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Delphi code
bmpRot
A unit for rotating TBitmaps 90, 180, or 270 degrees. Not entirely optimized, but quick enough. It rotates a 1600x1200 image in 800 msec on my Pentium II (400 MHz).
TPanZoomPanel
A TPanel that can display an image, pan, zoom, and paint on it. Define a coordinate system at any time, and the panel will perform the necessary transformations to correctly scale the coordinates. You can even paint while zoomed in!
MessageDigests
MD2, MD4, MD5, SHA-1, and RIPEMD-160 algorithms. Also includes a class for making secure hashes (HMACs) out of these digests.
BlockCiphers
A block cipher class hierarchy, including TDESCipher and TBlowfishCipher. DES implementation encrypts 4.2 megs/sec on my Pentium II. Blowfish has been similarly optimized, encrypting 6.5 megs/sec.
EncryptedRegistry
This class has the same interface as TRegistry, but it encrypts/decrypts data being written/read. This requires the BlockCiphers unit.
RegistryNotification
TRegistryNotifier class. This class creates a thread that waits for a change in a registry key, and terminates when the event happens.
How old is this stuff?

Um, did I just say Pentium II? So yeah, this stuff was written back in 1996-1999. It has been tested on Delphi 1, 2, 3 and 4, but not on any version since.

Some of this code might not be pertinent, given the increasing availability of advanced features built in to Windows. However, for those stuck in GDI-land, the zooming/panning libraries might still be useful. Plus hard drive space is cheap, so here they are.

(The bitmap-rotation code should always be in the ether somewhere, to serve a future date when not one human remembers what a "pointer" was.)

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