Скачать или смотреть Adding a Background Color Outside a Polygon in react-map-gl

Learn how to add a `background color` outside your polygon in `react-map-gl` with clear steps and helpful code examples.
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This video is based on the question https://stackoverflow.com/q/73388416/ asked by the user 'Gelo Chang' ( https://stackoverflow.com/u/14272323/ ) and on the answer https://stackoverflow.com/a/73397016/ provided by the user 'devpoolxx' ( https://stackoverflow.com/u/7751999/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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How to Add a Background Color Outside a Polygon in react-map-gl

If you are working with react-map-gl and want to enhance your polygon visualizations, you might be wondering how to add a background color outside your polygon. This can help make the polygon stand out or simply improve the aesthetic of your map. In this post, we will guide you through the necessary steps to achieve this effect, ensuring that your polygon is highlighted and looks vibrant on the map.

Understanding the Problem

When you try to implement multiple <Layer /> components for your polygons, you may run into issues where only the first instance of the <Layer /> renders properly. This is often due to the fact that each layer must have a unique id to be displayed simultaneously. Additionally, using properties incorrectly might prevent the desired cardinals or highlights from showing properly.

Solution Overview

To effectively add a background color outside your polygon, you need to follow these steps:

Use Unique Layer IDs

Utilize the Turf.js package for masking the polygon

Let’s delve into each step in detail.

Step 1: Use Unique Layer IDs

For your layers to display properly, ensure that each <Layer /> component has a distinct id. You can also control the order of their appearance by using the beforeId property. Below is an example of how you can define your layers properly with unique IDs:

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

Step 2: Utilize the Turf.js Package

Now that you have set up the layers, the next step is to use the mask functionality from the @ turf/turf package. This will allow us to create a proper polygon mask to effectively fill the area outside of our specified polygon. Here’s how to implement it:

Import the necessary package and create your polygon and mask.

Use the turf.mask method to create masked data.

Here's a code snippet demonstrating how to implement this:

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

Conclusion

By implementing these steps, you will successfully add a background color outside of your polygon in react-map-gl. Remember to always use unique IDs for your layers and leverage the power of Turf.js for effective polygon masking. Whether enhancing visual aesthetics or clarifying your map’s information, these techniques can significantly improve your geographical data presentations.

Feel free to customize the colors and opacities to suit your design needs. Happy mapping!