image descriptors and defimage with :data

image descriptors and defimage with :data

[Nic Ferrier]

I'm building an image from a part returned by an IMAP server.

Instead of saving the part to a file and opening it that way I
thought it would be fun to have no file caching and just open the
image directly from the imap server.

My code gets the part from the imap server as a string and then
constructs an image descriptor for it.

It then uses insert-image to get it into a buffer.

But the image doesn't get displayed. 


Emacs 21 manual says that defimage must have at least the following
properties in the props list:

  :type
  :file

But I don't want to specify the image as a file. Can (defimage ...)
cope with something like the following?

      (defimage content-image
	((:type jpeg :data content)))


Nic Ferrier

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Re: image descriptors and defimage with :data

[Pavel Janík]

   From: Nic Ferrier <nferrier@tapsellferrier.co.uk>
   Date: 08 Feb 2002 03:50:53 +0000

   > But I don't want to specify the image as a file. Can (defimage ...)
   > cope with something like the following?
   > 
   >       (defimage content-image
   > 	((:type jpeg :data content)))

Of course. Can you please create a small sample so we can debug it? Try
to evaluate the following:

(progn
(defimage content-image ((:type xpm :data "/* XPM */
static char * letter_xpm[] = {
\"14 10 2 1\",
\".	c \#000000\",
\" 	c \#FFFFFF\",
\"..............\",
\"...        ...\",
\".  .      .  .\",
\".   .    .   .\",
\".    ....    .\",
\".   . .. .   .\",
\".  .      .  .\",
\". .        . .\",
\"..          ..\",
\"..............\"};
")))
(insert-image content-image))

-- 
Pavel Janík

/* Identify the flock of penguins.  */
                  -- 2.2.16 arch/alpha/kernel/setup.c

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Re: image descriptors and defimage with :data

[Richard Stallman]

    Emacs 21 manual says that defimage must have at least the following
    properties in the props list:

Where does it say that?  Here is the text I see:

    Each argument in @var{specs} has the form of a property list, and each
    one should specify at least the @code{:type} property and either the
    @code{:file} or the @code{:data} property.  The value of @code{:type}
    should be a symbol specifying the image type, the value of
    @code{:file} is the file to load the image from, and the value of
    @code{:data} is a string containing the actual image data.  Here is an
    example:

However, judging from the previous node in the manual, I think that
:data is not supported yet for image type JPEG.  If so, we would like
to support it; would you like to try to implement it?

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Re: image descriptors and defimage with :data

[Nic Ferrier]

Nic said:
     Emacs 21 manual says that defimage must have at least the following 
     properties in the props list: 

rms replied:  
> Where does it say that?  Here is the text I see: 
>  
>     Each argument in @var{specs} has the form of a property list, and each 
>     one should specify at least the @code{:type} property and either the 
>     @code{:file} or the @code{:data} property.  The value of @code{:type} 
>     should be a symbol specifying the image type, the value of 
>     @code{:file} is the file to load the image from, and the value of 
>     @code{:data} is a string containing the actual image data.  Here is an 
>     example: 
>  
> However, judging from the previous node in the manual, I think that 
> :data is not supported yet for image type JPEG.  If so, we would like 
> to support it; would you like to try to implement it? 

The function documentation string for defimage says this:

    Each image specification in SPECS is a property list.  The contents of
    a specification are image type dependent.  All specifications must at
    least contain the properties `:type TYPE' and either `:file FILE' or
    `:data DATA', where TYPE is a symbol specifying the image type,
    e.g. `xbm', FILE is the file to load the image from, and DATA is a
    string containing the actual image data.  The first image
    specification whose TYPE is supported, and FILE exists, is used to
    define SYMBOL.

I am trying to narrow the problem down so that I can either patch it
or give a better report.


Nic

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Re: image descriptors and defimage with :data

[Richard Stallman]

Use of :data is implemented only for some image types.
I suggest you check the specific code that handles JPEG type
and see if it implements :data.

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