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gdi32: Use atan2 to compute angles in WidenPath without triggering floating point errors.

This commit is contained in:
Alexandre Julliard 2008-05-22 20:43:55 +02:00
parent 93cbb7a5db
commit 00388c1b6a
1 changed files with 7 additions and 21 deletions
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28
dlls/gdi32/path.c
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@ -1967,9 +1967,8 @@ static BOOL PATH_WidenPath(DC *dc)
/* Beginning or end of the path if not closed */
if((!(pStrokes[i]->pFlags[pStrokes[i]->numEntriesUsed - 1] & PT_CLOSEFIGURE)) && (j == 0 || j == pStrokes[i]->numEntriesUsed - 1) ) {
/* Compute segment angle */
double xo, yo, xa, ya;
double xo, yo, xa, ya, theta;
POINT pt;
double theta, scalarProduct;
FLOAT_POINT corners[2];
if(j == 0) {
xo = pStrokes[i]->pPoints[j].x;
@ -1983,11 +1982,7 @@ static BOOL PATH_WidenPath(DC *dc)
xo = pStrokes[i]->pPoints[j].x;
yo = pStrokes[i]->pPoints[j].y;
}
scalarProduct = (xa - xo) /sqrt(pow((xa - xo), 2) + pow((ya - yo), 2));
theta = acos(scalarProduct);
if( (ya - yo) < 0) {
theta = -theta;
}
theta = atan2( ya - yo, xa - xo );
switch(endcap) {
case PS_ENDCAP_SQUARE :
pt.x = xo + round(sqrt(2) * penWidthOut * cos(M_PI_4 + theta));
@ -2023,8 +2018,7 @@ static BOOL PATH_WidenPath(DC *dc)
/* Compute angle */
INT previous, next;
double xa, ya, xb, yb, xo, yo;
double alpha, theta;
double scalarProduct, oa, ob, miterWidth;
double alpha, theta, miterWidth;
DWORD _joint = joint;
POINT pt;
GdiPath *pInsidePath, *pOutsidePath;
@ -2046,18 +2040,10 @@ static BOOL PATH_WidenPath(DC *dc)
ya = pStrokes[i]->pPoints[previous].y;
xb = pStrokes[i]->pPoints[next].x;
yb = pStrokes[i]->pPoints[next].y;
oa = sqrt(pow((xa - xo), 2) + pow((ya - yo), 2));
ob = sqrt(pow((xb - xo), 2) + pow((yb - yo), 2));
scalarProduct = ((xa - xo) * (xb - xo) + (ya - yo) * (yb - yo))/ (oa * ob);
alpha = acos(scalarProduct);
if(( (xa - xo) * (yb - yo) - (ya - yo) * (xb - xo) ) < 0) {
alpha = -alpha;
}
scalarProduct = (xo - xa) / oa;
theta = acos(scalarProduct);
if( (yo - ya) < 0) {
theta = -theta;
}
theta = atan2( yo - ya, xo - xa );
alpha = atan2( yb - yo, xb - xo ) - theta;
if (alpha > 0) alpha -= M_PI;
else alpha += M_PI;
if(_joint == PS_JOIN_MITER && dc->miterLimit < fabs(1 / sin(alpha/2))) {
_joint = PS_JOIN_BEVEL;
}