2004-03-31  Michael Natterer  <mitch@gimp.org>

	* app/core/gimp-transform-utils.c
	(gimp_transform_matrix_perspective): make sure 0.0/0.0 results
	in 1.0, not NaN.

	* app/core/gimpdrawable-transform.c
	(gimp_drawable_transform_tiles_affine): instead of returning NULL
	if the transformation shrinks the tiles completely away, return at
	least the pixel (or the row or column of pixels) which best covers
	the sub-pixel area of the transform result:

	- Changed rounding of the transformed coordinates from RINT()
	  to floor()/ceil() so we don't cut off sub-pixel portions of the
	  transform result.
	- Force the minimal size if the changed rounding didn't help.

	Fixes bug #138117.

	Also added paranoia code which falls back to clip_result if the
	passed matrix produces NaN coordinates (copied the FINITE() macro
	from image_cmds.c).