我想了解圈子之间的连接线是如何实现的。我试图通过它，但它只是我的脑袋。关于我在博客上找到的示例的文档不多。我想像我这样的其他新用户将面临同样的挑战。
如果任何人可以解释下面的示例代码，那就太棒了！
这是我为我的要求缩小的代码：
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title>d3.js selection frame example</title>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.js"></script>
<link rel="stylesheet" href="<%=request.getContextPath()%>/app.css" />
<script>
window.onload = function ()
{
var radius = 40;
window.states = [
{x: 43, y: 67, label: "first", transitions: []},
{x: 340, y: 150, label: "second", transitions: []},
{x: 200, y: 250, label: "third", transitions: []}
];
window.svg = d3.select('body')
.append("svg")
.attr("width", "960px")
.attr("height", "500px");
// define arrow markers for graph links
svg.append('svg:defs').append('svg:marker')
.attr('id', 'end-arrow')
.attr('viewBox', '0 -5 10 10')
.attr('refX', 4)
.attr('markerWidth', 8)
.attr('markerHeight', 8)
.attr('orient', 'auto')
.append('svg:path')
.attr('d', 'M0,-5L10,0L0,5')
.attr('class', 'end-arrow')
;
// line displayed when dragging new nodes
var drag_line = svg.append('svg:path')
.attr({
'class': 'dragline hidden',
'd': 'M0,0L0,0'
})
;
**// NEED EXPLANATION FROM HERE**
var gTransitions = svg.append('g').selectAll("path.transition");
var gStates = svg.append("g").selectAll("g.state");
var transitions = function () {
return states.reduce(function (initial, state) {
return initial.concat(
state.transitions.map(function (transition) {
return {source: state, transition: transition};
})
);
}, []);
};
var transformTransitionEndpoints = function (d, i) {
var endPoints = d.endPoints();
var point = [
d.type == 'start' ? endPoints[0].x : endPoints[1].x,
d.type == 'start' ? endPoints[0].y : endPoints[1].y
];
return "translate(" + point + ")";
}
var transformTransitionPoints = function (d, i) {
return "translate(" + [d.x, d.y] + ")";
}
var computeTransitionPath = (function () {
var line = d3.svg.line()
.x(function (d, i) {
return d.x;
})
.y(function (d, i) {
return d.y;
})
.interpolate("cardinal");
return function (d) {
var source = d.source,
target = d.transition.points.length && d.transition.points[0] || d.transition.target,
deltaX = target.x - source.x,
deltaY = target.y - source.y,
dist = Math.sqrt(deltaX * deltaX + deltaY * deltaY),
normX = deltaX / dist,
normY = deltaY / dist,
sourcePadding = radius + 4, //d.left ? 17 : 12,
sourceX = source.x + (sourcePadding * normX),
sourceY = source.y + (sourcePadding * normY);
source = d.transition.points.length && d.transition.points[ d.transition.points.length - 1] || d.source;
target = d.transition.target;
deltaX = target.x - source.x;
deltaY = target.y - source.y;
dist = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
normX = deltaX / dist;
normY = deltaY / dist;
targetPadding = radius + 8;//d.right ? 17 : 12,
targetX = target.x - (targetPadding * normX);
targetY = target.y - (targetPadding * normY);
var points =
[{x: sourceX, y: sourceY}].concat(
d.transition.points,
[{x: targetX, y: targetY}]
)
;
var l = line(points);
return l;
};
})();
var dragPoint = d3.behavior.drag()
.on("drag", function (d, i) {
console.log("transitionmidpoint drag");
var gTransitionPoint = d3.select(this);
gTransitionPoint.attr("transform", function (d, i) {
d.x += d3.event.dx;
d.y += d3.event.dy;
return "translate(" + [d.x, d.y] + ")"
});
// refresh transition path
gTransitions.selectAll("path").attr('d', computeTransitionPath);
// refresh transition endpoints
gTransitions.selectAll("circle.endpoint").attr({
transform: transformTransitionEndpoints
});
// refresh transition points
gTransitions.selectAll("circle.point").attr({
transform: transformTransitionPoints
});
d3.event.sourceEvent.stopPropagation();
});
var renderTransitionMidPoints = function (gTransition) {
gTransition.each(function (transition) {
var transitionPoints = d3.select(this).selectAll('circle.point').data(transition.transition.points, function (d) {
return transition.transition.points.indexOf(d);
});
transitionPoints.enter().append("circle")
.attr({
'class': 'point',
r: 4,
transform: transformTransitionPoints
})
.call(dragPoint);
transitionPoints.exit().remove();
});
};
var renderTransitionPoints = function (gTransition) {
gTransition.each(function (d) {
var endPoints = function () {
var source = d.source,
target = d.transition.points.length && d.transition.points[0] || d.transition.target,
deltaX = target.x - source.x,
deltaY = target.y - source.y,
dist = Math.sqrt(deltaX * deltaX + deltaY * deltaY),
normX = deltaX / dist,
normY = deltaY / dist,
sourceX = source.x + (radius * normX),
sourceY = source.y + (radius * normY);
source = d.transition.points.length && d.transition.points[ d.transition.points.length - 1] || d.source;
target = d.transition.target;
deltaX = target.x - source.x;
deltaY = target.y - source.y;
dist = Math.sqrt(deltaX * deltaX + deltaY * deltaY);
normX = deltaX / dist;
normY = deltaY / dist;
targetPadding = radius + 8;//d.right ? 17 : 12,
targetX = target.x - (radius * normX);
targetY = target.y - (radius * normY);
return [{x: sourceX, y: sourceY}, {x: targetX, y: targetY}];
};
var transitionEndpoints = d3.select(this).selectAll('circle.endpoint').data([
{endPoints: endPoints, type: 'start'},
{endPoints: endPoints, type: 'end'}
]);
transitionEndpoints.enter().append("circle")
.attr({
'class': function (d) {
return 'endpoint ' + d.type;
},
r: 4,
transform: transformTransitionEndpoints
})
;
transitionEndpoints.exit().remove();
});
};
var renderTransitions = function () {
gTransition = gTransitions.enter().append('g')
.attr({
'class': 'transition'
})
gTransition.append('path')
.attr({
d: computeTransitionPath,
class: 'background'
})
.on({
dblclick: function (d, i) {
gTransition = d3.select(d3.event.target.parentElement);
if (d3.event.ctrlKey) {
var p = d3.mouse(this);
gTransition.classed('selected', true);
d.transition.points.push({x: p[0], y: p[1]});
renderTransitionMidPoints(gTransition, d);
gTransition.selectAll('path').attr({
d: computeTransitionPath
});
} else {
var gTransition = d3.select(d3.event.target.parentElement),
transition = gTransition.datum(),
index = transition.source.transitions.indexOf(transition.transition);
transition.source.transitions.splice(index, 1)
gTransition.remove();
d3.event.stopPropagation();
}
}
});
gTransition.append('path')
.attr({
d: computeTransitionPath,
class: 'foreground'
});
renderTransitionPoints(gTransition);
renderTransitionMidPoints(gTransition);
gTransitions.exit().remove();
};
var renderStates = function () {
var gState = gStates.enter()
.append("g")
.attr({
"transform": function (d) {
return "translate(" + [d.x, d.y] + ")";
},
'class': 'state'
})
.call(drag);
gState.append("circle")
.attr({
r: radius + 4,
class: 'outer'
})
.on({
mousedown: function (d) {
console.log("state circle outer mousedown");
startState = d, endState = undefined;
// reposition drag line
drag_line
.style('marker-end', 'url(#end-arrow)')
.classed('hidden', false)
.attr('d', 'M' + d.x + ',' + d.y + 'L' + d.x + ',' + d.y);
// force element to be an top
this.parentNode.parentNode.appendChild(this.parentNode);
//d3.event.stopPropagation();
},
mouseover: function () {
svg.select("rect.selection").empty() && d3.select(this).classed("hover", true);
},
mouseout: function () {
svg.select("rect.selection").empty() && d3.select(this).classed("hover", false);
//$( this).popover( "hide");
}
});
gState.append("circle")
.attr({
r: radius,
class: 'inner'
})
.on({
mouseover: function () {
svg.select("rect.selection").empty() && d3.select(this).classed("hover", true);
},
mouseout: function () {
svg.select("rect.selection").empty() && d3.select(this).classed("hover", false);
},
});
};
var startState, endState;
var drag = d3.behavior.drag()
.on("drag", function (d, i) {
console.log("drag");
if (startState) {
return;
}
var selection = d3.selectAll('.selected');
// if dragged state is not in current selection
// mark it selected and deselect all others
if (selection[0].indexOf(this) == -1) {
selection.classed("selected", false);
selection = d3.select(this);
selection.classed("selected", true);
}
// move states
selection.attr("transform", function (d, i) {
d.x += d3.event.dx;
d.y += d3.event.dy;
return "translate(" + [d.x, d.y] + ")"
});
// move transistion points of each transition
// where transition target is also in selection
var selectedStates = d3.selectAll('g.state.selected').data();
var affectedTransitions = selectedStates.reduce(function (array, state) {
return array.concat(state.transitions);
}, [])
.filter(function (transition) {
return selectedStates.indexOf(transition.target) != -1;
});
affectedTransitions.forEach(function (transition) {
for (var i = transition.points.length - 1; i >= 0; i--) {
var point = transition.points[i];
point.x += d3.event.dx;
point.y += d3.event.dy;
}
});
// reappend dragged element as last
// so that its stays on top
selection.each(function () {
this.parentNode.appendChild(this);
});
// refresh transition path
gTransitions.selectAll("path").attr('d', computeTransitionPath);
// refresh transition endpoints
gTransitions.selectAll("circle.endpoint").attr({
transform: transformTransitionEndpoints
});
// refresh transition points
gTransitions.selectAll("circle.point").attr({
transform: transformTransitionPoints
});
d3.event.sourceEvent.stopPropagation();
})
.on("dragend", function (d) {
console.log("dragend");
// needed by FF
drag_line.classed('hidden', true)
.style('marker-end', '');
if (startState && endState) {
startState.transitions.push({label: "transition label 1", points: [], target: endState});
update();
}
startState = undefined;
d3.event.sourceEvent.stopPropagation();
});
svg.on({
mousedown: function () {
console.log("mousedown", d3.event.target);
if (d3.event.target.tagName == 'svg') {
if (!d3.event.ctrlKey) {
d3.selectAll('g.selected').classed("selected", false);
}
var p = d3.mouse(this);
}
},
mousemove: function () {
var p = d3.mouse(this);
// update drag line
drag_line.attr('d', 'M' + startState.x + ',' + startState.y + 'L' + p[0] + ',' + p[1]);
var state = d3.select('g.state .inner.hover');
endState = (!state.empty() && state.data()[0]) || undefined;
},
mouseup: function () {
console.log("mouseup");
// remove temporary selection marker class
d3.selectAll('g.state.selection').classed("selection", false);
},
mouseout: function ()
{
if (!d3.event.relatedTarget || d3.event.relatedTarget.tagName == 'HTML') {
// remove temporary selection marker class
d3.selectAll('g.state.selection').classed("selection", false);
}
}
});
update();
function update() {
gStates = gStates.data(states, function (d) {
return states.indexOf(d);
});
renderStates();
var _transitions = transitions();
gTransitions = gTransitions.data(_transitions, function (d) {
return _transitions.indexOf(d);
});
renderTransitions();
}
;
};
</script>
</head>
<body>
</body>
</html>
Css文件：
rect.selection {
stroke : gray;
stroke-dasharray: 2px;
stroke-opacity : 0.5;
fill : transparent;
}
g.state circle {
stroke : gray;
}
g.state circle.inner {
fill : white;
transition : fill 0.5s;
cursor : move;
}
g.state circle.inner.hover,
g.state circle.outer.hover {
fill : aliceblue;
}
g.state circle.outer.hover {
stroke-width : 1px;
}
g.state circle.outer {
stroke-width : 0px;
stroke-dasharray: 2px;
stroke-color : gray;
fill : transparent;
transition : all 0.5s;
cursor : pointer;
}
g.state.selected circle.outer {
stroke-width : 1px;
}
g.state text {
font : 12px sans-serif;
font-weight : bold;
pointer-events : none;
}
g.transition path,
path.dragline {
fill : none;
stroke : gray;
stroke-width: 1px;
}
g.transition path.foreground {
marker-end : url(#end-arrow);
}
g.transition.hover path.background {
stroke-dasharray: none;
stroke : aliceblue;
stroke-opacity : 1.0;
transition : all 0.5s;
}
g.transition path.background {
stroke-dasharray: none;
stroke-width: 8px;
stroke : transparent;
}
g.transition.selected path.foreground {
stroke-dasharray: 2px;
stroke-color : gray;
}
g.transition path {
cursor : default;
}
.end-arrow {
fill : gray;
stroke-width : 1px;
}
g.transition circle.endpoint {
display : none;
fill : none;
cursor : pointer;
stroke : gray;
stroke-dasharray: 2px;
}
g.transition circle.point {
display : none;
fill : aliceblue;
cursor : move;
stroke : gray;
}
g.transition.selected circle.endpoint,
g.transition.selected circle.point {
display : inline;
transition : all 0.5s;
}
g.transition:not( .selected).hover *,
path.dragline {
display : inline;
}
g.transition:not( .selected).hover {
transition : all 0.5s;
}
path.dragline {
pointer-events: none;
stroke-opacity : 0.5;
stroke-dasharray: 2px;
}
path.dragline.hidden {
stroke-width: 0;
}
/* disable text selection */
svg *::selection {
background : transparent;
}
svg *::-moz-selection {
background:transparent;
}
svg *::-webkit-selection {
background:transparent;
}
我理解d3的基础知识，例如附加新的圆圈和拖动行为，但主要是用于绘制和连接线圈的部分的过渡部分阻碍了我。
答案 0 :(得分：0)
在那里有很多实际上，看着它实际上并没有像你期望的那样使用典型的css transitions。如果需要，我将总结有趣的部分并进行扩展。有趣的部分如下：
var dragPoint = d3.behavior.drag()
.on("drag", function( d, i) {
console.log( "transitionmidpoint drag");
var gTransitionPoint = d3.select( this);
gTransitionPoint.attr( "transform", function( d, i) {
d.x += d3.event.dx;
d.y += d3.event.dy;
return "translate(" + [ d.x,d.y ] + ")"
});
// refresh transition path
gTransitions.selectAll( "path").attr( 'd', computeTransitionPath);
// refresh transition endpoints
gTransitions.selectAll( "circle.endpoint").attr({
transform : transformTransitionEndpoints
});
// refresh transition points
gTransitions.selectAll( "circle.point").attr({
transform : transformTransitionPoints
});
d3.event.sourceEvent.stopPropagation();
});
这是所有艰苦工作的地方。这段代码基本上说，每当drag事件发生时（例如你移动一个圆圈），就执行这个函数中的代码。
你可以看到这个分为几个部分：
d.x和d.y点击的点，这是从上一个事件中拖出的金额。这是使用translate转换完成的。d参数来完成的，这是指定SVG路径形状的方式。计算路径的代码在comuteTransitionPath函数内。