369 lines
9.2 KiB
C
369 lines
9.2 KiB
C
/* vips_text
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*
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* Written on: 20/5/04
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* 29/7/04
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* - !HAVE_PANGOFT2 was broken, thanks Kenneth
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* 15/11/04
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* - gah, still broken, thanks Stefan
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* 5/4/06
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* - return an error for im_text( "" ) rather than trying to make an
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* empty image
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* 2/2/10
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* - gtkdoc
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* 3/6/13
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* - rewrite as a class
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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/intl.h>
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#include <stdio.h>
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#include <string.h>
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#include <vips/vips.h>
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#ifdef HAVE_PANGOFT2
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#include <pango/pango.h>
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#include <pango/pangoft2.h>
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#include "conversion.h"
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typedef struct _VipsText {
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VipsConversion parent_instance;
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char *text;
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char *font;
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int width;
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VipsAlign align;
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int dpi;
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FT_Bitmap bitmap;
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PangoContext *context;
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PangoLayout *layout;
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} VipsText;
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typedef VipsConversionClass VipsTextClass;
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G_DEFINE_TYPE( VipsText, vips_text, VIPS_TYPE_CONVERSION );
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/* Just have one of these and reuse it.
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*
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* This does not unref cleanly on many platforms, so we will leak horribly
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* unless we reuse it. Sadly this means vips_text() needs to use a lock
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* internally to single-thread text rendering.
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*/
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static PangoFontMap *vips_text_fontmap = NULL;
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/* ... single-thread the body of vips_text() with this.
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*/
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static GMutex *vips_text_lock = NULL;
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static void
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vips_text_dispose( GObject *gobject )
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{
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VipsText *text = (VipsText *) gobject;
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VIPS_UNREF( text->layout );
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VIPS_UNREF( text->context );
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VIPS_FREE( text->bitmap.buffer );
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G_OBJECT_CLASS( vips_text_parent_class )->dispose( gobject );
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}
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static PangoLayout *
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text_layout_new( PangoContext *context,
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const char *text, const char *font, int width,
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VipsAlign align, int dpi )
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{
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PangoLayout *layout;
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PangoFontDescription *font_description;
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PangoAlignment palign;
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layout = pango_layout_new( context );
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pango_layout_set_markup( layout, text, -1 );
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font_description = pango_font_description_from_string( font );
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pango_layout_set_font_description( layout, font_description );
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pango_font_description_free( font_description );
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if( width > 0 )
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pango_layout_set_width( layout, width * PANGO_SCALE );
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switch( align ) {
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case VIPS_ALIGN_LOW:
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palign = PANGO_ALIGN_LEFT;
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break;
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case VIPS_ALIGN_CENTRE:
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palign = PANGO_ALIGN_CENTER;
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break;
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case VIPS_ALIGN_HIGH:
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palign = PANGO_ALIGN_RIGHT;
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break;
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default:
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palign = PANGO_ALIGN_LEFT;
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break;
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}
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pango_layout_set_alignment( layout, palign );
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return( layout );
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}
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static int
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vips_text_build( VipsObject *object )
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{
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VipsObjectClass *class = VIPS_OBJECT_GET_CLASS( object );
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VipsConversion *conversion = VIPS_CONVERSION( object );
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VipsText *text = (VipsText *) object;
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PangoRectangle logical_rect;
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int left;
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int top;
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int width;
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int height;
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int y;
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if( VIPS_OBJECT_CLASS( vips_text_parent_class )->build( object ) )
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return( -1 );
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if( !pango_parse_markup( text->text, -1, 0, NULL, NULL, NULL, NULL ) ) {
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vips_error( class->nickname,
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"%s", _( "invalid markup in text" ) );
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return( -1 );
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}
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if( !text->font )
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g_object_set( text, "font", "sans 12", NULL );
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g_mutex_lock( vips_text_lock );
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if( !vips_text_fontmap )
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vips_text_fontmap = pango_ft2_font_map_new();
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pango_ft2_font_map_set_resolution(
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PANGO_FT2_FONT_MAP( vips_text_fontmap ), text->dpi, text->dpi );
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text->context = pango_font_map_create_context(
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PANGO_FONT_MAP( vips_text_fontmap ) );
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if( !(text->layout = text_layout_new( text->context,
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text->text, text->font,
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text->width, text->align, text->dpi )) ) {
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g_mutex_unlock( vips_text_lock );
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return( -1 );
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}
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pango_layout_get_extents( text->layout, NULL, &logical_rect );
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#ifdef DEBUG
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printf( "logical left = %d, top = %d, width = %d, height = %d\n",
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PANGO_PIXELS( logical_rect.x ),
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PANGO_PIXELS( logical_rect.y ),
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PANGO_PIXELS( logical_rect.width ),
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PANGO_PIXELS( logical_rect.height ) );
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#endif /*DEBUG*/
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left = PANGO_PIXELS( logical_rect.x );
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top = PANGO_PIXELS( logical_rect.y );
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width = PANGO_PIXELS( logical_rect.width );
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height = PANGO_PIXELS( logical_rect.height );
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/* Can happen for "", for example.
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*/
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if( width == 0 || height == 0 ) {
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vips_error( class->nickname, "%s", _( "no text to render" ) );
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g_mutex_unlock( vips_text_lock );
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return( -1 );
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}
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text->bitmap.width = width;
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text->bitmap.pitch = (text->bitmap.width + 3) & ~3;
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text->bitmap.rows = height;
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if( !(text->bitmap.buffer =
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im_malloc( NULL, text->bitmap.pitch * text->bitmap.rows )) ) {
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g_mutex_unlock( vips_text_lock );
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return( -1 );
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}
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text->bitmap.num_grays = 256;
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text->bitmap.pixel_mode = ft_pixel_mode_grays;
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memset( text->bitmap.buffer, 0x00,
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text->bitmap.pitch * text->bitmap.rows );
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if( pango_layout_get_width( text->layout ) != -1 )
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pango_ft2_render_layout( &text->bitmap, text->layout,
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-left, -top );
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else
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pango_ft2_render_layout( &text->bitmap, text->layout, 0, 0 );
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g_mutex_unlock( vips_text_lock );
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vips_image_init_fields( conversion->out,
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text->bitmap.width, text->bitmap.rows, 1,
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VIPS_FORMAT_UCHAR, VIPS_CODING_NONE, VIPS_INTERPRETATION_B_W,
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1.0, 1.0 );
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vips_demand_hint( conversion->out,
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VIPS_DEMAND_STYLE_ANY, NULL );
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for( y = 0; y < text->bitmap.rows; y++ )
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if( vips_image_write_line( conversion->out, y,
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(VipsPel *) text->bitmap.buffer +
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y * text->bitmap.pitch ) )
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return( -1 );
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return( 0 );
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}
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static void *
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vips_text_make_lock( void *client )
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{
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if( !vips_text_lock )
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vips_text_lock = vips_g_mutex_new();
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return( NULL );
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}
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static void
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vips_text_class_init( VipsTextClass *class )
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{
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GObjectClass *gobject_class = G_OBJECT_CLASS( class );
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VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
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static GOnce once = G_ONCE_INIT;
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(void) g_once( &once, vips_text_make_lock, NULL );
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gobject_class->dispose = vips_text_dispose;
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gobject_class->set_property = vips_object_set_property;
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gobject_class->get_property = vips_object_get_property;
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vobject_class->nickname = "text";
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vobject_class->description = _( "make a text image" );
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vobject_class->build = vips_text_build;
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VIPS_ARG_STRING( class, "text", 4,
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_( "Text" ),
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_( "Text to render" ),
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VIPS_ARGUMENT_REQUIRED_INPUT,
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G_STRUCT_OFFSET( VipsText, text ),
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NULL );
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VIPS_ARG_STRING( class, "font", 4,
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_( "Font" ),
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_( "Font to render width" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsText, font ),
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NULL );
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VIPS_ARG_INT( class, "width", 4,
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_( "Width" ),
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_( "Maximum image width in pixels" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsText, width ),
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0, 1000000, 0 );
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VIPS_ARG_ENUM( class, "align", 5,
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_( "Align" ),
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_( "Align on the low, centre or high coordinate edge" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsText, align ),
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VIPS_TYPE_ALIGN, VIPS_ALIGN_LOW );
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VIPS_ARG_INT( class, "dpi", 4,
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_( "DPI" ),
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_( "DPI to render at" ),
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VIPS_ARGUMENT_OPTIONAL_INPUT,
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G_STRUCT_OFFSET( VipsText, dpi ),
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1, 1000000, 72 );
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}
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static void
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vips_text_init( VipsText *text )
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{
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text->align = VIPS_ALIGN_LOW;
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text->dpi = 72;
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text->bitmap.buffer = NULL;
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}
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#endif /*HAVE_PANGOFT2*/
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/**
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* vips_text:
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* @out: output image
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* @text: utf-8 text string to render
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* @...: %NULL-terminated list of optional named arguments
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*
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* Optional arguments:
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*
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* @font: font to render with
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* @width: render within this many pixels across
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* @alignment: left/centre/right alignment
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* @dpi: render at this resolution
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*
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* Draw the string @text to an image. @out is a one-band 8-bit
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* unsigned char image, with 0 for no text and 255 for text. Values inbetween
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* are used for anti-aliasing.
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*
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* @text is the text to render as a UTF-8 string. It can contain Pango markup,
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* for example "<i>The</i>Guardian".
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*
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* @font is the font to render with, as a fontconfig name. Examples might be
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* "sans 12" or perhaps "bitstream charter bold 10".
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*
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* @width is the maximum number of pixels across to draw within. If the
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* generated text is wider than this, it will wrap to a new line. In this
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* case, @alignment can be used to set the alignment style for multi-line
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* text. 0 means left-align, 1 centre, 2 right-align.
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*
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* @dpi sets the resolution to render at. "sans 12" at 72 dpi draws characters
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* approximately 12 pixels high.
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*
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* See also: vips_make_xy(), vips_text(), vips_gaussnoise().
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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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vips_text( VipsImage **out, const char *text, ... )
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{
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va_list ap;
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int result;
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va_start( ap, text );
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result = vips_call_split( "text", ap, out, text );
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va_end( ap );
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return( result );
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}
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