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Python库matplotlib之十一

• 事件处理
• • 滚动事件
  • figure/axes进入和离开事件

事件处理

滚动事件

下列程序运行时，滚动鼠标的滚轮，on_scroll函数被调用，依据滚轮的滚动方向，参数w被加1，或减1。

参数w改变，引起sin波形变化。

import matplotlib.pyplot as plt
import numpy as np

class sin_curve:
    MAX_W = 20

    def __init__(self, fig, ax):
        self.fig = fig
        self.ax = ax
        self.w = 1
        x = np.linspace(0, 5 * np.pi, 1000)
        y = np.sin(x)
        self.line, = self.ax.plot(x, y)

    def on_scroll(self, event):
        increment = 1 if event.button == 'up' else -1
        self.w += increment
        if self.w <= 0:
            self.w = sin_curve.MAX_W
        elif self.w > sin_curve.MAX_W:
            self.w = 1
        x = np.linspace(0, 10 * np.pi, 1000)
        y = np.sin(self.w * x)
        self.ax.set_title('w = ' + str(self.w))
        self.line.set_xdata(x)
        self.line.set_ydata(y)
        self.fig.canvas.draw()

if __name__ == "__main__":
    fig, ax = plt.subplots()
    sin_waveform = sin_curve(fig, ax)
    fig.canvas.mpl_connect('scroll_event', sin_waveform.on_scroll)
    plt.show()

程序运行屏幕输出

figure/axes进入和离开事件

下列程序通过处理figure和Axes进入和离开事件，控制sin函数的波形显示。
当鼠标进入Axes，特定的Axes中， timer控制sin的相位角，引起波形变化。

import matplotlib.pyplot as plt
import numpy as np

class fig_axes():
    def __init__(self, axs):
        self.timer = fig.canvas.new_timer(interval=100)
        self.timer.add_callback(self.timer_cb, axs)
        self.inc = 1
        self.ax = None
        self.canvas = None
        self.x = np.linspace(0, 10 * np.pi, 100)
        self.y = np.sin(self.x)

    def on_enter_axes(self, event):
        self.ax = event.inaxes;
        self.line, = self.ax.plot(self.x, self.y)
        event.inaxes.patch.set_facecolor('yellow')
        event.canvas.draw()
        self.canvas = event.canvas

    def on_leave_axes(self, event):
        event.inaxes.patch.set_facecolor('white')
        self.line, = self.ax.plot(self.x, self.y)
        event.inaxes.patch.set_facecolor('yellow')
        event.canvas.draw()
        self.ax = None

    def on_enter_figure(self, event):
        event.canvas.figure.patch.set_facecolor('red')
        event.canvas.draw()
        self.timer.start()

    def on_leave_figure(self, event):
        event.canvas.figure.patch.set_facecolor('white')
        event.canvas.draw()
        self.timer.stop()

    def timer_cb(self, axs):
        if self.ax == None:
            return
        self.ax.clear()
        self.inc += 1
        self.x = np.linspace(0, 10 * np.pi, 100)
        self.y = np.sin(self.x + self.inc)
        self.ax.plot(self.x, self.y)
        self.canvas.draw()

if __name__ == "__main__":
    fig, axs = plt.subplots(1, 2)
    fig.suptitle('mouse hover over figure or Axes to trigger events')

    fig_axes_1 = fig_axes(axs)

    fig.canvas.mpl_connect('figure_enter_event', fig_axes_1.on_enter_figure)
    fig.canvas.mpl_connect('figure_leave_event', fig_axes_1.on_leave_figure)
    fig.canvas.mpl_connect('axes_enter_event', fig_axes_1.on_enter_axes)
    fig.canvas.mpl_connect('axes_leave_event', fig_axes_1.on_leave_axes)

    plt.show()