netsurf/pdf/font_haru.c

/*
 * Copyright 2008 Adam Blokus <adamblokus@gmail.com>
 *
 * This file is part of NetSurf, http://www.netsurf-browser.org/
 *
 * NetSurf is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; version 2 of the License.
 *
 * NetSurf 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
 /** \file
  * Font handling in Haru pdf documents (implementation).
  *
  * The functions were written to implement the same interface as the Pango ones
  * so that the usage of the latter wouldn't have to be modified.
  */
 
#define FONT_HARU_DEBUG
 
#include <assert.h> 
#include <float.h> 
#include <math.h>
#include <string.h> 
 
#include "css/css.h"
#include "hpdf.h" 
#include "render/font.h"
#include "pdf/font_haru.h"
#include "utils/log.h"


static bool haru_nsfont_init(HPDF_Doc *pdf, HPDF_Page *page,
		const char *string, char **string_nt, int length);

static bool haru_nsfont_width(const struct css_style *style,
		const char *string, size_t length,
		int *width);

static bool haru_nsfont_position_in_string(const struct css_style *style,
		const char *string, size_t length,
		int x, size_t *char_offset, int *actual_x);

static bool haru_nsfont_split(const struct css_style *style,
		const char *string, size_t length,
	 	int x, size_t *char_offset, int *actual_x);
	 	

const struct font_functions haru_nsfont = {
	haru_nsfont_width,
 	haru_nsfont_position_in_string,
 	haru_nsfont_split
};


/**
 * Haru error handler
 * for debugging purposes - it immediately exits the program on the first error,
 * as it would otherwise flood the user with all resulting complications,
 * covering the most important error source.
 */
static void error_handler(HPDF_STATUS error_no,
		   HPDF_STATUS detail_no,
     void *user_data)
{
	LOG(("ERROR: in font_haru \n\terror_no=%x\n\tdetail_no=%d\n", 
		(HPDF_UINT)error_no, 
		(HPDF_UINT)detail_no));
#ifdef FONT_HARU_DEBUG	
	exit(1);
#endif	
}

static bool haru_nsfont_init(HPDF_Doc *pdf, HPDF_Page *page,
		const char *string, char **string_nt, int length)
{
	
	*pdf = HPDF_New(error_handler, NULL);
	
	if (*pdf == NULL)
		return false;

	*page = HPDF_AddPage(*pdf);
	
	if (*page == NULL) {
		HPDF_Free(*pdf);
		return false;	
	}
	
	*string_nt = malloc((length + 1) * sizeof(char));
	if (*string_nt == NULL) {
		HPDF_Free(*pdf);
		return false;
	}
	
	memcpy(*string_nt, string, length);
	(*string_nt)[length] = '\0';	
	return true;
}

/**
 * Measure the width of a string.
 *
 * \param  style   css_style for this text, with style->font_size.size ==
 *		   CSS_FONT_SIZE_LENGTH
 * \param  string  string to measure (no UTF-8 currently)
 * \param  length  length of string
 * \param  width   updated to width of string[0..length]
 * \return  true on success, false on error and error reported
 */
bool haru_nsfont_width(const struct css_style *style,
		const char *string, size_t length,
	 	int *width)
{
	HPDF_Doc pdf;
	HPDF_Page page;
	char *string_nt;
	HPDF_REAL width_real;
	
	if (length == 0) {
		*width = 0;
		return true;
	}
	
	if (!haru_nsfont_init(&pdf, &page, string, &string_nt, length))
		return false;
	
	if (!haru_nsfont_apply_style(style, pdf, page, NULL)) {
		free(string_nt);
		HPDF_Free(pdf);
		return false;
	}
	
	width_real = HPDF_Page_TextWidth(page, string_nt);
	*width = width_real;

#ifdef FONT_HARU_DEBUG		
	LOG(("Measuring string: %s ; Calculated width: %f %i",string_nt, width_real, *width));
#endif
	free(string_nt);
	HPDF_Free(pdf);
	
		
	return true;
}


/**
 * Find the position in a string where an x coordinate falls.
 *
 * \param  style	css_style for this text, with style->font_size.size ==
 *			CSS_FONT_SIZE_LENGTH
 * \param  string	string to measure (no UTF-8 currently)
 * \param  length	length of string
 * \param  x		x coordinate to search for
 * \param  char_offset	updated to offset in string of actual_x, [0..length]
 * \param  actual_x	updated to x coordinate of character closest to x
 * \return  true on success, false on error and error reported
 */

bool haru_nsfont_position_in_string(const struct css_style *style,
		const char *string, size_t length,
		int x, size_t *char_offset, int *actual_x)
{
	HPDF_Doc pdf;
	HPDF_Page page;
	char *string_nt;
	HPDF_UINT offset;
	HPDF_REAL real_width;
	HPDF_REAL width;
	
	
	if (!haru_nsfont_init(&pdf, &page, string, &string_nt, length))
		return false;
	
	if (!HPDF_Page_SetWidth(page, x)
			|| !haru_nsfont_apply_style(style, pdf, page, NULL)) {
		free(string_nt);
		HPDF_Free(pdf);
		return false;
	}

	
	offset = HPDF_Page_MeasureText(page, string_nt, x,
				       HPDF_FALSE, &real_width);
	

	if (real_width < x)
		*char_offset = offset;
	else {
		assert(fabs(real_width - x) < FLT_EPSILON);
		assert(offset > 0);
		*char_offset = offset - 1;
	}
	
	/*TODO: this is only the right edge of the character*/
	*actual_x = real_width;
	
#ifdef FONT_HARU_DEBUG	
	LOG(("Position in string: %s at x: %i; Calculated position: %i",
		string_nt, x, *char_offset));	
#endif	
	free(string_nt);
	HPDF_Free(pdf);
	
	return true;
}

/**
 * Find where to split a string to make it fit a width.
 *
 * \param  style	css_style for this text, with style->font_size.size ==
 *			CSS_FONT_SIZE_LENGTH
 * \param  string	string to measure (no UTF-8 currently)
 * \param  length	length of string
 * \param  x		width available
 * \param  char_offset	updated to offset in string of actual_x, [0..length]
 * \param  actual_x	updated to x coordinate of character closest to x
 * \return  true on success, false on error and error reported
 */

bool haru_nsfont_split(const struct css_style *style,
		       const char *string, size_t length,
	 int x, size_t *char_offset, int *actual_x)
{
	HPDF_Doc pdf;
	HPDF_Page page;
	char *string_nt;
	HPDF_REAL real_width;
	HPDF_UINT offset;
	
	
	if (!haru_nsfont_init(&pdf, &page, string, &string_nt, length))
		return false;
	
	if (!HPDF_Page_SetWidth(page, x)
		    || !haru_nsfont_apply_style(style, pdf, page, NULL)) {
		free(string_nt);
		HPDF_Free(pdf);
		return false;
	}
	
	offset = HPDF_Page_MeasureText(page, string_nt, x,
				        HPDF_TRUE, &real_width);
	
#ifdef FONT_HARU_DEBUG	
	LOG(("Splitting string: %s for width: %i ; Calculated position: %i Calculated real_width: %f", 
	string_nt, x, *char_offset, real_width));	
#endif	
	*char_offset = offset - 1;
	
	/*TODO: this is only the right edge of the character*/
	*actual_x = real_width;
	
	free(string_nt);
	HPDF_Free(pdf);
	
	return true;	
}

/**
 * Apply css_style to a Haru HPDF_Page
 *
 * \param  style	css_style for this page, with style->font_size.size ==
 *			CSS_FONT_SIZE_LENGTH
 * \param  doc		document owning the page
 * \param  page		the page to apply the style to
 * \param  font		if this is not NULL it is updated to the font from the
 *			style and nothing with the page is done
 * \return true on success, false on error and error reported
 */

bool haru_nsfont_apply_style(const struct css_style *style,
				     	HPDF_Doc doc, HPDF_Page page,
	  				HPDF_Font *font)
{
	
	HPDF_Font pdf_font;
	HPDF_REAL size;
	char font_name[50];
	bool roman;
	bool bold;
	bool styled;
	
	roman = false;
	bold = false;
	styled = false;
	
	
	/*TODO: style handling, we are mapping the
		styles on the basic 14 fonts only
	*/
	switch (style->font_family) {
		case CSS_FONT_FAMILY_SERIF:
			strcpy(font_name, "Times");
			roman = true;
			break;
		case CSS_FONT_FAMILY_MONOSPACE:
			strcpy(font_name, "Courier");
			break;
		case CSS_FONT_FAMILY_SANS_SERIF:
			strcpy(font_name, "Helvetica");
			break;
		case CSS_FONT_FAMILY_CURSIVE:			
		case CSS_FONT_FAMILY_FANTASY:		
		default:
			strcpy(font_name, "Times");
			roman=true;
			break;
	}
	
	if (style->font_weight == CSS_FONT_WEIGHT_BOLD){
		strcat(font_name, "-Bold");
		bold = true;
	}
	
	
		
		
	switch (style->font_style) {
		case CSS_FONT_STYLE_ITALIC:
		case CSS_FONT_STYLE_OBLIQUE:
			if (!bold) strcat(font_name,"-");
			if (roman)
				strcat(font_name,"Italic");
			else
				strcat(font_name,"Oblique");
			
			styled = true;
			break;
		default:
			break;
	}
	
	if (roman && !styled && !bold)
		strcat(font_name, "-Roman");

#ifdef FONT_HARU_DEBUG		
	LOG(("Setting font: %s", font_name));
#endif		
	
	if (font != NULL) {
		pdf_font = HPDF_GetFont(doc, font_name, "StandardEncoding");
		if (pdf_font == NULL)
			return false;
		*font = pdf_font;
	}
	else {
		
		if (style->font_size.value.length.unit  == CSS_UNIT_PX)
			size = style->font_size.value.length.value;
		else
			size = css_len2pt(&style->font_size.value.length, style);
	
		/*with 0.7 the pages look the best, this should be kept the same
		as the scale in print settings*/
		size = size / 0.7;
		
		pdf_font = HPDF_GetFont(doc, font_name, "StandardEncoding");
		if (pdf_font == NULL)
			return false;
		HPDF_Page_SetFontAndSize(page, pdf_font, size);
	}	
	
	return true;
}