a:prstGeom (Preset Geometry)

Description

\:prstGeom\ is the DrawingML element that defines a preset geometric shape. It is defined in ECMA-376 Part 1 §20.1.8.32.

Preset geometries provide built-in shape definitions for common shapes without requiring custom path definitions. This simplifies shape creation and ensures consistency across documents.

Preset geometries enable:

• Easy creation of standard shapes (circles, rectangles, stars, etc.)
• Consistent geometric properties across Office applications
• Adjustable shapes via adjustment handles
• Fast rendering with optimized geometry paths
• Shape libraries for templates and master slides
• Simple geometry without custom path complexity

Preset geometries differ from:

• Custom geometry (\:custGeom) — User-defined shape paths
• Path geometry (\:path) — Custom vector paths within geometries
• Transform (\:xfrm) — Position/size (separate from geometry)

Attributes

Content Model

\:prstGeom\ structure:

1. a:avLst (optional, 0–1) — Adjustment value list for shape customization

The adjustment list allows shapes to be customized (rounded corners, star points, etc.) using adjustment handles.

Child Elements Table

Preset Shape Reference

Common preset geometry identifiers:

Examples

Simple Rectangle (No Adjustments)

<a:spPr>
  <a:xfrm><a:off x="1000000" y="1000000"/><a:ext cx="3000000" cy="2000000"/></a:xfrm>
  <a:prstGeom prst="rect">
    <a:avLst/>
  </a:prstGeom>
</a:spPr>

using DocumentFormat.OpenXml.Drawing;

var spPr = new ShapeProperties();
var transform = new Transform2D();
transform.Append(new Offset { X = 1000000, Y = 1000000 });
transform.Append(new Extents { Cx = 3000000, Cy = 2000000 });
spPr.Append(transform);

var prstGeom = new PresetGeometry { Preset = PresetShapeValues.Rectangle };
prstGeom.Append(new AdjustmentValueList());
spPr.Append(prstGeom);

Rounded Rectangle with Adjustments

<a:prstGeom prst="roundRect">
  <a:avLst>
    <a:gd name="adj" fmla="*/ 50000 w 100000"/>
  </a:avLst>
</a:prstGeom>

var prstGeom = new PresetGeometry { Preset = PresetShapeValues.RoundRectangle };
var avLst = new AdjustmentValueList();
var gd = new GuideEntry 
{ 
  Name = "adj", 
  Formula = "*/ 50000 w 100000"  // Adjustment value
};
avLst.Append(gd);
prstGeom.Append(avLst);

Circle/Ellipse

<a:prstGeom prst="ellipse">
  <a:avLst/>
</a:prstGeom>

var prstGeom = new PresetGeometry { Preset = PresetShapeValues.Ellipse };
prstGeom.Append(new AdjustmentValueList());

Star (5-pointed)

<a:prstGeom prst="star5">
  <a:avLst/>
</a:prstGeom>

var prstGeom = new PresetGeometry { Preset = PresetShapeValues.Star5 };
prstGeom.Append(new AdjustmentValueList());

Flowchart Decision (Diamond)

<a:prstGeom prst="flowChartDecision">
  <a:avLst/>
</a:prstGeom>

var prstGeom = new PresetGeometry 
{ 
  Preset = PresetShapeValues.FlowChartDecision 
};
prstGeom.Append(new AdjustmentValueList());

Heart Shape

<a:prstGeom prst="heart">
  <a:avLst/>
</a:prstGeom>

var prstGeom = new PresetGeometry { Preset = PresetShapeValues.Heart };
prstGeom.Append(new AdjustmentValueList());

Shape Categories

Basic Shapes

Arrows

Flowchart Shapes

Stars & Callouts

Adjustment Values

Shape customization via \:avLst:

Example adjustment formula: ` ` Multiplies adjustment percentage (50000) by width, divides by 100000.

Rendering Behavior

Preset geometry rendering:

Common Patterns

Basic Box with Text

xml <a:prstGeom prst="rect"> <a:avLst/> </a:prstGeom>

Rounded Box (Office style)

xml <a:prstGeom prst="roundRect"> <a:avLst> <a:gd name="adj" fmla="15875"/> </a:avLst> </a:prstGeom>

Flowchart Template

xml <a:prstGeom prst="flowChartDecision"> <a:avLst/> </a:prstGeom>

Star Badge

xml <a:prstGeom prst="star5"> <a:avLst/> </a:prstGeom>

Interaction with Other Elements

Preset geometry works with:

• Transform (\:xfrm) — Position, size, rotation
• Fill (\:solidFill\, etc.) — Interior color
• Line (\:ln) — Outline/border
• Effects (\:effectLst) — Shadows, glows, reflection
• Text body (\:txBody) — Text inside shape
• Adjustment values (\:avLst) — Shape customization

Availability Matrix

Preset geometries available:

Notes

Element Characteristics

• Preset-based: Identifies shape by string ID, not geometry data
• Optimized rendering: No custom path calculations needed
• Adjustable: Many shapes support adjustment handles
• Consistent: Same ID = same geometry across Office applications
• Lightweight: Preset ID stored, actual path computed by renderer

Advantages

• File size: Minimal storage (just preset ID + adjustments)
• Consistency: Shapes render identically across applications
• Adjustability: Customizable without custom geometry
• Performance: Optimized rendering paths
• Ease of use: Simple shape creation via preset library

Disadvantages

• Limited flexibility: Cannot create arbitrary custom shapes
• Fixed variants: Only available preset shapes supported
• Adjustment limits: Only shape-specific adjustments available

Compatibility

• Office 2007 and later
• All preset shapes consistently supported
• Older clients render with degradation
• PDF export preserves preset shape rendering

Best Practices

• Use preset geometry for standard shapes
• Consider custom geometry (\:custGeom) only for non-standard needs
• Document which presets are used in templates
• Test preset rendering across Office versions
• Use adjustment values to customize without creating custom geometry
• Combine presets with fill/effects for professional appearance