maskUnits

The maskUnits attribute indicates which coordinate system to use for the geometry properties 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"
    maskUnits="userSpaceOnUse"
    x="20%"
    y="20%"
    width="60%"
    height="60%">
    <rect fill="black" x="0" y="0" width="100%" height="100%" />
    <circle fill="white" cx="50" cy="50" r="35" />
  </mask>

  <mask
    id="myMask2"
    maskUnits="objectBoundingBox"
    x="20%"
    y="20%"
    width="60%"
    height="60%">
    <rect fill="black" x="0" y="0" width="100%" height="100%" />
    <circle fill="white" cx="50" cy="50" 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)" xlink:href="#r1" fill="red" />
  <use mask="url(#myMask1)" xlink:href="#r2" fill="red" />
  <use mask="url(#myMask1)" xlink:href="#r3" fill="red" />

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

mask

For <mask>, maskUnits defines the coordinate system in use for the geometry attributes (x, y, width and height) of the element.

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

userSpaceOnUse: This value indicates that all coordinates for the geometry attributes refer to the user coordinate system as defined when the mask was created.
objectBoundingBox: This value indicates that all coordinates for the geometry attributes represent fractions or percentages of the bounding box of the element to which the mask is applied. 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-maskunits

Browser compatibility

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