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+ prevent division by zero in color-burn mode

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(FIXME: re-implement using latest(corrected) math from
    http://www.w3.org/TR/SVGCompositing/)
+ re-implemented grain-extract mode
This commit is contained in:
artemp 2012-08-03 15:34:21 +01:00
parent 8ea21d866d
commit 5414912160
1 changed files with 43 additions and 22 deletions
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65
deps/agg/include/agg_pixfmt_rgba.h vendored
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@ -1015,18 +1015,34 @@ namespace agg
// Dca' = Sa.(Sca.Da + Dca.Sa - Sa.Da)/Sca + Sca.(1 - Da) + Dca.(1 - Sa)
//
// Da' = Sa + Da - Sa.Da
// http://www.w3.org/TR/SVGCompositing/
// if Sca == 0 and Dca == Da
// Dca' = Sa × Da + Sca × (1 - Da) + Dca × (1 - Sa)
// = Sa × Da + Dca × (1 - Sa)
// = Da = Dca
// otherwise if Sca == 0
// Dca' = Sca × (1 - Da) + Dca × (1 - Sa)
// = Dca × (1 - Sa)
// otherwise if Sca > 0
// Dca' = Sa × Da - Sa × Da × min(1, (1 - Dca/Da) × Sa/Sca) + Sca × (1 - Da) + Dca × (1 - Sa)
// = Sa × Da × (1 - min(1, (1 - Dca/Da) × Sa/Sca)) + Sca × (1 - Da) + Dca × (1 - Sa)
// sa * da * (255 - std::min(255, (255 - p[0]/da)*(sa/(sc*sa)) +
static AGG_INLINE void blend_pix(value_type* p,
unsigned sr, unsigned sg, unsigned sb,
unsigned sa, unsigned cover)
{
if(cover < 255)
if (cover < 255)
{
sr = (sr * cover + 255) >> 8;
sg = (sg * cover + 255) >> 8;
sb = (sb * cover + 255) >> 8;
sa = (sa * cover + 255) >> 8;
}
if(sa)
if (sa)
{
calc_type d1a = base_mask - p[Order::A];
calc_type s1a = base_mask - sa;
@ -1042,15 +1058,15 @@ namespace agg
long_type sbda = sb * da;
long_type sada = sa * da;
p[Order::R] = (value_type)(((srda + drsa <= sada) ?
if ( sr > 0) p[Order::R] = (value_type)(((srda + drsa <= sada) ?
sr * d1a + dr * s1a :
sa * (srda + drsa - sada) / sr + sr * d1a + dr * s1a + base_mask) >> base_shift);
p[Order::G] = (value_type)(((sgda + dgsa <= sada) ?
if ( sg > 0 ) p[Order::G] = (value_type)(((sgda + dgsa <= sada) ?
sg * d1a + dg * s1a :
sa * (sgda + dgsa - sada) / sg + sg * d1a + dg * s1a + base_mask) >> base_shift);
p[Order::B] = (value_type)(((sbda + dbsa <= sada) ?
if ( sb > 0) p[Order::B] = (value_type)(((sbda + dbsa <= sada) ?
sb * d1a + db * s1a :
sa * (sbda + dbsa - sada) / sb + sb * d1a + db * s1a + base_mask) >> base_shift);
@ -1502,24 +1518,29 @@ namespace agg
unsigned sr, unsigned sg, unsigned sb,
unsigned sa, unsigned cover)
{
if (cover < 255)
{
sr = (sr * cover + 255) >> 8;
sg = (sg * cover + 255) >> 8;
sb = (sb * cover + 255) >> 8;
sa = (sa * cover + 255) >> 8;
}
if (sa > 0)
{
calc_type da = p[Order::A];
int dr = p[Order::R] - sr + 128;
int dg = p[Order::G] - sg + 128;
int db = p[Order::B] - sb + 128;
calc_type da = (p[Order::A] * sa + 255) >> 8;
p[Order::R] = dr < 0 ? 0 : (dr > 255 ? 255 : dr);
p[Order::G] = dg < 0 ? 0 : (dg > 255 ? 255 : dg);
p[Order::B] = db < 0 ? 0 : (db > 255 ? 255 : db);
p[Order::A] = (value_type)(sa + da - ((sa * da + base_mask) >> base_shift));
int dr = p[Order::R] - sr + 128;
int dg = p[Order::G] - sg + 128;
int db = p[Order::B] - sb + 128;
dr = dr < 0 ? 0 : (dr > 255 ? 255 : dr);
dg = dg < 0 ? 0 : (dg > 255 ? 255 : dg);
db = db < 0 ? 0 : (db > 255 ? 255 : db);
p[Order::A] = da;
if (da < 255)
{
p[Order::R] = (dr * da + 255) >> 8;
p[Order::G] = (dg * da + 255) >> 8;
p[Order::B] = (db * da + 255) >> 8;
}
else
{
p[Order::R] = dr;
p[Order::G] = dg;
p[Order::B] = db;
}
}
};