2005-09-03  Michael Natterer  <mitch@gimp.org>

	* app/base/pixel-region.[ch]: some general cleanup.

	(pixel_region_init_temp_buf)
	(pixel_region_init_data): new functions which initialize pixel
	regions on TempBufs and on raw contiguous arrays of pixel data.

	(pixel_region_configure): fixed a bug that has probably been there
	forever: when processing contiguous (non-tiled) data, interpret
	the original x and y coordinates of the region as offsets into
	the data. Before this fix, the initial x and y were simply ignored
	(by using them in a broken way), thus always forcing the upper
	left corner of the region being the beginning of the passed data.

	Lots of code was working around this problem by setting the
	pixel_region's data pointer to the proper starting pixel of the
	region in the middle the buffer.

	* libgimp/gimppixelrgn.c: some general cleanup.

	(gimp_pixel_rgn_configure): same fix as above. Fortunately, nobody
	seems to know that libgimp pixel regions can be used on arrays of
	data, just as core ones. Only two plug-ins were using this
	feature, and they are antique and written by spencer and federico,
	respectively. They both don't use offsets into the buffers and are
	not affected by this change. It's highly unlikely that anybody out
	there knows/uses this feature, so it can IMHO be safely changed.

	* app/base/temp-buf.c
	* app/core/gimpbuffer.c
	* app/core/gimpdrawable-combine.c
	* app/core/gimpdrawable-preview.c
	* app/core/gimpimage-preview.c
	* app/core/gimplayer.c
	* app/paint/gimpbrushcore.c
	* app/paint/gimpclone.c
	* app/paint/gimpconvolve.c
	* app/paint/gimpdodgeburn.c
	* app/paint/gimppaintcore.c
	* app/paint/gimpsmudge.c
	* app/tools/gimpiscissorstool.c
	* app/tools/gimppainttool.c: use the pixel_region_init_foo()
	functions instead of initializing regions of TempBufs and raw data
	manually. Removed lots of workarounds for the broken offset
	handling. The changed places of code are much more readable now.