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SetOverlayImage Method


Sets the overlay image for a certain index.

public void SetOverlayImage( 
   int index, 
   RasterImage overlayImage, 
   RasterGetSetOverlayImageMode mode 
Public Sub SetOverlayImage( _ 
   ByVal index As Integer, _ 
   ByVal overlayImage As RasterImage, _ 
   ByVal mode As RasterGetSetOverlayImageMode _ 
- (BOOL)setOverlay:(nullable LTRasterImage *)overlayImage  
             error:(NSError **)error 
public void setOverlayImage( 
  int index,  
  RasterImage overlayImage,  
  RasterGetSetOverlayImageMode mode 
void SetOverlayImage(  
   int index, 
   RasterImage^ overlayImage, 
   RasterGetSetOverlayImageMode mode 


The index of the overlay for which to set the image. This index is zero-based and should be less than or equal to MaxOverlays.

The new overlay image. This can be null, in which case the corresponding overlay image will be freed.

Determines how to insert the image, possible values are:

Mode Description
RasterGetSetOverlayImageMode.Copy A copy of overlayImage is inserted in the overlay list.
RasterGetSetOverlayImageMode.NoCopy overlayImage is set into the overlay list without making a copy. You should be careful when modifying overlayImage because you can modify/invalidate the entry in the overlay image list.
RasterGetSetOverlayImageMode.Move overlayImage is moved into the overlay list. It will also be disposed, so you cannot make changes to it. This is recommended over RasterGetSetOverlayImageMode.NoCopy.


This method is available in the (Document/Medical only) Toolkits.

Calling this method with a valid image set in overlayImage frees the old overlay image at the specified index and sets the overlay image at the index to the new image referenced by overlayImage.

If overlayImage is null, the old overlay image is freed and the size is reset to:

OverlayWidth = Image.ImageWidth - OverlayImage.Origin.X OverlayHeight = Image.ImageHeight - OverlayImage.Origin.Y

If mode is RasterGetSetOverlayImageMode.NoCopy and overlayImage is not null (Nothing), the image is inserted as is into the overlay array. This means whenever you update the data from overlayImage, the overlay image is changed too. Great care should be taken when using this flag because you can invalidate the overlay image stored in the array. For example, if you dispose the overlay image, the data pointed to by the overlay image from the internal array is also freed, but the array does not know that this has happened and thinks the data pointer is still valid. If the overlay image is accessed in some way, a crash will occur. A safer way of quickly setting the data is to use RasterGetSetOverlayImageMode.Move.

If mode is RasterGetSetOverlayImageMode.Move, the data from the overlayImage is copied into the overlay array and then the overlayImage object is disposed. This means that you can do anything with the overlayImage object and the overlay image stored in the array will be unaffected. This is the most efficient way of setting the overlay image, because no copy will take place. overlayImage must reference an image that is 1-bit, overwise, this method will throw an exception.

For more information, refer to Overlay Overview.


For an example, refer to GetOverlayImage


Target Platforms

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