blendmodes.c.svn-base

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#include "fitz-base.h"
#include "fitz-world.h"
#include "fitz-draw.h"

typedef unsigned char byte;

/*
PDF 1.4 blend modes, except Normal and Multiply which are Over and In respectively.
Only the actual blend routines are here, not the node rendering logic which lives in render.c.
These are slow.
*/


/* These functions apply to a single component, 0-255 range typically */

static int
fz_screen_byte(int bd, int s)
{
	return bd + s - fz_mul255(bd, s);
}


static int
fz_hardlight_byte(int bd, int s)
{
	int s2 = s << 1;
	if (s <= 127)
		return fz_mul255(bd, s2);
	else
		return fz_screen_byte(bd, s2);
}


static int
fz_overlay_byte(int bd, int s)
{
	return fz_hardlight_byte(s, bd); // note swapped order
}


static int
fz_darken_byte(int bd, int s)
{
	return MIN(bd, s);
}


static int
fz_lighten_byte(int bd, int s)
{
	return MAX(bd, s);
}


static int
fz_colordodge_byte(int bd, int s)
{
	if (s < 255)
		return MIN(255, 255 * bd / (255 - s));
	else
		return 255;
}


static int
fz_colorburn_byte(int bd, int s)
{
	if (s > 0)
		return 255 - MIN(255, 255 * (255 - bd) / s);
	else
		return 0;
}


static int
fz_softlight_byte(int bd, int s)
{
	/* review this */
	if (s < 128) {
		return bd - fz_mul255(fz_mul255((255 - (s<<1)), bd), 255 - bd);
	}
	else {
		int dbd;
		if (bd < 64)
			dbd = fz_mul255(fz_mul255((bd << 4) - 12, bd) + 4, bd);
		else
			dbd = (int)sqrtf(255.0f * bd);
		return bd + fz_mul255(((s<<1) - 255), (dbd - bd));
	}
}


static int
fz_difference_byte(int bd, int s)
{
	return ABS(bd - s);
}


static int
fz_exclusion_byte(int bd, int s)
{
	return bd + s - (fz_mul255(bd, s)<<1);
}


/* Non-separable blend modes */


static int
lum(int r, int g, int b)
{
	/* 0.3, 0.59, 0.11 in 16.16 fixed point */
	return (19662 * r + 38666 * g + 7208 * b) >> 16;
}


static void
clipcolor(int r, int g, int b, int *dr, int *dg, int *db)
{
	int l = lum(r, g, b);
	int n = MIN(MIN(r, g), b);
	int x = MAX(MAX(r, g), b);
	if (n < 0) {
		*dr = l + 255 * (r - l) / (l - n);
		*dg = l + 255 * (g - l) / (l - n);
		*db = l + 255 * (b - l) / (l - n);
	}
	else {
		*dr = l + 255 * (255 - l) / (x - l);
		*dg = l + 255 * (255 - l) / (x - l);
		*db = l + 255 * (255 - l) / (x - l);
	}
}


static void
setlum(int r, int g, int b, int l, int *dr, int *dg, int *db)
{
	int d = 255 - lum(r, g, b);
	clipcolor(r + d, g + d, b + d, dr, dg, db);
}


static int
sat(int r, int g, int b)
{
	return MAX(MAX(r, g), b) - MIN(MIN(r, g), b);
}


static void
setsat(int r, int g, int b, int s, int *dr, int *dg, int *db)
{
	int *m[3] = { &r, &g, &b }; /* min, med, max */
	int *t;
#define SWAP(a, b) (t = a, a = b, b = t)
	if (*m[0] > *m[1])
		SWAP(m[0], m[1]);
	if (*m[0] > *m[2])
		SWAP(m[0], m[2]);
	if (*m[1] > *m[2])
		SWAP(m[1], m[2]);

	if (*m[2] > *m[0]) {
		*m[1] = (*m[1] - *m[0]) * s / (*m[2] - *m[0]);
		*m[2] = s;
	}
	else {
		*m[1] = 0;
		*m[2] = 0;
	}
	*dr = r;
	*dg = g;
	*db = b;
}


static void
fz_hue_rgb(int *bdr, int *bdg, int *bdb, int sr, int sg, int sb)
{
	int tr, tg, tb;
	setsat(sr, sg, sb, sat(*bdr, *bdg, *bdb), &tr, &tg, &tb);
	setlum(tr, tg, tb, lum(*bdr, *bdg, *bdb), bdr, bdg, bdb);
}


static void
fz_saturation_rgb(int *bdr, int *bdg, int *bdb, int sr, int sg, int sb)
{
	int tr, tg, tb;
	setsat(*bdr, *bdg, *bdb, sat(sr, sg, sb), &tr, &tg, &tb);
	setlum(tr, tg, tb, lum(*bdr, *bdg, *bdb), bdr, bdg, bdb);	
}


static void
fz_color_rgb(int *bdr, int *bdg, int *bdb, int sr, int sg, int sb)
{
	setlum(sr, sg, sb, lum(*bdr, *bdg, *bdb), bdr, bdg, bdb);
}


static void
fz_luminosity_rgb(int *bdr, int *bdg, int *bdb, int sr, int sg, int sb)
{
	setlum(*bdr, *bdg, *bdb, lum(sr, sg, sb), bdr, bdg, bdb);
}


//fz_separable_blend(, fz_blendkind mode)
//{
//}