flood-opacity

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

The flood-opacity attribute indicates the opacity value to use across the current filter primitive subregion.

Note: As a presentation attribute, flood-opacity also has a CSS property counterpart: flood-opacity. When both are specified, the CSS property takes priority.

You can use this attribute with the following SVG elements:

<feFlood> and <feDropShadow>

Example

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

html

<svg viewBox="0 0 420 200" xmlns="http://www.w3.org/2000/svg">
  <filter id="flood1">
    <feFlood
      flood-color="seagreen"
      flood-opacity="1"
      x="0"
      y="0"
      width="200"
      height="200" />
  </filter>
  <filter id="flood2">
    <feFlood
      flood-color="seagreen"
      flood-opacity="0.3"
      x="0"
      y="0"
      width="200"
      height="200" />
  </filter>

  <rect x="0" y="0" width="200" height="200" filter="url(#flood1)" />
  <rect x="220" y="0" width="200" height="200" filter="url(#flood2)" />
</svg>

Usage notes

Value	`<alpha-value>`
Initial value	`1`
Animatable	Yes

<alpha-value>: A number or percentage indicating the opacity value to use across the current filter primitive subregion. A number of 0 or a percentage of 0% represents a fully transparent color, 1 or 100% represents a fully opaque color.