Converted to D by clayasaurus

Rotozoom/Zoom function for SDL
========================================================================================

(C) LGPL, A. Schiffler, aschiffler@cogeco.com - see LICENSE for details.


INTERFACE
---------
 
 
SDL_Surface * rotozoomSurface (SDL_Surface *src, double angle, double zoom, int smooth);

 Rotates and zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
 'angle' is the rotation in degrees. 'zoom' a scaling factor. If 'smooth' is 1
 then the destination 32bit surface is anti-aliased. If the surface is not 8bit
 or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.



SDL_Surface * zoomSurface (SDL_Surface *src, double zoomx, double zoomy, int smooth);

 Zoomes a 32bit or 8bit 'src' surface to newly created 'dst' surface.
 'zoomx' and 'zoomy' are scaling factors for width and height. If 'smooth' is 1
 then the destination 32bit surface is anti-aliased. If the surface is not 8bit
 or 32bit RGBA/ABGR it will be converted into a 32bit RGBA format on the fly.


Smoothing (interpolation) flags work only on 32bit surfaces:

 #define SMOOTHING_OFF		0
 #define SMOOTHING_ON		1


EXAMPLE
-------

Run 
	./configure
	make

Test with
	./testrotozoom

Check out the testrotozoom.c code for how to preprocess non-32bit surfaces
for better speed.

Unzip VisualC.zip for VC projects files.


CHANGES
-------

Ver 1.6 - Mon Nov 19 21:19:26 EST 2001
* Added interpolation to alpha channel (simplifies code)
* Ran the sourcecode through 'indent' for better readability

Ver 1.5 - Sat Jul  7 13:02:07 EDT 2001
* Added project files (VisualC.zip) and modifications for VC project building.
* Fixed old versioning in configure.in file.
* Fixed LICENSE file and LGPL source reference.

Ver 1.4 - Mon Jun  4 12:15:31 EDT 2001
* Removed SDL_SoftStretch call again in favour of an internal zoom routine.
* Added new zoomSurface() function with seperate X and Y zoom factors.

Ver 1.3 - Thu May 31 08:37:36 EDT 2001
* Modified code to handle RGBA or ABGR source surfaces transparently.
* More error checking, source surface locking.
* Slighly expanded test program with event handling.

Ver 1.2 - Wed May 30 18:18:05 EDT 2001
* Fixed the completely broken 32bit routine's pointer arithmetic.
* Uses SDL_SoftStretch in certain cases (angle=0, smooth=0).
* Convert source surface on the fly if not 8/32bit.
* Added license file - was empty before (duh).

Ver 1.1 - Wed May 23 15:04:42 EDT 2001
* Added automake/autoconf scripts and testprogram.

Ver 1.0 - Fri Mar 16 08:16:06 EST 2001
* Initial release


COMMENTS
--------

SDL_rotozoom was designed to work with SDL Ver. 1.2 and higher - see
http://www.libsdl.org for more info in the SDL library.

The code is not super optimal - but it should be fast enough even for some
realtime effects if the bitmaps are kept small.

The routines are mostly ment to be used for pre-rendering stuff in higher 
quality (i.e. smoothing) - that's also a reason why the API differs from 
SDL_BlitRect() and creates new target surfaces. The final rendering speed 
is dependent on the target surface size as as it is beeing xy-scanned when
rendering.

Note also that the smoothing toggle is dependent on the input surface bit 
depth. 8bit surfaces will never be smoothed - only 32bit surfaces will.


CONTRIBUTORS
------------

* VisualC project files and fixes from Giorgio Delmondo, giorgio@hurd.it -
  thanks Giorgio.