Routines (alphabetical) > Object Classes > Graphics Object Classes > IDLgrWindow::OnExpose

# IDLgrWindow::OnExpose

Syntax | Arguments | Keywords | Version History

The IDLgrWindow::OnExpose procedure method handles notification from the window that an expose event has occurred.

Note: This method is only useful in conjunction with the Export Bridge. By default, the OnExpose method will automatically redraw the graphics hierarchy specified by the GRAPHICS_TREE property. If you are using a subclass of IDLgrWindow and require additional functionality, you should override this method. Your method will be automatically called by the Export Bridge. For more information, see "Exporting Drawable Objects"(Chapter 11, IDL Connectivity Bridges in the `help/pdf` directory of your IDL installation).

## Syntax

Obj->[IDLgrWindow::]OnExpose, X, Y, Width, Height

## Arguments

### X

A floating-point value representing the x-coordinate of the lower left corner of the newly exposed portion of the canvas (in device coordinates).

### Y

A floating-point value representing the y-coordinate of the lower left corner of the newly exposed portion of the canvas (in device coordinates).

### Width

A floating-point value representing the width of the newly exposed portion of the canvas (in device coordinates).

### Height

A floating-point value representing the height of the newly exposed portion of the canvas (in device coordinates).

## Keywords

None

## Version History

6.3 | Introduced