doc/guile-png.texi (Selection): New section

doc/guile-png.texi

@@ -644,6 +644,59 @@ Height of the dimension.
 Check if @var{object} is a @code{<dimension>} instance.
 @end deffn
 
+@subsection Selection
+
+@code{(png graphics selection)} contains a @code{<selection>} class.
+
+@deftp {Class} <selection> @
+                        [#:image=#f] @
+                        [#:position=(make <point>)] @
+                        [#:dimension=(make <dimension>)]
+
+This class describes a selected are for the specified @var{image}.
+
+Constructor parameters:
+@table @asis
+@item #:image (img <png-image>)
+A PNG image.
+@item #:position (pos <point>)
+Position of the top left corner of the selection.
+@item #:dimension (dim <dimension>)
+The size of the selection.
+@end table
+
+@end deftp
+
+@deffn {Method} selection? object
+Check if @var{object} is a @code{<selection>} instance.
+@end deffn
+
+@deffn {Method} selection-image (selection <selection>)
+The base image of a @var{selection}.
+@end deffn
+
+@deffn {Method} selection-position (selection <selection>)
+The position of the selected area.
+@end deffn
+
+@deffn {Method} selection-dimension (selection <selection>)
+The size of the selected area.
+@end deffn
+
+@deffn {Method} png-image-select (image <png-image>) @
+                                 (position <point>) @
+                                 (dimension <dimension>)
+
+Create a new selection out of the specified @var{image}.
+
+@end deffn
+
+@deffn {Method} selection-crop (selection <selection>)
+
+Crop a part of the base image using a @var{selection}.
+
+@end deffn
+
 @section PNG Image Processing
 
 @code{(png image-processing)} provides high-level API for processing PNG