maskUnits

SVG Elements
1. A
2. B-C
3. D
  1. <defs>
  2. <desc>
4. E
  1. <ellipse>
5. F
6. G
7. H
  1. <hkern>
8. I
  1. <image>
9. J-L
  1. <line>
  2. <linearGradient>
10. M
11. N-P
12. Q-R
  1. <radialGradient>
  2. <rect>
13. S
  1. <script>
  2. <set>
  3. <stop>
  4. <style>
  5. <svg>
  6. <switch>
  7. <symbol>
14. T
15. U
  1. <use>
16. V-Z
  1. <view>
  2. <vkern>

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% }

<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	Status	Comment
CSS Masking Module Level 1 The definition of 'maskUnits' in that specification.	Candidate Recommendation
Scalable Vector Graphics (SVG) 1.1 (Second Edition) The definition of 'maskUnits' in that specification.	Recommendation	Initial definition

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