d3.behavior.drag = function() {

var event = d3.dispatch("drag", "dragstart", "dragend");

function drag() {

this

.on("mousedown.drag", mousedown)

.on("touchstart.drag", mousedown);

d3.select(window)

.on("mousemove.drag", d3_behavior_dragMove)

.on("touchmove.drag", d3_behavior_dragMove)

.on("mouseup.drag", d3_behavior_dragUp, true)

.on("touchend.drag", d3_behavior_dragUp, true)

.on("click.drag", d3_behavior_dragClick, true);

}

// snapshot the local context for subsequent dispatch

function start() {

d3_behavior_dragEvent = event;

d3_behavior_dragEventTarget = d3.event.target;

d3_behavior_dragOffset = d3_behavior_dragPoint((d3_behavior_dragTarget = this).parentNode);

d3_behavior_dragMoved = 0;

d3_behavior_dragArguments = arguments;

}

function mousedown() {

start.apply(this, arguments);

d3_behavior_dragDispatch("dragstart");

}

drag.on = function(type, listener) {

event.on(type, listener);

return drag;

};

return drag;

};

var d3_behavior_dragEvent,

d3_behavior_dragEventTarget,

d3_behavior_dragTarget,

d3_behavior_dragArguments,

d3_behavior_dragOffset,

d3_behavior_dragMoved,

d3_behavior_dragStopClick;

function d3_behavior_dragDispatch(type) {

var o = d3.event, p = d3_behavior_dragTarget.parentNode, dx = 0, dy = 0;

if (p) {

p = d3_behavior_dragPoint(p);

dx = p[0] - d3_behavior_dragOffset[0];

dy = p[1] - d3_behavior_dragOffset[1];

d3_behavior_dragOffset = p;

d3_behavior_dragMoved |= dx | dy;

}

try {

d3.event = {dx: dx, dy: dy};

d3_behavior_dragEvent[type].apply(d3_behavior_dragTarget, d3_behavior_dragArguments);

} finally {

d3.event = o;

}

o.preventDefault();

}

function d3_behavior_dragPoint(container, type) {

// TODO Track touch points by identifier.

var t = d3.event.changedTouches;

return t ? d3.svg.touches(container, t)[0] : d3.svg.mouse(container);

}

function d3_behavior_dragMove() {

if (!d3_behavior_dragTarget) return;

var parent = d3_behavior_dragTarget.parentNode;

// O NOES! The drag element was removed from the DOM.

if (!parent) return d3_behavior_dragUp();

d3_behavior_dragDispatch("drag");

d3_eventCancel();

}

function d3_behavior_dragUp() {

if (!d3_behavior_dragTarget) return;

d3_behavior_dragDispatch("dragend");

d3_behavior_dragTarget = null;

// If the node was moved, prevent the mouseup from propagating.

// Also prevent the subsequent click from propagating (e.g., for anchors).

if (d3_behavior_dragMoved && d3_behavior_dragEventTarget === d3.event.target) {

d3_behavior_dragStopClick = true;

d3_eventCancel();

}

}

function d3_behavior_dragClick() {

if (d3_behavior_dragStopClick && d3_behavior_dragEventTarget === d3.event.target) {

d3_eventCancel();

d3_behavior_dragStopClick = false;

d3_behavior_dragEventTarget = null;

}

}