preserveAspectRatio

O atributo preserveAspectRatio indica como um elemento com uma viewBox, fornecendo uma determinada proporção deve se ajustar a uma viewport com uma proporção diferente.

Because the aspect ratio of an SVG image is defined by the viewBox attribute, if this attribute isn't set, the preserveAspectRatio attribute has no effect (with one exception, the <image> element, as described below).

Example

html
<svg viewBox="-1 -1 162 92" xmlns="https://www.w3.org/2000/svg">
  <defs>
    <path
      id="smiley"
      d="M50,10 A40,40,1,1,1,50,90 A40,40,1,1,1,50,10 M30,40 Q36,35,42,40 M58,40 Q64,35,70,40 M30,60 Q50,75,70,60 Q50,75,30,60" />
  </defs>

  <!-- (width>height) meet -->
  <svg
    preserveAspectRatio="xMidYMid meet"
    x="0"
    y="0"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMinYMid meet"
    x="25"
    y="0"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMaxYMid meet"
    x="50"
    y="0"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>

  <!-- (width>height) slice -->
  <svg
    preserveAspectRatio="xMidYMin slice"
    x="0"
    y="15"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMidYMid slice"
    x="25"
    y="15"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMidYMax slice"
    x="50"
    y="15"
    viewBox="0 0 100 100"
    width="20"
    height="10">
    <use href="#smiley" />
  </svg>

  <!-- (width<height) meet -->
  <svg
    preserveAspectRatio="xMidYMin meet"
    x="75"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMidYMid meet"
    x="90"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMidYMax meet"
    x="105"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>

  <!-- (width<height) slice -->
  <svg
    preserveAspectRatio="xMinYMid slice"
    x="120"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMidYMid slice"
    x="135"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>
  <svg
    preserveAspectRatio="xMaxYMid slice"
    x="150"
    y="0"
    viewBox="0 0 100 100"
    width="10"
    height="25">
    <use href="#smiley" />
  </svg>

  <!-- none -->
  <svg
    preserveAspectRatio="none"
    x="0"
    y="30"
    viewBox="0 0 100 100"
    width="160"
    height="60">
    <use href="#smiley" />
  </svg>
</svg>

Syntax

preserveAspectRatio="<align> [<meetOrSlice>]"

Its value is made of one or two keywords: A required alignment value and an optional "meet or slice" reference as described below:

Alignment value

The alignment value indicates whether to force uniform scaling and, if so, the alignment method to use in case the aspect ratio of the viewBox doesn't match the aspect ratio of the viewport. The alignment value must be one of the following keywords:

  • none Do not force uniform scaling. Scale the graphic content of the given element non-uniformly if necessary such that the element's bounding box exactly matches the viewport rectangle. Note that if <align> is none, then the optional <meetOrSlice> value is ignored.
  • xMinYMin - Force uniform scaling. Align the <min-x> of the element's viewBox with the smallest X value of the viewport. Align the <min-y> of the element's viewBox with the smallest Y value of the viewport.
  • xMidYMin - Force uniform scaling. Align the midpoint X value of the element's viewBox with the midpoint X value of the viewport. Align the <min-y> of the element's viewBox with the smallest Y value of the viewport.
  • xMaxYMin - Force uniform scaling. Align the <min-x>+<width> of the element's viewBox with the maximum X value of the viewport. Align the <min-y> of the element's viewBox with the smallest Y value of the viewport.
  • xMinYMid - Force uniform scaling. Align the <min-x> of the element's viewBox with the smallest X value of the viewport. Align the midpoint Y value of the element's viewBox with the midpoint Y value of the viewport.
  • xMidYMid (the default) - Force uniform scaling. Align the midpoint X value of the element's viewBox with the midpoint X value of the viewport. Align the midpoint Y value of the element's viewBox with the midpoint Y value of the viewport.
  • xMaxYMid - Force uniform scaling. Align the <min-x>+<width> of the element's viewBox with the maximum X value of the viewport. Align the midpoint Y value of the element's viewBox with the midpoint Y value of the viewport.
  • xMinYMax - Force uniform scaling. Align the <min-x> of the element's viewBox with the smallest X value of the viewport. Align the <min-y>+<height> of the element's viewBox with the maximum Y value of the viewport.
  • xMidYMax - Force uniform scaling. Align the midpoint X value of the element's viewBox with the midpoint X value of the viewport. Align the <min-y>+<height> of the element's viewBox with the maximum Y value of the viewport.
  • xMaxYMax - Force uniform scaling. Align the <min-x>+<width> of the element's viewBox with the maximum X value of the viewport. Align the <min-y>+<height> of the element's viewBox with the maximum Y value of the viewport.
Meet or slice reference

The meet or slice reference is optional and, if provided, must be one of the following keywords:

  • meet (the default) - Scale the graphic such that:

    • aspect ratio is preserved
    • the entire viewBox is visible within the viewport
    • the viewBox is scaled up as much as possible, while still meeting the other criteria

    In this case, if the aspect ratio of the graphic does not match the viewport, some of the viewport will extend beyond the bounds of the viewBox (i.e., the area into which the viewBox will draw will be smaller than the viewport).

  • slice - Scale the graphic such that:

    • aspect ratio is preserved
    • the entire viewport is covered by the viewBox
    • the viewBox is scaled down as much as possible, while still meeting the other criteria

    In this case, if the aspect ratio of the viewBox does not match the viewport, some of the viewBox will extend beyond the bounds of the viewport (i.e., the area into which the viewBox will draw is larger than the viewport).

Elements

Seven elements are using this attribute: <svg>, <symbol>, <image>, <feImage>, <marker>, <pattern>, and <view>.

feImage

For <feImage>, preserveAspectRatio defines how the referenced image should fit in the rectangle define by the <feImage> element.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

image

For <image>, preserveAspectRatio defines how the referenced image should fit in the rectangle define by the <image> element.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

marker

For <marker>, preserveAspectRatio indicates if a uniform scaling must be performed to fit the element viewport.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

pattern

For <pattern>, preserveAspectRatio indicates if a uniform scaling must be performed to fit the element viewport.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

svg

For <svg>, preserveAspectRatio indicates if a uniform scaling must be performed to fit the element viewport.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

symbol

For <symbol>, preserveAspectRatio indicates if a uniform scaling must be performed to fit the element viewport.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

view

For <view>, preserveAspectRatio indicates if a uniform scaling must be performed to fit the element viewport.

Value <align> <meetOrSlice>?
Default value xMidYMid meet
Animatable Yes

Especificações

Specification
Filter Effects Module Level 1
# element-attrdef-feimage-preserveaspectratio
Scalable Vector Graphics (SVG) 2
# PreserveAspectRatioAttribute