[Seaside] serve jpg image files from form objects

Martin Schubert martin.schubert at informatik.uni-ulm.de
Thu Jun 1 16:22:15 UTC 2006

Am 01.06.2006 um 08:40 schrieb Michel Bany:

> Martin Schubert a écrit :
>> i want to serve a jpg-file which is stored in a Form object.
>> so i do : aForm _ (Form fromFileNamed: 'wave.jpg')
> Method #fromFileNamed: is smart enough to decode various picture  
> formats
> and turn them into bitmaps. That's why it can understand your jpeg  
> file. However
> after this was executed, the knowledge that its source was jpeg is  
> lost.
> Not so smart.
>> this doesn`t work, and when i am acceptin the following, seaside   
>> seems to convert the jpg file to gif or wracks up the picture  
>> file  somehow :
>>     html imageWithDocument: aForm
>>         mimeType: 'image/jpeg'
>>         fileName: root name,'Picture', '.jpg'.
> The above creates a document handler. When invoked for the  
> rendering, this document handler
> needs to encode the bitmap into a MIME document. For some reason,  
> the GIF encoding
> is selected by Seaside. See Form>>asMIMEDocument.

i tried to extend the Form with the following method and some  
variations but i cant get it work. it allways renders an image of  
type gif and it looks like this as well

	| aStream |
	aStream _ (RWBinaryOrTextStream on: '').
	JPEGReadWriter putForm: (self asFormOfDepth: self depth) onStream:  
	^MIMEDocument contentType: 'image/jpeg' content: aStream contents

so any help on how to fix that would be great.

as far as the html canvas api is concerned i don`t know anything  
about it. is there an example about the methods where the rendering  
is done. is the #renderContenOn: omitted?

thanks so far !!!

> A possible solution would be to subclass Form so that it remembers  
> the encoding of
> its source, re-implementing #asMIMEDocument to take this into account.
> Another solution may be to use the Canvas api, where the image tag  
> is handled quite
> differently.
> Michel.
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