go-fitz/include/mupdf/fitz/structured-text.h

// Copyright (C) 2004-2021 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
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// any later version.
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// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
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//
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// For commercial licensing, see <https://www.artifex.com/> or contact
// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
// CA 94129, USA, for further information.

#ifndef MUPDF_FITZ_STRUCTURED_TEXT_H
#define MUPDF_FITZ_STRUCTURED_TEXT_H

#include "mupdf/fitz/system.h"
#include "mupdf/fitz/types.h"
#include "mupdf/fitz/context.h"
#include "mupdf/fitz/geometry.h"
#include "mupdf/fitz/font.h"
#include "mupdf/fitz/image.h"
#include "mupdf/fitz/output.h"
#include "mupdf/fitz/device.h"
#include "mupdf/fitz/pool.h"

/**
	Simple text layout (for use with annotation editing primarily).
*/
typedef struct fz_layout_char
{
	float x, advance;
	const char *p; /* location in source text of character */
	struct fz_layout_char *next;
} fz_layout_char;

typedef struct fz_layout_line
{
	float x, y, font_size;
	const char *p; /* location in source text of start of line */
	fz_layout_char *text;
	struct fz_layout_line *next;
} fz_layout_line;

typedef struct
{
	fz_pool *pool;
	fz_matrix matrix;
	fz_matrix inv_matrix;
	fz_layout_line *head, **tailp;
	fz_layout_char **text_tailp;
} fz_layout_block;

/**
	Create a new layout block, with new allocation pool, zero
	matrices, and initialise linked pointers.
*/
fz_layout_block *fz_new_layout(fz_context *ctx);

/**
	Drop layout block. Free the pool, and linked blocks.

	Never throws exceptions.
*/
void fz_drop_layout(fz_context *ctx, fz_layout_block *block);

/**
	Add a new line to the end of the layout block.
*/
void fz_add_layout_line(fz_context *ctx, fz_layout_block *block, float x, float y, float h, const char *p);

/**
	Add a new char to the line at the end of the layout block.
*/
void fz_add_layout_char(fz_context *ctx, fz_layout_block *block, float x, float w, const char *p);

/**
	Text extraction device: Used for searching, format conversion etc.

	(In development - Subject to change in future versions)
*/

typedef struct fz_stext_char fz_stext_char;
typedef struct fz_stext_line fz_stext_line;
typedef struct fz_stext_block fz_stext_block;

/**
	FZ_STEXT_PRESERVE_LIGATURES: If this option is activated
	ligatures are passed through to the application in their
	original form. If this option is deactivated ligatures are
	expanded into their constituent parts, e.g. the ligature ffi is
	expanded into three separate characters f, f and i.

	FZ_STEXT_PRESERVE_WHITESPACE: If this option is activated
	whitespace is passed through to the application in its original
	form. If this option is deactivated any type of horizontal
	whitespace (including horizontal tabs) will be replaced with
	space characters of variable width.

	FZ_STEXT_PRESERVE_IMAGES: If this option is set, then images
	will be stored in the structured text structure. The default is
	to ignore all images.

	FZ_STEXT_INHIBIT_SPACES: If this option is set, we will not try
	to add missing space characters where there are large gaps
	between characters.

	FZ_STEXT_DEHYPHENATE: If this option is set, hyphens at the
	end of a line will be removed and the lines will be merged.

	FZ_STEXT_PRESERVE_SPANS: If this option is set, spans on the same line
	will not be merged. Each line will thus be a span of text with the same
	font, colour, and size.

	FZ_STEXT_MEDIABOX_CLIP: If this option is set, characters entirely
	outside each page's mediabox will be ignored.
*/
enum
{
	FZ_STEXT_PRESERVE_LIGATURES = 1,
	FZ_STEXT_PRESERVE_WHITESPACE = 2,
	FZ_STEXT_PRESERVE_IMAGES = 4,
	FZ_STEXT_INHIBIT_SPACES = 8,
	FZ_STEXT_DEHYPHENATE = 16,
	FZ_STEXT_PRESERVE_SPANS = 32,
	FZ_STEXT_MEDIABOX_CLIP = 64,
};

/**
	A text page is a list of blocks, together with an overall
	bounding box.
*/
typedef struct
{
	fz_pool *pool;
	fz_rect mediabox;
	fz_stext_block *first_block, *last_block;
} fz_stext_page;

enum
{
	FZ_STEXT_BLOCK_TEXT = 0,
	FZ_STEXT_BLOCK_IMAGE = 1
};

/**
	A text block is a list of lines of text (typically a paragraph),
	or an image.
*/
struct fz_stext_block
{
	int type;
	fz_rect bbox;
	union {
		struct { fz_stext_line *first_line, *last_line; } t;
		struct { fz_matrix transform; fz_image *image; } i;
	} u;
	fz_stext_block *prev, *next;
};

/**
	A text line is a list of characters that share a common baseline.
*/
struct fz_stext_line
{
	int wmode; /* 0 for horizontal, 1 for vertical */
	fz_point dir; /* normalized direction of baseline */
	fz_rect bbox;
	fz_stext_char *first_char, *last_char;
	fz_stext_line *prev, *next;
};

/**
	A text char is a unicode character, the style in which is
	appears, and the point at which it is positioned.
*/
struct fz_stext_char
{
	int c;
	int color; /* sRGB hex color */
	fz_point origin;
	fz_quad quad;
	float size;
	fz_font *font;
	fz_stext_char *next;
};

FZ_DATA extern const char *fz_stext_options_usage;

/**
	Create an empty text page.

	The text page is filled out by the text device to contain the
	blocks and lines of text on the page.

	mediabox: optional mediabox information.
*/
fz_stext_page *fz_new_stext_page(fz_context *ctx, fz_rect mediabox);
void fz_drop_stext_page(fz_context *ctx, fz_stext_page *page);

/**
	Output structured text to a file in HTML (visual) format.
*/
void fz_print_stext_page_as_html(fz_context *ctx, fz_output *out, fz_stext_page *page, int id);
void fz_print_stext_header_as_html(fz_context *ctx, fz_output *out);
void fz_print_stext_trailer_as_html(fz_context *ctx, fz_output *out);

/**
	Output structured text to a file in XHTML (semantic) format.
*/
void fz_print_stext_page_as_xhtml(fz_context *ctx, fz_output *out, fz_stext_page *page, int id);
void fz_print_stext_header_as_xhtml(fz_context *ctx, fz_output *out);
void fz_print_stext_trailer_as_xhtml(fz_context *ctx, fz_output *out);

/**
	Output structured text to a file in XML format.
*/
void fz_print_stext_page_as_xml(fz_context *ctx, fz_output *out, fz_stext_page *page, int id);

/**
	Output structured text to a file in JSON format.
*/
void fz_print_stext_page_as_json(fz_context *ctx, fz_output *out, fz_stext_page *page, float scale);

/**
	Output structured text to a file in plain-text UTF-8 format.
*/
void fz_print_stext_page_as_text(fz_context *ctx, fz_output *out, fz_stext_page *page);

/**
	Search for occurrence of 'needle' in text page.

	Return the number of hits and store hit quads in the passed in
	array.

	NOTE: This is an experimental interface and subject to change
	without notice.
*/
int fz_search_stext_page(fz_context *ctx, fz_stext_page *text, const char *needle, int *hit_mark, fz_quad *hit_bbox, int hit_max);

/**
	Return a list of quads to highlight lines inside the selection
	points.
*/
int fz_highlight_selection(fz_context *ctx, fz_stext_page *page, fz_point a, fz_point b, fz_quad *quads, int max_quads);

enum
{
	FZ_SELECT_CHARS,
	FZ_SELECT_WORDS,
	FZ_SELECT_LINES,
};

fz_quad fz_snap_selection(fz_context *ctx, fz_stext_page *page, fz_point *ap, fz_point *bp, int mode);

/**
	Return a newly allocated UTF-8 string with the text for a given
	selection.

	crlf: If true, write "\r\n" style line endings (otherwise "\n"
	only).
*/
char *fz_copy_selection(fz_context *ctx, fz_stext_page *page, fz_point a, fz_point b, int crlf);

/**
	Return a newly allocated UTF-8 string with the text for a given
	selection rectangle.

	crlf: If true, write "\r\n" style line endings (otherwise "\n"
	only).
*/
char *fz_copy_rectangle(fz_context *ctx, fz_stext_page *page, fz_rect area, int crlf);

/**
	Options for creating a pixmap and draw device.
*/
typedef struct
{
	int flags;
	float scale;
} fz_stext_options;

/**
	Parse stext device options from a comma separated key-value
	string.
*/
fz_stext_options *fz_parse_stext_options(fz_context *ctx, fz_stext_options *opts, const char *string);

/**
	Create a device to extract the text on a page.

	Gather the text on a page into blocks and lines.

	The reading order is taken from the order the text is drawn in
	the source file, so may not be accurate.

	page: The text page to which content should be added. This will
	usually be a newly created (empty) text page, but it can be one
	containing data already (for example when merging multiple
	pages, or watermarking).

	options: Options to configure the stext device.
*/
fz_device *fz_new_stext_device(fz_context *ctx, fz_stext_page *page, const fz_stext_options *options);

/**
	Create a device to OCR the text on the page.

	Renders the page internally to a bitmap that is then OCRd. Text
	is then forwarded onto the target device.

	target: The target device to receive the OCRd text.

	ctm: The transform to apply to the mediabox to get the size for
	the rendered page image. Also used to calculate the resolution
	for the page image. In general, this will be the same as the CTM
	that you pass to fz_run_page (or fz_run_display_list) to feed
	this device.

	mediabox: The mediabox (in points). Combined with the CTM to get
	the bounds of the pixmap used internally for the rendered page
	image.

	with_list: If with_list is false, then all non-text operations
	are forwarded instantly to the target device. This results in
	the target device seeing all NON-text operations, followed by
	all the text operations (derived from OCR).

	If with_list is true, then all the marking operations are
	collated into a display list which is then replayed to the
	target device at the end.

	language: NULL (for "eng"), or a pointer to a string to describe
	the languages/scripts that should be used for OCR (e.g.
	"eng,ara").

	datadir: NULL (for ""), or a pointer to a path string otherwise
	provided to Tesseract in the TESSDATA_PREFIX environment variable.

	progress: NULL, or function to be called periodically to indicate
	progress. Return 0 to continue, or 1 to cancel. progress_arg is
	returned as the void *. The int is a value between 0 and 100 to
	indicate progress.

	progress_arg: A void * value to be parrotted back to the progress
	function.
*/
fz_device *fz_new_ocr_device(fz_context *ctx, fz_device *target, fz_matrix ctm, fz_rect mediabox, int with_list, const char *language,
			const char *datadir, int (*progress)(fz_context *, void *, int), void *progress_arg);

fz_document *fz_open_reflowed_document(fz_context *ctx, fz_document *underdoc, const fz_stext_options *opts);


#endif