Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail From: Terry Reedy Newsgroups: comp.lang.python Subject: Re: Image loading problem Date: Sat, 21 May 2016 15:23:42 -0400 Lines: 50 Message-ID: References: <743e5fbe-3a6c-49ea-ac5e-9bc055f652b5@googlegroups.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Trace: news.uni-berlin.de JMB6zAFtiChdiPxlwIzcPwRyenUDdUf8mgwfB1iCNEHA== Return-Path: X-Original-To: python-list@python.org Delivered-To: python-list@mail.python.org X-Spam-Status: OK 0.000 X-Spam-Evidence: '*H*': 1.00; '*S*': 0.00; 'attributes': 0.07; 'dict': 0.09; 'instance.': 0.09; 'received:80.91': 0.09; 'received:80.91.229': 0.09; 'received:gmane.org': 0.09; 'received:list': 0.09; 'jan': 0.11; 'def': 0.13; '(but': 0.15; 'loaded.': 0.16; 'main().': 0.16; 'mean,': 0.16; 'out?': 0.16; 'received:80.91.229.3': 0.16; 'received:io': 0.16; 'received:plane.gmane.org': 0.16; 'received:psf.io': 0.16; 'reedy': 0.16; 'select.': 0.16; 'tk()': 0.16; 'wrote:': 0.16; 'app': 0.16; 'odd': 0.18; 'project,': 0.18; 'load': 0.20; 'prevent': 0.20; 'function,': 0.22; 'subject:problem': 0.22; 'tkinter': 0.22; 'trying': 0.22; 'import': 0.24; 'header:In-Reply- To:1': 0.24; 'script': 0.25; 'header:User-Agent:1': 0.26; 'example': 0.26; 'header:X-Complaints-To:1': 0.26; 'function': 0.28; 'img': 0.29; 'code:': 0.29; 'somebody': 0.30; 'window': 0.30; 'run': 0.33; 'class': 0.33; 'thanks!': 0.34; 'list': 0.34; 'instance': 0.35; 'but': 0.36; 'to:addr:python-list': 0.36; 'pm,': 0.36; 'subject:: ': 0.37; 'being': 0.37; 'display': 0.37; 'method': 0.37; 'received:org': 0.37; 'skip:p 20': 0.38; 'to:addr:python.org': 0.40; 'your': 0.60; 'email addr:yahoo.com': 0.63; 'received:96': 0.63; 'otten': 0.84; 'received:fios.verizon.net': 0.91 X-Injected-Via-Gmane: http://gmane.org/ X-Gmane-NNTP-Posting-Host: pool-96-227-207-81.phlapa.fios.verizon.net User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.1.0 In-Reply-To: X-BeenThere: python-list@python.org X-Mailman-Version: 2.1.22 Precedence: list List-Id: General discussion list for the Python programming language List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Mailman-Original-Message-ID: X-Mailman-Original-References: <743e5fbe-3a6c-49ea-ac5e-9bc055f652b5@googlegroups.com> Xref: csiph.com comp.lang.python:108928 On 5/21/2016 12:54 PM, Peter Otten wrote: > sweating_ant@yahoo.com wrote: > >> I am working on an image project, and I can display my image in main(). I > mean, I can load my image in my main(). Needless, it is awkward. I am trying > to load my image with a function, but got an empty image window popped up, > no image content loaded. Please take a look at code: >> >> >> >> rom Tkinter import * >> >> def load_img(win): >> img = PhotoImage(file="xxx.gif") >> Label(win, image=img).pack() >> >> win = Tk() >> load_img(win) >> win.mainloop() >> >> Somebody can help me out? Thanks! > > It's not your fault, there's an odd quirk in the library: you have to keep a > reference of the PhotoImage instance around to prevent the image from being > garbage-collected. For example > > from Tkinter import * > > def load_img(win): > global img > > img = PhotoImage(file="xxx.gif") > Label(win, image=img).pack() > > win = Tk() > load_img(win) > win.mainloop() > > will work because img is now a global that is not deleted until the script > ends (but don't run the function twice -- then the first image will > disappear). The usual procedure is to create an App class and make images attributes of the App instance. Then load_img would be a method and the first line would be 'self.img = ...'. One can also have a list of images, to use in a slide show, or a dict of images, so users can select. -- Terry Jan Reedy