Ensure only fractional floats are converted to SkFixed in SubpixelAlignment.

BUG=skia:4632
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1779083003

Review URL: https://codereview.chromium.org/1779083003
This commit is contained in:
benjaminwagner 2016-03-11 04:33:44 -08:00 committed by Commit bot
parent e683c56115
commit db6bd3239f

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@ -381,14 +381,16 @@ private:
// produce the correct sub-pixel alignment. If a position is aligned with an axis a shortcut
// of 0 is used for the sub-pixel position.
static SkIPoint SubpixelAlignment(SkAxisAlignment axisAlignment, SkPoint position) {
// Only the fractional part of position.fX and position.fY matter, because the result of
// this function will just be passed to FixedToSub.
switch (axisAlignment) {
case kX_SkAxisAlignment:
return {SkScalarToFixed(position.fX + kSubpixelRounding), 0};
return {SkScalarToFixed(SkScalarFraction(position.fX) + kSubpixelRounding), 0};
case kY_SkAxisAlignment:
return {0, SkScalarToFixed(position.fY + kSubpixelRounding)};
return {0, SkScalarToFixed(SkScalarFraction(position.fY) + kSubpixelRounding)};
case kNone_SkAxisAlignment:
return {SkScalarToFixed(position.fX + kSubpixelRounding),
SkScalarToFixed(position.fY + kSubpixelRounding)};
return {SkScalarToFixed(SkScalarFraction(position.fX) + kSubpixelRounding),
SkScalarToFixed(SkScalarFraction(position.fY) + kSubpixelRounding)};
}
SkFAIL("Should not get here.");
return {0, 0};