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/* Part of SWI-Prolog
Author: Jan Wielemaker
E-mail: J.Wielemaker@vu.nl
WWW: http://www.swi-prolog.org
Copyright (c) 2002-2015, University of Amsterdam
VU University Amsterdam
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions
are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in
the documentation and/or other materials provided with the
distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
*/
:- module(http_image,
[ reply_image/2 % +Image, +Options
]).
:- use_module(library(readutil)).
:- use_module(library(pce)).
/** <module> Serve dynamically generated images through XPCE
*/
%! reply_image(+Image, +Options)
%
% Formulate a CGI reply from an XPCE graphical. This call handles
% anything that can be converted into a pixmap object, notably any
% XPCE graphical object.
%
% Currently the only option recognised is content_type(+Type) to
% specify the type. image/jpeg and image/gif are the only sensible
% values. The default is to generate gif.
%
% If this module is used as a server on X11-based systems the user
% must ensure the presence of an X11 server. The XPCE library
% 'Xserver' provides code to start a `head-less' (i.e. server that
% doesn't need a physical display) server and adjust the
% environment to make XPCE use this server.
% (*) Note that this code uses a text_buffer as intermediate for the
% data. this is pretty dubious as binary data is not well supported this
% way. It still works, but only when using newline(posix) for Windows.
reply_image(Image, Options) :-
( memberchk(content_type(Type), Options)
-> image_format(Type, ImgType)
; Type = image/gif,
ImgType = gif
),
get(@pce, convert, Image, pixmap, Pixmap),
new(TB, text_buffer),
send(TB, undo_buffer_size, 0),
send(Pixmap, save, TB, ImgType),
format('Content-type: ~w~n~n', [Type]),
pce_open(TB, read, Data),
set_stream(Data, newline(posix)), % (*)
copy_stream_data(Data, current_output),
close(Data),
free(TB),
( Pixmap \== Image
-> free(Pixmap)
; true
).
image_format(image/Type, Type) :- !.
image_format(Format, Type) :-
atom_concat('image/', Type, Format).
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