PyQtGraph - 获取图像视图的前台角色

下面的文章讨论了我们如何在 PyQTGaph 中获得图像视图对象的前景角色。图像视图中基本上有两种角色，一种是前景，另一种是背景。前景角色定义了用于绘制前景的图像视图调色板的颜色。

PyQtGraph 是一个图形和用户界面Python库，用于设计和科学应用程序中通常需要的功能。它提供了用于显示数据（绘图、视频等）的快速交互式图形。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/亮级别和可编辑渐变的可移动区域的图像数据的直方图，提供颜色查找表供参考。

用于创建图像视图 ImageView() 被使用

句法：

imv = pg.ImageView()
 

为了获取前景角色，我们使用 foregroundRole() 方法和图像视图对象。它不接受任何参数并返回一个 QPalette 对象。
句法 ：

imv.foregroundRole()

执行：

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)
  
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
  
        # setting image to image view
        # 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)
  
        # getting foreground role of the image view
        value = imv.foregroundRole()
  
        # setting text to the label
        label.setText("Foreground Role : " + str(value))
  
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

输出 ：