maskContentUnits

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since January 2020.

The maskContentUnits attribute indicates which coordinate system to use for the contents of the <mask> element.

You can use this attribute with the following SVG elements:

<mask>

Example

html,
body,
svg {
  height: 100%;
}

html

<svg viewBox="0 0 100 100" xmlns="http://www.w3.org/2000/svg">
  <mask id="myMask1" maskContentUnits="userSpaceOnUse">
    <rect fill="black" x="0" y="0" width="100%" height="100%" />
    <circle fill="white" cx="50" cy="50" r="35" />
  </mask>

  <mask id="myMask2" maskContentUnits="objectBoundingBox">
    <rect fill="black" x="0" y="0" width="100%" height="100%" />
    <circle fill="white" cx=".5" cy=".5" r=".35" />
  </mask>

  <!-- Some reference rect to materialized the mask -->
  <rect id="r1" x="0" y="0" width="45" height="45" />
  <rect id="r2" x="0" y="55" width="45" height="45" />
  <rect id="r3" x="55" y="55" width="45" height="45" />
  <rect id="r4" x="55" y="0" width="45" height="45" />

  <!-- The first 3 rect are masked with useSpaceOnUse units -->
  <use mask="url(#myMask1)" href="#r1" fill="red" />
  <use mask="url(#myMask1)" href="#r2" fill="red" />
  <use mask="url(#myMask1)" href="#r3" fill="red" />

  <!-- The last rect is masked with objectBoundingBox units -->
  <use mask="url(#myMask2)" href="#r4" fill="red" />
</svg>

mask

For <mask>, maskContentUnits defines the coordinate system in use for the content of the element.

Value	`userSpaceOnUse` \| `objectBoundingBox`
Default value	`userSpaceOnUse`
Animatable	Yes

userSpaceOnUse: This value indicates that all coordinates inside the <mask> element refer to the user coordinate system as defined when the mask was created.
objectBoundingBox: This value indicates that all coordinates inside the <mask> element are relative to the bounding box of the element the mask is applied to. A bounding box could be considered the same as if the content of the <mask> were bound to a "0 0 1 1" viewBox.

Specifications

Specification
CSS Masking Module Level 1 # element-attrdef-mask-maskcontentunits

Browser compatibility

BCD tables only load in the browser