a:alpha (Alpha Value)

Describes the alpha-channel adjustment used by a:alpha in DrawingML color values..

Parent elements

Child elements

(none)

Description

a:alpha is a DrawingML or SVG namespace element used to describe a specific part of a shape, text run, theme, or graphic. In the ECMA-376 DrawingML model, it participates in the XML content tree that defines visual appearance, geometry, and formatting for OOXML content.

The element is commonly encountered in presentation, document, and spreadsheet packages where shapes, charts, pictures, or text boxes are serialized as Open XML. The examples below illustrate a typical usage pattern and a corresponding Open XML SDK implementation.

Attributes

Attribute	Type	Possible Values	Description
`val`	ST_FixedPercentage	0..100000	Alpha transparency value applied to a color.

XML Example

<a:srgbClr val="FF0000">
  <a:alpha val="65000"/>
</a:srgbClr>

using DocumentFormat.OpenXml.Drawing;

var alpha = new Alpha { Val = 65000 };
var color = new RgbColorModelHex { Val = "FF0000" };
color.Append(alpha);

Notes

The permitted child elements and attribute values depend on the surrounding OOXML part and the schema version in use.
In practice, DrawingML content is usually generated from higher-level shape or picture APIs rather than built manually element-by-element.
When this element appears inside a document package, it is typically linked by relationships or contained in a drawing part that is referenced from a shape or graphic object.