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drag.js
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drag.js
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import {dispatch} from "d3-dispatch";
import {event, customEvent, select, mouse, touch} from "d3-selection";
import nodrag, {yesdrag} from "./nodrag";
import noevent, {nopropagation} from "./noevent";
import constant from "./constant";
import DragEvent from "./event";
// Ignore right-click, since that should open the context menu.
function defaultFilter() {
return !event.button;
}
function defaultContainer() {
return this.parentNode;
}
function defaultSubject(d) {
return d == null ? {x: event.x, y: event.y} : d;
}
function defaultTouchable() {
return "ontouchstart" in this;
}
export default function() {
var filter = defaultFilter,
container = defaultContainer,
subject = defaultSubject,
touchable = defaultTouchable,
gestures = {},
listeners = dispatch("start", "drag", "end"),
active = 0,
mousedownx,
mousedowny,
mousemoving,
touchending,
clickDistance2 = 0;
function drag(selection) {
selection
.on("mousedown.drag", mousedowned)
.filter(touchable)
.on("touchstart.drag", touchstarted)
.on("touchmove.drag", touchmoved)
.on("touchend.drag touchcancel.drag", touchended)
.style("touch-action", "none")
.style("-webkit-tap-highlight-color", "rgba(0,0,0,0)");
}
function mousedowned() {
if (touchending || !filter.apply(this, arguments)) return;
var gesture = beforestart("mouse", container.apply(this, arguments), mouse, this, arguments);
if (!gesture) return;
select(event.view).on("mousemove.drag", mousemoved, true).on("mouseup.drag", mouseupped, true);
nodrag(event.view);
nopropagation();
mousemoving = false;
mousedownx = event.clientX;
mousedowny = event.clientY;
gesture("start");
}
function mousemoved() {
noevent();
if (!mousemoving) {
var dx = event.clientX - mousedownx, dy = event.clientY - mousedowny;
mousemoving = dx * dx + dy * dy > clickDistance2;
}
gestures.mouse("drag");
}
function mouseupped() {
select(event.view).on("mousemove.drag mouseup.drag", null);
yesdrag(event.view, mousemoving);
noevent();
gestures.mouse("end");
}
function touchstarted() {
if (!filter.apply(this, arguments)) return;
var touches = event.changedTouches,
c = container.apply(this, arguments),
n = touches.length, i, gesture;
for (i = 0; i < n; ++i) {
if (gesture = beforestart(touches[i].identifier, c, touch, this, arguments)) {
nopropagation();
gesture("start");
}
}
}
function touchmoved() {
var touches = event.changedTouches,
n = touches.length, i, gesture;
for (i = 0; i < n; ++i) {
if (gesture = gestures[touches[i].identifier]) {
noevent();
gesture("drag");
}
}
}
function touchended() {
var touches = event.changedTouches,
n = touches.length, i, gesture;
if (touchending) clearTimeout(touchending);
touchending = setTimeout(function() { touchending = null; }, 500); // Ghost clicks are delayed!
for (i = 0; i < n; ++i) {
if (gesture = gestures[touches[i].identifier]) {
nopropagation();
gesture("end");
}
}
}
function beforestart(id, container, point, that, args) {
var p = point(container, id), s, dx, dy,
sublisteners = listeners.copy();
if (!customEvent(new DragEvent(drag, "beforestart", s, id, active, p[0], p[1], 0, 0, sublisteners), function() {
if ((event.subject = s = subject.apply(that, args)) == null) return false;
dx = s.x - p[0] || 0;
dy = s.y - p[1] || 0;
return true;
})) return;
return function gesture(type) {
var p0 = p, n;
switch (type) {
case "start": gestures[id] = gesture, n = active++; break;
case "end": delete gestures[id], --active; // nobreak
case "drag": p = point(container, id), n = active; break;
}
customEvent(new DragEvent(drag, type, s, id, n, p[0] + dx, p[1] + dy, p[0] - p0[0], p[1] - p0[1], sublisteners), sublisteners.apply, sublisteners, [type, that, args]);
};
}
drag.filter = function(_) {
return arguments.length ? (filter = typeof _ === "function" ? _ : constant(!!_), drag) : filter;
};
drag.container = function(_) {
return arguments.length ? (container = typeof _ === "function" ? _ : constant(_), drag) : container;
};
drag.subject = function(_) {
return arguments.length ? (subject = typeof _ === "function" ? _ : constant(_), drag) : subject;
};
drag.touchable = function(_) {
return arguments.length ? (touchable = typeof _ === "function" ? _ : constant(!!_), drag) : touchable;
};
drag.on = function() {
var value = listeners.on.apply(listeners, arguments);
return value === listeners ? drag : value;
};
drag.clickDistance = function(_) {
return arguments.length ? (clickDistance2 = (_ = +_) * _, drag) : Math.sqrt(clickDistance2);
};
return drag;
}