How does the SVG path length attribute affect path drawing and animation effects?

Use SVG pathlength attributes: control path drawing and animation

Although pathlength attribute of SVG is practical, it is often ignored by developers. This article will explore its role and application methods in depth to help you better understand and apply this attribute.

Detailed explanation of pathlength attribute

The pathlength property allows you to customize length values ​​for SVG paths. This value does not change the path shape, but affects the drawing method and animation effect. For example, it can accurately control the path to be drawn within a specific time.

The main application scenarios of pathlength :

1. Path length normalization: Even if the actual length is different, you can set the same pathlength value for multiple paths, thus achieving consistent drawing effects in the animation.
2. Animation speed control: Adjusting pathlength can accurately control the path animation speed to ensure that drawing or movement is completed within the specified time.
3. Optimize user experience: In some cases, adjusting pathlength can make the path presentation more in line with design expectations and user experience.

How to use pathlength attribute

The method of using is simple, just add pathlength attribute to the SVG path element and assign a value. Examples are as follows:

<svg height="100" width="100">
  <path d="m10,10 c20,40 40,60 80,90" fill="none" pathlength="100" stroke="black" stroke-width="2"></path>
</svg>

Even if the actual length of the path is not 100, after setting pathlength="100" , the browser will use this length as the benchmark. This is particularly important in animation calculations.

For example, to implement an animation that completes path drawing in 5 seconds, you can use CSS animation:

 @keyframes draw {
  to {
    stroke-dashoffset: 0;
  }
}

.path {
  stroke-dasharray: 100;
  stroke-dashoffset: 100;
  animation: draw 5s linear forwards;
}

The values ​​of stroke-dasharray and stroke-dashoffset are based on 100 calculations of pathlength settings, thus achieving accurate path drawing animations.

Through the above example, you can see that pathlength property not only simplifies path length management, but also improves the flexibility and controllability of SVG paths. Hope this article helps you better understand and apply pathlength attribute.

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