int SkIntersections::horizontal(const SkDLine& line, double left, double right,
double y, bool flipped) {
fMax = 3; // clean up parallel at the end will limit the result to 2 at the most
// see if end points intersect the opposite line
double t;
const SkDPoint leftPt = { left, y };
if ((t = line.exactPoint(leftPt)) >= 0) {
insert(t, (double) flipped, leftPt);
}
if (left != right) {
const SkDPoint rightPt = { right, y };
if ((t = line.exactPoint(rightPt)) >= 0) {
insert(t, (double) !flipped, rightPt);
}
for (int index = 0; index < 2; ++index) {
if ((t = SkDLine::ExactPointH(line[index], left, right, y)) >= 0) {
insert((double) index, flipped ? 1 - t : t, line[index]);
}
}
}
int result = horizontal_coincident(line, y);
if (result == 1 && fUsed == 0) {
fT[0][0] = HorizontalIntercept(line, y);
double xIntercept = line[0].fX + fT[0][0] * (line[1].fX - line[0].fX);
if (between(left, xIntercept, right)) {
fT[1][0] = (xIntercept - left) / (right - left);
if (flipped) {
// OPTIMIZATION: ? instead of swapping, pass original line, use [1].fX - [0].fX
for (int index = 0; index < result; ++index) {
fT[1][index] = 1 - fT[1][index];
}
}
fPt[0].fX = xIntercept;
fPt[0].fY = y;
fUsed = 1;
}
}
if (fAllowNear || result == 2) {
if ((t = line.nearPoint(leftPt, nullptr)) >= 0) {
insert(t, (double) flipped, leftPt);
}
if (left != right) {
const SkDPoint rightPt = { right, y };
if ((t = line.nearPoint(rightPt, nullptr)) >= 0) {
insert(t, (double) !flipped, rightPt);
}
for (int index = 0; index < 2; ++index) {
if ((t = SkDLine::NearPointH(line[index], left, right, y)) >= 0) {
insert((double) index, flipped ? 1 - t : t, line[index]);
}
}
}
}
cleanUpParallelLines(result == 2);
return fUsed;
}
int SkIntersections::horizontal(const SkDLine& line, double y) {
fMax = 2;
int horizontalType = horizontal_coincident(line, y);
if (horizontalType == 1) {
fT[0][0] = horizontal_intercept(line, y);
} else if (horizontalType == 2) {
fT[0][0] = 0;
fT[0][1] = 1;
}
return fUsed = horizontalType;
}
