python - Tkinter 在点击时获取鼠标坐标并将它们用作变量

Question

我是 Python 的新手。因此，不要生我的气，因为我确信我缺少一些基本的东西。这是我的问题:

我正在尝试从图像中提取鼠标点击坐标并将这些坐标用作变量。

代码允许导入和图像，我想从中提取坐标。一些提示询问用户图表的大小和范围，之后我想通过分别单击 x 轴和 y 轴上的原点和终点来设置坐标网格。思路是利用这3组坐标，通过一些转换函数(见代码)将它们转换成压力和温度坐标。

# Determine the origin by clicking
# Probably with classes??
class Origin:
    def getorigin(eventorigin):
          eventorigin.x0 = eventorigin.x
          eventorigin.y0 = eventorigin.y
    #mouseclick event
    w.bind("<Button 1>",getorigin)
# What do I do here??
x0 = ...
y0 = ...

我真的不知道如何将通过单击获得的坐标分配给一个新变量，以便稍后在代码中使用。

我可以打印坐标，但由于它们是一个函数，所以它们是局部的，在函数之外无法使用(据我所知)。因此，使用类的方法可能会更好，但我不知道该怎么做。

感谢任何帮助。

完整代码(改编):

from tkinter import *
from tkinter.filedialog import askopenfilename
from PIL import Image, ImageTk
import tkinter.simpledialog

root = Tk()

#setting up a tkinter canvas
w = Canvas(root, width=1000, height=1000)
w.pack()

#adding the image
File = askopenfilename(parent=root, initialdir="./",title='Select an image')
original = Image.open(File)
original = original.resize((1000,1000)) #resize image
img = ImageTk.PhotoImage(original)
w.create_image(0, 0, image=img, anchor="nw")

#ask for pressure and temperature extent
xmt = tkinter.simpledialog.askfloat("Temperature", "degrees in x-axis")
ymp = tkinter.simpledialog.askfloat("Pressure", "bars in y-axis")

#ask for real PT values at origin
xc = tkinter.simpledialog.askfloat("Temperature", "Temperature at origin")
yc = tkinter.simpledialog.askfloat("Pressure", "Pressure at origin")

#instruction on 3 point selection to define grid
tkinter.messagebox.showinfo("Instructions", "Click: \n" 
                                            "1) Origin \n"
                                            "2) Temperature end \n"
                                            "3) Pressure end")

# From here on I have no idea how to get it to work...

# Determine the origin by clicking
def getorigin(eventorigin):
    global x0,y0
    x0 = eventorigin.x
    y0 = eventorigin.y
    print(x0,y0)
#mouseclick event
w.bind("<Button 1>",getorigin)

# Determine the extent of the figure in the x direction (Temperature)
def getextentx(eventextentx):
    global xe
    xe = eventextentx.x
    print(xe)
#mouseclick event
w.bind("<Button 1>",getextentx)

# Determine the extent of the figure in the y direction (Pressure)
def getextenty(eventextenty):
    global ye
    ye = eventextenty.y
    print(ye)
#mouseclick event
w.bind("<Button 1>",getextenty)

#message to confirm that the grid is set up
tkinter.messagebox.showinfo("Grid", "Grid is set. You can start picking coordinates.")

#Coordinate transformation into Pressure-Temperature space
def printcoords(event):
    xmpx = xe-x0
    xm = xmt/xmpx
    ympx = ye-y0
    ym = -ymp/ympx

    #coordinate transformation
    newx = (event.x-x0)*(xm)+xc
    newy = (event.y-y0)*(ym)+yc

    #outputting x and y coords to console
    print (newx,newy)
#mouseclick event
w.bind("<Button 1>",printcoords)

root.mainloop()

Answer 1

如果我在之前的评论中所说的是你想要做的，因为 tkinter 不会暂停程序来等待鼠标点击事件，你将不得不这样做:它会在每次鼠标按钮时重新绑定(bind)它获得点击

from tkinter import *
from tkinter.filedialog import askopenfilename
from PIL import Image, ImageTk
import tkinter.simpledialog

root = Tk()

#setting up a tkinter canvas
w = Canvas(root, width=1000, height=1000)
w.pack()

#adding the image
File = askopenfilename(parent=root, initialdir="./",title='Select an image')
original = Image.open(File)
original = original.resize((1000,1000)) #resize image
img = ImageTk.PhotoImage(original)
w.create_image(0, 0, image=img, anchor="nw")

#ask for pressure and temperature extent
xmt = tkinter.simpledialog.askfloat("Temperature", "degrees in x-axis")
ymp = tkinter.simpledialog.askfloat("Pressure", "bars in y-axis")

#ask for real PT values at origin
xc = tkinter.simpledialog.askfloat("Temperature", "Temperature at origin")
yc = tkinter.simpledialog.askfloat("Pressure", "Pressure at origin")

#instruction on 3 point selection to define grid
tkinter.messagebox.showinfo("Instructions", "Click: \n" 
                                            "1) Origin \n"
                                            "2) Temperature end \n"
                                            "3) Pressure end")

# From here on I have no idea how to get it to work...

# Determine the origin by clicking
def getorigin(eventorigin):
    global x0,y0
    x0 = eventorigin.x
    y0 = eventorigin.y
    print(x0,y0)
    w.bind("<Button 1>",getextentx)
#mouseclick event
w.bind("<Button 1>",getorigin)

# Determine the extent of the figure in the x direction (Temperature)
def getextentx(eventextentx):
    global xe
    xe = eventextentx.x
    print(xe)
    w.bind("<Button 1>",getextenty)

# Determine the extent of the figure in the y direction (Pressure)
def getextenty(eventextenty):
    global ye
    ye = eventextenty.y
    print(ye)
    tkinter.messagebox.showinfo("Grid", "Grid is set. You can start picking coordinates.")
    w.bind("<Button 1>",printcoords)

#Coordinate transformation into Pressure-Temperature space
def printcoords(event):
    xmpx = xe-x0
    xm = xmt/xmpx
    ympx = ye-y0
    ym = -ymp/ympx

    #coordinate transformation
    newx = (event.x-x0)*(xm)+xc
    newy = (event.y-y0)*(ym)+yc

    #outputting x and y coords to console
    print (newx,newy)

root.mainloop()