a:glow (Glow Effect)

Description

\:glow\ is the DrawingML glow effect element that adds a soft, diffused light effect radiating from a shape’s edges. It is defined in ECMA-376 Part 1 §20.1.8.7.

Glow effects create a luminous halo around shapes, commonly used for:

• Highlighting important shapes in diagrams and flowcharts
• Creating emphasis and visual hierarchy in presentations
• Achieving modern, polished designs with light effects
• Simulating light emission from glowing objects
• Improving visual appeal and drawing attention to key elements

The glow effect uses a configurable blur radius to control the intensity and spread of the glowing light. Glow color determines the appearance—typically matching the shape color with transparency, or using accent colors for emphasis.

Glow effects are lighter-weight than shadows and render consistently across all Office applications.

Attributes

Content Model

\:glow\ contains exactly one color element specifying glow color:

• \:srgbClr: RGB color for glow
• \:schemeClr: Theme color for glow
• \:hslClr: HSL color for glow
• \:sysClr: System color for glow

Child Elements Table

Examples

Blue Glow Effect

<a:effectLst>
  <a:glow rad=\"76200\">
    <a:srgbClr val=\"0070C0\">
      <a:alpha val=\"100000\"/>
    </a:srgbClr>
  </a:glow>
</a:effectLst>

using DocumentFormat.OpenXml.Drawing;

var effectLst = new EffectList();
var glow = new Glow { Radius = 76200 };

var srgbClr = new RgbColorModelHex { Val = \"0070C0\" };
var alpha = new Alpha { Val = 100000 };
srgbClr.Append(alpha);
glow.Append(srgbClr);

effectLst.Append(glow);

Strong Yellow Glow (High intensity)

<a:glow rad=\"152400\">
  <a:srgbClr val=\"FFFF00\">
    <a:alpha val=\"80000\"/>
  </a:srgbClr>
</a:glow>

var glow = new Glow { Radius = 152400 };  // Larger radius = softer glow

var srgbClr = new RgbColorModelHex { Val = \"FFFF00\" };
var alpha = new Alpha { Val = 80000 };
srgbClr.Append(alpha);
glow.Append(srgbClr);

Glow with Theme Color

<a:glow rad=\"101600\">
  <a:schemeClr val=\"accent1\">
    <a:alpha val=\"90000\"/>
  </a:schemeClr>
</a:glow>

var glow = new Glow { Radius = 101600 };

var schemeClr = new SchemeColor { Val = ColorSchemeIndexValues.Accent1 };
var alpha = new Alpha { Val = 90000 };
schemeClr.Append(alpha);
glow.Append(schemeClr);

Soft Red Glow (Large blur radius)

<a:glow rad=\"203200\">
  <a:srgbClr val=\"FF0000\">
    <a:alpha val=\"70000\"/>
  </a:srgbClr>
</a:glow>

var glow = new Glow { Radius = 203200 };  // ~0.22 inch blur

var srgbClr = new RgbColorModelHex { Val = \"FF0000\" };
var alpha = new Alpha { Val = 70000 };  // 70% opacity
srgbClr.Append(alpha);
glow.Append(srgbClr);

White Glow with Tint Modification

<a:glow rad=\"127000\">
  <a:srgbClr val=\"4472C4\">
    <a:alpha val=\"85000\"/>
    <a:tint val=\"50000\"/>
  </a:srgbClr>
</a:glow>

var glow = new Glow { Radius = 127000 };

var srgbClr = new RgbColorModelHex { Val = \"4472C4\" };
srgbClr.Append(new Alpha { Val = 85000 });
srgbClr.Append(new Tint { Val = 50000 });  // Make lighter
glow.Append(srgbClr);

Reference Tables

Glow Radius Values (EMU to Inches/Points)

Common Glow Colors and Uses

Notes

Element Relationships

• Parents: Effect list (\:effectLst), effect DAG (\:effectDag), effect style list (\:effectStyleLst)
• Effect Hierarchy: Glow is an effect node; multiple effects stack in order
• Color Definition: Requires exactly one color element with optional alpha modifier
• Mutual Exclusivity: Glow and other light effects (reflection, glow) may render differently depending on client

Implementation Details

• Blur Radius: Only required attribute; controls glow softness and spread distance
• Radius Units: EMU (English Metric Units); 914400 EMU = 1 inch
• Color Requirements: Any color type supported (RGB, scheme, HSL, system)
• Transparency: Alpha value crucial for natural appearance; full opacity (100000) may appear harsh
• Rendering: Glow effects render consistently across Word, PowerPoint, Excel, and Impress
• Performance: Glow is lightweight; multiple glows per shape allowed but performance-sensitive
• Layering: Glow can combine with shadow effects for enhanced depth
• Theme Integration: Using scheme colors enables automatic color updates with theme changes
• Common Values: 76200 (6pt) for subtle, 152400 (12pt) for strong glows
• Semantic Meaning: Glow typically indicates selection, emphasis, or important state
• Compatibility: Glow effects supported in Office 2007 and later; older clients may ignore