text: /* base class for all conversion operations
   *
   * properties:
   * 	- single output image
   */
  
  /*
  
      Copyright (C) 1991-2005 The National Gallery
  
      This library 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 2.1 of the License, or (at your option) any later version.
  
      This library 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 library; if not, write to the Free Software
      Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
      02110-1301  USA
  
   */
  
  /*
  
      These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
  
   */
  
  /*
  #define DEBUG
   */
  
  #ifdef HAVE_CONFIG_H
  #include <config.h>
  #endif /*HAVE_CONFIG_H*/
  #include <vips/intl.h>
  
  #include <stdio.h>
  #include <stdlib.h>
  #include <math.h>
  
  #include <vips/vips.h>
  #include <vips/internal.h>
  
  #include "pconversion.h"
  
  /** 
   * SECTION: conversion
   * @short_description: convert images in some way: change band format, change header, insert, extract, join
   * @see_also: <link linkend="libvips-resample">resample</link>
   * @stability: Stable
   * @include: vips/vips.h
   *
   * These operations convert an image in some way. They can be split into a two
   * main groups.
   *
   * The first set of operations change an image's format in some way. You
   * can change the band format (for example, cast to 32-bit unsigned
   * int), form complex images from real images, convert images to
   * matrices and back, change header fields, and a few others.
   *
   * The second group move pixels about in some way. You can flip, rotate,
   * extract, insert and join pairs of images in various ways.
   *
   */
  
  /**
   * vips_composite: (method)
   * @in: (array length=n) (transfer none): array of input images
   * @out: (out): output image
   * @n: number of input images
   * @mode: array of (@n - 1) #VipsBlendMode
   * @...: %NULL-terminated list of optional named arguments
   *
   * Optional arguments:
   *
   * * @compositing_space: #VipsInterpretation to composite in
   * * @premultiplied: %gboolean, images are already premultiplied
   * * @x: #VipsArrayInt, position of subimages
   * * @y: #VipsArrayInt, position of subimages
   *
   * Composite an array of images together. 
   *
   * Images are placed in a stack, with @in[0] at the bottom and @in[@n - 1] at
   * the top. Pixels are blended together working from the bottom upwards, with 
   * the blend mode at each step being set by the corresponding #VipsBlendMode
   * in @mode.
   *
   * Images are transformed to a compositing space before processing. This is
   * #VIPS_INTERPRETATION_sRGB, #VIPS_INTERPRETATION_B_W,
   * #VIPS_INTERPRETATION_RGB16, or #VIPS_INTERPRETATION_GREY16 
   * by default, depending on 
   * how many bands and bits the input images have. You can select any other 
   * space, such as #VIPS_INTERPRETATION_LAB or #VIPS_INTERPRETATION_scRGB.
   *
   * The output image is in the compositing space. It will always be 
   * #VIPS_FORMAT_FLOAT unless one of the inputs is #VIPS_FORMAT_DOUBLE, in 
   * which case the output will be double as well.
   *
   * Complex images are not supported.
   *
   * The output image will always have an alpha band. A solid alpha is
   * added to any input missing an alpha. 
   *
   * The images do not need to match in size or format. They will be expanded to
   * the smallest common size and format in the usual way. Images are positioned
   * using the @x and @y parameters, if set. 
   *
   * Image are normally treated as unpremultiplied, so this operation can be used
   * directly on PNG images. If your images have been through vips_premultiply(),
   * set @premultiplied. 
   *
   * See also: vips_insert().
   *
   * Returns: 0 on success, -1 on error
   */
  
  /**
   * vips_composite2: (method)
   * @base: first input image
   * @overlay: second input image
   * @out: (out): output image
   * @mode: composite with this blend mode
   * @...: %NULL-terminated list of optional named arguments
   *
   * Optional arguments:
   *
   * * @compositing_space: #VipsInterpretation to composite in
   * * @premultiplied: %gboolean, images are already premultiplied
   * * @x: %gint, position of overlay
   * * @y: %gint, position of overlay
   *
   * Composite @overlay on top of @base with @mode. See vips_composite().
   *
   * Returns: 0 on success, -1 on error
   */
  
  /**
   * VipsBlendMode:
   * @VIPS_BLEND_MODE_CLEAR: where the second object is drawn, the first is removed
   * @VIPS_BLEND_MODE_SOURCE: the second object is drawn as if nothing were below
   * @VIPS_BLEND_MODE_OVER: the image shows what you would expect if you held two semi-transparent slides on top of each other
   * @VIPS_BLEND_MODE_IN: the first object is removed completely, the second is only drawn where the first was
   * @VIPS_BLEND_MODE_OUT: the second is drawn only where the first isn't
   * @VIPS_BLEND_MODE_ATOP: this leaves the first object mostly intact, but mixes both objects in the overlapping area
   * @VIPS_BLEND_MODE_DEST: leaves the first object untouched, the second is discarded completely
   * @VIPS_BLEND_MODE_DEST_OVER: like OVER, but swaps the arguments
   * @VIPS_BLEND_MODE_DEST_IN: like IN, but swaps the arguments
   * @VIPS_BLEND_MODE_DEST_OUT: like OUT, but swaps the arguments
   * @VIPS_BLEND_MODE_DEST_ATOP: like ATOP, but swaps the arguments
   * @VIPS_BLEND_MODE_XOR: something like a difference operator
   * @VIPS_BLEND_MODE_ADD: a bit like adding the two images
   * @VIPS_BLEND_MODE_SATURATE: a bit like the darker of the two
   * @VIPS_BLEND_MODE_MULTIPLY: at least as dark as the darker of the two inputs
   * @VIPS_BLEND_MODE_SCREEN: at least as light as the lighter of the inputs
   * @VIPS_BLEND_MODE_OVERLAY: multiplies or screens colors, depending on the lightness
   * @VIPS_BLEND_MODE_DARKEN: the darker of each component
   * @VIPS_BLEND_MODE_LIGHTEN: the lighter of each component
   * @VIPS_BLEND_MODE_COLOUR_DODGE: brighten first by a factor second
   * @VIPS_BLEND_MODE_COLOUR_BURN: darken first by a factor of second
   * @VIPS_BLEND_MODE_HARD_LIGHT: multiply or screen, depending on lightness
   * @VIPS_BLEND_MODE_SOFT_LIGHT: darken or lighten, depending on lightness
   * @VIPS_BLEND_MODE_DIFFERENCE: difference of the two
   * @VIPS_BLEND_MODE_EXCLUSION: somewhat like DIFFERENCE, but lower-contrast
   *
   * The various Porter-Duff and PDF blend modes. See vips_composite(), 
   * for example.
   *
   * The Cairo docs have a nice explanation of all the blend modes:
   *
   * https://www.cairographics.org/operators
   *
   * The non-separable modes are not implemented.
   */
  
  /** 
   * VipsAlign:
   * @VIPS_ALIGN_LOW: align low coordinate edge
   * @VIPS_ALIGN_CENTRE: align centre
   * @VIPS_ALIGN_HIGH: align high coordinate edge
   *
   * See vips_join() and so on.
   *
   * Operations like vips_join() need to be told whether to align images on the
   * low or high coordinate edge, or centre.
   *
   * See also: vips_join().
   */
  
  /** 
   * VipsAngle:
   * @VIPS_ANGLE_D0: no rotate
   * @VIPS_ANGLE_D90: 90 degrees clockwise
   * @VIPS_ANGLE_D180: 180 degree rotate
   * @VIPS_ANGLE_D270: 90 degrees anti-clockwise
   *
   * See vips_rot() and so on.
   *
   * Fixed rotate angles.
   *
   * See also: vips_rot().
   */
  
  /** 
   * VipsInteresting:
   * @VIPS_INTERESTING_NONE: do nothing
   * @VIPS_INTERESTING_CENTRE: just take the centre
   * @VIPS_INTERESTING_ENTROPY: use an entropy measure
   * @VIPS_INTERESTING_ATTENTION: look for features likely to draw human attention
   * @VIPS_INTERESTING_LOW: position the crop towards the low coordinate
   * @VIPS_INTERESTING_HIGH: position the crop towards the high coordinate
   * @VIPS_INTERESTING_ALL: everything is interesting
   *
   * Pick the algorithm vips uses to decide image "interestingness". This is used
   * by vips_smartcrop(), for example, to decide what parts of the image to
   * keep.
   *
   * #VIPS_INTERESTING_NONE and #VIPS_INTERESTING_LOW mean the same -- the
   * crop is positioned at the top or left. #VIPS_INTERESTING_HIGH positions at
   * the bottom or right. 
   *
   * See also: vips_smartcrop().
   */
  
  /**
   * VipsCompassDirection:
   * @VIPS_COMPASS_DIRECTION_CENTRE: centre
   * @VIPS_COMPASS_DIRECTION_NORTH: north
   * @VIPS_COMPASS_DIRECTION_EAST: east
   * @VIPS_COMPASS_DIRECTION_SOUTH: south
   * @VIPS_COMPASS_DIRECTION_WEST: west
   * @VIPS_COMPASS_DIRECTION_NORTH_EAST: north-east
   * @VIPS_COMPASS_DIRECTION_SOUTH_EAST: south-east
   * @VIPS_COMPASS_DIRECTION_SOUTH_WEST: south-west
   * @VIPS_COMPASS_DIRECTION_NORTH_WEST: north-west
   *
   * A direction on a compass. Used for vips_gravity(), for example. 
   */
  
  /**
   * VipsAngle45:
   * @VIPS_ANGLE45_D0: no rotate
   * @VIPS_ANGLE45_D45: 45 degrees clockwise 
   * @VIPS_ANGLE45_D90: 90 degrees clockwise
   * @VIPS_ANGLE45_D135: 135 degrees clockwise
   * @VIPS_ANGLE45_D180: 180 degrees 
   * @VIPS_ANGLE45_D225: 135 degrees anti-clockwise
   * @VIPS_ANGLE45_D270: 90 degrees anti-clockwise
   * @VIPS_ANGLE45_D315: 45 degrees anti-clockwise
   *
   * See vips_rot45() and so on.
   *
   * Fixed rotate angles.
   *
   * See also: vips_rot45().
   */
  
  /** 
   * VipsExtend:
   * @VIPS_EXTEND_BLACK: extend with black (all 0) pixels
   * @VIPS_EXTEND_COPY: copy the image edges
   * @VIPS_EXTEND_REPEAT: repeat the whole image
   * @VIPS_EXTEND_MIRROR: mirror the whole image
   * @VIPS_EXTEND_WHITE: extend with white (all bits set) pixels
   * @VIPS_EXTEND_BACKGROUND: extend with colour from the @background property
   *
   * See vips_embed(), vips_conv(), vips_affine() and so on.
   *
   * When the edges of an image are extended, you can specify
   * how you want the extension done. 
   *
   * #VIPS_EXTEND_BLACK --- new pixels are black, ie. all bits are zero. 
   *
   * #VIPS_EXTEND_COPY --- each new pixel takes the value of the nearest edge
   * pixel
   *
   * #VIPS_EXTEND_REPEAT --- the image is tiled to fill the new area
   *
   * #VIPS_EXTEND_MIRROR --- the image is reflected and tiled to reduce hash
   * edges
   *
   * #VIPS_EXTEND_WHITE --- new pixels are white, ie. all bits are set
   *
   * #VIPS_EXTEND_BACKGROUND --- colour set from the @background property
   *
   * We have to specify the exact value of each enum member since we have to 
   * keep these frozen for back compat with vips7.
   *
   * See also: vips_embed().
   */
  
  /** 
   * VipsDirection:
   * @VIPS_DIRECTION_HORIZONTAL: left-right 
   * @VIPS_DIRECTION_VERTICAL: top-bottom
   *
   * See vips_flip(), vips_join() and so on.
   *
   * Operations like vips_flip() need to be told whether to flip left-right or
   * top-bottom. 
   *
   * See also: vips_flip(), vips_join().
   */
  
  G_DEFINE_ABSTRACT_TYPE( VipsConversion, vips_conversion, VIPS_TYPE_OPERATION );
  
  static int
  vips_conversion_build( VipsObject *object )
  {
  	VipsConversion *conversion = VIPS_CONVERSION( object );
  
  #ifdef DEBUG
  	printf( "vips_conversion_build: " );
  	vips_object_print_name( object );
  	printf( "\n" );
  #endif /*DEBUG*/
  
  	g_object_set( conversion, "out", vips_image_new(), NULL ); 
  
  	if( VIPS_OBJECT_CLASS( vips_conversion_parent_class )->build( object ) )
  		return( -1 );
  
  	return( 0 );
  }
  
  static void
  vips_conversion_class_init( VipsConversionClass *class )
  {
  	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
  	VipsObjectClass *vobject_class = VIPS_OBJECT_CLASS( class );
  
  	gobject_class->set_property = vips_object_set_property;
  	gobject_class->get_property = vips_object_get_property;
  
  	vobject_class->nickname = "conversion";
  	vobject_class->description = _( "conversion operations" );
  	vobject_class->build = vips_conversion_build;
  
  	VIPS_ARG_IMAGE( class, "out", 2, 
  		_( "Output" ), 
  		_( "Output image" ),
  		VIPS_ARGUMENT_REQUIRED_OUTPUT, 
  		G_STRUCT_OFFSET( VipsConversion, out ) );
  }
  
  static void
  vips_conversion_init( VipsConversion *conversion )
  {
  }
  
  /* Called from iofuncs to init all operations in this dir. Use a plugin system
   * instead?
   */
  void
  vips_conversion_operation_init( void )
  {
  	extern GType vips_copy_get_type( void ); 
  	extern GType vips_tile_cache_get_type( void ); 
  	extern GType vips_line_cache_get_type( void ); 
  	extern GType vips_sequential_get_type( void ); 
  	extern GType vips_cache_get_type( void ); 
  	extern GType vips_embed_get_type( void ); 
  	extern GType vips_gravity_get_type( void ); 
  	extern GType vips_flip_get_type( void ); 
  	extern GType vips_insert_get_type( void ); 
  	extern GType vips_join_get_type( void ); 
  	extern GType vips_arrayjoin_get_type( void ); 
  	extern GType vips_extract_area_get_type( void ); 
  	extern GType vips_crop_get_type( void ); 
  	extern GType vips_smartcrop_get_type( void ); 
  	extern GType vips_extract_band_get_type( void ); 
  	extern GType vips_replicate_get_type( void ); 
  	extern GType vips_cast_get_type( void ); 
  	extern GType vips_bandjoin_get_type( void ); 
  	extern GType vips_bandjoin_const_get_type( void ); 
  	extern GType vips_bandrank_get_type( void ); 
  	extern GType vips_black_get_type( void ); 
  	extern GType vips_rot_get_type( void ); 
  	extern GType vips_rot45_get_type( void ); 
  	extern GType vips_autorot_get_type( void ); 
  	extern GType vips_ifthenelse_get_type( void ); 
  	extern GType vips_switch_get_type( void ); 
  	extern GType vips_recomb_get_type( void ); 
  	extern GType vips_bandmean_get_type( void ); 
  	extern GType vips_bandfold_get_type( void ); 
  	extern GType vips_bandunfold_get_type( void ); 
  	extern GType vips_flatten_get_type( void ); 
  	extern GType vips_premultiply_get_type( void ); 
  	extern GType vips_unpremultiply_get_type( void ); 
  	extern GType vips_bandbool_get_type( void ); 
  	extern GType vips_gaussnoise_get_type( void ); 
  	extern GType vips_grid_get_type( void ); 
  	extern GType vips_transpose3d_get_type( void ); 
  	extern GType vips_scale_get_type( void ); 
  	extern GType vips_wrap_get_type( void ); 
  	extern GType vips_zoom_get_type( void ); 
  	extern GType vips_subsample_get_type( void ); 
  	extern GType vips_msb_get_type( void ); 
  	extern GType vips_byteswap_get_type( void ); 
  #ifdef HAVE_PANGOFT2
  	extern GType vips_text_get_type( void ); 
  #endif /*HAVE_PANGOFT2*/
  	extern GType vips_xyz_get_type( void ); 
  	extern GType vips_falsecolour_get_type( void ); 
  	extern GType vips_gamma_get_type( void ); 
  	extern GType vips_composite_get_type( void ); 
  	extern GType vips_composite2_get_type( void ); 
  
  	vips_copy_get_type();
  	vips_tile_cache_get_type(); 
  	vips_line_cache_get_type(); 
  	vips_sequential_get_type(); 
  	vips_cache_get_type(); 
  	vips_embed_get_type();
  	vips_gravity_get_type();
  	vips_flip_get_type();
  	vips_insert_get_type();
  	vips_join_get_type();
  	vips_arrayjoin_get_type();
  	vips_extract_area_get_type();
  	vips_crop_get_type();
  	vips_smartcrop_get_type();
  	vips_extract_band_get_type();
  	vips_replicate_get_type();
  	vips_cast_get_type();
  	vips_bandjoin_get_type();
  	vips_bandjoin_const_get_type();
  	vips_bandrank_get_type();
  	vips_black_get_type();
  	vips_rot_get_type();
  	vips_rot45_get_type();
  	vips_autorot_get_type();
  	vips_ifthenelse_get_type();
  	vips_switch_get_type(); 
  	vips_recomb_get_type(); 
  	vips_bandmean_get_type(); 
  	vips_bandfold_get_type(); 
  	vips_bandunfold_get_type(); 
  	vips_flatten_get_type(); 
  	vips_premultiply_get_type(); 
  	vips_unpremultiply_get_type(); 
  	vips_bandbool_get_type(); 
  	vips_gaussnoise_get_type(); 
  	vips_grid_get_type(); 
  	vips_transpose3d_get_type(); 
  	vips_scale_get_type(); 
  	vips_wrap_get_type(); 
  	vips_zoom_get_type(); 
  	vips_subsample_get_type(); 
  	vips_msb_get_type(); 
  	vips_byteswap_get_type(); 
  #ifdef HAVE_PANGOFT2
  	vips_text_get_type(); 
  #endif /*HAVE_PANGOFT2*/
  	vips_xyz_get_type(); 
  	vips_falsecolour_get_type(); 
  	vips_gamma_get_type(); 
  	vips_composite_get_type(); 
  	vips_composite2_get_type(); 
  }
  