111 lines
2.4 KiB
C
111 lines
2.4 KiB
C
/* Convert pre-multipled argb to rgba
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*
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* 11/12/11
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* - from im_rad2float.c
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*/
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/*
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This file is part of VIPS.
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VIPS is free software; you can redistribute it and/or modify
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it under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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/*
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These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
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*/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif /*HAVE_CONFIG_H*/
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#include <vips/intl.h>
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#include <stdio.h>
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#include <math.h>
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#include <vips/vips.h>
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static void
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argb2rgba( guint32 *in, VipsPel *out, int n, void *_bg )
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{
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guint32 bg = GPOINTER_TO_UINT( _bg );
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int i;
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for( i = 0; i < n; i++ ) {
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guint32 x = in[i];
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guint8 a = x >> 24;
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/* Convert from ARGB to RGBA and undo premultiplication.
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*/
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if( a != 0 ) {
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out[0] = 255 * ((x >> 16) & 255) / a;
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out[1] = 255 * ((x >> 8) & 255) / a;
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out[2] = 255 * (x & 255) / a;
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}
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else {
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/* Use background color.
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*/
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out[0] = (bg >> 16) & 255;
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out[1] = (bg >> 8) & 255;
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out[2] = bg & 255;
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}
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out[3] = a;
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out += 4;
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}
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}
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/**
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* im_argb2rgba:
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* @in: input image
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* @out: output image
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*
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* Convert Cairo-style pre-multiplied argb to png-style rgba. Background
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* pixels are painted with the metadata item "background-rgb".
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*
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* See also: im_openslide2vips().
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*
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* Returns: 0 on success, -1 on error.
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*/
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int
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im_argb2rgba( VipsImage *in, IMAGE *out )
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{
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guint32 bg;
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/* check for RAD coding
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if( in->Coding != IM_CODING_RAD ) {
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im_error( "im_rad2float", "%s", _( "not a RAD image" ) );
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return( -1 );
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}
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*/
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if( im_cp_desc( out, in ) )
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return( -1 );
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out->Coding = IM_CODING_NONE;
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if( vips_image_get_int( in, VIPS_META_BACKGROUND_RGB, (int *) &bg ) )
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bg = 0xffffff;
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if( im_wrapone( in, out,
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(im_wrapone_fn) argb2rgba, GUINT_TO_POINTER( bg ), NULL ) )
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return( -1 );
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return( 0 );
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}
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