diff options
| author | scuri <scuri> | 2009-10-27 19:45:36 +0000 |
|---|---|---|
| committer | scuri <scuri> | 2009-10-27 19:45:36 +0000 |
| commit | c4ca69d3fa84dca98dce71c7a71b61413d6be165 (patch) | |
| tree | 8c149cd3deaf31fa406270b26a45982471c8b88e /src/drv/cdirgb.c | |
| parent | 8a059c0ddda38d88aee6c8657b41ef81adb0171c (diff) | |
Fixed: compositing in IMAGERGB when canvas has a semi-transparent alpha channel and a color with semi transparent alpha are used.
Diffstat (limited to 'src/drv/cdirgb.c')
| -rw-r--r-- | src/drv/cdirgb.c | 35 |
1 files changed, 20 insertions, 15 deletions
diff --git a/src/drv/cdirgb.c b/src/drv/cdirgb.c index 7f6f64b..d623abc 100644 --- a/src/drv/cdirgb.c +++ b/src/drv/cdirgb.c @@ -56,13 +56,13 @@ struct _cdCtxCanvas #define _sNormX(_ctxcanvas, _x) (_x < 0? 0: _x < _ctxcanvas->canvas->w? _x: _ctxcanvas->canvas->w-1) #define _sNormY(_ctxcanvas, _y) (_y < 0? 0: _y < _ctxcanvas->canvas->h? _y: _ctxcanvas->canvas->h-1) -#define RGB_COMPOSE(_SRC, _SRC_ALPHA, _DST, _TMP_MULTI, _TMP_ALPHA) (unsigned char)(((_SRC_ALPHA)*(_SRC) + (_TMP_MULTI)*(_DST)) / (_TMP_ALPHA)) +#define RGB_COMPOSE_OVER(_SRC, _SRC_ALPHA, _DST, _TMP_MULTI, _TMP_ALPHA) (unsigned char)(((_SRC_ALPHA)*(_SRC) + (_TMP_MULTI)*(_DST)) / (_TMP_ALPHA)) #define RGBA_COLOR_COMBINE(_ctxcanvas, _pdst_red, _pdst_green, _pdst_blue, _pdst_alpha, _src_red, _src_green, _src_blue, _src_alpha) \ { \ unsigned char _tmp_red = 0, _tmp_green = 0, _tmp_blue = 0; \ \ - if (_pdst_alpha) /* (_pdst_alpha != NULL) */ \ + if (_pdst_alpha) /* destiny has alpha */ \ { \ if (_src_alpha != 255) /* some transparency */ \ { \ @@ -84,12 +84,17 @@ struct _cdCtxCanvas } \ else /* (0<*_pdst_alpha<255 && 0<_src_alpha<255) destiny and source are semi-transparent */ \ { \ - /* Closed Compositing Formulas for SRC over DST, Colors Not Premultiplied by Alpha: */ \ + /* Closed Compositing SRC over DST (see smith95a.pdf) */ \ + /* Colors NOT Premultiplied by Alpha */ \ + /* DST = SRC * SRC_ALPHA + DST * DST_ALPHA * (1 - SRC_ALPHA) */ \ + /* DST_ALPHA = SRC_ALPHA + DST_ALPHA * (1 - SRC_ALPHA) */ \ + /* DST /= DST_ALPHA */ \ int _tmp_multi = *_pdst_alpha * (255 - _src_alpha); \ - int _tmp_alpha = _src_alpha + _tmp_multi; \ - _tmp_red = RGB_COMPOSE(_src_red, _src_alpha, *_pdst_red, _tmp_multi, _tmp_alpha); \ - _tmp_green = RGB_COMPOSE(_src_green, _src_alpha, *_pdst_green, _tmp_multi, _tmp_alpha); \ - _tmp_blue = RGB_COMPOSE(_src_blue, _src_alpha, *_pdst_blue, _tmp_multi, _tmp_alpha); \ + int _tmp_src_alpha = _src_alpha*255; \ + int _tmp_alpha = _tmp_src_alpha + _tmp_multi; \ + _tmp_red = RGB_COMPOSE_OVER(_src_red, _tmp_src_alpha, *_pdst_red, _tmp_multi, _tmp_alpha); \ + _tmp_green = RGB_COMPOSE_OVER(_src_green, _tmp_src_alpha, *_pdst_green, _tmp_multi, _tmp_alpha); \ + _tmp_blue = RGB_COMPOSE_OVER(_src_blue, _tmp_src_alpha, *_pdst_blue, _tmp_multi, _tmp_alpha); \ *_pdst_alpha = (unsigned char)(_tmp_alpha / 255); \ } \ } \ @@ -109,7 +114,7 @@ struct _cdCtxCanvas *_pdst_alpha = (unsigned char)255; /* set destiny as opaque */ \ } \ } \ - else /* (_pdst_alpha == NULL) */ \ + else /* destiny does NOT have alpha */ \ { \ if (_src_alpha != 255) /* source has some transparency */ \ { \ @@ -147,9 +152,9 @@ struct _cdCtxCanvas *_pdst_blue ^= _tmp_blue; \ break; \ case CD_NOT_XOR: \ - *_pdst_red = (unsigned char)~(_tmp_red ^ *_pdst_red); \ - *_pdst_green = (unsigned char)~(_tmp_green ^ *_pdst_green); \ - *_pdst_blue = (unsigned char)~(_tmp_blue ^ *_pdst_blue); \ + *_pdst_red = (unsigned char)~(_tmp_red ^ *_pdst_red); \ + *_pdst_green = (unsigned char)~(_tmp_green ^ *_pdst_green); \ + *_pdst_blue = (unsigned char)~(_tmp_blue ^ *_pdst_blue); \ break; \ } \ } @@ -406,7 +411,7 @@ static void cdclear(cdCtxCanvas* ctxcanvas) memset(ctxcanvas->red, cdRed(ctxcanvas->canvas->background), size); memset(ctxcanvas->green, cdGreen(ctxcanvas->canvas->background), size); memset(ctxcanvas->blue, cdBlue(ctxcanvas->canvas->background), size); - if (ctxcanvas->alpha) memset(ctxcanvas->alpha, cdAlpha(ctxcanvas->canvas->background), size); + if (ctxcanvas->alpha) memset(ctxcanvas->alpha, cdAlpha(ctxcanvas->canvas->background), size); /* here is the normal alpha coding */ } static void irgPostProcessIntersect(unsigned char* clip, int size) @@ -1525,8 +1530,8 @@ static cdCtxImage* cdcreateimage(cdCtxCanvas* ctxcanvas, int w, int h) if (ctxcanvas->alpha) ctximage->alpha = ctximage->red + 3*size; - memset(ctximage->red, 0xFF, 3*size); - if (ctximage->alpha) memset(ctximage->alpha, 0, size); /* transparent */ + memset(ctximage->red, 0xFF, 3*size); /* white */ + if (ctximage->alpha) memset(ctximage->alpha, 0, size); /* transparent, this is the normal alpha coding */ return ctximage; } @@ -1927,7 +1932,7 @@ static void cdcreatecanvas(cdCanvas* canvas, void *data) ctxcanvas->alpha = ctxcanvas->red + 3*size; memset(ctxcanvas->red, 0xFF, 3*size); /* white */ - if (ctxcanvas->alpha) memset(ctxcanvas->alpha, 0, size); /* transparent */ + if (ctxcanvas->alpha) memset(ctxcanvas->alpha, 0, size); /* transparent, this is the normal alpha coding */ } ctxcanvas->clip = (unsigned char*)malloc(w*h); |