Tkinter - 让第二个画布显示另一个画布的内容 [英] Tkinter - making a second canvas display the contents of another

问题描述

我正在寻找一种方法，可以让一个画布显示另一个画布的内容，而无需复制其中绘制的对象.第二个画布需要只是一个显示，它将在第一个画布上绘制的内容作为输入.

I'm looking for a way to make one canvas display the contents of another WITHOUT duplicating the objects that are drawn in it. The second canvas needs to be just a display which takes as input what is drawn on the first one.

我知道 .postscript 方法将内容写入文件或变量中，但我不知道如何(如果可能)让另一个画布将其显示为图像.

I know that the .postscript method writes the contents in a file or a variable, but I don't know how(if it's possible) to make another canvas display it as an image.

我忘了说，我的操作系统是 windows.如果有人也能告诉我一个跨平台的解决方案，那就太好了.

I forgot to mention, my operating system is windows. It would be great if someone can tell me a cross-platform solution also.

Edit2:我不想通过复制对象来做到这一点的原因是因为它们正在移动，并且每隔一段时间它们中的一些会被破坏并创建新的对象.此外，它是一个实时系统，复制对象及其行为可能会减慢速度.

the reason I don't want to do it by duplicating the objects is because they are moving and at some interval some of them are destroyed and new ones are created. Also it's a real-time system and duplicating the objects with their behaviors might slow things down.

推荐答案

没有内置的方法可以做到这一点.画布不支持任何类型的对等互连或复制.但是，如果您没有任何嵌入的小部件，将所有对象的副本保存在第二个画布中非常容易和快速.

There is no built-in way to do this. The canvas doesn't support any sort of peering or duplication. However, keeping copies of all the objects in a second canvas is pretty easy and fast if you don't have any embedded widgets.

一个简单的方法是将画布小部件子类化，然后创建 draw_line、draw_oval、coords 等的新实现以在对等画布上绘制.以下示例显示了如何以这种方式协调三个画布，其中 1000 个对象以不同的速率向下移动:

A simple way to do this is to subclass the canvas widget, then create new implementations of draw_line, draw_oval, coords, etc to draw on a peer canvas. The following example shows how to coordinate three canvases in this manner, with 1000 objects that are moving downward at different rates:

import Tkinter as tk
import random

class SampleApp(tk.Tk):
    def __init__(self, *args, **kwargs):
        tk.Tk.__init__(self, *args, **kwargs)
        self.canvas1 = PeeredCanvas(self, width=300, height=300, border=1, relief="sunken")
        self.canvas2 = PeeredCanvas(self, width=300, height=300, border=1, relief="sunken")
        self.canvas3 = PeeredCanvas(self, width=300, height=300, border=1, relief="sunken")
        self.canvas1.add_peer(self.canvas2)
        self.canvas1.add_peer(self.canvas3)
        toolbar = tk.Frame(self)
        clear_button = tk.Button(self, text="Refresh", command=self.refresh)
        clear_button.pack(in_=toolbar, side="left")
        toolbar.pack(side="top", fill="x")
        self.canvas1.pack(side="left", fill="both", expand=True)
        self.canvas2.pack(side="left", fill="both", expand=True)
        self.canvas3.pack(side="left", fill="both", expand=True)
        self.animate(10)

    def animate(self, delay):
        '''Move all items down at a random rate'''
        for item in self.canvas1.find_all():
            delta_x = 0
            delta_y = random.randrange(1, 4)
            self.canvas1.move(item, delta_x, delta_y)
        self.after(delay, self.animate, delay)

    def refresh(self, count=100):
        '''Redraw 'count' random circles'''
        self.canvas1.delete("all")
        width=self.canvas1.winfo_width()
        height=self.canvas1.winfo_height()
        for i in range(count):
            if i%2 == 0:
                tags = ("even",)
            else:
                tags = ("odd",)
            x = random.randrange(10, width-10)
            y = random.randrange(10, height-10)
            radius = random.randrange(10,100, 10)/2
            self.canvas1.create_oval([x,y, x+radius, y+radius], tags=tags)
        self.canvas1.itemconfigure("even", fill="red", outline="white")
        self.canvas1.itemconfigure("odd", fill="white", outline="red")

class PeeredCanvas(tk.Canvas):
    '''A class that duplicates all objects on one or more peer canvases'''
    def __init__(self, *args, **kwargs):
        self.peers = []
        tk.Canvas.__init__(self, *args, **kwargs)

    def add_peer(self, peer):
        if self.peers is None:
            self.peers = []
        self.peers.append(peer)

    def move(self, *args, **kwargs):
        tk.Canvas.move(self, *args, **kwargs)
        for peer in self.peers:
            peer.move(*args, **kwargs)

    def itemconfigure(self, *args, **kwargs):
        tk.Canvas.itemconfigure(self, *args, **kwargs)
        for peer in self.peers:
            peer.itemconfigure(*args, **kwargs)

    def delete(self, *args, **kwargs):
        tk.Canvas.delete(self, *args)
        for peer in self.peers:
            peer.delete(*args)

    def create_oval(self, *args, **kwargs):
        tk.Canvas.create_oval(self, *args, **kwargs)
        for peer in self.peers:
            peer.create_oval(*args, **kwargs)


app = SampleApp()
app.mainloop()

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