背景
我正在为大学做一个实验来比较不同的拖动技术。为此，我使用d3，需要使用不同的设备，其中一个是触摸板。
我迄今为止的研究
现在有一种技术需要在触摸板上双击+按住行为。我发现这个例子是用d3v3制作的。这几乎是我想要实现的行为(只是有不同的视觉反馈(。
问题
我使用的是d3 v5，我知道我需要从d3 v3版本手动添加d3.rebind()函数，我做到了。然而，我仍然有问题。当我试图在黑圈上创建事件时，我得到了以下错误(根据rioV8的答案在这里编辑(：
Uncaught TypeError: Cannot read property 'apply' of undefined
因为我无法从提供的示例中弄清楚整个代码在做什么，所以我有问题要自己找到解决方案。如果有人能给我一些提示就太好了。
现在，我只想实现每个事件tap、touch、release的console.log()语句
我的代码
这是我的代码bl.ocks.org版本的链接。
这是我的代码：
<!DOCTYPE html>
<meta charset="utf-8">
<head>
<script src="http://d3js.org/d3.v5.js"></script>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
</head>
<body>
<style>
#svg-div {
position: absolute;
width: 2400px;
height: 1200px;
}
.ref-circle{
fill: none;
stroke: grey;
}
.drag-circle{
fill: black;
stroke: none;
}
.target-circle{
fill: red;
stroke: none;
}
.active {
stroke: #000;
stroke-width: 2px;
}
</style>
<div id="svg-div"></div>
<script>
/////////////////////////////////////////////
//THIS IS JUST SOME DRAWING SETTINGS UNIMPORTANT FOR THIS QUESTION,
//BUT IF YOU WANT TO RUN IT YOU CAN SEE SOME VISUAL FEEDBACK
/////////////////////////////////////////////
//-----------------------------------------------------------------------
//variables of svg
height = 1200,
width = 2400,
radiusDrag = 30,
radiusTargetList = [40,70,100],
refDistance = 800,
center = {x:1200, y:600},
angle = 17.143;
//create parameters of circles
var refCircle = [{x: 1200, y: 600, r: 400}];
//Choose current radius of target and delete its entry from the targetSize list
var radiusTarget = radiusTargetList[Math.floor(Math.random() * radiusTargetList.length)];
radiusTargetList.splice(radiusTargetList.indexOf(radiusTarget),1);
//function to create the circle coordinates
function create_circles() {
var initDragCircle = [];
var initTargetCircle = [];
var angleSum = 0;
for (var i = 0; i < 21; i++){
initDragCircle.push([{x: center.x + (refDistance/2) * Math.cos( (angleSum+angle) * Math.PI / 180 ), y: center.y + (refDistance/2) * Math.sin( (angleSum+angle) * Math.PI / 180 )}]);
initTargetCircle.push([{x: center.x + ((refDistance/2) + radiusTarget) * Math.cos( (angleSum+180+(angle/2)) * Math.PI / 180 ), y: center.y + ((refDistance/2) + radiusTarget) * Math.sin( (angleSum+180+(angle/2)) * Math.PI / 180 )}]);
angleSum += angle;
};
var counter = 0;
var stepper = -11;
var dCircle = [];
var tCircle = [];
for (var i = 0; i < 21; i++){
dCircle.push(initDragCircle[counter]);
tCircle.push(initTargetCircle[counter]);
if (stepper == -11) {
stepper = 10;
} else {
stepper = -11;
};
if (counter == 10) {
counter = 20;
stepper = 10;
} else {
counter += stepper;
};
};
dragCircle = dCircle;
targetCircle = tCircle;
}
//-----------------------------------------------------------------------
//function to draw the experiment
function start_experiment() {
//create the circles
create_circles();
//create svg
var svg = d3.select("#svg-div").append("svg")
.attr("width", width)
.attr("height", height);
//add circles to svg
svg.selectAll(".ref-circle")
.data(refCircle)
.enter()
.append('circle')
.attr("class", "ref-circle")
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", function(d) { return d.r; });
svg.selectAll(".drag-circle")
.data(dragCircle[0])
.enter()
.append('circle')
.attr("class", "drag-circle")
.attr("cx", function(d) {return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", radiusDrag)
.call(mtouch);
svg.selectAll(".target-circle")
.data(targetCircle[0])
.enter()
.append('circle')
.attr("class", "target-circle")
.attr("cx", function(d) { return d.x; })
.attr("cy", function(d) { return d.y; })
.attr("r", radiusTarget)
};
/////////////////////////////////////
//----HOLD + TAP functionality
/////////////////////////////////////
//For now I just want to have some feedback for each event
function tapped(d) {
console.log('tap');
}
function touched() {
console.log('touched');
}
function released() {
console.log('released');
}
////////////////////////////////////
// THIS IS THE PART FROM THE MENTIONED EXAMPLE
/// Based on the d3.behavior.drag and d3.behavior.zoom.
mtouch_events = function() {
var event = d3_eventDispatch(mtouch, "tap", "dbltap", "hold", "drag", "mdrag", 'touch', 'release')
,fingers = [] // array of augmented touches = fingers
,id2finger = {} // maps ids to fingers
,last_taps = [] // [{timeStamp: xxx, pos: [x,y]}, ...], used to detect dbltaps
,mouse_id = 'mouse'
,tap_max_time = 250
,tap_max_dist2 = 10*10
,hold_time = 500
,hold_max_dist2 = 10*10
,dbltap_max_delay = 400
,dbltap_max_dist = 20;
function mtouch(select) {
select.on("touchstart.mtouch", touchstarted)
.on("mousedown.mtouch", mousedown)
.on("touchmove.mtouch", touchmoved)
.on("touchend.mtouch", touchended)
.on("touchcancel.mtouch", touchended);
}
mtouch.call = function(f) {
f.apply(mtouch, arguments); return this;
}
/// On mousedown, start listening for mousemove and mouseup events on the
/// whole window. Also call the touchstarted function. If it was not the left
/// mousebutton that was pressed, do nothing.
function mousedown() {
if (!detectLeftButton(d3.event)) return;
var w = d3.select(window);
var thiz = this, argumentz = arguments;
w.on("mousemove.mtouch", function() { touchmoved.apply(thiz, argumentz) });
w.on("mouseup.mtouch", function() {
w.on("mousemove.mtouch", null);
w.on("mouseup.mtouch", null);
touchended.apply(thiz, argumentz);
});
touchstarted.apply(this, arguments);
}
function touchstarted() {
d3.event.preventDefault();
var target = this
,event_ = event.of(target, arguments)
,touches = get_changed_touches();
for (var i=0,N=touches.length; i<N; i++) {
var finger = new Finger(touches[i].identifier, event_, target);
fingers.push(finger);
id2finger[touches[i].identifier] = finger;
event_({type: 'touch', finger: finger, fingers: fingers});
}
}
function touchmoved() {
d3.event.preventDefault();
var target = this
,event_ = event.of(target, arguments)
,touches = get_changed_touches();
for (var i=0,N=fingers.length; i<N; i++) fingers[i].changed = false;
var df = [];
for (var i=0,N=touches.length; i<N; i++) {
var finger = id2finger[touches[i].identifier];
if (!finger) continue;
finger.move(event_);
df.push(finger);
}
event_({type: 'mdrag', dragged_fingers: df, fingers: fingers});
}
function touchended() {
d3.event.preventDefault();
var target = this
,event_ = event.of(target, arguments)
,touches = get_changed_touches();
for (var i=0,N=touches.length; i<N; i++) {
var finger = id2finger[touches[i].identifier];
if (!finger) continue;
finger.end(event_);
delete id2finger[touches[i].identifier];
fingers = d3.values(id2finger);
event_({type: 'release', finger: finger, fingers: fingers});
}
}
function Finger(id, event, target) {
this.id = id;
this.target = target;
this.event = event;
this.parent = target.parentNode;
this.timeStamp0 = d3.event.timeStamp;
this.timeStamp = this.timeStamp0;
this.hold_timer = setTimeout(this.held.bind(this), hold_time);
this.pos = get_position(this.parent, this.id);
this.pos0 = [this.pos[0], this.pos[1]];
this.dist_x = 0; // dx between current and starting point
this.dist_y = 0;
this.dx = 0; // dx in the last dragging step
this.dy = 0;
this.dt = 0; // dt in the last dragging step
this.changed = true; // used by gesture to check whether it needs to update
this.gesture = null; // is set when finger gets bound to a gesture
}
Finger.prototype.cancel_hold = function() {
if (this.hold_timer) clearTimeout(this.hold_timer);
this.hold_timer = null;
}
Finger.prototype.held = function() {
this.event({type: 'hold', id: this.id, fingers: fingers});
this.hold_timer = null;
}
Finger.prototype.move = function(event) {
this.changed = true;
this.event = event;
var p = get_position(this.parent, this.id)
,t = d3.event.timeStamp;
this.dx = p[0] - this.pos[0];
this.dy = p[1] - this.pos[1];
this.dist_x = p[0] - this.pos0[0];
this.dist_y = p[1] - this.pos0[1];
this.pos = p;
this.dt = t-this.timeStamp;
this.timeStamp = t;
if (this.dist_x*this.dist_x+this.dist_y*this.dist_y > hold_max_dist2) {
this.cancel_hold();
}
if (this.gesture) return;
event({type: 'drag', finger: this, x: this.pos[0], y: this.pos[1]
,dx: this.dx, dy: this.dy, fingers: fingers});
}
Finger.prototype.end = function(event) {
var dt = d3.event.timeStamp - this.timeStamp0;
if (dt <= tap_max_time && (this.dist_x*this.dist_x+this.dist_y*this.dist_y) <= tap_max_dist2) {
if (match_tap(d3.event.timeStamp, this.pos[0], this.pos[1])) {
event({type: 'dbltap', finger: this, fingers: fingers});
} else {
event({type: 'tap', finger: this, fingers: fingers});
}
}
this.cancel_hold();
}
function get_changed_touches() {
return d3.event.changedTouches || [{identifier: mouse_id}];
}
function detectLeftButton(event) {
if ('buttons' in event) return event.buttons === 1;
else if ('which' in event) return event.which === 1;
else return event.button === 1;
}
/// Returns true if any tap in the last_taps list is spatially and temporally
/// close enough to the passed time and postion to count as a dbltap. If not,
/// the passed data is added as new tap. All taps that are too old are removed.
function match_tap(timeStamp, x, y) {
var idx = -1, pos = [x,y];
last_taps = last_taps.filter(function (tap, i) {
if (timeStamp - tap.timeStamp <= dbltap_max_delay
&& get_distance(tap.pos, pos) <= dbltap_max_dist) idx = i;
return tap.timeStamp-timeStamp <= dbltap_max_delay && idx !== i;
});
if (idx === -1) last_taps.push({timeStamp: timeStamp, pos: pos});
return idx !== -1;
}
function get_position(container, id) {
if (id === mouse_id) return d3.mouse(container);
else return d3.touches(container).filter(function(p) { return p.identifier === id; })[0];
}
function get_distance(p1, p2) {
return Math.sqrt((p1[0]-p2[0])*(p1[0]-p2[0]) + (p1[1]-p2[1])*(p1[1]-p2[1]));
}
return d3.rebind(mtouch, event, "on");
};
///////////////////////////
// HERE IS THE MANUALLY ADDED REBIND FUNCTION
///////////////////////////
// Copies a variable number of methods from source to target.
d3.rebind = function(target, source) {
var i = 1, n = arguments.length, method;
while (++i < n) target[method = arguments[i]] = d3_rebind(target, source, source[method]);
return target;
};
// Method is assumed to be a standard D3 getter-setter:
// If passed with no arguments, gets the value.
// If passed with arguments, sets the value and returns the target.
function d3_rebind(target, source, method) {
return function() {
var value = method.apply(source, arguments);
return value === source ? target : value;
};
}
/// Replication of the internal d3_eventDispatch method.
function d3_eventDispatch(target) {
var dispatch = d3.dispatch.apply(this, Array.apply(null, arguments).slice(1));
dispatch.of = function(thiz, argumentz) {
return function(e1) {
try {
var e0 =
e1.sourceEvent = d3.event;
e1.target = target;
d3.event = e1;
dispatch[e1.type].apply(thiz, argumentz);
} finally {
d3.event = e0;
}
};
};
return dispatch;
}
var mtouch = mtouch_events()
.on("tap", tapped)
.on("touch", touched)
.on("release", released);
start_experiment();
</script>
</body>
如果selection.call(func)，d3选择是函数的第一个参数。
function mtouch(select) {
select.on("touchstart.mtouch", touchstarted)
.on("mousedown.mtouch", mousedown)
.on("touchmove.mtouch", touchmoved)
.on("touchend.mtouch", touchended)
.on("touchcancel.mtouch", touchended);
}