is it possible to make SVG circle fill color from bottom to top based on percentage?

Question

<svg viewbox="-20 -20 100 100">

  <circle r="15.29563" cx="0" stroke="#7dc4c2" fill="#5ea4a2">

</svg>

How to fill the circle as below based on percentage!!

http://i.stack.imgur.com/gVAN5.png

Thanks in advance.

Solution 1

you could use a gradient with stop-opacity to do this. you would add two "middle" stops with opacity 0 and 1 respectively an set the offset of both to the percentage you need.

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="200" height="200">
  <linearGradient id="lg" x1="0.5" y1="1" x2="0.5" y2="0">
      <stop offset="0%" stop-opacity="1" stop-color="royalblue"/>
      <stop offset="40%" stop-opacity="1" stop-color="royalblue"/>
      <stop offset="40%" stop-opacity="0" stop-color="royalblue"/>
      <stop offset="100%" stop-opacity="0" stop-color="royalblue"/>
  </linearGradient>
  <circle cx="50" cy="50" r="45" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
</svg>

you could even animate it

<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 100 100" width="200" height="200">
      <linearGradient id="lg" x1="0.5" y1="1" x2="0.5" y2="0">
          <stop offset="0%" stop-opacity="1" stop-color="royalblue"/>
          <stop offset="40%" stop-opacity="1" stop-color="royalblue">
            <animate attributeName="offset" values="0;1;0" repeatCount="indefinite" dur="10s" begin="0s"/>
          </stop>
          <stop offset="40%" stop-opacity="0" stop-color="royalblue">
            <animate attributeName="offset" values="0;1;0" repeatCount="indefinite" dur="10s"  begin="0s"/>
          </stop>
          <stop offset="100%" stop-opacity="0" stop-color="royalblue"/>
      </linearGradient>
      <circle cx="50" cy="50" r="45" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
</svg>

the advantage is that this works on any shape and size without changing the gradient

   <svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 600 300" width="400" height="200">
      <linearGradient id="lg" x1="0.5" y1="1" x2="0.5" y2="0">
          <stop offset="0%" stop-opacity="1" stop-color="royalblue"/>
          <stop offset="40%" stop-opacity="1" stop-color="royalblue"/>
          <stop offset="40%" stop-opacity="0" stop-color="royalblue"/>
          <stop offset="100%" stop-opacity="0" stop-color="royalblue"/>
      </linearGradient>
      <circle cx="50" cy="50" r="45" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
     <circle cx="250" cy="150" r="145" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
     <rect x="400" y="20" width="100" height="100" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
     <path d="M50 150L95 290 h-90z" fill="url(#lg)" stroke="crimson" stroke-width="5"/>

     <path d="M450 205 A45 45 0 0 1 450 295A100 100 0 0 0 450 205z" fill="url(#lg)" stroke="crimson" stroke-width="5"/>
   </svg>

Solution 2

The easiest way to do this is to create a mask with a circular hole in it, and then animate a rectangle behind it. For example:

<path fill="#fff" fill-rule="evenodd"
        d="M0 0 200 0 200 200 0 200ZM20 100 A80 80 0 0 0 180 100 80 80 0 0 0 20 100Z"/>

The path data here starts with a square box 200 units wide (M0 0 200 0 200 200 0 200Z) and then uses two arcs to draw a circle of diameter 80 units inside it (A80 80 0 0 0 180 100 80 80 0 0 0 20 100Z). The evenodd fill rule ensures that the circle is cut out from the square.

If you want the circle to fill from bottom to top, then you'll have to use a rotate transformation:

<rect transform="rotate(180 100 100)" x="20" y="20" width="160" height="0" fill="#47f" id="fillup"/>

This spins the coordinate system around the middle of the SVG image so that the rect grows upwards when you increase its height. Here, I'm using a CSS transition to change the height of the rect when you hover over it. But you can use Javascript or JQuery to change the height to whatever you want.

Here's a working example:

svg #fillup { height:0px; transition:height 0.5s; }
svg:hover #fillup { height:160px; }

<svg width="200" height="200" viewBox="0 0 200 200">
  <rect x="10" y="10" width="180" height="180" fill="#eee"/>
  <rect transform="rotate(180 100 100)" x="20" y="20"
        width="160" height="0" fill="#47f" id="fillup"/>
  <path fill="#fff" fill-rule="evenodd"
        d="M0 0 200 0 200 200 0 200ZM20 100 A80 80 0 0 0
           180 100 80 80 0 0 0 20 100Z"/>
  <circle cx="100" cy="100" r="90" fill="none" stroke="#888"
          stroke-width="20"/>
  <circle cx="100" cy="100" r="99" fill="none" stroke="#333"
          stroke-width="1"/>
  <circle cx="100" cy="100" r="80" fill="none" stroke="#333"
          stroke-width="1"/>
</svg>