tangentAt: function (t) {
var shape = this.shape;
var p = isLine(shape)
? [shape.x2 - shape.x1, shape.y2 - shape.y1]
: bezierCurveProto.tangentAt.call(this, t);
return vec2.normalize(p, p);
}
function updateSymbolBeforeLineUpdate () {
var lineGroup = this;
var line = lineGroup.childOfName('line');
// If line not changed
if (!this.__dirty && !line.__dirty) {
return;
}
var symbolFrom = lineGroup.childOfName('fromSymbol');
var symbolTo = lineGroup.childOfName('toSymbol');
var label = lineGroup.childOfName('label');
var fromPos = line.pointAt(0);
var toPos = line.pointAt(line.shape.percent);
var d = vector.sub([], toPos, fromPos);
vector.normalize(d, d);
if (symbolFrom) {
symbolFrom.attr('position', fromPos);
// Rotate the arrow
// FIXME Hard coded ?
if (isSymbolArrow(symbolTo)) {
symbolTo.attr('rotation', tangentRotation(fromPos, toPos));
}
}
if (symbolTo) {
symbolTo.attr('position', toPos);
if (isSymbolArrow(symbolFrom)) {
symbolFrom.attr('rotation', tangentRotation(toPos, fromPos));
}
}
label.attr('position', toPos);
var textPosition;
var textAlign;
var textBaseline;
// End
if (label.__position === 'end') {
textPosition = [d[0] * 5 + toPos[0], d[1] * 5 + toPos[1]];
textAlign = d[0] > 0.8 ? 'left' : (d[0] < -0.8 ? 'right' : 'center');
textBaseline = d[1] > 0.8 ? 'top' : (d[1] < -0.8 ? 'bottom' : 'middle');
}
// Start
else {
textPosition = [-d[0] * 5 + fromPos[0], -d[1] * 5 + fromPos[1]];
textAlign = d[0] > 0.8 ? 'right' : (d[0] < -0.8 ? 'left' : 'center');
textBaseline = d[1] > 0.8 ? 'bottom' : (d[1] < -0.8 ? 'top' : 'middle');
}
label.attr({
style: {
// Use the user specified text align and baseline first
textBaseline: label.__textBaseline || textBaseline,
textAlign: label.__textAlign || textAlign
},
position: textPosition
});
}