PyQtGraph – 条形图的不透明度变化信号

在本文中，我们将看到如何在 PyQtGraph 模块中获取条形图的不透明度变化信号。 PyQtGraph 是一个用于Python的图形和用户界面库，它提供了设计和科学应用程序中通常需要的功能。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，其次是提供帮助快速应用程序开发的工具（例如，Qt Designer 中使用的属性树）。条形图或条形图是一种图表或图形，它用矩形条显示分类数据，矩形条的高度或长度与其所代表的值成正比。条形可以垂直或水平绘制。垂直条形图有时也称为柱形图。不透明度是衡量电磁或其他类型辐射（尤其是可见光）不可穿透性的指标。在辐射传输中，它描述了辐射在介质中的吸收和散射，例如等离子体、电介质、屏蔽材料、玻璃等。

我们可以在下面给出的命令的帮助下创建一个绘图窗口和条形图

# creating a pyqtgraph plot window
window = pg.plot()

# creating a bar graph of green color
bargraph = pg.BarGraphItem(x=x, height=y1, width=0.6, brush='g')

In order to do this we use opacityChanged.connect method with the bar graph object

Syntax : bargraph.opacityChanged.connect(method)

Argument : It takes method as argument

Return : It returns None

下面是实现

# importing Qt widgets
from PyQt5.QtWidgets import * import sys
  
# importing pyqtgraph as pg
import pyqtgraph as pg
from PyQt5.QtGui import *
  
# Bar Graph class
class BarGraphItem(pg.BarGraphItem):
  
    # constructor which inherit original
    # BarGraphItem
    def __init__(self, *args, **kwargs):
        pg.BarGraphItem.__init__(self, *args, **kwargs)
  
    # creating a mouse double click event
    def mouseDoubleClickEvent(self, e):
  
        # changing the opacity of the bar graph
        self.setOpacity(0.3)
  
  
  
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()
  
    # method for components
    def UiComponents(self):
  
        # creating a widget object
        widget = QWidget()
  
        # creating a label
        label = QLabel("Geeksforgeeks")
  
        # creating a plot window
        plot = pg.plot()
  
        # create list for y-axis
        y1 = [5, 5, 7, 10, 3, 8, 9, 1, 6, 2]
  
        # create horizontal list i.e x-axis
        x = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
  
        # create pyqt5graph bar graph item
        # with width = 0.6
        # with bar colors = green
        bargraph = BarGraphItem(x = x, height = y1, width = 0.6, brush ='g')
  
        # add item to plot window
        # adding bargraph item to the plot window
        plot.addItem(bargraph)
  
        # Creating a grid layout
        layout = QGridLayout()
  
        # 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(plot, 0, 1, 3, 1)
  
        # setting this widget as central widget of the main widow
        self.setCentralWidget(widget)
  
        # signal emitted when opacity is changed
        bargraph.opacityChanged.connect(lambda: do_action())
  
        # do action method called by bar graph
        def do_action():
  
            # setting text to the label
            label.setText("Opacity is Changed")
  
  
  
  
# create pyqt5 app
App = QApplication(sys.argv)
  
# create the instance of our Window
window = Window()
  
# start the app
sys.exit(App.exec())

输出 ：