Matplotlib B1-Motion（按住鼠標鍵的運動）是否等效？

Question

是否存在類似於Tkinter <B1-Motion>鍵的matplotlib事件？ 這樣，僅當用戶在移動鼠標的同時按住B1時才調用函數嗎？

我目前正在研究本文檔，但沒有看到這樣的選擇，如果沒有，我可以通過一些簡單的方法來重新創建它嗎？

def notify_motion(event):
    """
    Only called when button 1 is clicked and motion detected
    """

    ...

Answer 1

canvas.mpl_connect不提供key_down + motion事件。 可能的破解方法是存儲是否按住鼠標按鈕（或鍵）並使用motion_notify_event的屬性。

在此示例中，在wx ，我們可以按住鼠標並在圖上繪制一個紅色矩形：

import wx
import matplotlib
matplotlib.use('WXAgg')
from matplotlib.backends.backend_wxagg import FigureCanvasWxAgg as FigureCanvas
from matplotlib.figure import Figure
from matplotlib.patches import Rectangle
import matplotlib.cm as cm
import matplotlib.pyplot as plt

class Frame(wx.Frame):
    def __init__(self, parent):
        wx.Frame.__init__(self, parent=parent)
        self.boxSizer1 = wx.BoxSizer(orient=wx.VERTICAL)
        self.SetSizer(self.boxSizer1)
        self.figure = Figure()
        self.canvas = FigureCanvas(self, -1, self.figure)
        self.boxSizer1.Add(self.canvas, 1, wx.EXPAND)
        self.x0 = None
        self.y0 = None
        self.x1 = None
        self.y1 = None
        self.axes   = [self.figure.add_subplot(111), ]
        self.axes[0].plot(range(100), range(100))
        self.canvas.Bind(wx.EVT_ENTER_WINDOW, self.ChangeCursor)
        self.canvas.mpl_connect('button_press_event', self.on_press)
        self.canvas.mpl_connect('button_release_event', self.on_release)
        self.canvas.mpl_connect('motion_notify_event', self.on_motion)
        self.rect = Rectangle((0,0), 1, 1, fill=False, ec='r')
        self.axes[0].add_patch(self.rect)
        #store a property of whether the mouse key is pressed
        self.pressed = False



    def ChangeCursor(self, event):
        '''Change cursor into crosshair type when enter the plot area'''
        self.canvas.SetCursor(wx.StockCursor(wx.CURSOR_CROSS))



    def on_press(self, event):
        '''Draw ROI rectangle'''
        self.pressed = True
        self.x0 = int(event.xdata)
        self.y0 = int(event.ydata)


    def on_release(self, event):
        '''When mouse is on plot and button is released, redraw ROI rectangle, update ROI values'''
        self.pressed = False
        self.redraw_rect(event)


    def redraw_rect(self, event):
        '''Draw the ROI rectangle overlay'''
        try:
            self.x1 = int(event.xdata)
            self.y1 = int(event.ydata)
            self.rect.set_xy((self.x0, self.y0))
            self.rect.set_width(self.x1 - self.x0)
            self.rect.set_height(self.y1 - self.y0)
        except:
            pass
        self.canvas.draw()

    def on_motion(self, event):
        '''If the mouse is on plot and if the mouse button is pressed, redraw ROI rectangle'''
        if self.pressed:
            # redraw the rect
            self.redraw_rect(event)

class App(wx.App):
    def OnInit(self):
        frame = Frame(None)
        self.SetTopWindow(frame)
        frame.Show(True)
        return True

if __name__=='__main__':
    app=App(0)
    app.MainLoop()

Answer 2

我不知道您是否仍然在乎這個問題，無論如何，有一個使用matplotlib.backend_bases.MouseEvent類的button屬性的非常簡單的解決方案，因為如果按下光標， event.button將為1如果按下則為None被釋放。

以下是我的代碼，通過按住並移動光標來畫一條線：

import matplotlib.pyplot as plt
import numpy as np

def moved_and_pressed(event):
    if event.button==1:
        x = np.append(line.get_xdata(), event.xdata)
        y = np.append(line.get_ydata(), event.ydata)
        line.set_data(x, y)
        fig.canvas.draw()

fig, ax = plt.subplots(1,1, figsize=(5,3), dpi=100)
line, = ax.plot([], [], 'k')
ax.set_xlim(0,10); ax.set_ylim(0,10)
cid = fig.canvas.mpl_connect('motion_notify_event', moved_and_pressed)
plt.show()

希望能幫助到你。