add alpha section to Band

added Flatten, Premultiply, Unpremultiply, Blend

Author: jcupitt

ChangeLog

@@ -3,6 +3,8 @@ started 8.5 24/1/17
 - gaussnoise goes via vips8 now
 - add snake option to array join [Joe Padfield]
 - parse_float was broken for numbers starting "0."
+- add alpha section to Image / Band menu ... Flatten, Premultiply,
+  Unpremultiply, Blend
 
 started 8.4.1 25/9/16
 - simplify nip2-icon.rc build, bgilbert

share/nip2/start/Filter.def

@@ -1005,7 +1005,7 @@ Filter_blend_item = class
 	} 
 
 	Blend_alpha_item = class
-		Menuaction "_Alpha" "blend images with optional alpha channels" {
+		Menuaction "Blend _Alpha" "blend images with optional alpha channels" {
 		// usage: layerit foreground background
 		// input images must be either 1 or 3 bands, optionally + 1 band 
 		// which is used as the alpha channel

share/nip2/start/Image.def

@@ -1062,6 +1062,30 @@ Image_band_item = class
 
     sep1 = Menuseparator;
 
+	Flatten_item = class Menuaction "_Flatten" "flatten alpha out of image" {
+		action x = class
+			_result {
+			_vislevel = 3;
+
+			bg = Expression "Background" 0;
+
+			_result = map_unary (flattenimage bg) x;
+		}
+	}
+
+	Premultiply_item = class Menuaction "_Premultiply" "premultiply alpha" {
+		action x = premultiply x;
+	}
+
+	Unpremultiply_item = class 
+		Menuaction "_Unpremultiply" "unpremultiply alpha" {
+		action x = unpremultiply x; 
+	}
+
+	Blend_alpha_item = Filter_blend_item.Blend_alpha_item;
+
+    sep1a = Menuseparator;
+
 	Bandand_item = class
 		Menuaction "Bitwise Band AND" "bitwise AND of image bands" {
 		action x = bandand x;

share/nip2/start/_convert.def

@@ -21,6 +21,36 @@ to_matrix x
 		= error (_ "not image");
 }
 
+/* Try to make a Vector ... works for Vector/Image/Real, plus image/real
+ */
+to_vector x
+	= to_vector x.expr, is_Expression x
+	= x, is_Vector x
+	= oo_unary_function to_vector_op x, is_class x
+	= tov x
+{
+	to_vector_op = Operator "to_vector" tov Operator_type.COMPOUND false;
+
+	tov x
+		= Vector (itov x), is_image x
+		= Vector [x], is_real x
+		= Vector x, is_real_list x
+		= Vector x?0, is_matrix x && len x == 1
+		= Vector (transpose x)?0, is_matrix x && len x?0 == 1
+		= error (_ "bad arguments to " ++ "to_vector");
+
+	itov i
+		= v, is_image i 
+		= error (_ "not image")
+	{
+		m = im_vips2mask ((double) i);
+		v 
+			= m.value?0, m.height == 1
+			= (transpose m.value)?0, m.width == 1
+			= error (_ "image is not 1xN or Nx1");
+	}
+}
+
 /* Try to make an Image ... works for Vector/Matrix/Real, plus image/real
  * Special case for Colour ... pull out the colour_space and set Type in the
  * image.

share/nip2/start/_stdenv.def

@@ -2528,3 +2528,53 @@ gaussnoise width height mean sigma
 		$sigma => to_real sigma
 	];
 }
+
+flattenimage bg x 
+	= oo_unary_function flatten_op x, is_class x
+	= flt (to_vector bg) x, is_image x 
+	= error (_ "bad arguments to " ++ "flattenimage")
+{
+	flatten_op = Operator "flatten" 
+		(flattenimage bg) Operator_type.COMPOUND_REWRAP false;
+
+	flt bg x
+		= out
+	{
+		[out] = vips_call "flatten" [x] [
+			$background => bg.value 
+		];
+	}
+}
+
+premultiply x 
+	= oo_unary_function premultiply_op x, is_class x
+	= prem x, is_image x 
+	= error (_ "bad arguments to " ++ "premultiply")
+{
+	premultiply_op = Operator "premultiply" 
+		premultiply Operator_type.COMPOUND_REWRAP false;
+
+	prem x
+		= out
+	{
+		[out] = vips_call "premultiply" [x] [
+		];
+	}
+}
+
+unpremultiply x 
+	= oo_unary_function unpremultiply_op x, is_class x
+	= unprem x, is_image x 
+	= error (_ "bad arguments to " ++ "unpremultiply")
+{
+	unpremultiply_op = Operator "unpremultiply" 
+		unpremultiply Operator_type.COMPOUND_REWRAP false;
+
+	unprem x
+		= out
+	{
+		[out] = vips_call "unpremultiply" [x] [
+		];
+	}
+}
+

src/heap.c

@@ -1891,7 +1891,7 @@ heap_ip_to_gvalue( PElement *in, GValue *out )
 			im_ref_string_set( out, name );
 		}
 #if VIPS_MAJOR_VERSION > 7 || VIPS_MINOR_VERSION > 39
-		/* vips_value_set_array_image() is a 7.40 feature.
+		/* vips_value_set_array_*() is a 7.40 feature.
 		 */
 		else if( heap_is_imagevec( in, &result ) &&
 			result ) { 
@@ -1914,6 +1914,16 @@ heap_ip_to_gvalue( PElement *in, GValue *out )
 				g_object_ref( ivec[i] ); 
 			}
 		}
+		else if( heap_is_realvec( in, &result ) &&
+			result ) { 
+			double realvec[100];
+			int n;
+
+			if( (n = heap_get_realvec( in, realvec, 100 )) < 0 ) 
+				return( FALSE );
+			g_value_init( out, VIPS_TYPE_ARRAY_DOUBLE );
+			vips_value_set_array_double( out, realvec, n );
+		}
 #endif
 		else {
 			error_top( _( "Unimplemented list type." ) );