From e88490b4f27bf7192dcbfe409ade17dc367dc8cb Mon Sep 17 00:00:00 2001 From: homm Date: Sat, 23 Mar 2013 14:26:14 +0400 Subject: [PATCH] =?UTF-8?q?Precision=20improvement.=20=E2=89=8860%=20perfo?= =?UTF-8?q?rmance=20lost?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- libImaging/AlphaComposite.c | 29 +++++++++++++---------------- 1 file changed, 13 insertions(+), 16 deletions(-) diff --git a/libImaging/AlphaComposite.c b/libImaging/AlphaComposite.c index 8cc519d3f..ce4dca2b0 100644 --- a/libImaging/AlphaComposite.c +++ b/libImaging/AlphaComposite.c @@ -50,35 +50,32 @@ ImagingAlphaComposite(Imaging imDst, Imaging imSrc) for (y = 0; y < imDst->ysize; y++) { - rgba8* pdst = (rgba8*) imDst->image[y]; - rgba8* psrc = (rgba8*) imSrc->image[y]; - rgba8* pout = (rgba8*) imOut->image[y]; + rgba8* dst = (rgba8*) imDst->image[y]; + rgba8* src = (rgba8*) imSrc->image[y]; + rgba8* out = (rgba8*) imOut->image[y]; for (x = 0; x < imDst->xsize; x ++) { - rgba8 src = psrc[x]; - if (src.a == 0) { + if (src->a == 0) { // Copy 4 bytes at once. - pout[x] = pdst[x]; + *out = *dst; } else { - rgba8 dst = pdst[x]; - rgba8* out = &pout[x]; - // Integer implementation with increased precision. // Each variable has extra meaningful bits. // Divisions are rounded. - UINT16 blend = dst.a * (255 - src.a); // 16 bit max - UINT16 outa = (src.a << 4) + ((blend + 0x8) >> 4); // 12 - UINT16 coef1 = (src.a << 16) / outa; // 12 + UINT16 blend = dst->a * (255 - src->a); // 16 bit max + UINT16 outa = (src->a << 4) + ((blend << 4) + 127) / 255; // 12 + UINT16 coef1 = ((src->a * 255) << 8) / outa; // 12 UINT16 coef2 = (blend << 8) / outa; // 12 - out->r = (src.r * coef1 + dst.r * coef2 + 0x800) >> 12; - out->g = (src.g * coef1 + dst.g * coef2 + 0x800) >> 12; - out->b = (src.b * coef1 + dst.b * coef2 + 0x800) >> 12; - out->a = (outa + 0x8) >> 4; + out->r = ((src->r * coef1 + dst->r * coef2 + 0x7ff) / 255) >> 4; + out->g = ((src->g * coef1 + dst->g * coef2 + 0x7ff) / 255) >> 4; + out->b = ((src->b * coef1 + dst->b * coef2 + 0x7ff) / 255) >> 4; + out->a = (outa + 0x7) >> 4; } + dst++; src++; out++; } }