
from PyQt5.QtWidgets import *
  
# importing system
import sys
  
# importing numpy as np
import numpy as np
  
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
from PyQt5.QtCore import *
  
  
# Image View class
class ImageView(pg.ImageView):
  
    # constructor which inherit original
    # ImageView
    def __init__(self, *args, **kwargs):
        pg.ImageView.__init__(self, *args, **kwargs)
  
    # roi changed method
    def roiChanged(self):
  
        # printing message
        print("ROI Changed")
  
  
class Window(QMainWindow):
  
    def __init__(self):
        super().__init__()
  
        # setting title
        self.setWindowTitle("PyQtGraph")
  
        # setting geometry
        self.setGeometry(100, 100, 600, 500)
  
        # icon
        icon = QIcon("skin.png")
  
        # setting icon to the window
        self.setWindowIcon(icon)
  
        # calling method
        self.UiComponents()
  
        # showing all the widgets
        self.show()
  
        # setting fixed size of window
        self.setFixedSize(QSize(600, 500))
  
    # method for components
    def UiComponents(self):
  
        # creating a widget object
        widget = QWidget()
  
        # creating a label
        label = QLabel("Geeksforgeeks Image View")
  
        # setting minimum width
        label.setMinimumWidth(130)
  
        # making label do word wrap
        label.setWordWrap(True)
  
        # setting configuration options
        pg.setConfigOptions(antialias=True)
  
        # creating image view view object
        imv = ImageView()
  
        # Create random 3D data set with noisy signals
        img = pg.gaussianFilter(np.random.normal(
            size=(200, 200)), (5, 5)) * 20 + 100
  
        # setting new axis to image
        img = img[np.newaxis, :, :]
  
        # decay data
        decay = np.exp(-np.linspace(0, 0.3, 100))[:, np.newaxis, np.newaxis]
  
        # random data
        data = np.random.normal(size=(100, 200, 200))
        data += img * decay
        data += 2
  
        # adding time-varying signal
        sig = np.zeros(data.shape[0])
        sig[30:] += np.exp(-np.linspace(1, 10, 70))
        sig[40:] += np.exp(-np.linspace(1, 10, 60))
        sig[70:] += np.exp(-np.linspace(1, 10, 30))
  
        sig = sig[:, np.newaxis, np.newaxis] * 3
        data[:, 50:60, 30:40] += sig
  
        # Displaying the data and assign each frame a time value from 1.0 to 3.0
        imv.setImage(data, xvals=np.linspace(1., 3., data.shape[0]))
  
        # Set a custom color map
        colors = [
            (0, 0, 0),
            (4, 5, 61),
            (84, 42, 55),
            (15, 87, 60),
            (208, 17, 141),
            (255, 255, 255)
        ]
  
        # color map
        cmap = pg.ColorMap(pos=np.linspace(0.0, 1.0, 6), color=colors)
  
        # setting color map to the image view
        imv.setColorMap(cmap)
  
        # Creating a grid layout
        layout = QGridLayout()
  
        # minimum width value of the label
        label.setFixedWidth(130)
  
        # setting this layout to the widget
        widget.setLayout(layout)
  
        # adding label in the layout
        layout.addWidget(label, 1, 0)
  
        # plot window goes on right side, spanning 3 rows
        layout.addWidget(imv, 0, 1, 3, 1)
  
        # setting this widget as central widget of the main widow
        self.setCentralWidget(widget)
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

输出 ：

ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed
ROI Changed