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/* This file is part of MyPaint.
* Copyright (C) 2012 by Andrew Chadwick <a.t.chadwick@gmail.com>
*
* This program 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; either version 2 of the License, or
* (at your option) any later version.
*/
inline void
#ifdef COMPOSITE_MODE_RGBA
rgba_composite_src_over_rgba
#else
rgba_composite_src_over_rgbu
#endif
(const uint16_t src_p[],
uint16_t dst_p[],
const uint16_t opac)
{
const uint16_t src_alpha = CLAMP((uint32_t)(opac*src_p[3])>>15, 0, 1<<15);
const uint32_t one_minus_src_alpha = (1<<15) - src_alpha;
// Dca: destination component with premult alpha
// Da: destination alpha channel
//
// Dca' = Sca*Da + Sca*(1 - Da) + Dca*(1 - Sa)
// = Sca + Dca*(1 - Sa)
//
dst_p[0] = ((uint32_t)src_p[0]*opac + one_minus_src_alpha*dst_p[0]) >> 15;
dst_p[1] = ((uint32_t)src_p[1]*opac + one_minus_src_alpha*dst_p[1]) >> 15;
dst_p[2] = ((uint32_t)src_p[2]*opac + one_minus_src_alpha*dst_p[2]) >> 15;
#ifdef COMPOSITE_MODE_RGBA
// Da' = Sa*Da + Sa*(1 - Da) + Da*(1 - Sa)
// = (Sa*Da + Sa - Sa*Da) + Da*(1 - Sa)
// = Sa + Da*(1 - Sa)
//
dst_p[3] = src_alpha + ((one_minus_src_alpha*dst_p[3]) >> 15);
#endif
}
inline void
#ifdef COMPOSITE_MODE_RGBA
rgba_composite_multiply_rgba
#else
rgba_composite_multiply_rgbu
#endif
(const uint16_t src_p[],
uint16_t dst_p[],
const uint16_t opac)
{
// Dca' = Sca*Dca + Sca*(1 - Da) + Dca*(1 - Sa)
//
// If Da == 1, which is the case in RGBU mode, this becomes
//
// Dca' = Sca*Dca + 0 + Dca*(1 - Sa)
// = Dca * (Sca + (1 - Sa))
//
const uint16_t src_alpha = CLAMP((uint32_t)(opac * src_p[3]) / (1<<15),
0, 1<<15);
const uint32_t one_minus_src_alpha = (1<<15) - src_alpha;
const uint32_t src_col0 = ((uint32_t) src_p[0] * opac) >> 15;
const uint32_t src_col1 = ((uint32_t) src_p[1] * opac) >> 15;
const uint32_t src_col2 = ((uint32_t) src_p[2] * opac) >> 15;
dst_p[0] = ((uint32_t)src_col0*dst_p[0]+one_minus_src_alpha*dst_p[0])>>15;
dst_p[1] = ((uint32_t)src_col1*dst_p[1]+one_minus_src_alpha*dst_p[1])>>15;
dst_p[2] = ((uint32_t)src_col2*dst_p[2]+one_minus_src_alpha*dst_p[2])>>15;
#ifdef COMPOSITE_MODE_RGBA
// Sca*(1 - Da) != 0, add it in
const uint32_t one_minus_dst_alpha = (1<<15) - dst_p[3];
dst_p[0] += (((uint32_t)src_col0 * one_minus_dst_alpha) >> 15);
dst_p[1] += (((uint32_t)src_col1 * one_minus_dst_alpha) >> 15);
dst_p[2] += (((uint32_t)src_col2 * one_minus_dst_alpha) >> 15);
// Da' = Sa*Da + Sa*(1 - Da) + Da*(1 - Sa)
// = (Sa*Da + Sa - Sa*Da) + Da*(1 - Sa)
// = Sa + (1 - Sa)*Da
dst_p[3] = src_alpha + ((one_minus_src_alpha*dst_p[3]) >> 15);
#endif
}
inline void
#ifdef COMPOSITE_MODE_RGBA
rgba_composite_screen_rgba
#else
rgba_composite_screen_rgbu
#endif
(const uint16_t src_p[],
uint16_t dst_p[],
const uint16_t opac)
{
// Dca' = (Sca*Da + Dca*Sa - Sca*Dca) + Sca*(1 - Da) + Dca*(1 - Sa)
// = Sca + Dca - Sca*Dca
const uint32_t col0 = ((uint32_t)src_p[0]*opac)
+ (((uint32_t)dst_p[0]) << 15);
const uint32_t col1 = ((uint32_t)src_p[1]*opac)
+ (((uint32_t)dst_p[1]) << 15);
const uint32_t col2 = ((uint32_t)src_p[2]*opac)
+ (((uint32_t)dst_p[2]) << 15);
const uint32_t src_col0 = ((uint32_t)src_p[0] * opac) >> 15;
const uint32_t src_col1 = ((uint32_t)src_p[1] * opac) >> 15;
const uint32_t src_col2 = ((uint32_t)src_p[2] * opac) >> 15;
dst_p[0] = (col0 - ((uint32_t)src_col0*dst_p[0])) >> 15;
dst_p[1] = (col1 - ((uint32_t)src_col1*dst_p[1])) >> 15;
dst_p[2] = (col2 - ((uint32_t)src_col2*dst_p[2])) >> 15;
#ifdef COMPOSITE_MODE_RGBA
// Da' = Sa + Da - Sa*Da
const uint32_t src_alpha = ((uint32_t)src_p[3] * opac) >> 15;
dst_p[3] = src_alpha + (uint32_t)dst_p[3]
- ((src_alpha * (uint32_t)dst_p[3]) >> 15);
#endif
}
inline void
#ifdef COMPOSITE_MODE_RGBA
rgba_composite_color_dodge_rgba
#else
rgba_composite_color_dodge_rgbu
#endif
(const uint16_t src_p[],
uint16_t dst_p[],
const uint16_t opac)
{
const uint32_t src_alpha = ((uint32_t)src_p[3]*opac)>>15;
const uint32_t one_minus_src_alpha = (1<<15) - src_alpha;
#ifdef COMPOSITE_MODE_RGBA
const uint32_t dst_alpha = dst_p[3];
const uint32_t one_minus_dst_alpha = (1<<15) - dst_alpha;
#endif
for (int c=0; c<3; c++) {
const uint32_t s = ((uint32_t)src_p[c]*opac)>>15;
const uint32_t d = dst_p[c];
const uint32_t src_alpha_minus_src = src_alpha - s;
if (src_alpha_minus_src == 0 && d == 0) {
// Sca == Sa and Dca == 0
// Dca' = Sca*(1 - Da) + Dca*(1 - Sa)
// = Sca*(1 - Da)
#ifdef COMPOSITE_MODE_RGBA
dst_p[c] = CLAMP((s * one_minus_dst_alpha) >> 15, 0, (1<<15));
#else
dst_p[c] = 0;
#endif
}
else if (src_alpha_minus_src == 0) {
// otherwise if Sca == Sa
// Dca' = Sa*Da + Sca*(1 - Da) + Dca*(1 - Sa)
// = Sca*Da + Sca*(1 - Da) + Dca*(1 - Sa)
// = Sca*(Da + 1 - Da) + Dca*(1 - Sa)
// = Sca + Dca*(1 - Sa)
dst_p[c] = CLAMP( s + ((d * one_minus_src_alpha)>>15),
0, (1<<15) );
}
else {
// Sca < Sa
// Dca' = Sa*Da * min(1, Dca/Da * Sa/(Sa - Sca))
// + Sca*(1 - Da) + Dca*(1 - Sa)
const uint32_t dst_times_src_alpha_B30 = d*src_alpha;
// when 1 < Dca/Da * Sa/(Sa - Sca)
// 1 < (Dca*Sa) / (Da*(Sa - Sca)
// (Da*(Sa - Sca) < (Dca*Sa) because Sca - Sa is -ve and nonzero
#ifdef COMPOSITE_MODE_RGBA
if (dst_times_src_alpha_B30 > (dst_alpha * src_alpha_minus_src))
#else
if (dst_times_src_alpha_B30 > (src_alpha_minus_src << 15))
#endif
{
// min(...)==1
// Dca' = Sa * Da * min(...) + Sca*(1 - Da) + Dca*(1 - Sa)
// Dca' = Sa * Da + Sca*(1 - Da) + Dca*(1 - Sa)
dst_p[c] = CLAMP(
( (d * one_minus_src_alpha) // B30
#ifdef COMPOSITE_MODE_RGBA
+ (s * one_minus_dst_alpha) // B30
+ (src_alpha * dst_alpha) // B30
#else
// + (s * 0)
+ (src_alpha << 15) // B30
#endif
) >> 15,
0, 1<<15);
}
else {
// min(...) == Dca/Da * Sa/(Sa - Sca)
// Dca' = Sa * Da * min(...) + Sca*(1 - Da) + Dca*(1 - Sa)
// Dca' = Sa * Da * Dca/Da * Sa/(Sa - Sca)
// + Sca*(1 - Da) + Dca*(1 - Sa)
// Dca' = Sa * Dca * Sa/(Sa - Sca)
// + Sca*(1 - Da) + Dca*(1 - Sa)
dst_p[c] = CLAMP(
( src_alpha * (dst_times_src_alpha_B30>>15)
/ src_alpha_minus_src )
#ifdef COMPOSITE_MODE_RGBA
+ ((s * one_minus_dst_alpha) >> 15)
#endif
+ ((d * one_minus_src_alpha) >> 15),
0, 1<<15);
}
}
#ifdef HEAVY_DEBUG
assert(dst_p[c] <= (1<<15));
assert(src_p[c] <= (1<<15));
#endif
}
#ifdef COMPOSITE_MODE_RGBA
// Da' = Sa + Da - Sa*Da
dst_p[3] = CLAMP(src_alpha + dst_alpha - ((src_alpha*dst_alpha)>>15),
0, (1<<15));
#ifdef HEAVY_DEBUG
assert(src_p[0] <= src_p[3]);
assert(dst_p[0] <= dst_p[3]);
assert(src_p[1] <= src_p[3]);
assert(dst_p[1] <= dst_p[3]);
assert(src_p[2] <= src_p[3]);
assert(dst_p[2] <= dst_p[3]);
#endif //HEAVY_DEBUG
#endif //COMPOSITE_MODE_RGBA
#ifdef HEAVY_DEBUG
assert(dst_p[3] <= (1<<15));
assert(src_p[3] <= (1<<15));
#endif
}
inline void
#ifdef COMPOSITE_MODE_RGBA
rgba_composite_color_burn_rgba
#else
rgba_composite_color_burn_rgbu
#endif
(const uint16_t src_p[],
uint16_t dst_p[],
const uint16_t opac)
{
const uint32_t src_alpha30 = (uint32_t)src_p[3]*opac;
const uint32_t src_alpha = src_alpha30>>15;
const uint32_t one_minus_src_alpha = (1<<15) - src_alpha;
#ifdef COMPOSITE_MODE_RGBA
const uint32_t dst_alpha = dst_p[3];
const uint32_t one_minus_dst_alpha = (1<<15) - dst_alpha;
#else
const uint32_t dst_alpha = 1<<15;
#endif
for (int c=0; c<3; c++) {
const uint32_t s30 = (uint32_t)src_p[c] * opac;
const uint32_t s = s30 >> 15;
const uint32_t d = dst_p[c];
if (s == 0) {
if (d != dst_alpha) {
//if Sca == 0 and Dca == Da
// Dca' = Sa*Da + Sca*(1 - Da) + Dca*(1 - Sa)
// = Sa*Dca + Dca*(1 - Sa)
// = Sa*Dca + Dca - Sa*Dca
// = Dca
//otherwise if Sca == 0
// Dca' = Sca*(1 - Da) + Dca*(1 - Sa)
// = Dca*(1 - Sa)
dst_p[c] = CLAMP(((d * one_minus_src_alpha) >> 15),
0, (1<<15));
}
}
else {
#ifdef HEAVY_DEBUG
assert(s <= (1<<15));
assert(s > 0);
#endif
//otherwise if Sca > 0
// let i = Sca*(1 - Da) + Dca*(1 - Sa)
// let m = (1 - Dca/Da) * Sa/Sca
//
// Dca' = Sa*Da - Sa*Da * min(1, (1 - Dca/Da) * Sa/Sca) + i
// = Sa*Da * (1 - min(1, (1 - Dca/Da) * Sa/Sca)) + i
#ifdef COMPOSITE_MODE_RGBA
uint32_t res = (s*one_minus_dst_alpha + d*one_minus_src_alpha)>>15;
if (dst_alpha > 0) {
const uint32_t m = ( ((1<<15) - ((d << 15) / dst_alpha))
* src_alpha) / s;
if (m < (1<<15)) {
res += ( ((src_alpha * dst_alpha) >> 15)
* ((1<<15) - m) ) >> 15;
}
}
#else
uint32_t res = (d*one_minus_src_alpha)>>15;
const uint32_t m = (((1<<15) - d)
* src_alpha) / s;
if (m < (1<<15)) {
res += ( src_alpha
* ((1<<15) - m) ) >> 15;
}
#endif
dst_p[c] = CLAMP(res, 0, (1<<15));
}
#ifdef HEAVY_DEBUG
assert(dst_p[c] <= (1<<15));
assert(src_p[c] <= (1<<15));
#endif
}
#ifdef COMPOSITE_MODE_RGBA
// Da' = Sa + Da - Sa*Da
dst_p[3] = CLAMP(src_alpha + dst_alpha - ((src_alpha*dst_alpha)>>15),
0, (1<<15));
#ifdef HEAVY_DEBUG
assert(src_p[0] <= src_p[3]);
assert(dst_p[0] <= dst_p[3]);
assert(src_p[1] <= src_p[3]);
assert(dst_p[1] <= dst_p[3]);
assert(src_p[2] <= src_p[3]);
assert(dst_p[2] <= dst_p[3]);
#endif //HEAVY_DEBUG
#endif //COMPOSITE_MODE_RGBA
#ifdef HEAVY_DEBUG
assert(dst_p[3] <= (1<<15));
assert(src_p[3] <= (1<<15));
#endif
}
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