mask-origin

Summary

The mask-origin CSS property determines the origin of a mask.

For elements rendered as a single box, this property specifies the mask positioning area. In other words, this property specifies the origin position of an image specified by the mask-image CSS property. For elements rendered as multiple boxes, such as inline boxes on several lines or boxes on several pages, it specifies which boxes box-decoration-break operates upon to determine the mask positioning area.

Syntax

/* Keyword values */
mask-origin: content-box;
mask-origin: padding-box;
mask-origin: border-box;
mask-origin: margin-box;
mask-origin: fill-box;
mask-origin: stroke-box;
mask-origin: view-box;

/* Multiple values */
mask-origin: padding-box, content-box;
mask-origin: view-box, fill-box, border-box;

/* Non-standard keyword values */
 -webkit-mask-origin: content;
 -webkit-mask-origin: padding;
 -webkit-mask-origin: border;

/* Global values */
mask-origin: inherit;
mask-origin: initial;
mask-origin: unset;

Values

content-box

The position is relative to the content box.

padding-box

The position is relative to the padding box. For single boxes 0 0 is the upper left corner of the padding edge, 100% 100% is the lower right corner.

border-box

The position is relative to the border box.

margin-box

The position is relative to the margin box.

fill-box

The position is relative to the object bounding box.

stroke-box

The position is relative to the stroke bounding box.

view-box

Uses the nearest SVG viewport as reference box. If a viewBox attribute is specified for the element creating the SVG viewport, the reference box is positioned at the origin of the coordinate system established by the viewBox attribute and the dimension of the reference box is set to the width and height values of the viewBox attribute.

content

Same as content-box.

padding

Same as padding-box.

border

Same as border-box.

Formal syntax

<geometry-box>#
where 
<geometry-box> = <shape-box> | fill-box | stroke-box | view-box
where 
<shape-box> = <box> | margin-box
where 
<box> = border-box | padding-box | content-box

Example

CSS Content

#masked {
  width: 100px;
  height: 100px;
  margin: 10px;
  border: 10px solid blue;
  background-color: #8cffa0;
  padding: 10px;
  mask-image: url(https://mdn.mozillademos.org/files/12676/star.svg);
  mask-origin: border-box; /* Can be changed in the live sample */
}

<div id="masked">
</div>
<select id="origin">
  <option value="content-box">content-box</option>
  <option value="padding-box">padding-box</option>
  <option value="border-box" selected>border-box</option>
  <option value="margin-box">margin-box</option>
  <option value="fill-box">fill-box</option>
  <option value="stroke-box">stroke-box</option>
  <option value="view-box">view-box</option>
</select>

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

Specifications

Browser compatibility

[1] WebKit and Blink currently don't support the value margin-box.

[2] Gecko currently doesn't implement this feature. It is only available in Nightly and Dev Edition. See bug 1251161.