dip.c

ELinks is an advanced and well-established feature-rich text mode web (HTTP/FTP/..) browser. ELinks

/* dip.c
 * Digital Image Processing routines
 * (c) 2000-2002 Karel 'Clock' Kulhavy
 * This file is a part of the Links program, released under GPL.
 * This does various utilities for digital image processing including font
 * rendering.
 */

#include "cfg.h"

#ifdef G

#include "links.h"

#ifdef HAVE_MATH_H
#include <math.h>
#endif /* HAVE_MATH_H */

#endif
int dither_letters=1;

double user_gamma=1.0; /* 1.0 for 64 lx. This is the number user directly changes in the menu */
			  
double display_red_gamma=2.2; /* Red gamma exponent of the display */
double display_green_gamma=2.2; /* Green gamma exponent of the display */
double display_blue_gamma=2.2; /* Blue gamma exponent of the display */
#ifdef G

/* #define this if you want to report missing letters to stderr.
 * Leave it commented up for normal operation and releases! */
/* #define REPORT_UNKNOWN 1 */

double sRGB_gamma=0.45455;      /* For HTML, which runs
				 * according to sRGB standard. Number
				 * in HTML tag is linear to photons raised
				 * to this power.
				 */

unsigned long aspect=65536; /* aspect=65536 for 320x240
		        * aspect=157286 for 640x200 (tall pixels)
                        * Defines aspect ratio of screen pixels. 
		        * aspect=(196608*xsize+ysize<<1)/(ysize<<1);
		        * Default is 65536 because we assume square pixel
			* when not specified otherwise. Aspect is ratio of
			* the pixel height (in milimeters) to pixel width,
			* multiplied by 65536. */
unsigned long aspect_native=65536; /* Like aspect, but not influenced by
			* user, just determined by graphics driver.
			*/

/* Limitation: No input image's dimension may exceed 2^(32-1-8) pixels.
 */

/* Each input byte represents 1 byte (gray). The question whether 0 is
 * black or 255 is black doesn't matter.
 */

/* These constants represent contrast-enhancement and sharpen filter (which is one filter
 * together) that is applied onto the letters to enhance their appearance at low height.
 * They were determined by experiment for several values, interpolated, checked and tuned.
 * If you change them, don't wonder if the letters start to look strange.
 * The numers in the comments denote which height the line applies for.
 */
float fancy_constants[64]={
	0,3,		/*  1 */
	.1,3,   	/*  2 */
	.2,3,   	/*  3 */
	.3,2.9,   	/*  4 */
	.4,2.7,   	/*  5 */
	.4,2.5,   	/*  6 */
	.4,2,   	/*  7 */
	.5,2, 		/*  8 */
	.4,2, 		/*  9 */
	.38,1.9, 	/* 10 */
	.36,1.8, 	/* 11 */
	.33,1.7, 	/* 12 */
	.30,1.6, 	/* 13 */
	.25,1.5, 	/* 14 */
	.20,1.5, 	/* 15 */
	.15,1.5, 	/* 16 */
	.14,1.5, 	/* 17 */
	.13,1.5, 	/* 18 */
	.12,1.5, 	/* 19 */
	.12,1.5, 	/* 20 */
	.12,1.5, 	/* 21 */
	.12,1.5, 	/* 22 */
	.11,1.5, 	/* 23 */
	.10,1.4, 	/* 24 */
	.09,1.3, 	/* 25 */
	.08,1.3, 	/* 26 */
	.04,1.2, 	/* 27 */
	.04,1.2, 	/* 28 */
	.02,1.1, 	/* 29 */
	.02,1.1, 	/* 30 */
	.01,1, 		/* 31 */
	.01,1  		/* 32 */
};

/* prototypes */
void decimate_3(unsigned short **, int, int);
struct letter *find_stored_letter(int *, int);
void read_stored_data(png_structp, png_bytep, png_uint_32);
void my_png_warning(png_structp, png_const_charp);
void my_png_error(png_structp, png_const_charp);
struct font_cache_entry *supply_color_cache_entry (struct graphics_driver *, struct style *, struct letter *);
void get_underline_pos(int, int *, int *);
int compare_font_entries(void *, void *);
void init_font_cache(int);
void recode_font_name(unsigned char **);
int compare_family(unsigned char *, unsigned char *);
int fill_style_table(int *, unsigned char *);


/* This shall be hopefully reasonably fast and portable
 * We assume ix is <65536. If not, the letters will be smaller in
 * horizontal dimension (because of overflow) but this will not cause
 * a segfault. 65536 pixels wide bitmaps are not normal and will anyway
 * exhaust the memory.
 */
static inline int compute_width (int ix, int iy, int required_height)
{
	int width;
	unsigned long reg;
	
	reg=(unsigned long)aspect*(unsigned long)required_height;
	
	if (reg>=0x1000000UL){
		/* It's big */
		reg=(reg+32768)>>16;
		width=(reg*ix+(iy>>1))/iy;
	}else{
		/* It's small */
		reg=(reg+128)>>8;
		iy<<=8;
		width=(reg*ix+(iy>>1))/iy;
	}
	if (width<1) width=1;
	return width;
}

struct lru font_cache; /* This is a cache for screen-ready colored bitmaps
                        * of lettrs and/or alpha channels for these (are the
			* same size, only one byte per pixel and are used
			* for letters with an image under them )
			*/

/* Each input byte represents 1 byte (gray). The question whether 0 is
 * black or 255 is black doesn't matter.
 */

inline static void add_col_gray(unsigned *col_buf, unsigned char *ptr, int
		line_skip, int n, unsigned weight)
{
	for (;n;n--){
		*col_buf+=weight*(*ptr);
		ptr+=line_skip;
		col_buf++;
	}
}

/* line_skip is in pixels. The column contains the whole pixels (R G B)
 * We assume unsigned short holds at least 16 bits. */
inline static void add_col_color(unsigned *col_buf, unsigned short *ptr
	, int line_skip, int n, unsigned weight)
{
	for (;n;n--){
		*col_buf+=weight*(*ptr);
		col_buf[1]+=weight*ptr[1];
		col_buf[2]+=weight*ptr[2];
		ptr+=line_skip;
		col_buf+=3;
	}
}

 /* We assume unsigned short holds at least 16 bits. */
inline static void add_row_gray(unsigned *row_buf, unsigned char *ptr, int n,
	unsigned weight)
{
	for (;n;n--){
		*row_buf+=weight**ptr;
		ptr++;
		row_buf++;
	}
}

/* n is in pixels. pixel is 3 unsigned shorts in series */
 /* We assume unsigned short holds at least 16 bits. */
inline static void add_row_color(unsigned *row_buf, unsigned short *ptr, int n, unsigned weight)
{
	for (;n;n--){
		*row_buf+=weight**ptr;
		row_buf[1]+=weight*ptr[1];
		row_buf[2]+=weight*ptr[2];
		ptr+=3;
		row_buf+=3;
	}
}

/* We assume unsigned holds at least 32 bits */
inline static void emit_and_bias_col_gray(unsigned *col_buf, unsigned char *out, int
		line_skip, int n, unsigned weight)
{
	unsigned half=weight>>1;

	for (;n;n--){
		*out=*col_buf/weight;
		out+=line_skip;
		*col_buf++=half;
	}
}

/* We assume unsigned holds at least 32 bits */
static inline void bias_buf_gray(unsigned *col_buf, int n, unsigned half)
{
	for (;n;n--) *col_buf++=half;
}

/* We assume unsigned holds at least 32 bits */
inline static void bias_buf_color(unsigned *col_buf, int n, unsigned half)
{
	for (;n;n--){
		*col_buf=half;
		col_buf[1]=half;
		col_buf[2]=half;
		col_buf+=3;
	}
	/* System activated */
}
		
/* line skip is in pixels. Pixel is 3*unsigned short */
/* We assume unsigned holds at least 32 bits */
/* We assume unsigned short holds at least 16 bits. */
inline static void emit_and_bias_col_color(unsigned *col_buf
	, unsigned short *out, int line_skip, int n, unsigned weight)
{
	unsigned half=weight>>1;

	for (;n;n--){
		*out=(*col_buf)/weight;
		*col_buf=half;
		out[1]=col_buf[1]/weight;
		col_buf[1]=half;
		/* The following line is an enemy of the State and will be
		 * prosecuted according to the Constitution of The United States
		 * Cap. 20/3 ix. Sel. Bill 12/1920
		 * Moses 12/20 Erizea farizea 2:2:1:14
		 */
		out[2]=col_buf[2]/weight;
		col_buf[2]=half;
		out+=line_skip;
		col_buf+=3;
	}
}
		
/* We assume unsigned holds at least 32 bits */
inline static void emit_and_bias_row_gray(unsigned *row_buf, unsigned char *out, int n
		,unsigned weight)
{
	unsigned half=weight>>1;
	
	for (;n;n--){
		*out++=*row_buf/weight;
		*row_buf++=half;
	}
}

/* n is in pixels. pixel is 3 unsigned shorts in series. */
/* We assume unsigned holds at least 32 bits */
/* We assume unsigned short holds at least 16 bits. */
inline static void emit_and_bias_row_color(unsigned *row_buf, unsigned short
		*out, int n, unsigned weight)
{
	unsigned half=weight>>1;

	for (;n;n--){
		*out=*row_buf/weight;
		*row_buf=half;
		out[1]=row_buf[1]/weight;
		row_buf[1]=half;
		out[2]=row_buf[2]/weight;
		row_buf[2]=half;
		out+=3;
		row_buf+=3;
	}
}
		
/* For enlargement only -- does linear filtering.
 * Allocates output and frees input.
 * We assume unsigned holds at least 32 bits */
inline static void enlarge_gray_horizontal(unsigned char *in, int ix, int y
	,unsigned char ** out, int ox)
{
	unsigned *col_buf;
	int total;
	int out_pos,in_pos,in_begin,in_end;
	unsigned half=(ox-1)>>1;
	unsigned char *outptr;
	unsigned char *inptr;

	if (ox && (unsigned)ox * (unsigned)y / (unsigned)ox != (unsigned)y) overalloc();
	if ((unsigned)ox * (unsigned)y > MAXINT) overalloc();
	outptr=mem_alloc(ox*y);
	inptr=in;
	*out=outptr;
	if (ix==1){
		/* Dull copying */
		for (;y;y--){
			memset(outptr,*inptr,ox);
			outptr+=ox;
			inptr++;
		}
		mem_free(in);
	}else{
		total=(ix-1)*(ox-1);
		if ((unsigned)y > MAXINT / sizeof(*col_buf)) overalloc();
		col_buf=mem_alloc(y*sizeof(*col_buf));
		bias_buf_gray(col_buf, y, half);
		out_pos=0;
		in_pos=0;
		again:
		in_begin=in_pos;
		in_end=in_pos+ox-1;
		add_col_gray(col_buf,inptr, ix, y, in_end-out_pos);
		add_col_gray(col_buf,inptr+1, ix, y, out_pos-in_begin);
		emit_and_bias_col_gray(col_buf,outptr,ox,y,ox-1);
		outptr++;
		out_pos+=ix-1;
		if (out_pos>in_end){
			in_pos=in_end;
			inptr++;
		}
		if (out_pos>total){
			mem_free(in);
			mem_free(col_buf);
			return;
		}
		goto again;
	}
	/* Rohan, oh Rohan... */
	/* ztracena zeme :) */
}

/* For enlargement only -- does linear filtering
 * Frees input and allocates output.
 * We assume unsigned holds at least 32 bits
 */
static inline void enlarge_color_horizontal(unsigned short *ina, int ix, int y,
	unsigned short ** outa, int ox)
{
	unsigned *col_buf;
	int total,a,out_pos,in_pos,in_begin,in_end;
	unsigned half=(ox-1)>>1;
	unsigned skip=3*ix;
	unsigned oskip=3*ox;
	unsigned short *out, *in;

	if (ix==ox){
		*outa=ina;
		return;
	}
	if (ox && (unsigned)ox * (unsigned)y / (unsigned)ox != (unsigned)y) overalloc();
	if ((unsigned)ox * (unsigned)y > MAXINT / 3 / sizeof(*out)) overalloc();
	out=mem_alloc(sizeof(*out)*3*ox*y);
	*outa=out;
	in=ina;
	if (ix==1){
		for (;y;y--,in+=3) for (a=ox;a;a--,out+=3){
			*out=*in;
			out[1]=in[1];
			out[2]=in[2];
		}
		mem_free(ina);
		return;
	}
	total=(ix-1)*(ox-1);
	if ((unsigned)y > MAXINT / 3 / sizeof(*col_buf)) overalloc();
	col_buf=mem_alloc(y*3*sizeof(*col_buf));
	bias_buf_color(col_buf,y,half);
	out_pos=0;
	in_pos=0;
	again:
	in_begin=in_pos;
	in_end=in_pos+ox-1;
	add_col_color(col_buf,in,skip,y
		,in_end-out_pos);
	add_col_color(col_buf,in+3,skip,y
		,out_pos-in_begin);
	emit_and_bias_col_color(col_buf,out,oskip,y,ox-1);
	out+=3;
	out_pos+=ix-1;
	if (out_pos>in_end){
		in_pos=in_end;
		in+=3;
	}
	if (out_pos>total){
		mem_free(col_buf);
		mem_free(ina);
		return;
	}
	goto again;
}

/* Works for both enlarging and diminishing. Linear resample, no low pass.
 * Automatically mem_frees the "in" and allocates "out". */
/* We assume unsigned holds at least 32 bits */
inline static void scale_gray_horizontal(unsigned char *in, int ix, int y
	,unsigned char ** out, int ox)
{
	unsigned *col_buf;
	int total=ix*ox;
	int out_pos,in_pos,in_begin,in_end,out_end;
	unsigned char *outptr;
	unsigned char *inptr;

	if (ix<ox){
		enlarge_gray_horizontal(in,ix,y,out,ox);
		return;
	}else if (ix==ox){
		*out=in;
		return;
	}
	if (ox && (unsigned)ox * (unsigned)y / (unsigned)ox != (unsigned)y) overalloc();
	if ((unsigned)ox * (unsigned)y > MAXINT) overalloc();
	outptr=mem_alloc(ox*y);
	inptr=in;
	*out=outptr;
	if ((unsigned)y > MAXINT / sizeof(*col_buf)) overalloc();
	col_buf=mem_alloc(y*sizeof(*col_buf));
	bias_buf_gray(col_buf, y, ix>>1);
	out_pos=0;
	in_pos=0;
	again:
	in_begin=in_pos;
	in_end=in_pos+ox;
	out_end=out_pos+ix;
	if (in_begin<out_pos)in_begin=out_pos;
	if (in_end>out_end)in_end=out_end;
	add_col_gray(col_buf,inptr,ix,y,in_end-in_begin);
	in_end=in_pos+ox;
	if (out_end>=in_end){
		in_pos=in_end;
		inptr++;
	}
	if (out_end<=in_end){
			emit_and_bias_col_gray(col_buf,outptr,ox,y,ix);
			out_pos=out_pos+ix;
			outptr++;
	}
	if (out_pos==total) {
		mem_free(in);
		mem_free(col_buf);
		return;
	}
	goto again;
}

/* Works for both enlarging and diminishing. Linear resample, no low pass.
 * Does only one color component.
 * Frees ina and allocates outa.
 * If ox*3<=ix, and display_optimize, performs optimization for LCD.
 */
inline static void scale_color_horizontal(unsigned short *ina, int ix, int y,
		unsigned short **outa, int ox)
{
	unsigned *col_buf;
	int total=ix*ox;
	int out_pos,in_pos,in_begin,in_end,out_end;
	unsigned skip=3*ix;
	unsigned oskip=3*ox;
	unsigned short *in, *out;

	if (ix==ox){
		*outa=ina;
		return;
	}
	if (ix<ox){
		enlarge_color_horizontal(ina,ix,y,outa,ox);
		return;
	}else if (ix==ox){
		*outa=ina;
		return;
	}
	if (ox && (unsigned)ox * (unsigned)y / (unsigned)ox != (unsigned)y) overalloc();
	if ((unsigned)ox * (unsigned)y > MAXINT / 3 / sizeof(*out)) overalloc();
	out=mem_alloc(sizeof(*out)*3*ox*y);
	*outa=out;
	in=ina;
	if ((unsigned)y > MAXINT / 3 / sizeof(*col_buf)) overalloc();
	col_buf=mem_alloc(y*3*sizeof(*col_buf));
	bias_buf_color(col_buf,y,ix>>1);
	out_pos=0;
	in_pos=0;
	again:
	in_begin=in_pos;
	in_end=in_pos+ox;
	out_end=out_pos+ix;
	if (in_begin<out_pos)in_begin=out_pos;
	if (in_end>out_end)in_end=out_end;
	add_col_color(col_buf,in,skip,y,in_end-in_begin);
	in_end=in_pos+ox;
	if (out_end>=in_end){
		in_pos=in_end;
		in+=3;
	}
	if (out_end<=in_end){
			emit_and_bias_col_color(col_buf,out,oskip,y,ix);
			out_pos=out_pos+ix;
			out+=3;
	}
	if (out_pos==total) {
		mem_free(ina);
		mem_free(col_buf);
		return;
	}
	goto again;
}

/* For magnification only. Does linear filtering. */
/* We assume unsigned holds at least 32 bits */
inline static void enlarge_gray_vertical(unsigned char *in, int x, int iy,
	unsigned char ** out ,int oy)
{
	unsigned *row_buf;
	int total;
	int out_pos,in_pos,in_begin,in_end;
	int half=(oy-1)>>1;
	unsigned char *outptr;
	unsigned char *inptr;

	if (iy==1){
		if (x && (unsigned)x * (unsigned)oy / (unsigned)x != (unsigned)oy) overalloc();
		if ((unsigned)x * (unsigned)oy > MAXINT) overalloc();
		outptr=mem_alloc(oy*x);
		*out=outptr;
		for(;oy;oy--,outptr+=x)
			memcpy(outptr,in,x);
		mem_free(in);
	}
	else if (iy==oy){
		*out=in;