在d3中并不没有什么方法能直接获取到两条line、path或两个其他图形的交点，所以我们借助2D.js帮助我们计算交点。
2D.js
- From kevlindev
- 以两条线的为例
- 获取
svg中两条line并初始化
- 通过
Intersection.intersectShapes来计算交点
绘制交点
- 以直线和曲线为例，先绘制图形。
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<div id="test-svg">
</div>
</body>
<script src="https://d3js.org/d3.v5.js"></script>
<script type="text/javascript" src="js/2D.js"></script>
<script>
window.onload = function() {
// 数据
var data = [{
date: new Date(2019, 3, 24),
value: 23.24
}, {
date: new Date(2019, 3, 25),
value: 72.15
}, {
date: new Date(2019, 3, 26),
value: 38.84
}, {
date: new Date(2019, 3, 27),
value: 58.62
}, {
date: new Date(2019, 3, 30),
value: 10.80
}, {
date: new Date(2019, 4, 1),
value: 85.47
}];
var data2 = [{
date: new Date(2019, 3, 24),
value: 18.24
}, {
date: new Date(2019, 4, 1),
value: 90.47
}];
var width = 800,
height = 400,
padding = {
top: 40,
right: 40,
bottom: 40,
left: 40
};
var colors = d3.schemeSet2;
var svg = d3.select("#test-svg")
.append('svg')
.attr('width', width + 'px')
.attr('height', height + 'px');
// x轴:时间轴
var xScale = d3.scaleTime()
.domain(d3.extent(data, function(d) {
return d.date;
}))
.range([padding.left, width - padding.right]);
var xAxis = d3.axisBottom()
.scale(xScale)
.tickSize(10);
svg.append('g')
.call(xAxis)
.attr("transform", "translate(0," + (height - padding.bottom) + ")")
.selectAll("text")
.attr("font-size", "10px")
.attr("dx", "50px");
var ymax = d3.max(data, function(d) {
return d.value;
});
// y轴
var yScale = d3.scaleLinear()
.domain([0, ymax])
.range([height - padding.bottom, padding.top]);
var yAxis = d3.axisLeft()
.scale(yScale)
.ticks(10);
svg.append('g')
.call(yAxis)
.attr("transform", "translate(" + padding.left + ",0)");
// 曲线
var curveLine = d3.line()
.x(function(d) {
return xScale(d.date);
})
.y(function(d) {
return yScale(d.value);
})
.curve(d3.curveCatmullRom.alpha(0.5));
// 直线
var line = d3.line()
.x(function(d) {
return xScale(d.date);
})
.y(function(d) {
return yScale(d.value);
});
var container = svg.append("g");
container.append("path")
.datum(data)
.attr("d", curveLine)
.attr("class", "cmn")
.attr('stroke', '#FFA354')
.attr("fill", "none");
container.append("path")
.datum(data2)
.attr("d", line)
.attr("class", "csmn")
.attr('stroke', '#FFA354')
.attr("fill", "none");
}
</script>
</html>
使用2D.js获取绘制交点
Intersection.intersectShapes(shapes[0], shapes[1])
var shapes = [];
var children = container.selectAll("path");
// 获取path
for(var i = 0; i < children._groups[0].length; i++) {
var child = children._groups[0][i];
var shape = new Path(child);
shapes.push(shape);
}
// 计算交点
var inter = Intersection.intersectShapes(shapes[0], shapes[1]);
// 绘制交点
svg.selectAll("circle")
.data(inter.points)
.join("circle")
.attr("r", 3)
.attr("cx", function(d) {
return d.x;
})
.attr("cy", function(d) {
return d.y;
})
.attr("fill", "steelblue");
同理也可以使用两个图形
- 两个
rect
svg.append("rect")
.attr("x", 100)
.attr("y", 100)
.attr("width", 100)
.attr("height", 200)
.attr("fill", "none")
.attr('stroke', '#FFA354')
.attr('stroke-width', 1.5);
svg.append("rect")
.attr("x", 0)
.attr("y", 150)
.attr("width", 300)
.attr("height", 100)
.attr("fill", "none")
.attr('stroke', '#FFA354')
.attr('stroke-width', 1.5);
var shapes = [];
var children = svg.selectAll("rect");
// 获取path
for(var i = 0; i < children._groups[0].length; i++) {
var child = children._groups[0][i];
var shape = new Rectangle(child);
shapes.push(shape);
}
// 计算交点
var inter = Intersection.intersectShapes(shapes[0], shapes[1]);
// 绘制交点
svg.selectAll("circle")
.data(inter.points)
.join("circle")
.attr("r", 3)
.attr("cx", function(d) {
return d.x;
})
.attr("cy", function(d) {
return d.y;
})
.attr("fill", "steelblue");
- 注：旋转和缩放后可能会存在问题，计算出的交点还是没有操作之前的。
.attr('transform','rotate(30)')
.attr('transform','scale(1.2,1.2)')
