/**
* This function is optimized for drawing with subpixel precision.
* @param brush brush to draw the line with
* @param from starting point
* @param to ending point
* @param distance distance from previous dab.
*/
void Layer::drawSoftLine(const Brush& brush, const BrushMaskGenerator &mask, const Point& from, const Point& to, qreal &distance)
{
qreal dx = to.x() - from.x();
qreal dy = to.y() - from.y();
const qreal dist = hypot(dx, dy);
dx = dx / dist;
dy = dy / dist;
const qreal dp = (to.pressure() - from.pressure()) / dist;
const qreal spacing0 = qMax(1.0, brush.spacingDist(from.pressure()));
qreal i;
if(distance>=spacing0)
i = 0;
else if(distance==0)
i = spacing0;
else
i = distance;
Point p(from.x() + dx*i, from.y() + dy*i, qBound(0.0, from.pressure() + dp*i, 1.0));
while(i<=dist) {
const qreal spacing = qMax(1.0, brush.spacingDist(p.pressure()));
directDab(brush, mask, p);
p.rx() += dx * spacing;
p.ry() += dy * spacing;
p.setPressure(qBound(0.0, p.pressure() + dp * spacing, 1.0));
i += spacing;
}
distance = i-dist;
}
/**
* This line drawing function is optimized for drawing with no subpixel
* precision.
* The last point is not drawn, so successive lines can be drawn blotches.
*/
void Layer::drawHardLine(const Brush &brush, const Point& from, const Point& to, StrokeState &state) {
const qreal dp = (to.pressure()-from.pressure()) / hypot(to.x()-from.x(), to.y()-from.y());
int x0 = qFloor(from.x());
int y0 = qFloor(from.y());
qreal p = from.pressure();
int x1 = qFloor(to.x());
int y1 = qFloor(to.y());
int dy = y1 - y0;
int dx = x1 - x0;
int stepx, stepy;
if (dy < 0) {
dy = -dy;
stepy = -1;
} else {
stepy = 1;
}
if (dx < 0) {
dx = -dx;
stepx = -1;
} else {
stepx = 1;
}
dy *= 2;
dx *= 2;
qreal distance = state.distance;
if (dx > dy) {
int fraction = dy - (dx >> 1);
while (x0 != x1) {
const qreal spacing = brush.spacingDist(p);
if (fraction >= 0) {
y0 += stepy;
fraction -= dx;
}
x0 += stepx;
fraction += dy;
if(++distance >= spacing) {
directDab(brush, Point(x0, y0, p), state);
distance = 0;
}
p += dp;
}
} else {
