add Trim menu item

Author: jcupitt

ChangeLog

@@ -1,3 +1,6 @@
+started 8.9.0 10/4/20
+- add find_trim
+
 started 8.7.1 13/11/18
 - fix uint status bar pixels >2**31 [Rob Erdmann]
 - fix crash on redhat [bgilbert]

configure.ac

@@ -1,6 +1,6 @@
 # Process this file with autoconf to produce a configure script.
 
-AC_INIT([nip2], [8.7.1], [vipsip@jiscmail.ac.uk])
+AC_INIT([nip2], [8.9.0], [vipsip@jiscmail.ac.uk])
 
 # foreign stops complaints about a missing README (we use README.md instead)
 # and missing INSTALL (the standard Gnu INSTALL is not very useful)
@@ -16,8 +16,8 @@ dnl of them.
 dnl
 
 m4_define([nip_major_version], [8])
-m4_define([nip_minor_version], [7])
-m4_define([nip_micro_version], [1])
+m4_define([nip_minor_version], [9])
+m4_define([nip_micro_version], [0])
 m4_define([nip_version],
           [nip_major_version.nip_minor_version.nip_micro_version])
 

share/nip2/start/Image.def

@@ -1286,6 +1286,29 @@ Image_crop_item = class
 	}
 }
 
+Trim_item = class Menuaction "_Trim" "crop away edges" {
+	action x = class
+		_result {
+		_vislevel = 3;
+
+		thresh = Scale "threshold" 0 100 10;
+		background = Expression "Background" default_background
+		{
+			default_background 
+				= map mean (bandsplit (extract_area 0 0 1 1 x));
+		}
+
+		_result
+			= Region x l t w h
+		{
+			[l, t, w, h] = vips_call "find_trim" [x.value] [
+				$threshold => thresh.value,
+				$background => background.expr
+			];
+		}
+	}
+}
+
 Image_insert_item = class
 	Menuaction "_Insert" "insert a small image into a large image" {
 	action a b