// _ _ _____ _ _ // | | | | / ____| | | | | // | | _ _| | _____| (_____ ____ _ _ __| |_ _ __ ___| |_ // | | | | | | |/ / _ \\___ \ \ /\ / / _` | '__| __| | '_ \ / _ \ __| // | |___| |_| | < __/____) \ V V / (_| | | | |_ _| | | | __/ |_ // |______\__,_|_|\_\___|_____/ \_/\_/ \__,_|_| \__(_)_| |_|\___|\__| //
SVG Paths: The Road to Better Visualizations

SVG

SVG Paths: The Road to Better Visualizations

The SVG `path` element is well known, yet often underutilized. There is lots of information written about it, but I've seen a few misconceptions around creating custom visualizations, so I think it warrants another post

In this post, we will explore an example where an SVG path element can be used instead of a more complicated implementation. This can apply to many cases where multiple elements are composed together when a single path element with do the job.

In this example, we are going to draw an arrow like the one shown in the header above.

But don’t do it like this:

Note the artifacts that we get, like the line between the triangle and the rectangle. This is because we are drawing an svg rect, then appending a triangle on top of it. This can be tempting when using a library like D3, which provides wrappers that easily produce rectangles, circles, lines, etc. But instead of composing multiple shapes together, I suggest taking a much simpler path.

Let’s try drawing the same arrow, but using a single SVG path element instead:

And here is the code for that arrow:

  <!-- use 'viewBox' to set a lengthxwidth coordinate system of 200x60 -->
  <svg width="100%" viewBox="0 0 200 60">
    <path class="path" fill-opacity="0.0" stroke="#000000" d="
          M 0 20
          l 100 0
          l 0 -10
          l 30 22
          l -30 22
          l 0 -10
          l -100 0
          z
    "/>
  </svg>

Let’s explore how this path element is drawn. Here is a breakdown of how we use the “d” attribute above to draw the arrow:

M 0 20 – This is our starting point in the top-left corner of the arrow (x=0, y=20 in our viewBox)

l 100 0 – Move 100 units to the right

l 0 -10 – Move 10 units up

l 30 22 – Move 30 units right, 22 units down (this is the tip of our arrow!)

l -30 22 – Move 30 units left, 22 units down

l 0 -10 – Move 10 units down

l -100 0 – Move 100 units to the left

z – Close our arrow polygon by moving back to our starting point

And here is that same arrow, with an added animation to emphasize the trajectory of the path:

And as a bonus, imagine trying to draw the animation above over multiple polygons! But for our example above, we only need to add the following styles to our <path> element, which has been labeled with the class name path:

<style>
.path {
  stroke-dasharray: 700;
  stroke-dashoffset: 700;
  animation: dash 5s linear forwards infinite;
}

@keyframes dash {
  to {
    stroke-dashoffset: 0;
  }
}
</style>

Conclusion

I hope this is useful to anyone new to drawing custom SVG shapes. The path element is very powerful in that it can create any polygon, line, or curved shape. I added some links to the SVG path docs and its d attribute below.

Further reading:

SVG <path> documentation

docs for the <path> element’s “d” attribute

SVG <path> tutorial

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