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--- a/src/gui/painting/qdrawhelper.cpp 2014-12-05 19:24:36.000000000 +0300
+++ b/src/gui/painting/qdrawhelper.cpp 2019-08-03 15:31:42.034910641 +0300
@@ -3506,8 +3506,10 @@
}
/*
- if Sca.Da + Dca.Sa >= Sa.Da
+ if Sca.Da + Dca.Sa > Sa.Da
Dca' = Sa.Da + Sca.(1 - Da) + Dca.(1 - Sa)
+ else if Sca == Sa
+ Dca' = Dca.Sa + Sca.(1 - Da) + Dca.(1 - Sa)
otherwise
Dca' = Dca.Sa/(1-Sca/Sa) + Sca.(1 - Da) + Dca.(1 - Sa)
*/
@@ -3518,8 +3520,10 @@
const int src_da = src * da;
const int temp = src * (255 - da) + dst * (255 - sa);
- if (src_da + dst_sa >= sa_da)
+ if (src_da + dst_sa > sa_da)
return qt_div_255(sa_da + temp);
+ else if (src == sa || sa == 0)
+ return qt_div_255(temp);
else
return qt_div_255(255 * dst_sa / (255 - 255 * src / sa) + temp);
}
@@ -3589,8 +3593,10 @@
}
/*
- if Sca.Da + Dca.Sa <= Sa.Da
+ if Sca.Da + Dca.Sa < Sa.Da
Dca' = Sca.(1 - Da) + Dca.(1 - Sa)
+ else if Sca == 0
+ Dca' = Dca.Sa + Sca.(1 - Da) + Dca.(1 - Sa)
otherwise
Dca' = Sa.(Sca.Da + Dca.Sa - Sa.Da)/Sca + Sca.(1 - Da) + Dca.(1 - Sa)
*/
@@ -3602,8 +3608,10 @@
const int temp = src * (255 - da) + dst * (255 - sa);
- if (src == 0 || src_da + dst_sa <= sa_da)
+ if (src_da + dst_sa < sa_da)
return qt_div_255(temp);
+ else if (src == 0)
+ return qt_div_255(dst_sa + temp);
return qt_div_255(sa * (src_da + dst_sa - sa_da) / src + temp);
}
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