[Zope] How a method only returns the data of an image

[Trevor Toenjes]

Clever. :) I think this approach will work for now.  It seems the easiest
solution.
Sometimes easier is better.

The redirect does seem to slow down the response a little.
I will revisit the whole setHeader manipulation at a later date.

Thanks.
-Trevor

> -----Original Message-----
> From: zope-admin@zope.org [mailto:zope-admin@zope.org]On Behalf Of Joel
> Burton
> Sent: Monday, March 11, 2002 10:02 AM
> To: Trevor Toenjes
> Cc: zope@zope.org
> Subject: Re: [Zope] How a method only returns the data of an image
>
>
> On Mon, 11 Mar 2002, Trevor Toenjes wrote:
>
> > I need to make a method act like the clone of an image.
> > Without extending the Image class...(I would like to do this in DTML or
> > python-script)
> > I am simply trying to get a method to return the exact data of an Image
> > object, so it can be used in normal HTML <IMG
> > src="myimage.jpg?somevariable">.  If the Image is a method, it
> can execute
> > some logic based on the QUERY_STRING.
> >
> > example:  DTML_Method "myimage.jpg"
> > # should look and smell like a JPG to the browser (but also execute some
> > logic without
> > # effecting the image header data)
> > ----
> > |  <dtml-call "RESPONSE.setHeader('Content-type', 'image/jpeg')">
> > |  <dtml-var expr="therealimage.data">
> > |  <dtml-var somelogic>
> > ----
> > But this doesn't return the proper data or Content-Length:
> > "therealimage" is a standard Zope Image object.
>
> One very easy solution is to have your script just redirect to the object.
> <dtml-call "RESPONSE.redirect(...)">
>
> Advantages:
>
> * The user's browser can take advantage of their local cached copy, if
> they have one, and any proxy servers can take advantage of their local
> cached copy, if they have one, of the image. If there's a query as part of
> the URL, many caching mechanisms won't show a cached version.
>
> Disadavantages:
>
> * User can see the real image URL (which might be a problem is your script
> is meant to check credetials before presenting it)
>
> * Two HTTP requests rather than one (but would still be faster in most
> cases because of the caching)
>
>
> Otherwise, you could get the image size with therealimage.get_size()
> and put this in the header.
>
> Anyone: is the a call to create the header for an image correctly by
> itself? Looking briefly through Image.py, I didn't see it.
>
> --
>
> Joel BURTON  |  joel@joelburton.com  |  joelburton.com  |  aim:
> wjoelburton
> Independent Knowledge Management Consultant
>
>
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