mask-repeat

One or more <repeat-style> values, separated by commas.

<repeat-style>

单值语法可将两个值简写为一个：

单值	与之等效的双值
repeat-x	repeat no-repeat
repeat-y	no-repeat repeat
repeat	repeat repeat
space	space space
round	round round
no-repeat	no-repeat no-repeat

在双值语法中，第一个值代表了水平方向的行为，第二个值代表了垂直方向的行为。下面是每个选项的用法解释：

repeat	The image is repeated as much as needed to cover the whole mask painting area. The last image will be clipped if it doesn't fit.
space	The image is repeated as much as possible without clipping. The first and last images are pinned to either side of the element, and whitespace is distributed evenly between the images. The mask-position property is ignored unless only one image can be displayed without clipping. The only case where clipping happens using space is when there isn't enough room to display one image.
round	As the allowed space increases in size, the repeated images will stretch (leaving no gaps) until there is room for another one to be added. When the next image is added, all of the current ones compress to allow room. Example: An image with an original width of 260px, repeated three times, might stretch until each repetition is 300px wide, and then another image will be added. They will then compress to 225px.
no-repeat	The image is not repeated (and hence the mask painting area will not necessarily be entirely covered). The position of the non-repeated mask image is defined by the mask-position CSS property.

mask-repeat = 
  <repeat-style>#  

<repeat-style> = 
  repeat-x                                     |
  repeat-y                                     |
  [ repeat | space | round | no-repeat ]{1,2}  

CSS

#masked {
  width: 250px;
  height: 250px;
  background: blue linear-gradient(red, blue);
  mask-image: url(star.svg);
  mask-repeat: repeat; /* 可在实时示例 live sample 中修改 */
  margin-bottom: 10px;
}

<div id="masked"></div>
<select id="repetition">
  <option value="repeat-x">repeat-x</option>
  <option value="repeat-y">repeat-y</option>
  <option value="repeat" selected>repeat</option>
  <option value="space">space</option>
  <option value="round">round</option>
  <option value="no-repeat">no-repeat</option>
</select>

var repetition = document.getElementById("repetition");
repetition.addEventListener("change", function (evt) {
  document.getElementById("masked").style.maskRepeat = evt.target.value;
});

You can specify a different <repeat-style> for each mask image, separated by commas:

.examplethree {
  mask-image: url("mask1.png"), url("mask2.png");
  mask-repeat: repeat-x, repeat-y;
}

Each image is matched with the corresponding repeat style, from first specified to last.