Encrypt Annotation Object

The encrypt annotation object (ANNOBJECT_ENCRYPT) is a rectangular object that is used to encrypt rectangular portions of a bitmap.

It can also be used to encrypt the entire bitmap. In automated mode, the encrypt object is created by clicking and dragging the mouse to create the rectangular encrypt object. In design mode, the encrypt object is visible but partially transparent to show the part of the image that it covers. In run mode, the encrypt object is invisible.

You must call AnnEncryptApply method to apply the encrypt object. Once applied, the portion of the bitmap under the encrypt object becomes scrambled, and the encrypt object state changes to decryptor. Using different keys before calling this function gives different scrambling patterns The decryptor state differs from the encryptor state in that a decryptor cannot be moved, and cannot be changed to an encryptor. The scrambling can be removed by calling AnnEncryptApply on the decrypt object with the appropriate arguments. If successful, the decryptor state changes to encryptor. An encrypt object in the encryptor state can be moved, can have its key changed, and can be changed to a decrypt object.

The encrypt object is useful for encrypting portions of a bitmap. After encrypting, the scrambled bitmap cannot easily be unscrambled without the associated annotation file. The scrambling can be removed by using the associated annotation file, or by using automation mode to manually change the state from encryptor to a decryptor, position it correctly, and setting the key appropriately.

Overlapping regions can be encrypted. When encrypting overlapping regions, note the following points:

$image\sqrblit.gif$ All annotation objects have an order in which they are drawn (the Z-order).

$image\sqrblit.gif$ The encryptors are encrypted from the front of the Z-order to the back.

$image\sqrblit.gif$ Those that are drawn first are encrypted first. Those that are drawn last ("on top" of other encryptors) are encrypted last.

$image\sqrblit.gif$ The Z-order can be changed through automation by right-clicking and choosing "Send To Front" or "Send To Back".

$image\sqrblit.gif$ The decrypt objects are decrypted in reverse order of the encrypt objects.

Use the AnnGetEncryptOptions method to get the encrypt options of an encrypt or a decrypt object. These options are in an ILEADRasterAnnotation Interface, TAnnEncryptOptions.

Use the AnnSetEncryptOptions method to set the encrypt options of an encrypt or a decrypt object. These options are in an ILEADRasterAnnotation Interface, TAnnEncryptOptions.

Use the AnnGetSecondaryMetafile method to retrieve the current metafile for an encrypt object in a ‘decryptor’ state.

With low-level functions, you must define the size and position of the rectangle. Other applicable properties have the following defaults, which you can change:

Visible	Defaults to FALSE. It can be changed using the AnnSetVisible method.
Selected	Defaults to FALSE. It can be changed using the AnnSetSelected method.
Name	Defaults to an empty string. It can be changed using the AnnSetNameOptions method.
Metafile	Defaults to a black skeleton key. It can be changed using the AnnSetMetafile method.
Secondary Metafile	Defaults to a red skeleton key. It can be changed using the AnnSetMetafile method.
Hyperlink	Defaults to None. It can be changed using the AnnSetHyperlinkString method.
Tag (identifier)	Defaults to 0. It can be changed using the AnnSetTag method.
Window handle	Defaults to NULL or the handle inherited from the container. It can be changed for all objects using the AnnSetWnd method.
User mode	Defaults to design mode or the mode inherited from the container. It can be changed for all objects using the AnnUserMode property.

For information on flipping, reversing or rotating annotation objects, refer to Flipping, Reversing and Rotating Annotation Objects.