472 lines
9.9 KiB
C
472 lines
9.9 KiB
C
#include "fitz.h"
|
|
|
|
/*
|
|
|
|
The functions in this file implement various flavours of Porter-Duff blending.
|
|
|
|
We take the following as definitions:
|
|
|
|
Cx = Color (from plane x)
|
|
ax = Alpha (from plane x)
|
|
cx = Cx.ax = Premultiplied color (from plane x)
|
|
|
|
The general PorterDuff blending equation is:
|
|
|
|
Blend Z = X op Y cz = Fx.cx + Fy. cy where Fx and Fy depend on op
|
|
|
|
The two operations we use in this file are: '(X in Y) over Z' and
|
|
'S over Z'. The definitions of the 'over' and 'in' operations are as
|
|
follows:
|
|
|
|
For S over Z, Fs = 1, Fz = 1-as
|
|
For X in Y, Fx = ay, Fy = 0
|
|
|
|
We have 2 choices; we can either work with premultiplied data, or non
|
|
premultiplied data. Our
|
|
|
|
First the premultiplied case:
|
|
|
|
Let S = (X in Y)
|
|
Let R = (X in Y) over Z = S over Z
|
|
|
|
cs = cx.Fx + cy.Fy (where Fx = ay, Fy = 0)
|
|
= cx.ay
|
|
as = ax.Fx + ay.Fy
|
|
= ax.ay
|
|
|
|
cr = cs.Fs + cz.Fz (where Fs = 1, Fz = 1-as)
|
|
= cs + cz.(1-as)
|
|
= cx.ay + cz.(1-ax.ay)
|
|
ar = as.Fs + az.Fz
|
|
= as + az.(1-as)
|
|
= ax.ay + az.(1-ax.ay)
|
|
|
|
This has various nice properties, like not needing any divisions, and
|
|
being symmetric in color and alpha, so this is what we use. Because we
|
|
went through the pain of deriving the non premultiplied forms, we list
|
|
them here too, though they are not used.
|
|
|
|
Non Pre-multiplied case:
|
|
|
|
Cs.as = Fx.Cx.ax + Fy.Cy.ay (where Fx = ay, Fy = 0)
|
|
= Cx.ay.ax
|
|
Cs = (Cx.ay.ax)/(ay.ax)
|
|
= Cx
|
|
Cr.ar = Fs.Cs.as + Fz.Cz.az (where Fs = 1, Fz = 1-as)
|
|
= Cs.as + (1-as).Cz.az
|
|
= Cx.ax.ay + Cz.az.(1-ax.ay)
|
|
Cr = (Cx.ax.ay + Cz.az.(1-ax.ay))/(ax.ay + az.(1-ax-ay))
|
|
|
|
Much more complex, it seems. However, if we could restrict ourselves to
|
|
the case where we were always plotting onto an opaque background (i.e.
|
|
az = 1), then:
|
|
|
|
Cr = Cx.(ax.ay) + Cz.(1-ax.ay)
|
|
= (Cx-Cz)*(1-ax.ay) + Cz (a single MLA operation)
|
|
ar = 1
|
|
|
|
Sadly, this is not true in the general case, so we abandon this effort
|
|
and stick to using the premultiplied form.
|
|
|
|
*/
|
|
|
|
typedef unsigned char byte;
|
|
|
|
/* These are used by the non-aa scan converter */
|
|
|
|
void
|
|
fz_paint_solid_alpha(byte * restrict dp, int w, int alpha)
|
|
{
|
|
int t = FZ_EXPAND(255 - alpha);
|
|
while (w--)
|
|
{
|
|
*dp = alpha + FZ_COMBINE(*dp, t);
|
|
dp ++;
|
|
}
|
|
}
|
|
|
|
void
|
|
fz_paint_solid_color(byte * restrict dp, int n, int w, byte *color)
|
|
{
|
|
int n1 = n - 1;
|
|
int sa = FZ_EXPAND(color[n1]);
|
|
int k;
|
|
while (w--)
|
|
{
|
|
int ma = FZ_COMBINE(FZ_EXPAND(255), sa);
|
|
for (k = 0; k < n1; k++)
|
|
dp[k] = FZ_BLEND(color[k], dp[k], ma);
|
|
dp[k] = FZ_BLEND(255, dp[k], ma);
|
|
dp += n;
|
|
}
|
|
}
|
|
|
|
/* Blend a non-premultiplied color in mask over destination */
|
|
|
|
static inline void
|
|
fz_paint_span_with_color_2(byte * restrict dp, byte * restrict mp, int w, byte *color)
|
|
{
|
|
int sa = FZ_EXPAND(color[1]);
|
|
int g = color[0];
|
|
while (w--)
|
|
{
|
|
int ma = *mp++;
|
|
ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
|
|
dp[0] = FZ_BLEND(g, dp[0], ma);
|
|
dp[1] = FZ_BLEND(255, dp[1], ma);
|
|
dp += 2;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_with_color_4(byte * restrict dp, byte * restrict mp, int w, byte *color)
|
|
{
|
|
int sa = FZ_EXPAND(color[3]);
|
|
int r = color[0];
|
|
int g = color[1];
|
|
int b = color[2];
|
|
while (w--)
|
|
{
|
|
int ma = *mp++;
|
|
ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
|
|
dp[0] = FZ_BLEND(r, dp[0], ma);
|
|
dp[1] = FZ_BLEND(g, dp[1], ma);
|
|
dp[2] = FZ_BLEND(b, dp[2], ma);
|
|
dp[3] = FZ_BLEND(255, dp[3], ma);
|
|
dp += 4;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_with_color_N(byte * restrict dp, byte * restrict mp, int n, int w, byte *color)
|
|
{
|
|
int n1 = n - 1;
|
|
int sa = FZ_EXPAND(color[n1]);
|
|
int k;
|
|
while (w--)
|
|
{
|
|
int ma = *mp++;
|
|
ma = FZ_COMBINE(FZ_EXPAND(ma), sa);
|
|
for (k = 0; k < n1; k++)
|
|
dp[k] = FZ_BLEND(color[k], dp[k], ma);
|
|
dp[k] = FZ_BLEND(255, dp[k], ma);
|
|
dp += n;
|
|
}
|
|
}
|
|
|
|
void
|
|
fz_paint_span_with_color(byte * restrict dp, byte * restrict mp, int n, int w, byte *color)
|
|
{
|
|
switch (n)
|
|
{
|
|
case 2: fz_paint_span_with_color_2(dp, mp, w, color); break;
|
|
case 4: fz_paint_span_with_color_4(dp, mp, w, color); break;
|
|
default: fz_paint_span_with_color_N(dp, mp, n, w, color); break;
|
|
}
|
|
}
|
|
|
|
/* Blend source in mask over destination */
|
|
|
|
static inline void
|
|
fz_paint_span_with_mask_2(byte * restrict dp, byte * restrict sp, byte * restrict mp, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int masa;
|
|
int ma = *mp++;
|
|
ma = FZ_EXPAND(ma);
|
|
masa = FZ_COMBINE(sp[1], ma);
|
|
masa = 255 - masa;
|
|
masa = FZ_EXPAND(masa);
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_with_mask_4(byte * restrict dp, byte * restrict sp, byte * restrict mp, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int masa;
|
|
int ma = *mp++;
|
|
ma = FZ_EXPAND(ma);
|
|
masa = FZ_COMBINE(sp[3], ma);
|
|
masa = 255 - masa;
|
|
masa = FZ_EXPAND(masa);
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_with_mask_N(byte * restrict dp, byte * restrict sp, byte * restrict mp, int n, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int k = n;
|
|
int masa;
|
|
int ma = *mp++;
|
|
ma = FZ_EXPAND(ma);
|
|
masa = FZ_COMBINE(sp[n-1], ma);
|
|
masa = 255-masa;
|
|
masa = FZ_EXPAND(masa);
|
|
while (k--)
|
|
{
|
|
*dp = FZ_COMBINE2(*sp, ma, *dp, masa);
|
|
sp++; dp++;
|
|
}
|
|
}
|
|
}
|
|
|
|
static void
|
|
fz_paint_span_with_mask(byte * restrict dp, byte * restrict sp, byte * restrict mp, int n, int w)
|
|
{
|
|
switch (n)
|
|
{
|
|
case 2: fz_paint_span_with_mask_2(dp, sp, mp, w); break;
|
|
case 4: fz_paint_span_with_mask_4(dp, sp, mp, w); break;
|
|
default: fz_paint_span_with_mask_N(dp, sp, mp, n, w); break;
|
|
}
|
|
}
|
|
|
|
/* Blend source in constant alpha over destination */
|
|
|
|
static inline void
|
|
fz_paint_span_2_with_alpha(byte * restrict dp, byte * restrict sp, int w, int alpha)
|
|
{
|
|
alpha = FZ_EXPAND(alpha);
|
|
while (w--)
|
|
{
|
|
int masa = FZ_COMBINE(sp[1], alpha);
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
dp++; sp++;
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
dp++; sp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_4_with_alpha(byte * restrict dp, byte * restrict sp, int w, int alpha)
|
|
{
|
|
alpha = FZ_EXPAND(alpha);
|
|
while (w--)
|
|
{
|
|
int masa = FZ_COMBINE(sp[3], alpha);
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
sp++; dp++;
|
|
*dp = FZ_BLEND(*sp, *dp, masa);
|
|
sp++; dp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_N_with_alpha(byte * restrict dp, byte * restrict sp, int n, int w, int alpha)
|
|
{
|
|
alpha = FZ_EXPAND(alpha);
|
|
while (w--)
|
|
{
|
|
int masa = FZ_COMBINE(sp[n-1], alpha);
|
|
int k = n;
|
|
while (k--)
|
|
{
|
|
*dp = FZ_BLEND(*sp++, *dp, masa);
|
|
dp++;
|
|
}
|
|
}
|
|
}
|
|
|
|
/* Blend source over destination */
|
|
|
|
static inline void
|
|
fz_paint_span_1(byte * restrict dp, byte * restrict sp, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int t = FZ_EXPAND(255 - sp[0]);
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp ++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_2(byte * restrict dp, byte * restrict sp, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int t = FZ_EXPAND(255 - sp[1]);
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_4(byte * restrict dp, byte * restrict sp, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int t = FZ_EXPAND(255 - sp[3]);
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
}
|
|
}
|
|
|
|
static inline void
|
|
fz_paint_span_N(byte * restrict dp, byte * restrict sp, int n, int w)
|
|
{
|
|
while (w--)
|
|
{
|
|
int k = n;
|
|
int t = FZ_EXPAND(255 - sp[n-1]);
|
|
while (k--)
|
|
{
|
|
*dp = *sp++ + FZ_COMBINE(*dp, t);
|
|
dp++;
|
|
}
|
|
}
|
|
}
|
|
|
|
void
|
|
fz_paint_span(byte * restrict dp, byte * restrict sp, int n, int w, int alpha)
|
|
{
|
|
if (alpha == 255)
|
|
{
|
|
switch (n)
|
|
{
|
|
case 1: fz_paint_span_1(dp, sp, w); break;
|
|
case 2: fz_paint_span_2(dp, sp, w); break;
|
|
case 4: fz_paint_span_4(dp, sp, w); break;
|
|
default: fz_paint_span_N(dp, sp, n, w); break;
|
|
}
|
|
}
|
|
else if (alpha > 0)
|
|
{
|
|
switch (n)
|
|
{
|
|
case 2: fz_paint_span_2_with_alpha(dp, sp, w, alpha); break;
|
|
case 4: fz_paint_span_4_with_alpha(dp, sp, w, alpha); break;
|
|
default: fz_paint_span_N_with_alpha(dp, sp, n, w, alpha); break;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Pixmap blending functions
|
|
*/
|
|
|
|
void
|
|
fz_paint_pixmap_with_rect(fz_pixmap *dst, fz_pixmap *src, int alpha, fz_bbox bbox)
|
|
{
|
|
unsigned char *sp, *dp;
|
|
int x, y, w, h, n;
|
|
|
|
assert(dst->n == src->n);
|
|
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(dst));
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
|
|
|
x = bbox.x0;
|
|
y = bbox.y0;
|
|
w = bbox.x1 - bbox.x0;
|
|
h = bbox.y1 - bbox.y0;
|
|
if ((w | h) == 0)
|
|
return;
|
|
|
|
n = src->n;
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
|
|
|
while (h--)
|
|
{
|
|
fz_paint_span(dp, sp, n, w, alpha);
|
|
sp += src->w * n;
|
|
dp += dst->w * n;
|
|
}
|
|
}
|
|
|
|
void
|
|
fz_paint_pixmap(fz_pixmap *dst, fz_pixmap *src, int alpha)
|
|
{
|
|
unsigned char *sp, *dp;
|
|
fz_bbox bbox;
|
|
int x, y, w, h, n;
|
|
|
|
assert(dst->n == src->n);
|
|
|
|
bbox = fz_bound_pixmap(dst);
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
|
|
|
x = bbox.x0;
|
|
y = bbox.y0;
|
|
w = bbox.x1 - bbox.x0;
|
|
h = bbox.y1 - bbox.y0;
|
|
if ((w | h) == 0)
|
|
return;
|
|
|
|
n = src->n;
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
|
|
|
while (h--)
|
|
{
|
|
fz_paint_span(dp, sp, n, w, alpha);
|
|
sp += src->w * n;
|
|
dp += dst->w * n;
|
|
}
|
|
}
|
|
|
|
void
|
|
fz_paint_pixmap_with_mask(fz_pixmap *dst, fz_pixmap *src, fz_pixmap *msk)
|
|
{
|
|
unsigned char *sp, *dp, *mp;
|
|
fz_bbox bbox;
|
|
int x, y, w, h, n;
|
|
|
|
assert(dst->n == src->n);
|
|
assert(msk->n == 1);
|
|
|
|
bbox = fz_bound_pixmap(dst);
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(src));
|
|
bbox = fz_intersect_bbox(bbox, fz_bound_pixmap(msk));
|
|
|
|
x = bbox.x0;
|
|
y = bbox.y0;
|
|
w = bbox.x1 - bbox.x0;
|
|
h = bbox.y1 - bbox.y0;
|
|
if ((w | h) == 0)
|
|
return;
|
|
|
|
n = src->n;
|
|
sp = src->samples + ((y - src->y) * src->w + (x - src->x)) * src->n;
|
|
mp = msk->samples + ((y - msk->y) * msk->w + (x - msk->x)) * msk->n;
|
|
dp = dst->samples + ((y - dst->y) * dst->w + (x - dst->x)) * dst->n;
|
|
|
|
while (h--)
|
|
{
|
|
fz_paint_span_with_mask(dp, sp, mp, n, w);
|
|
sp += src->w * n;
|
|
dp += dst->w * n;
|
|
mp += msk->w;
|
|
}
|
|
}
|