将 canvas 从 tkinter 保存到文件

Question

所以我遵循了这个 post： How can I convert canvas content to an image?

当我尝试按照上一条建议进行操作时，我遇到了以下问题：

当我这样叫的时候，image/screenshot拍的太早了，所以拍不到需要的图像。这是代码：

from tkinter import *
from PIL import ImageGrab
root = Tk()
cv = Canvas(root)

cv.pack()

cv.create_rectangle(10,10,50,50)
#cv.create_line([0, 10, 10, 10], fill='green')


cv.update()


#print(root.winfo_width())

def getter(widget):
    x=root.winfo_rootx()+widget.winfo_x()
    print(x)
    y=root.winfo_rooty()+widget.winfo_y()
    print(y)
    x1=x+widget.winfo_width()
    print(x1)
    y1=y+widget.winfo_height()
    print(y1)
    ImageGrab.grab().crop((x,y,x1,y1)).save("em.jpg")

getter(cv)
root.mainloop()

顺便说一句，如果有更简单的解决方案，我将不胜感激！问题是保存部分稍后将动态添加到代码中，因此解决方案应尽可能轻便。

提前致谢！

PS：也许甚至可以在不事先显示的情况下保存 canvas？仅凭代码？

Answer 1

下面是截取 tkinter canvas 屏幕截图的代码。 PIL.ImageGrab 模块在 Linux 中不起作用；将其替换为 pyscreenshot。在 Ubuntu 16.04 中测试了这段代码。您可能需要检查它是否在 Windows/OSx 中运行。请注意函数 self._grabtofile 中的注释。

备注： 在 Ubuntu 中，此脚本必须直接在 commandline/terminal 上执行才能工作。从 python3.

的 IDLE 执行时它不起作用

总结：

能够显示 tkinter 的屏幕截图 canvas 并将其保存到文件 a 使用两个事件。
能够截取 tkinter canvas（w/o 显示）并将其保存到使用一个事件的文件。

工作代码：

#!/usr/bin/python3
# -*- coding: utf-8 -*-

try:
    import tkinter as tk # Python 3 tkinter modules
except ImportError:
    import Tkinter as tk # Python 2 tkinter modules

from PIL import Image, ImageTk 
#from PIL import Image, ImageTk, ImageGrab  # For Windows & OSx
import pyscreenshot as ImageGrab # For Linux

class App(tk.Frame):
    def __init__(self, parent):
        tk.Frame.__init__(self, parent)
        self.parent=parent

        file = 'images.jpg'
        self.img = Image.open(file)
        #self.img.show() #Check to proof image can be read in and displayed correctly.
        self.photo = ImageTk.PhotoImage(self.img)
        print('size of self.img =', self.img.size)
        centerx= self.img.size[0]//2
        centery= self.img.size[1]//2
        print ('center of self.img = ', centerx, centery)

        self.cv = tk.Canvas(self)
        self.cv.create_image(centerx, centery, image=self.photo)
        self.cv.create_rectangle(centerx*0.5,centery*0.5,centerx*1.5,centery*1.5,
                                 outline='blue')
        self.cv.grid(row=0, column=0, columnspan=3, sticky='nsew') 

        self.snappic=tk.Button(self, text='SNAP', command=self._snapCanvas)
        self.snappic.grid(row=1, column=0, sticky='nsew')

        self.savepic=tk.Button(self, text='SAVE', command=self._save)
        self.savepic.grid(row=1, column=1, sticky='nsew')

        self.directsavepic=tk.Button(self, text='Grab_to_File', command=self._grabtofile)
        self.directsavepic.grid(row=1, column=2, sticky='nsew')

        self.snapsave=tk.Button(self, text='SNAP & SAVE', command=self._snapsaveCanvas)
        self.snapsave.grid(row=2, column=0, columnspan=2, sticky='nsew')

    def _snapCanvas(self):
        print('\n def _snapCanvas(self):')
        canvas = self._canvas() # Get Window Coordinates of Canvas
        self.grabcanvas = ImageGrab.grab(bbox=canvas)
        self.grabcanvas.show()

    def _save(self):
        self.grabcanvas.save("out.jpg")
        print('Screenshoot of tkinter.Canvas saved in "out.jpg"')

    def _grabtofile(self):
        '''Remark: The intension was to directly save a screenshoot of the canvas in
                   "out_grabtofile.png".
                   Issue 1: Only a full screenshot was save.
                   Issue 2: Saved image format defaults to .png. Other format gave errors. 
                   Issue 3: "ImageGrab.grab_to_file" only able to return full screenshoot
                            and not just the canvas. '''
        print('\n def _grabtofile(self):')
        canvas = self._canvas()  # Get Window Coordinates of Canvas
        print('canvas = ', canvas)
        ImageGrab.grab_to_file("out_grabtofile.png", ImageGrab.grab(bbox=canvas))
        print('Screenshoot of tkinter.Canvas directly saved in "out_grabtofile.png"')

    def _snapsaveCanvas(self):
        print('\n def _snapsaveCanvas(self):')
        canvas = self._canvas()  # Get Window Coordinates of Canvas
        self.grabcanvas = ImageGrab.grab(bbox=canvas).save("out_snapsave.jpg")
        print('Screencshot tkinter canvas and saved as "out_snapsave.jpg w/o displaying screenshoot."')

    def _canvas(self):
        print('  def _canvas(self):')
        print('self.cv.winfo_rootx() = ', self.cv.winfo_rootx())
        print('self.cv.winfo_rooty() = ', self.cv.winfo_rooty())
        print('self.cv.winfo_x() =', self.cv.winfo_x())
        print('self.cv.winfo_y() =', self.cv.winfo_y())
        print('self.cv.winfo_width() =', self.cv.winfo_width())
        print('self.cv.winfo_height() =', self.cv.winfo_height())
        x=self.cv.winfo_rootx()+self.cv.winfo_x()
        y=self.cv.winfo_rooty()+self.cv.winfo_y()
        x1=x+self.cv.winfo_width()
        y1=y+self.cv.winfo_height()
        box=(x,y,x1,y1)
        print('box = ', box)
        return box


if __name__ == '__main__':
    root = tk.Tk()
    root.title('App'), root.geometry('300x300')
    app = App(root)
    app.grid(row=0, column=0, sticky='nsew')

    root.rowconfigure(0, weight=1)
    root.columnconfigure(0, weight=1)

    app.rowconfigure(0, weight=10)
    app.rowconfigure(1, weight=1)
    app.columnconfigure(0, weight=1)
    app.columnconfigure(1, weight=1)
    app.columnconfigure(2, weight=1)

    app.mainloop()

GUI 截图：

GUI 的屏幕截图 tk.Canvas:

Answer 2

我知道这是一个旧的 post 但我只想分享对我有用的东西，希望它能帮助遇到类似问题的人。

import tkinter as tk
from PIL import Image
import io
import os
import subprocess

root = Tk()

cv = Canvas(root)
cv.pack()

cv.create_rectangle(10,10,50,50)

ps = cv.postscript(colormode='color')
img = Image.open(io.BytesIO(ps.encode('utf-8')))
img.save('filename.jpg', 'jpeg')

root.mainloop()

在此解决方案中，您必须安装 ghostscript 和 Pillow。对于 MacOS，使用

安装 ghostscript

brew install ghostscript

和枕头 pip install Pillow

将 canvas 从 tkinter 保存到文件

Saving canvas from tkinter to file

python

canvas

tkinter

tkinter-canvas