static SkScalar quad_folded_len(const SkPoint pts[3]) {
SkScalar t = SkFindQuadMaxCurvature(pts);
SkPoint pt = SkEvalQuadAt(pts, t);
SkVector a = pts[2] - pt;
SkScalar result = a.length();
if (0 != t) {
SkVector b = pts[0] - pt;
result += b.length();
}
SkASSERT(SkScalarIsFinite(result));
return result;
}
static void calc_dash_scaling(SkScalar* parallelScale, SkScalar* perpScale,
const SkMatrix& viewMatrix, const SkPoint pts[2]) {
SkVector vecSrc = pts[1] - pts[0];
SkScalar magSrc = vecSrc.length();
SkScalar invSrc = magSrc ? SkScalarInvert(magSrc) : 0;
vecSrc.scale(invSrc);
SkVector vecSrcPerp;
vecSrc.rotateCW(&vecSrcPerp);
viewMatrix.mapVectors(&vecSrc, 1);
viewMatrix.mapVectors(&vecSrcPerp, 1);
// parallelScale tells how much to scale along the line parallel to the dash line
// perpScale tells how much to scale in the direction perpendicular to the dash line
*parallelScale = vecSrc.length();
*perpScale = vecSrcPerp.length();
}
static void unitToPointsMatrix(const SkPoint pts[2], SkMatrix* matrix) {
SkVector vec = pts[1] - pts[0];
SkScalar mag = vec.length();
SkScalar inv = mag ? SkScalarInvert(mag) : 0;
vec.scale(inv);
matrix->setSinCos(vec.fY, vec.fX);
matrix->preTranslate(pts[0].fX, pts[0].fY);
matrix->preScale(mag, mag);
}
static void pts_to_unit_matrix(const SkPoint pts[2], SkMatrix* matrix) {
SkVector vec = pts[1] - pts[0];
SkScalar mag = vec.length();
SkScalar inv = mag ? SkScalarInvert(mag) : 0;
vec.scale(inv);
matrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
matrix->postTranslate(-pts[0].fX, -pts[0].fY);
matrix->postScale(inv, inv);
}
static void toUnitMatrix(const SkPoint pts[2], SkMatrix* matrix) {
SkVector vec = pts[1] - pts[0];
const float mag = vec.length();
const float inv = mag ? 1.0f / mag : 0;
vec.scale(inv);
matrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
matrix->postTranslate(-pts[0].fX, -pts[0].fY);
matrix->postScale(inv, inv);
}
static SkMatrix pts_to_unit_matrix(const SkPoint pts[2]) {
SkVector vec = pts[1] - pts[0];
SkScalar mag = vec.length();
SkScalar inv = mag ? SkScalarInvert(mag) : 0;
vec.scale(inv);
SkMatrix matrix;
matrix.setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
matrix.postTranslate(-pts[0].fX, -pts[0].fY);
matrix.postScale(inv, inv);
return matrix;
}
// calculates the rotation needed to aligned pts to the x axis with pts[0] < pts[1]
// Stores the rotation matrix in rotMatrix, and the mapped points in ptsRot
static void align_to_x_axis(const SkPoint pts[2], SkMatrix* rotMatrix, SkPoint ptsRot[2] = NULL) {
SkVector vec = pts[1] - pts[0];
SkScalar mag = vec.length();
SkScalar inv = mag ? SkScalarInvert(mag) : 0;
vec.scale(inv);
rotMatrix->setSinCos(-vec.fY, vec.fX, pts[0].fX, pts[0].fY);
if (ptsRot) {
rotMatrix->mapPoints(ptsRot, pts, 2);
// correction for numerical issues if map doesn't make ptsRot exactly horizontal
ptsRot[1].fY = pts[0].fY;
}
}
static void bloat_quad(const SkPoint qpts[3], const SkMatrix* toDevice,
const SkMatrix* toSrc, BezierVertex verts[kQuadNumVertices]) {
SkASSERT(!toDevice == !toSrc);
// original quad is specified by tri a,b,c
SkPoint a = qpts[0];
SkPoint b = qpts[1];
SkPoint c = qpts[2];
if (toDevice) {
toDevice->mapPoints(&a, 1);
toDevice->mapPoints(&b, 1);
toDevice->mapPoints(&c, 1);
}
// make a new poly where we replace a and c by a 1-pixel wide edges orthog
// to edges ab and bc:
//
// before | after
// | b0
// b |
// |
// | a0 c0
// a c | a1 c1
//
// edges a0->b0 and b0->c0 are parallel to original edges a->b and b->c,
// respectively.
BezierVertex& a0 = verts[0];
BezierVertex& a1 = verts[1];
BezierVertex& b0 = verts[2];
BezierVertex& c0 = verts[3];
BezierVertex& c1 = verts[4];
SkVector ab = b;
ab -= a;
SkVector ac = c;
ac -= a;
SkVector cb = b;
cb -= c;
// We should have already handled degenerates
SkASSERT(ab.length() > 0 && cb.length() > 0);
ab.normalize();
SkVector abN;
abN.setOrthog(ab, SkVector::kLeft_Side);
if (abN.dot(ac) > 0) {
abN.negate();
}
cb.normalize();
SkVector cbN;
cbN.setOrthog(cb, SkVector::kLeft_Side);
if (cbN.dot(ac) < 0) {
cbN.negate();
}
a0.fPos = a;
a0.fPos += abN;
a1.fPos = a;
a1.fPos -= abN;
c0.fPos = c;
c0.fPos += cbN;
c1.fPos = c;
c1.fPos -= cbN;
intersect_lines(a0.fPos, abN, c0.fPos, cbN, &b0.fPos);
if (toSrc) {
toSrc->mapPointsWithStride(&verts[0].fPos, sizeof(BezierVertex), kQuadNumVertices);
}
}