svg-圆
介绍一款强大的svg操作库，能够通过简单的代码，实现svg绘制与操纵，实现拖拽等功能
本文将通过一个简单的示例，介绍如何在SVG中绘制一条可拖拽的圆
代码仓库
代码仓库：github
代码仓库：gitee
实战项目：MyPrint
操作简单，组件丰富的一站式打印解决方案打印设计器
体验地址：前往
代码仓库：github
代码仓库：gitee
demo 效果
实战项目效果
正文
基础HTML结构
首先，我们需要在HTML中设置基本的SVG元素，以便绘制图形。
html
<html lang="en">
<head>
<meta charset="UTF-8">
<title>MyPrint|打印设计|SVG|圆</title>
<script src="https://cdn.jsdelivr.net/npm/d3@7"></script>
<script src="./d3-utils.js"></script>
<style>
body {
width: 100vw;
height: 100vh;
margin: 0;
display: flex;
justify-content: center;
align-items: center;
}
.chart {
width: 100%;
height: 100%;
overflow: visible;
}
.chart_wrapper {
width: 700px;
height: 700px;
box-shadow: 2px 2px 10px rgba(10, 10, 10, 0.1);
border-radius: 10px;
}
</style>
</head>
<body>
<div class="chart_wrapper">
<svg id="chartRef" class="chart">
<path class="u-path" :d="path"/>
<line class="u-line"/>
<line class="u-line"/>
</svg>
</div>
</body>
</html>初始化图形
我们定义了一个freshSvg函数来初始化SVG图形。这个函数定义了一些基本的变量，如圆心坐标、半径、起始角度和结束角度等。
js
function freshSvg() {
const x0 = 310,
y0 = 130,
x = 320,
y = 320,
radius = 100,
startAngle = 0,
endAngle = 2 * Math.PI - 1,
moveto00 = false,
anticlockwise = true;
// ...
}绘制圆弧
接下来，我们定义了一个draw函数，用于绘制圆弧。我们使用D3.js的path.arc方法，根据圆心、半径、起始角度和结束角度绘制圆弧。
const path = d3.path();
path.arc(x, y, radius, startAngle, endAngle, anticlockwise);
实现拖拽功能
我们实现了一个draggable函数，用于为圆弧图形添加拖拽功能。这个函数允许用户通过拖动控制点来动态调整圆弧的大小和位置。
js
function draggable(chart, points, labels, lines, draw, options) {
// 实现拖拽逻辑
update(chart, points, labels, lines, draw, options);
d3.select(chart)
.call(
d3.drag()
.on("start", event => { /* 处理拖拽开始 */ })
.on("drag", event => { /* 处理拖拽进行中 */ })
.on("end", () => { /* 处理拖拽结束 */ })
.on("start.render drag.render end.render", () =>
update(chart, points, labels, lines, draw, options)
)
);
}更新图形
最后，我们定义了一个update函数，用于在拖拽过程中更新图形的显示。这确保了当用户拖动控制点时，SVG图形会实时更新并反映变化。
js
function update(chart, points, labels, lines, draw, options) {
// 更新图形显示
}完整实现
html
<html lang="en">
<head>
<meta charset="UTF-8">
<title>MyPrint|打印设计|SVG|圆</title>
<script src="https://cdn.jsdelivr.net/npm/d3@7"></script>
<script src="./d3-utils.js"></script>
<style>
body {
width: 100vw;
height: 100vh;
margin: 0;
display: flex;
justify-content: center;
align-items: center;
}
.chart {
width: 100%;
height: 100%;
overflow: visible;
}
.chart_wrapper {
width: 700px;
height: 700px;
box-shadow: 2px 2px 10px rgba(10, 10, 10, 0.1);
border-radius: 10px;
}
</style>
</head>
<body>
<div class="chart_wrapper">
<svg id="chartRef" class="chart">
<path class="u-path" :d="path"/>
<line class="u-line"/>
<line class="u-line"/>
</svg>
</div>
</body>
<script>
const chartElement = document.getElementById('chartRef')
const path = d3.path();
function freshSvg() {
const x0 = 310,
y0 = 130,
x = 320,
y = 320,
radius = 100,
startAngle = 0,
endAngle = 2 * Math.PI - 1,
moveto00 = false,
anticlockwise = true;
const points = [
[x + radius * Math.cos(startAngle), y + radius * Math.sin(startAngle)],
[+radius * Math.cos(endAngle), y + radius * Math.sin(endAngle)]
],
labels = ["开始角度", ""],
lines = [],
draw = () => {
const startAngle = Math.atan2(points[0][1] - x, points[0][0] - y),
endAngle = 2 * Math.PI,
radius = Math.sqrt((points[0][1] - x) ** 2 + (points[0][0] - y) ** 2);
points[0][0] = x + radius * Math.cos(startAngle);
points[0][1] = x + radius * Math.sin(startAngle);
points[1][0] = x + radius * Math.cos(endAngle);
points[1][1] = x + radius * Math.sin(endAngle);
const path = d3.path();
if (moveto00) path.moveTo(...points[2]);
path.arc(x, y, radius, startAngle, endAngle, anticlockwise);
return path;
};
if (moveto00) {
points.push([x0, y0]);
labels.push("⟨x0, y0⟩");
}
draggable(chartElement, points, labels, lines, draw);
}
freshSvg()
function update(chart, points, labels, lines, draw, options) {
d3.select(chart)
.select(".u-path")
.style("stroke", "orange")
.style("fill", options ? (options.fill ? options.fill : "none") : "none")
.attr("d", draw());
d3.select(chart)
.selectAll(".u-point")
.style("stroke", "orange")
.style("fill", "orange")
.data(points)
.join(enter =>
enter
.append("g")
.classed("u-point", true)
.call(g => {
g.append("circle").attr("r", 3);
g.append("text")
.text((d, i) => labels[i])
.attr("dy", d => (d[1] > 100 ? 15 : -5));
})
)
.attr("transform", d => `translate(${d})`);
d3.select(chart)
.selectAll(".u-line")
.style("stroke", "#aaa")
.style("stroke-dasharray", "2 2")
.data(lines)
.join("line")
.attr("x1", d => d[0][0])
.attr("y1", d => d[0][1])
.attr("x2", d => d[1][0])
.attr("y2", d => d[1][1])
.classed("u-line", true);
}
function draggable(chart, points, labels, lines, draw, options) {
update(chart, points, labels, lines, draw, options);
const dist = (p, m) => {
return Math.sqrt((p[0] - m[0]) ** 2 + (p[1] - m[1]) ** 2);
};
var subject, dx, dy;
function dragSubject(event) {
const p = d3.pointer(event.sourceEvent, chart);
subject = d3.least(points, (a, b) => dist(p, a) - dist(p, b));
if (dist(p, subject) > 48) subject = null;
if (subject)
d3.select(chart)
.style("cursor", "hand")
.style("cursor", "grab");
else d3.select(chart).style("cursor", null);
return subject;
}
d3.select(chart)
.on("mousemove", event => dragSubject({sourceEvent: event}))
.call(
d3.drag()
.subject(dragSubject)
.on("start", event => {
if (subject) {
d3.select(chart).style("cursor", "grabbing");
dx = subject[0] - event.x;
dy = subject[1] - event.y;
}
})
.on("drag", event => {
if (subject) {
subject[0] = event.x + dx;
subject[1] = event.y + dy;
}
})
.on("end", () => {
d3.select(chart).style("cursor", "grab");
})
.on("start.render drag.render end.render", () =>
update(chart, points, labels, lines, draw, options)
)
);
}
</script>
</html>