Returns <code>getWidth</code> alpha values starting at offset
<code>x</code> in scanline <code>y</code> in the receiver's alpha
data starting at <code>startIndex</code>. The alpha values
are unsigned, between <code>(byte)0</code> (transparent) and
<code>(byte)255</code> (opaque).
@param x the x position of the pixel to begin getting alpha values
@param y the y position of the pixel to begin getting alpha values
@param getWidth the width of the data to get
@param alphas the buffer in which to put the alpha values
@param startIndex the offset into the image to begin getting alpha values
@exception IndexOutOfBoundsException if getWidth is too large
@exception IllegalArgumentException <ul>
<li>ERROR_NULL_ARGUMENT - if pixels is null</li>
<li>ERROR_INVALID_ARGUMENT - if x or y is out of bounds</li>
<li>ERROR_INVALID_ARGUMENT - if getWidth is negative</li>
</ul>
Returns <code>getWidth</code> alpha values starting at offset <code>x</code> in scanline <code>y</code> in the receiver's alpha data starting at <code>startIndex</code>. The alpha values are unsigned, between <code>(byte)0</code> (transparent) and <code>(byte)255</code> (opaque).
@param x the x position of the pixel to begin getting alpha values @param y the y position of the pixel to begin getting alpha values @param getWidth the width of the data to get @param alphas the buffer in which to put the alpha values @param startIndex the offset into the image to begin getting alpha values
@exception IndexOutOfBoundsException if getWidth is too large @exception IllegalArgumentException <ul> <li>ERROR_NULL_ARGUMENT - if pixels is null</li> <li>ERROR_INVALID_ARGUMENT - if x or y is out of bounds</li> <li>ERROR_INVALID_ARGUMENT - if getWidth is negative</li> </ul>