Expand Method—ArcGIS Pro

Creates a new envelope expanded by the amount specified. Expand moves the X and Y coordinates of the sides toward or away from each other to scale the size of the Envelope.

Syntax

C#
Visual Basic (Declaration)

public Envelope Expand( 
   double sx,
   double sy,
   bool asRatio
)

Public Function Expand( _
   ByVal sx As Double, _
   ByVal sy As Double, _
   ByVal asRatio As Boolean _
) As Envelope

Parameters

sx: Scale X factor. Factor must be 0 or greater. Values greater than 1 creates a larger envelope, and less then 1 shrinks it.
sy: Scale Y factor. Factor must be 0 or greater. Values greater than 1 creates a larger envelope, and less then 1 shrinks it.
asRatio: If asRatio = TRUE, the expansion is multiplicative. If FALSE, the expansion is additive.

Return Value

Expanded envelope

Remarks

If asRatio = FALSE, the expansion is additive.
XMin = XMin - sx
YMin = YMin - sy
XMax = XMax + sx
YMax = YMax + sy

If asRatio = TRUE, the expansion is multiplicative. If the user wants to increase the envelope width by 10%, then dx = 1.1. On the other hand, if the user intends to decrease the width by 10%, then dx = 0.9. No negative number allowed when asRatio is set to TRUE.
XMin = XMin - (sx-1)*Width/2
YMin = YMin - (sy-1)*Height/2
XMax = XMax + (sx-1)*Width/2
YMax = YMax + (sy-1)*Height/2
The Envelope remains centered at the same position.

Example

Example: Expand the envelope by 10%

Envelope expanded = myEnvelope.Expand(1.1,1.1,true);

// Use a builder convenience method or use a builder constructor.

// Builder convenience methods don't need to run on the MCT.
Envelope envelope = EnvelopeBuilder.CreateEnvelope(100.0, 100.0, 500.0, 500.0);

// shrink the envelope by 50%
Envelope result = envelope.Expand(0.5, 0.5, true);

// Builder constructors need to run on the MCT.
ArcGIS.Desktop.Framework.Threading.Tasks.QueuedTask.Run(() =>
{
  using (EnvelopeBuilder eBuilder = new EnvelopeBuilder(100.0, 100.0, 500.0, 500.0))
  {
    // shrink by 50%
    eBuilder.Expand(0.5, 0.5, true);

    result = eBuilder.ToGeometry();
  }
});

Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

Reference

Envelope Class
Envelope Members