How to query exactly selected items in Paper.js? - paperjs

Question

According to my understanding, project.getItems({selected: true}) returns wrong results: I'm selecting a curve, it returns the parent Path: Sketch
Try clicking on a curve or a segment. Whole path will be moved. Then try changing the behavior by setting var workaround = false to var workaround = true to observe desired behavior.
How can I get exactly what is really selected?
Current workaround
I'm currently adding those objects into an array on selection and use those items instead of project.getItems({selected: true}).

Answer 1

The thing is that in Paper.js architecture, curves and segments are not items (they are part of a specific item which is the path). So you shouldn't expect project.getItems() to return anything else than items.
Another thing you have to know is that a path is assumed selected if any of its part is selected (curves, segments, points, handles, position, bounds, ...). And a curve is assumed selected if all of its parts are selected (points and handles).
With that in mind, you can create an algorithm to retrieve "what is really selected" based on project.getItems({selected: true}) as its first part. Then, you need to loop through curves and segments to check if they are selected.
Here is a sketch demonstrating a possible solution.
var vector = new Point(10, 10);
// Create path.
var path = new Path({
segments: [
[100, 100],
[200, 100],
[260, 170],
[360, 170],
[420, 250]
],
strokeColor: 'red',
strokeWidth: 10
});
// Translate given thing along global vector.
function translateThing(thing) {
switch (thing.getClassName()) {
case 'Path':
thing.position += vector;
break;
case 'Curve':
thing.segment1.point += vector;
thing.segment2.point += vector;
break;
case 'Segment':
thing.point += vector;
break;
}
}
// On mouse down...
function onMouseDown(event) {
// ...only select what was clicked.
path.selected = false;
hit = paper.project.hitTest(event.point);
if (hit && hit.location) {
hit.location.curve.selected = true;
}
else if (hit && hit.segment) {
hit.segment.selected = true;
}
// We check all items for demo purpose.
// Move all selected things.
// First get selected items in active layer...
project.activeLayer.getItems({ selected: true })
// ...then map them to what is really selected...
.map(getSelectedThing)
// ...then translate them.
.forEach(translateThing);
}
// This method returns what is really selected in a given item.
// Here we assume that only one thing can be selected at the same time.
// Returned thing can be either a Curve, a Segment or an Item.
function getSelectedThing(item) {
// Only check curves and segments if item is a path.
if (item.getClassName() === 'Path') {
// Check curves.
for (var i = 0, l = item.curves.length; i < l; i++) {
if (item.curves[i].selected) {
return item.curves[i];
}
}
// Check segments.
for (var i = 0, l = item.segments.length; i < l; i++) {
if (item.segments[i].selected) {
return item.segments[i];
}
}
}
// return item by default.
return item;
}
That said, depending on your real use case, your current workaround could be more appropriate than this approach.