libvips/libsrc/conversion/im_text.c

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/* @(#) Make an image containting text as a bitmap. One band uchar output,
* @(#) with 0 - 255 for black - white.
* @(#)
* @(#) int
* @(#) im_text( IMAGE *out, const char *text, const char *font,
* @(#) int width, int alignment, int dpi )
* @(#)
* @(#) Font is a Pango font specification, eg. "Sans 12", or "Times News
* @(#) Roman Italic 12". text should be coded as utf-8. dpi is resolution
* @(#) in dots per inch. alignment is 0, 1 and 2 for right, centre and left
* @(#) alignment. width is the wrap width in pixels.
* @(#)
* @(#) Returns 0 on success and -1 on error.
*
* Written on: 20/5/04
* 29/7/04
* - !HAVE_PANGOFT2 was broken, thanks Kenneth
* 15/11/04
* - gah, still broken, thanks Stefan
* 5/4/06
* - return an error for im_text( "" ) rather than trying to make an
* empty image
*/
/*
This file is part of VIPS.
VIPS is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
*/
#ifdef HAVE_CONFIG_H
#include <config.h>
#endif /*HAVE_CONFIG_H*/
#include <vips/intl.h>
#include <stdio.h>
#include <string.h>
#include <vips/vips.h>
#ifdef HAVE_PANGOFT2
#include <pango/pango.h>
#include <pango/pangoft2.h>
#endif /*HAVE_PANGOFT2*/
#ifdef WITH_DMALLOC
#include <dmalloc.h>
#endif /*WITH_DMALLOC*/
#ifdef HAVE_PANGOFT2
static PangoLayout *
text_layout_new( PangoContext *context,
const char *text, const char *font, int width, int alignment, int dpi )
{
PangoLayout *layout;
PangoFontDescription *font_description;
layout = pango_layout_new( context );
pango_layout_set_markup( layout, text, -1 );
font_description = pango_font_description_from_string( font );
pango_layout_set_font_description( layout, font_description );
pango_font_description_free( font_description );
if( width > 0 )
pango_layout_set_width( layout, width * PANGO_SCALE );
if( alignment < 0 || alignment > 2 )
alignment = PANGO_ALIGN_RIGHT;
pango_layout_set_alignment( layout, (PangoAlignment) alignment );
return( layout );
}
static int
text_ft_to_vips( FT_Bitmap *bitmap, IMAGE *out )
{
int y;
if( im_outcheck( out ) )
return( -1 );
im_initdesc( out, bitmap->width, bitmap->rows, 1,
IM_BBITS_BYTE, IM_BANDFMT_UCHAR,
IM_CODING_NONE, IM_TYPE_B_W, 1.0, 1.0, 0, 0 );
if( im_setupout( out ) )
return( -1 );
for( y = 0; y < bitmap->rows; y++ )
if( im_writeline( y, out,
(PEL *) bitmap->buffer + y * bitmap->pitch ) )
return( -1 );
return( 0 );
}
static int
text_layout_render_to_image( PangoLayout *layout, IMAGE *out )
{
PangoRectangle logical_rect;
FT_Bitmap bitmap;
int left;
int top;
int width;
int height;
pango_layout_get_extents( layout, NULL, &logical_rect );
#ifdef DEBUG
printf( "logical left = %d, top = %d, width = %d, height = %d\n",
PANGO_PIXELS( logical_rect.x ),
PANGO_PIXELS( logical_rect.y ),
PANGO_PIXELS( logical_rect.width ),
PANGO_PIXELS( logical_rect.height ) );
#endif /*DEBUG*/
left = PANGO_PIXELS( logical_rect.x );
top = PANGO_PIXELS( logical_rect.y );
width = PANGO_PIXELS( logical_rect.width );
height = PANGO_PIXELS( logical_rect.height );
/* Can happen for "", for example.
*/
if( width == 0 || height == 0 ) {
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im_error( "im_text",
"%s", _( "no text to render" ) );
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return( -1 );
}
bitmap.width = width;
bitmap.pitch = (bitmap.width + 3) & ~3;
bitmap.rows = height;
if( !(bitmap.buffer = im_malloc( NULL, bitmap.pitch * bitmap.rows )) )
return( -1 );
bitmap.num_grays = 256;
bitmap.pixel_mode = ft_pixel_mode_grays;
memset( bitmap.buffer, 0x00, bitmap.pitch * bitmap.rows );
if( pango_layout_get_width( layout ) != -1 )
pango_ft2_render_layout( &bitmap, layout, -left, -top );
else
pango_ft2_render_layout( &bitmap, layout, 0, 0 );
if( text_ft_to_vips( &bitmap, out ) ) {
im_free( bitmap.buffer );
return( -1 );
}
im_free( bitmap.buffer );
return( 0 );
}
static int
text_render_to_image( PangoContext *context, IMAGE *out,
const char *text, const char *font, int width, int alignment, int dpi )
{
PangoLayout *layout;
if( !(layout = text_layout_new( context, text, font,
width, alignment, dpi )) )
return( -1 );
if( text_layout_render_to_image( layout, out ) ) {
g_object_unref( layout );
return( -1 );
}
g_object_unref( layout );
return( 0 );
}
int
im_text( IMAGE *out, const char *text, const char *font,
int width, int alignment, int dpi )
{
static PangoFontMap *fontmap = NULL;
PangoContext *context;
if( !pango_parse_markup( text, -1, 0, NULL, NULL, NULL, NULL ) ) {
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im_error( "im_text",
"%s", _( "invalid markup in text" ) );
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return( -1 );
}
/* Just have one of these, ever. It doesn't close properly when we
* _unref(), so keep it around for reuse.
*/
if( !fontmap )
fontmap = pango_ft2_font_map_new();
pango_ft2_font_map_set_resolution( PANGO_FT2_FONT_MAP( fontmap ),
dpi, dpi );
context = pango_ft2_font_map_create_context(
PANGO_FT2_FONT_MAP( fontmap ) );
if( text_render_to_image( context, out, text, font,
width, alignment, dpi ) ) {
g_object_unref( context );
return( -1 );
}
g_object_unref( context );
return( 0 );
}
#else /*!HAVE_PANGOFT2*/
int
im_text( IMAGE *out, const char *text, const char *font,
int width, int alignment, int dpi )
{
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im_error( "im_text",
"%s", _( "pangoft2 support disabled" ) );
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return( -1 );
}
#endif /*HAVE_PANGOFT2*/