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# Recursive Dilation for Visual ICON Selection

IP.com Disclosure Number: IPCOM000111985D
Original Publication Date: 1994-Apr-01
Included in the Prior Art Database: 2005-Mar-26
Document File: 4 page(s) / 127K

IBM

## Related People

Redpath, SD: AUTHOR [+2]

## Abstract

A method is presented for an efficient process for providing a technique for CUA's definition of a Visual for Icon Selection.

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Recursive Dilation for Visual ICON Selection

Fig. 1

A method is presented for an efficient process for providing a
technique for CUA's definition of a Visual for Icon Selection.

Following is a description of the process.  The bit mask for an
icon is used as the dilation bitmap.  The dilation bitmap (bitmap) is
bitblt into a working memory area four times (Fig. 1).  Each
iteration shifts the bitmap on a diagonal.  It is mathematically
shown below.

bitblt(bitmap,x+1,y+1);   /*top right diagonal*/

bitblt(bitmap,x+1,y-1);   /*bottom right diagonal*/

bitblt(bitmap,x-1,y-1);   /*bottom left diagonal*/

bitblt(bitmap,x-1,y+1);   /*top left diagonal*/

The  working  memory  area  is  now  used again as the dilation
bitmap.  The working memory area bitmap (wbitmap) is  bitblt  to  the
screen  four times.   Each iteration shifts the bitmap on a diagonal.
It is mathematically shown below.

bitblt(wbitmap,x+1,y+1);   /*top right diagonal*/

bitblt(wbitmap,x+1,y-1);   /*bottom right diagonal*/

bitblt(wbitmap,x-1,y-1);   /*bottom left diagonal*/

bitblt(wbitmap,x-1,y+1);   /*top left diagonal*/

Finally, the icon is bitblt on the screen.   The  result  is  a
smooth  outline around the icon with no stair edges.  Total number of
bitblts is nine.  Since the bit mask is only one  bit  per  pel,  the
total  cost of drawing an outline around an eight-bit-per-pel icon is
an or...