static FskErr
DashNextSegment(DashBuddy *db, const FskFixedPoint2D *pt)
{
FskErr err;
FskFixedPoint2D q;
FskFixedVector2D v;
FskFixed segPhase, endPhase, deltaPhase;
FskFract t;
UInt32 i;
q = db->lastPt; /* Point of last state change */
v.x = pt->x - db->lastPt.x; v.y = pt->y - db->lastPt.y; /* Vector along the line segment */
segPhase = FskFixedHypot(FskFixedDotProduct2D(&v, db->dashBasis+0), FskFixedDotProduct2D(&v, db->dashBasis+1)); /* Phase delta for this segment (Riemannian metric) */
endPhase = db->dashPhase + segPhase; /* Phase at end of this line segment */
while (db->thisPhaseSegment[1] <= endPhase) {
/* We know that we're going to cross a dash segment */
deltaPhase = db->thisPhaseSegment[1] - db->dashPhase; /* Phase change since the last state change */
t = FskFracDiv(deltaPhase, segPhase); q.x += FskFracMul(t, v.x); q.y += FskFracMul(t, v.y); /* Compute location of next transition */
if ((i = FskGrowableArrayGetItemCount(db->ptArray)) > 0) DrawDashSegment(db, &q); /* ON transitioning to OFF: end and draw this dash segment */
else (void)FskGrowableArrayAppendItem(db->ptArray, &q); /* OFF transition to ON: add the start point */
if (++(db->thisPhaseSegment) >= db->resetSegmentPhase) { /* Advance phase segment... */
db->thisPhaseSegment = db->dashSegmentPhases; /* ... and reset if at the end of the phase period */
endPhase -= db->dashPeriod; /* The end is getting closer */
}
db->dashPhase = db->thisPhaseSegment[0]; /* Set the phase */
}
/* The end is still within the same dash segment */
if ((i = FskGrowableArrayGetItemCount(db->ptArray)) > 0) err = FskGrowableArrayAppendItem(db->ptArray, pt); /* In the ON state: add a kink point */
else err = kFskErrNone; /* In the OFF state */
db->dashPhase = endPhase; /* Update the phase */
db->lastPt = *pt;
return err;
}
static FskErr
BeveledJoin(const LineSeg *seg0, const LineSeg *seg1, FskGrowableFixedPoint2DArray fwdPoly, FskGrowableFixedPoint2DArray revPoly)
{
FskErr err = kFskErrNone;
FskFract sinAng, cosAng, snmHaf, sinHaf, cosHaf;
FskFixed bevHafWidth, mitLength, maxElbow;
FskFractVector2D u;
FskFixedVector2D b, c, e;
FskFixedPoint2D p[3];
sinAng = FskFractCrossProduct2D(&seg0->par, &seg1->par); /* Sine of change in trajectory */
if (sinAng == 0) /* Collinear */
goto bail; /* All done */
cosAng = FskFractDotProduct(&seg0->par.x, &seg1->par.x, 2); /* Cosine of change in trajectory */
if (cosAng > FRACT_ONE) cosAng = FRACT_ONE;
else if (cosAng < -FRACT_ONE) cosAng = -FRACT_ONE;
cosHaf = FskFracSqrt(FRACT_HALF - (cosAng >> 1)); /* Cosine of half the subtended angle */
snmHaf = FskFracSqrt(FRACT_HALF + (cosAng >> 1)); /* Sine of half the subtended angle */
if (snmHaf != 0) {
sinHaf = snmHaf;
if (sinAng < 0) sinHaf = -sinHaf;
u.x = FskFixedNLinear2D(seg0->par.x, cosHaf, seg0->par.y, sinHaf, 30); /* Unit vector to elbow, inside or outside */
u.y = FskFixedNLinear2D(seg0->par.y, cosHaf, -seg0->par.x, sinHaf, 30);
bevHafWidth = (FskFixed)(((FskInt64)(seg0->strokeWidth) * cosHaf / (FRACT_ONE + snmHaf) + 1) >> 1);
c.x = FskFixedNMul(seg0->strokeWidth, u.x, 31); /* Midpoint of bevel */
c.y = FskFixedNMul(seg0->strokeWidth, u.y, 31);
b.x = FskFracMul(bevHafWidth, -u.y); /* Half-vector of bevel */
b.y = FskFracMul(bevHafWidth, u.x);
mitLength = FskFixedNDiv(seg0->strokeWidth, snmHaf, 29);
if ((maxElbow = (seg0->strokeWidth)) < seg0->length) /* Limit the extent of the inside bevel joint */
maxElbow = seg0->length;
if (maxElbow < seg1->length)
maxElbow = seg1->length;
if (mitLength > maxElbow)
mitLength = maxElbow;
e.x = FskFracMul(mitLength, u.x); /* Scaled vector to elbow, inside */
e.y = FskFracMul(mitLength, u.y);
if (sinAng > 0) { /* Positive rotation */
p[0].x = seg0->pt[1].x + c.x - b.x; /* First bevel point */
p[0].y = seg0->pt[1].y + c.y - b.y;
p[1].x = seg0->pt[1].x + c.x + b.x; /* Second bevel point */
p[1].y = seg0->pt[1].y + c.y + b.y;
p[2].x = seg0->pt[1].x - e.x; /* Inside elbow */
p[2].y = seg0->pt[1].y - e.y;
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItems(revPoly, &p[0], 2));
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItem( fwdPoly, &p[2]));
}
else { /* Negative rotation */
p[0].x = seg0->pt[1].x + c.x + b.x; /* First bevel point */
p[0].y = seg0->pt[1].y + c.y + b.y;
p[1].x = seg0->pt[1].x + c.x - b.x; /* Second bevel point */
p[1].y = seg0->pt[1].y + c.y - b.y;
p[2].x = seg0->pt[1].x - e.x; /* Inside elbow */
p[2].y = seg0->pt[1].y - e.y;
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItems(fwdPoly, &p[0], 2));
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItem( revPoly, &p[2]));
}
}
static FskErr
RoundedJoin(const LineSeg *seg0, const LineSeg *seg1, FskGrowableFixedPoint2DArray fwdPoly, FskGrowableFixedPoint2DArray revPoly)
{
FskErr err = kFskErrNone;
FskFract sinAng, cosAng, snmHaf, sinHaf, cosHaf;
FskFixed mitLength, maxElbow;
FskFractVector2D u;
FskFixedVector2D v0, v1, e;
FskFixedPoint2D p[4];
sinAng = FskFractCrossProduct2D(&seg0->par, &seg1->par); /* Sine of change in trajectory */
if (sinAng == 0) /* Collinear */
goto bail; /* All done */
cosAng = FskFractDotProduct(&seg0->par.x, &seg1->par.x, 2); /* Cosine of change in trajectory */
if (cosAng > FRACT_ONE) cosAng = FRACT_ONE;
else if (cosAng < -FRACT_ONE) cosAng = -FRACT_ONE;
cosHaf = FskFracSqrt(FRACT_HALF - (cosAng >> 1)); /* Cosine of half the subtended angle */
snmHaf = FskFracSqrt(FRACT_HALF + (cosAng >> 1)); /* Sine of half the subtended angle */
if (snmHaf != 0) {
sinHaf = snmHaf;
if (sinAng < 0) sinHaf = -sinHaf;
v0.x = FskFixedNMul(seg0->perp.x, seg0->strokeWidth, 31); /* Perpendicular excursion from seg0 */
v0.y = FskFixedNMul(seg0->perp.y, seg0->strokeWidth, 31);
v1.x = FskFixedNMul(seg1->perp.x, seg0->strokeWidth, 31); /* Perpendicular excursion from seg1 */
v1.y = FskFixedNMul(seg1->perp.y, seg0->strokeWidth, 31);
u.x = FskFixedNLinear2D(seg0->par.x, cosHaf, seg0->par.y, sinHaf, 30); /* Unit vector to elbow, inside or outside */
u.y = FskFixedNLinear2D(seg0->par.y, cosHaf, -seg0->par.x, sinHaf, 30);
mitLength = FskFixedNDiv(seg0->strokeWidth, snmHaf, 29);
if ((maxElbow = (seg0->strokeWidth)) < seg0->length) /* Limit the extent of the inside bevel joint */
maxElbow = seg0->length;
if (maxElbow < seg1->length)
maxElbow = seg1->length;
if (mitLength > maxElbow)
mitLength = maxElbow;
e.x = FskFracMul(mitLength, u.x); /* Scaled vector to elbow, inside */
e.y = FskFracMul(mitLength, u.y);
if (sinAng > 0) { /* Positive rotation */
p[0].x = seg0->pt[1].x - v0.x; /* Start of arc */
p[0].y = seg0->pt[1].y - v0.y;
p[2].x = seg0->pt[1].x - v1.x; /* End of arc */
p[2].y = seg0->pt[1].y - v1.y;
p[1].x = seg0->pt[1].x + e.x; /* Outside elbow point */
p[1].y = seg0->pt[1].y + e.y;
p[3].x = seg0->pt[1].x - e.x; /* Inside elbow point */
p[3].y = seg0->pt[1].y - e.y;
BAIL_IF_ERR(err = FskTessellateRationalBezier2DRegularly(&p[0], &p[1], &snmHaf, 3, NULL, revPoly));
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItem(fwdPoly, &p[3]));
}
else { /* Negative rotation */
p[0].x = seg0->pt[1].x + v0.x; /* Start of arc */
p[0].y = seg0->pt[1].y + v0.y;
p[2].x = seg0->pt[1].x + v1.x; /* End of arc */
p[2].y = seg0->pt[1].y + v1.y;
p[1].x = seg0->pt[1].x + e.x; /* Outside elbow point */
p[1].y = seg0->pt[1].y + e.y;
p[3].x = seg0->pt[1].x - e.x; /* Inside elbow point */
p[3].y = seg0->pt[1].y - e.y;
BAIL_IF_ERR(err = FskTessellateRationalBezier2DRegularly(&p[0], &p[1], &snmHaf, 3, NULL, fwdPoly));
BAIL_IF_ERR(err = FskGrowableFixedPoint2DArrayAppendItem(revPoly, &p[3]));
}
}
/* else 0 degrees subtended (180 degree about face): what to do? */
bail:
return err;
}
