Скачать или смотреть How to Get the Bounding Box of the Intersection of SVG Paths in JavaScript

Discover an effective method to calculate the `bounding box` of overlapping SVG shapes, allowing you to define the precise area of intersection.
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Getting the Bounding Box of the Intersection of SVG Paths

SVG (Scalable Vector Graphics) allows for versatile and complex shapes, which often leads to the need to find intersections between these shapes. If you've ever found yourself in a situation where you needed to identify the bounding box surrounding the intersection of two or more paths, you've come to the right place. In this guide, we'll walk through a practical solution to this problem using JavaScript and SVG elements.

The Challenge

You have multiple SVG shapes, say circles, and you're interested in identifying the area where these shapes intersect. This is crucial for tasks such as creating symbols, clipping paths, or analyzing overlap areas. The complication arises when trying to get the bounding box of the intersection—commonly, using intersection.getBBox() will return the bounding box prior to any clipping, which is not what you need.

What We Want to Achieve:

Find the bounding box of the intersected area.

Use JavaScript to compute the bounding box of the intersection dynamically.

The Solution

To solve this challenge, we can follow a step-by-step method that involves using a canvas to draw the SVG, capturing the image data, and analyzing that data to determine the bounding box coordinates.

Steps to Get the Bounding Box

Here’s how you can implement the solution:

Create the SVG and Set Up the Canvas:

Use an <svg> element that contains your shapes.

Create a <canvas> element that matches the dimensions of your SVG.

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Serialize the SVG as Base64:

Convert your SVG to a string and then to a base64 format to use it as an image source.

[[See Video to Reveal this Text or Code Snippet]]

Draw the SVG on the Canvas:

Once the image is loaded, draw it onto the canvas.

[[See Video to Reveal this Text or Code Snippet]]

Analyze the Image Data:

Loop through the pixel data returned from the canvas and find the smallest and largest x and y coordinates of non-transparent pixels (black in our case).

[[See Video to Reveal this Text or Code Snippet]]

Define the New ViewBox:

Using the calculated coordinates, construct a new viewBox for the intersected area.

[[See Video to Reveal this Text or Code Snippet]]

Complete Code Example:

Here’s a full example of how this can be implemented:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By using this method, you're not just able to identify the bounding box of the intersection of your SVG paths, but you're also engaging with the SVG API and canvas capabilities in a way that can be utilized for various projects. This approach is robust, and while it’s tailored to SVG interactivity, it can also lead to creative applications in web development or graphic design.

Now that you have the tools and knowledge, get started and explore the intersections in your SVGs!