a:innerShdw (Inner Shadow)

Description

a:innerShdw is the DrawingML inner shadow effect element that creates a shadow on the inside edges of a shape. It is defined in ECMA-376 Part 1 §20.1.8.8.

Inner shadow effects simulate depth and inset appearance by:

• Shadowing the interior edges of a shape
• Creating a recessed or embossed look
• Using offset, blur radius, and color to control appearance
• Enhancing visual hierarchy in diagrams

Inner shadows are useful for:

• Creating 3D-like inset effects
• Emphasizing shape boundaries
• Adding visual sophistication to designs
• Making shapes appear pressed or carved

Attributes

Examples

Simple Inner Shadow

<a:innerShdw blurRad="50800" dist="38100" dir="2700000">
  <a:srgbClr val="000000">
    <a:alpha val="60000"/>
  </a:srgbClr>
</a:innerShdw>

using DocumentFormat.OpenXml.Drawing;

var innerShdw = new InnerShadow 
{ 
  BlurRadius = 50800,    // ~0.055 inch blur
  Distance = 38100,      // ~0.042 inch offset
  Direction = 2700000    // 270 degrees (left)
};

var srgbClr = new RgbColorModelHex { Val = "000000" };
var alpha = new Alpha { Val = 60000 }; // 60% opacity
srgbClr.Append(alpha);
innerShdw.Append(srgbClr);

Strong Inset Effect

<a:innerShdw blurRad="76200" dist="76200" dir="2700000" algn="l" rotWithShape="1">
  <a:srgbClr val="404040">
    <a:alpha val="70000"/>
  </a:srgbClr>
</a:innerShdw>

var innerShdw = new InnerShadow 
{ 
  BlurRadius = 76200,
  Distance = 76200,
  Direction = 2700000,
  Alignment = RectangleAlignmentValues.Left,
  RotateWithShape = true
};

var srgbClr = new RgbColorModelHex { Val = "404040" };
var alpha = new Alpha { Val = 70000 };
srgbClr.Append(alpha);
innerShdw.Append(srgbClr);

Notes

• Shadow direction: 0°=right, 2700000=left (in 60,000ths of degree)
• Blur radius controls softness of shadow edge
• Distance controls offset from shape edge
• Inner shadows typically use dark colors with reduced opacity
• Rotate with shape option keeps effect oriented properly when shape rotates
• Inner shadows can be combined with outer shadows and other effects