在python中获取画布坐标-尤其适用于mac

Question

from keras.models import load_model
from tkinter import *
import tkinter as tk
import appscript
#import win32gui
from PIL import ImageGrab, Image
import numpy as np
model = load_model('mnist.h5')
def predict_digit(img):
#resize image to 28x28 pixels
img = img.resize((28,28))
#convert rgb to grayscale
img = img.convert('L')
img = np.array(img)
#reshaping to support our model input and normalizing
img = img.reshape(1,28,28,1)
img = img/255.0
#predicting the class
res = model.predict([img])[0]
return np.argmax(res), max(res)
class App(tk.Tk):
def __init__(self):
tk.Tk.__init__(self)
self.x = self.y = 0

# Creating elements
self.canvas = tk.Canvas(self, width=300, height=300, bg = "white", cursor="cross")
self.label = tk.Label(self, text="Draw..", font=("Helvetica", 48))
self.classify_btn = tk.Button(self, text = "Recognise", command = self.classify_handwriting)   
self.button_clear = tk.Button(self, text = "Clear", command = self.clear_all)

# Grid structure
self.canvas.grid(row=0, column=0, pady=2, sticky=W, )
self.label.grid(row=0, column=1,pady=2, padx=2)
self.classify_btn.grid(row=1, column=1, pady=2, padx=2)
self.button_clear.grid(row=1, column=0, pady=2)

#self.canvas.bind("<Motion>", self.start_pos)
self.canvas.bind("<B1-Motion>", self.draw_lines)
def clear_all(self):
self.canvas.delete("all")

def classify_handwriting(self):
HWND = self.canvas.winfo_id()  # get the handle of the canvas
rect=self.canvas.coords(HWND)
#rect = win32gui.GetWindowRect(HWND)  # get the coordinate of the canvas
a,b,c,d = rect
rect=(a+4,b+4,c-4,d-4)
im = ImageGrab.grab(rect)
digit, acc = predict_digit(im)
self.label.configure(text= str(digit)+', '+ str(int(acc*100))+'%')
def draw_lines(self, event):
self.x = event.x
self.y = event.y
r=8
HWND=self.canvas.create_oval(self.x-r, self.y-r, self.x + r, self.y + r, fill='black')

app = App()
mainloop()

有人能帮我吗？特别是这个部分：

HWND = self.canvas.winfo_id()  # get the handle of the canvas
rect=self.canvas.coords(HWND)
#rect = win32gui.GetWindowRect(HWND)  # get the coordinate of the canvas
a,b,c,d = rect
rect=(a+4,b+4,c-4,d-4)
im = ImageGrab.grab(rect)

这是出现的错误：

Exception in Tkinter callback
Traceback (most recent call last):
File "/Users/xxx/opt/anaconda3/lib/python3.8/tkinter/__init__.py", line 1883, in __call__
return self.func(*args)
File "<ipython-input-4-28fb2cc31a85>", line 52, in classify_handwriting
a,b,c,d = rect
ValueError: not enough values to unpack (expected 4, got 0)

我正在尝试创建一个ocr程序，通过让用户画一个数字并高精度返回当前值来识别手写。但面临的问题是画布以及如何在不使用win32gui模块的情况下获得坐标(因为我是mac用户(，所以我正在寻找win32gui方法GetWindowRect 的解决方案或替代方案

Answer 1

self.canvas.coords(HWND)将返回画布上对象的坐标，该对象的id或标记为HWND中的任何对象。它不返回画布本身的坐标。

由于HWND不表示画布上的项目，因此self.canvas.coords(HWND)返回一个空列表。这就是为什么您会得到错误not enough values to unpack——您的代码需要四个值，但列表中没有。

如果你想要画布在物理屏幕上的坐标，还有其他方法可以使用。请参阅以下代码：

x, y = (self.canvas.winfo_rootx(), self.canvas.winfo_rooty())
width, height = (self.canvas.winfo_width(), self.canvas.winfo_height())
a, b, c, d = (x, y, x+width, y+height)

Answer 2

正确！它在MACOS上运行良好。评论"；导入win32gui"；线修改"；分类_手写"；功能如下：

def classify_handwriting(self):
x, y = (self.canvas.winfo_rootx(), self.canvas.winfo_rooty())
width, height = (self.canvas.winfo_width(), 
self.canvas.winfo_height())
a, b, c, d = (x, y, x+width, y+height)
im = ImageGrab.grab(bbox=(a,b,c,d))

希望它能在你当地的环境中工作！