Returns an <code>ImageData</code> based on the receiver
Modifications made to this <code>ImageData</code> will not
affect the Image.
@return an <code>ImageData</code> containing the image's data and attributes
@exception SWTException <ul>
<li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li>
<li>ERROR_INVALID_IMAGE - if the image is not a bitmap or an icon</li>
</ul>
Returns an <code>ImageData</code> based on the receiver Modifications made to this <code>ImageData</code> will not affect the Image.
@return an <code>ImageData</code> containing the image's data and attributes
@exception SWTException <ul> <li>ERROR_GRAPHIC_DISPOSED - if the receiver has been disposed</li> <li>ERROR_INVALID_IMAGE - if the image is not a bitmap or an icon</li> </ul>
@see ImageData