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📜  D3.js-Shapes API(1)

📅  最后修改于: 2023-12-03 15:00:19.475000             🧑  作者: Mango

D3.js - Shapes API

D3.js is a powerful JavaScript library for manipulating HTML documents based on data. The Shapes API is a part of D3.js library that allows us to create and modify shapes using SVG (Scalable Vector Graphics) elements. The Shapes API is very useful when working with data visualizations because you can create various shapes to represent data points.

Getting Started

To use the D3.js Shapes API, you should first add the D3.js library to your HTML document. You can download the library from the official website or use a CDN (Content Delivery Network) such as cdnjs.

<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/d3/7.0.0/d3.min.js"></script>
</head>

Once you have added the D3.js library to your HTML document, you can start creating shapes using the Shapes API.

Shapes API Examples
Creating a Rectangle

To create a rectangle using the Shapes API, you can use the rect() method. The rect() method creates a new rectangle with the specified width and height.

const svg = d3.select("svg");

svg.append("rect")
  .attr("x", 50)
  .attr("y", 50)
  .attr("width", 100)
  .attr("height", 50);

In the example above, d3.select("svg") selects the SVG element within the document, and .append("rect") appends a new rect element to the SVG element. The attr() method sets the attributes for the rectangle, such as the x and y position, and the width and height.

Creating a Circle

To create a circle using the Shapes API, you can use the circle() method. The circle() method creates a new circle with the specified radius.

const svg = d3.select("svg");

svg.append("circle")
  .attr("cx", 100)
  .attr("cy", 100)
  .attr("r", 50);

In the example above, d3.select("svg") selects the SVG element within the document, and .append("circle") appends a new circle element to the SVG element. The attr() method sets the attributes for the circle, such as the cx and cy position, and the r radius.

Creating an Ellipse

To create an ellipse using the Shapes API, you can use the ellipse() method. The ellipse() method creates a new ellipse with the specified x-radius, y-radius, and rotation.

const svg = d3.select("svg");

svg.append("ellipse")
  .attr("cx", 100)
  .attr("cy", 100)
  .attr("rx", 60)
  .attr("ry", 30)
  .attr("transform", "rotate(45)");

In the example above, d3.select("svg") selects the SVG element within the document, and .append("ellipse") appends a new ellipse element to the SVG element. The attr() method sets the attributes for the ellipse, such as the cx and cy position, the rx and ry radii, and the transform attribute for rotation.

Creating a Line

To create a line using the Shapes API, you can use the line() method. The line() method creates a new line with the specified start and end points.

const svg = d3.select("svg");

svg.append("line")
  .attr("x1", 50)
  .attr("y1", 50)
  .attr("x2", 150)
  .attr("y2", 100);

In the example above, d3.select("svg") selects the SVG element within the document, and .append("line") appends a new line element to the SVG element. The attr() method sets the attributes for the line, such as the x1 and y1 starting points, and the x2 and y2 ending points.

Conclusion

The Shapes API is a powerful part of the D3.js library that allows us to create and modify shapes using SVG elements. In this tutorial, we covered how to create a rectangle, circle, ellipse, and line using the Shapes API. With these examples, you should be able to start creating your own data visualizations using D3.js.