Clip-path and SVG rect inside animation - css

Question

I am trying to make a fancy animation only in CSS. I started with a tutorial on W3 School and wanted to make it better. My idea is to have a square loader turning clockwise while another inside would turn in the opposite direction.
On this link you will see what I'm talking about, the only difference is that I would like the red part to be turning in the opposite direction.
In order to do so I tried adding another div with class name .spinner. Here's my try at it: https://jsfiddle.net/avhjj4ps/
.loader-container {
position: absolute;
left: calc(50% - 75px);
width: 150px;
height: 150px;
padding: 5px;
border: 1px solid red;
top: calc(50% - 75px);
}
img {
width: 200px;
margin: 20px;
/*animation: move 2s alternate infinite linear;*/
}
#myClip, #svg {
position: absolute;
left: 50%;
top: 50%;
}
.loader, .spinner {
position: absolute;
}
.loader {
left: calc(50% - 35px);
top: calc(50% - 35px);
width: 40px;
height: 40px;
border: 15px solid transparent;
border-top: 15px solid none;
/*-webkit-animation: loader 2s linear infinite;
animation: loader 2s linear infinite;*/
}
.spinner {
left: calc(50% - 55.1px);
top: calc(50% - 55.1px);
/*clip-path: url(#myClip);*/
width: 40px;
border-radius: 50%;
height: 40px;
border: 36px solid #f3f3f3;
border-top: 36px solid #5cb85c;
/*-webkit-animation: spin 2s linear infinite;
animation: spin 2s linear infinite;*/
}
#-webkit-keyframes loader {
0% { -webkit-transform: rotate(0deg); }
100% { -webkit-transform: rotate(360deg); }
}
#keyframes loader {
0% { transform: rotate(0deg); }
100% { transform: rotate(360deg); }
}
#-webkit-keyframes spin {
0% { -webkit-transform: rotate(0deg); }
100% { -webkit-transform: rotate(-360deg); }
}
#keyframes spin {
0% { transform: rotate(0deg); }
100% { transform: rotate(-360deg); }
}
<div class="loader-container">
<div class="loader"></div>
<div class="spinner"></div>
<svg id="svg" width="0" height="0">
<defs>
<clipPath id="myClip">
<rect x="-35" y="-35" width="15" height="70" />
<rect x="20" y="-35" width="15" height="70" />
<rect x="-35" y="-35" width="70" height="15" />
<rect x="-35" y="20" width="70" height="15" />
</clipPath>
</defs>
</svg>
</div>
I am trying to show the green spinner only where there is the square loader. It would be like a mask. In the above snippet (also available here: http://codepen.io/anon/pen/ZOoByA), I'm trying to use the clip-path property.
Can some tell me why clip-path: url(#myClip); doesn't work ? When I comment this line the loader shows completely, however while active it's not showing at all.

Answer 1

You can create your loader in svg with some polygons and then clip the inner green loader away with clipPath.
First, define the gray border as a polygon:
<polygon id="loader" points="0,0 0,70 70,70 70,0 0,0 15,15 55,15 55,55 15,55 15,15" />
As we will reuse this shape (the actual loader and the clip-path shape), we put into the defs tag:
<svg height="0" width="0">
<defs>
<polygon id="loader" points="..." />
</defs>
</svg>
Then we put the clipPath into the same defs tag:
<clipPath id="loaderClipper">
<use xlink:href="#loader" x="15" y="15" />
</clipPath>
The offset of 15 is calculated in the following way: The loader's width is 70, but if it is rotated by 45 degrees, it's width is 70√2 which rounds to 100. The whitespace in the left and in the right is (100 - 70) / 2 = 15.
The svg for the actual used element looks like this:
<svg width="100" height="100" viewbox="0 0 100 100" clip-path="url(#loaderClipper)">
<use xlink:href="#loader" class="loader" x="15" y="15" />
<polygon class="spinner" points="0,0 100,0 50,50" x="30" y="30" />
</svg>
And some css for colors and the animation:
svg {
animation: rotate 2s linear infinite;
transform-origin: 50px 50px;
}
.loader {
fill: #dcdada;
}
.spinner {
fill: #5cb85c;
animation: rotate 1s linear infinite reverse;
transform-origin: 50px 50px;
}
Result fiddle: https://jsfiddle.net/apLepsv3/10/
Successfully tested on both mobile and desktop Firefox and Chrome.

Answer 2

For a CSS-only solution without SVG you need some helper elements:
<div class="loader">
<div class="square"></div>
<div class="cutter">
<div class="spinner">
</div>
</div>
</div>
And then this CSS code:
.square {
width: 40px;
height: 40px;
background: #f3f3f3;
z-index: 1;
}
.cutter {
width: 70px;
height: 70px;
left: -15px;
top: -15px;
overflow: hidden;
}
.spinner {
width: 54px;
border-radius: 50%;
height: 54px;
border: 8px solid transparent;
border-top: 8px solid #5cb85c;
-webkit-animation: spin 1s linear infinite;
animation: spin 1s linear infinite;
margin-left: -15px;
margin-top: -15px;
}
Result: https://jsfiddle.net/avhjj4ps/3/
Disadvantage: Inner square must have a solid background (no gradient or image) if it has to match the parent's / body's background.

Answer 3

You can create the spinner with HTML and CSS and then cut the overflow away by using the clip-path property in combination with a svg <clipPath> element.
Your html structure of the spinner:
<div class="loader">
<div class="spinner">
</div>
</div>
Now position the two elements over each other:
.loader {
width: 40px;
height: 40px;
position: relative;
left: 30px;
top: 30px;
border: 15px solid #dcdada;
border-top: 15px solid none;
-webkit-animation: loader 2s linear infinite;
animation: loader 2s linear infinite;
}
.spinner {
width: 0px;
height: 0px;
position: relative;
left: -30px;
top: -30px;
border: 50px solid transparent;
border-top: 50px solid #5cb85c;
-webkit-animation: spin 1s linear infinite;
animation: spin 1s linear infinite;
}
But there's still that green overflow outside and inside of the gray border. So we need to cut it away with a svg <polygon>.
<svg height="0" width="0">
<defs>
<clipPath id="loaderClipper">
<polygon points="0,0 0,70 70,70 70,0 0,0 15,15 55,15 55,55 15,55 15,15"/>
</clipPath>
</defs>
</svg>
The points define a 70x70 square with a 40x40 square cut off.
Then add the clip-path property that references to the svg <clipPath> element:
.loader {
clip-path: url(#loaderClipper);
}
Fiddle: https://jsfiddle.net/apLepsv3/2/
Disadvantage: Only supported in Firefox, not Chrome