129 lines
3.2 KiB
C
129 lines
3.2 KiB
C
/* Shared code for cairo based loaders like svgload and pdfload.
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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., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 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/vips.h>
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#include <vips/internal.h>
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/* Convert from Cairo-style premultiplied BGRA to RGBA.
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*
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* See also openslide's argb2rgba().
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*/
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void
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vips__premultiplied_bgra2rgba( guint32 * restrict p, int n )
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{
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int x;
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for( x = 0; x < n; x++ ) {
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guint32 bgra = GUINT32_FROM_BE( p[x] );
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guint8 a = bgra & 0xff;
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guint32 rgba;
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if( a == 0 ||
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a == 255 )
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rgba =
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(bgra & 0x00ff00ff) |
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(bgra & 0x0000ff00) << 16 |
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(bgra & 0xff000000) >> 16;
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else
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/* Undo premultiplication.
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*/
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rgba =
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((255 * ((bgra >> 8) & 0xff) / a) << 24) |
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((255 * ((bgra >> 16) & 0xff) / a) << 16) |
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((255 * ((bgra >> 24) & 0xff) / a) << 8) |
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a;
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p[x] = GUINT32_TO_BE( rgba );
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}
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}
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/* Unpremultiplied RGBA (vips convention) to cairo-style premul BGRA.
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*/
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void
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vips__rgba2bgra_premultiplied( guint32 * restrict p, int n )
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{
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int x;
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for( x = 0; x < n; x++ ) {
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guint32 rgba = GUINT32_FROM_BE( p[x] );
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guint8 a = rgba & 0xff;
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guint32 bgra;
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if( a == 0 )
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bgra = 0;
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else if( a == 255 )
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bgra = (rgba & 0x00ff00ff) |
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(rgba & 0x0000ff00) << 16 |
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(rgba & 0xff000000) >> 16;
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else {
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int r = (rgba >> 24) & 0xff;
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int g = (rgba >> 16) & 0xff;
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int b = (rgba >> 8) & 0xff;
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r = ((r * a) + 128) >> 8;
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g = ((g * a) + 128) >> 8;
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b = ((b * a) + 128) >> 8;
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bgra = (b << 24) | (g << 16) | (r << 8) | a;
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}
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p[x] = GUINT32_TO_BE( bgra );
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}
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}
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/* Convert from PDFium-style BGRA to RGBA.
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*/
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void
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vips__bgra2rgba( guint32 * restrict p, int n )
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{
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int x;
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for( x = 0; x < n; x++ ) {
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guint32 bgra = GUINT32_FROM_BE( p[x] );
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guint rgba;
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/* Leave G and A, swap R and B.
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*/
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rgba =
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(bgra & 0x00ff00ff) |
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(bgra & 0x0000ff00) << 16 |
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(bgra & 0xff000000) >> 16;
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p[x] = GUINT32_TO_BE( rgba );
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}
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}
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