Bug 546549 : Better Type Checking reviewed by mitch

Bug 546549 : Better Type Checking reviewed by mitch

2008-08-06  Sven Herzberg  <sven@imendio.com>

	Bug 546549 : Better Type Checking
	reviewed by mitch

	* gdk-pixbuf.c (gdk_pixbuf_copy), (gdk_pixbuf_get_colorspace),
	(gdk_pixbuf_get_n_channels), (gdk_pixbuf_get_has_alpha),
	(gdk_pixbuf_get_bits_per_sample), (gdk_pixbuf_get_pixels),
	(gdk_pixbuf_get_width), (gdk_pixbuf_get_height),
	(gdk_pixbuf_get_rowstride): use GDK_IS_PIXBUF() and not pixbuf != NULL
	in g_return_*() statements

svn path=/trunk/; revision=21025