[Overview][Types][Classes][Procedures and functions][Index] | Reference for unit 'ImgList' (#lcl)

# TCustomImageList.Overlay

Assigns an overlay index for the specified image in the image list.

## Declaration

Source position: imglist.pp line 385

`public procedure TCustomImageList.Overlay(`
`AIndex: Integer;`
`Overlay: TOverlay`
`);`

## Arguments

`AIndex` |  | Ordinal position of the image used as an overlay.
`Overlay` |  | Ordinal position in the internal array where the image index is stored.

## Description

Overlay is a procedure which makes an image in the image list an overlay. An overlay image is drawn transparently over another image. An image list can have up 15 images designated as overlay images (0 is reserved for none).

AIndex contains the position in the image list for the image to use as an overlay image.

Overlay is a TOverlay value that indicates the position in the internal array of overlay indexes where the value in AIndex is stored. The overlay indexes are essentially one-based because an overlay index of zero means that no overlay image is needed.

The Overlay method tells the image list that the image in AIndex is an overlay image referenced using the value in the Overlay parameter instead of the ordinal position in the image list.

Overlay sets the value in the HasOverlays property to True when AIndex contains a valid index position in the image list. Otherwise, the image indexes in each of the internal overlay positions are re-examined to determine the value for HasOverlays.

Use the DrawOverlay method to draw an image along with a specific overlay image.

Use ClearOverlays to reset the image indexes stored in the internal member to the unused value (-1).

## See also

TCustomImageList.HasOverlays |  | Indicates if any images in the list have been used as an overlay image.
TCustomImageList.ClearOverlays |  | Clears images indexes assigned as overlay images in the image list.
TCustomImageList.DrawOverlay |  | Renders an image with an overlay to the specified canvas.
TCustomImageListResolution.DrawOverlay |  | Draws the specified image with the given overlay.
TOverlay |  | Represents the valid index positions used to access overlay image assignments.