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Bug 59386 - off-by-one error in gtk alpha compositor divisor 

causing blending artifacts, plus cleanup by moving compositing
calculation to a macro.  r=bryner, sr=blizzard
This commit is contained in:
tor%cs.brown.edu 2000-11-08 05:17:23 +00:00
Родитель 08583edc80
Коммит 37c216df3d
1 изменённых файлов: 23 добавлений и 31 удалений
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54
gfx/src/gtk/nsImageGTK.cpp
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@ -379,6 +379,9 @@ findIndex24(unsigned mask)
}
}
// blending macro
#define MOZ_BLEND(bg, fg, alpha) (((bg)*(255-(alpha)) + (fg)*(alpha))/255)
// 32-bit (888) truecolor convert/composite function
void
nsImageGTK::DrawComposited32(PRBool isLSB, PRBool flipBytes,
@ -410,15 +413,10 @@ nsImageGTK::DrawComposited32(PRBool isLSB, PRBool flipBytes,
for (unsigned i=0; i<width;
i++, baseRow+=4, targetRow+=3, imageRow+=3, alphaRow++) {
targetRow[0] =
(unsigned(baseRow[redIndex]) * (255-*alphaRow) +
unsigned(imageRow[0]) * *alphaRow) >> 8;
targetRow[1] =
(unsigned(baseRow[greenIndex]) * (255-*alphaRow) +
unsigned(imageRow[1]) * *alphaRow) >> 8;
targetRow[2] =
(unsigned(baseRow[blueIndex]) * (255-*alphaRow) +
unsigned(imageRow[2]) * *alphaRow) >> 8;
unsigned alpha = *alphaRow;
targetRow[0] = MOZ_BLEND(baseRow[redIndex], imageRow[0], alpha);
targetRow[1] = MOZ_BLEND(baseRow[greenIndex], imageRow[1], alpha);
targetRow[2] = MOZ_BLEND(baseRow[blueIndex], imageRow[2], alpha);
}
}
}
@ -450,15 +448,10 @@ nsImageGTK::DrawComposited24(PRBool isLSB, PRBool flipBytes,
for (unsigned i=0; i<width;
i++, baseRow+=3, targetRow+=3, imageRow+=3, alphaRow++) {
targetRow[0] =
(unsigned(baseRow[redIndex]) * (255-*alphaRow) +
unsigned(imageRow[0]) * *alphaRow) >> 8;
targetRow[1] =
(unsigned(baseRow[greenIndex]) * (255-*alphaRow) +
unsigned(imageRow[1]) * *alphaRow) >> 8;
targetRow[2] =
(unsigned(baseRow[blueIndex]) * (255-*alphaRow) +
unsigned(imageRow[2]) * *alphaRow) >> 8;
unsigned alpha = *alphaRow;
targetRow[0] = MOZ_BLEND(baseRow[redIndex], imageRow[0], alpha);
targetRow[1] = MOZ_BLEND(baseRow[greenIndex], imageRow[1], alpha);
targetRow[2] = MOZ_BLEND(baseRow[blueIndex], imageRow[2], alpha);
}
}
}
@ -505,15 +498,16 @@ nsImageGTK::DrawComposited16(PRBool isLSB, PRBool flipBytes,
pix = *((short *)tmp);
} else
pix = *((short *)baseRow);
targetRow[0] =
(redScale[(pix&visual->red_mask)>>visual->red_shift] *
(255-*alphaRow) + unsigned(imageRow[0]) * *alphaRow) >> 8;
unsigned alpha = *alphaRow;
targetRow[0] =
MOZ_BLEND(redScale[(pix&visual->red_mask)>>visual->red_shift],
imageRow[0], alpha);
targetRow[1] =
(greenScale[(pix&visual->green_mask)>>visual->green_shift] *
(255-*alphaRow) + unsigned(imageRow[1]) * *alphaRow) >> 8;
MOZ_BLEND(greenScale[(pix&visual->green_mask)>>visual->green_shift],
imageRow[1], alpha);
targetRow[2] =
(blueScale[(pix&visual->blue_mask)>>visual->blue_shift] *
(255-*alphaRow) + unsigned(imageRow[2]) * *alphaRow) >> 8;
MOZ_BLEND(blueScale[(pix&visual->blue_mask)>>visual->blue_shift],
imageRow[2], alpha);
}
}
}
@ -654,12 +648,10 @@ nsImageGTK::DrawCompositedGeneral(PRBool isLSB, PRBool flipBytes,
unsigned char *alphaRow = mAlphaBits +(y+offsetY)*mAlphaRowBytes+offsetX;
for (unsigned i=0; i<width; i++) {
targetRow[3*i] = (unsigned(targetRow[3*i])*(255-alphaRow[i]) +
unsigned(imageRow[3*i])*alphaRow[i])>>8;
targetRow[3*i+1] = (unsigned(targetRow[3*i+1])*(255-alphaRow[i]) +
unsigned(imageRow[3*i+1])*alphaRow[i])>>8;
targetRow[3*i+2] = (unsigned(targetRow[3*i+2])*(255-alphaRow[i]) +
unsigned(imageRow[3*i+2])*alphaRow[i])>>8;
unsigned alpha = alphaRow[i];
targetRow[3*i] = MOZ_BLEND(targetRow[3*i], imageRow[3*i], alpha);
targetRow[3*i+1] = MOZ_BLEND(targetRow[3*i+1], imageRow[3*i+1], alpha);
targetRow[3*i+2] = MOZ_BLEND(targetRow[3*i+2], imageRow[3*i+2], alpha);
}
}
}