使用PIL在Tkinter中显示动画GIF [英] Displaying animated GIFs in Tkinter using PIL

问题描述

我正在尝试制作一个程序来使用Tkinter显示动画GIF.这是我最初使用的代码:

I'm trying to make a program to display an animated GIF using Tkinter. Here is the code that I originally used:

from __future__ import division # Just because division doesn't work right in 2.7.4
from Tkinter import *
from PIL import Image,ImageTk
import threading
from time import sleep

def anim_gif(name):
    ## Returns { 'frames', 'delay', 'loc', 'len' }
    im = Image.open(name)
    gif = { 'frames': [],
            'delay': 100,
            'loc' : 0,
            'len' : 0 }
    pics = []
    try:
        while True:
            pics.append(im.copy())
            im.seek(len(pics))
    except EOFError: pass

    temp = pics[0].convert('RGBA')
    gif['frames'] = [ImageTk.PhotoImage(temp)]
    temp = pics[0]
    for item in pics[1:]:
        temp.paste(item)
        gif['frames'].append(ImageTk.PhotoImage(temp.convert('RGBA')))

    try: gif['delay'] = im.info['duration']
    except: pass
    gif['len'] = len(gif['frames'])
    return gif

def ratio(a,b):
    if b < a: d,c = a,b
    else: c,d = a,b
    if b == a: return 1,1
    for i in reversed(xrange(2,int(round(a / 2)))):
        if a % i == 0 and b % i == 0:
            a /= i
            b /= i
    return (int(a),int(b))

class App(Frame):
    def show(self,image=None,event=None):
        self.display.create_image((0,0),anchor=NW,image=image)   

    def animate(self,event=None):
        self.show(image=self.gif['frames'][self.gif['loc']])
        self.gif['loc'] += 1
        if self.gif['loc'] == self.gif['len']:
            self.gif['loc'] = 0
        if self.cont:
            threading.Timer((self.gif['delay'] / 1000),self.animate).start()

    def kill(self,event=None):
        self.cont = False
        sleep(0.1)
        self.quit()

    def __init__(self,master):
        Frame.__init__(self,master)
        self.grid(row=0,sticky=N+E+S+W)
        self.rowconfigure(1,weight=2)
        self.rowconfigure(3,weight=1)
        self.columnconfigure(0,weight=1)
        self.title = Label(self,text='No title')
        self.title.grid(row=0,sticky=E+W)
        self.display = Canvas(self)
        self.display.grid(row=1,sticky=N+E+S+W)
        self.user = Label(self,text='Posted by No Username')
        self.user.grid(row=2,sticky=E+W)
        self.comment = Text(self,height=4,width=40,state=DISABLED)
        self.comment.grid(row=3,sticky=N+E+S+W)
        self.cont = True
        self.gif = anim_gif('test.gif')
        self.animate()

        root.protocol("WM_DELETE_WINDOW",self.kill)


root = Tk()
root.rowconfigure(0,weight=1)
root.columnconfigure(0,weight=1)
app = App(root)
app.mainloop()

try: root.destroy()
except: pass

test.gif是以下GIF:

test.gif is the following GIF:

这很好，但是GIF的质量很差.我尝试将其更改为以下内容:

This works fine, but the GIF quality is terrible. I tried changing it to what follows:

def anim_gif(name):
    ## Returns { 'frames', 'delay', 'loc', 'len' }
    im = Image.open(name)
    gif = { 'frames': [],
            'delay': 100,
            'loc' : 0,
            'len' : 0 }
    pics = []
    try:
        while True:
            gif['frames'].append(im.copy())
            im.seek(len(gif['frames']))
    except EOFError: pass

    try: gif['delay'] = im.info['duration']
    except: pass
    gif['len'] = len(gif['frames'])
    return gif

class App(Frame):
    def show(self,image=None,event=None):
        can_w = self.display['width']
        can_h = self.display['height']

        pic_w,pic_h = image.size
        rat_w,rat_h = ratio(pic_w,pic_h)

        while pic_w > int(can_w) or pic_h > int(can_h):
            pic_w -= rat_w
            pic_h -= rat_h

        resized = image.resize((pic_w,pic_h))
        resized = ImageTk.PhotoImage(resized)
        self.display.create_image((0,0),anchor=NW,image=resized)   

但是，这偶尔会闪烁图像.虽然图片看起来不错，但作为程序却毫无用处.我究竟做错了什么?

However, this will occasionally flash a picture. While the picture looks good, it's pretty useless as a program. What am I doing wrong?

推荐答案

对于其中一个，您正在为每个帧创建一个新的画布对象.最终，您将有成千上万的图像相互堆叠.这是非常低效的；当您开始有成千上万个对象时，canvas小部件会出现性能问题.

For one, you are creating a new canvas object for every frame. Eventually you will have thousands of images stacked on top of one another. This is highly inefficient; the canvas widget has performance issues when you start to have thousands of objects.

与其在画布上创建新的图像对象，不如使用 itemconfig 方法.

Instead of creating new image objects on the canvas, just reconfigure the existing object with the itemconfig method of the canvas.

第二，对于这样一个简单的任务，您不需要复杂的线程处理.在tkinter中有一个众所周知的用于制作动画的模式:绘制一帧，然后让该函数在将来使用after对其进行调用.

Second, you don't need the complexities of threading for such a simple task. There is a well known pattern in tkinter for doing animations: draw a frame, then have that function use after to call itself in the future.

类似这样的东西:

def animate(self):
    if self._image_id is None:
        self._image_id = self.display.create_image(...)
    else:
        self.itemconfig(self._image_id, image= the_new_image)
    self.display.after(self.gif["delay"], self.animate)

最后，除非有严格的理由使用画布，否则可以使用标签"小部件来降低复杂性.

Finally, unless there's a strict reason to use a canvas, you can lower the complexity a little more by using a Label widget.

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