add a @background option to embed and dzsave

you can now set the background colour for edge tiles in dzsave and embed, eg.:

vips dzsave k2.jpg x --background "1 2 3"

ChangeLog

@@ -1,5 +1,7 @@
 3/10/12 started 7.31.0
 - dzsave can write zoomify and google maps layout as well
+- embed has 'background' option
+- dzsave --layout google has a @background option
 
 2/10/12 started 7.30.4
 - remove options from format string in .dzi (thanks Martin)

libvips/conversion/embed.c

@@ -23,6 +23,8 @@
  * 	- cleanups
  * 15/10/11
  * 	- rewrite as a class
+ * 10/10/12
+ *	- add @background
  */
 
 /*
@@ -79,11 +81,16 @@ typedef struct _VipsEmbed {
 	VipsImage *in;
 
 	VipsExtend extend;
+	VipsArea *background;
 	int x;
 	int y;
 	int width;
 	int height;
 
+	/* Pixel we paint calculated from background.
+	 */
+	VipsPel *ink;
+
 	/* Geometry calculations. 
 	 */
 	VipsRect rout;		/* Whole output area */
@@ -257,6 +264,14 @@ vips_embed_gen( VipsRegion *or, void *seq, void *a, void *b, gboolean *stop )
 				embed->extend == 0 ? 0 : 255 );
 		break;
 
+	case VIPS_EXTEND_BACKGROUND:
+		/* Paint the borders a solid value.
+		 */
+		for( i = 0; i < 8; i++ )
+			vips_region_paint_pel( or, &embed->border[i], 
+				embed->ink ); 
+		break;
+
 	case VIPS_EXTEND_COPY:
 		/* Extend the borders.
 		 */
@@ -327,6 +342,15 @@ vips_embed_build( VipsObject *object )
 	if( vips_image_pio_input( embed->in ) )
 		return( -1 );
 
+	if( !(embed->ink = vips__vector_to_ink( 
+		"VipsEmbed", embed->in,
+		embed->background->data, embed->background->n )) )
+		return( -1 );
+
+	if( !vips_object_get_argument_assigned( object, "extend" ) &&
+		vips_object_get_argument_assigned( object, "background" ) )
+		embed->extend = VIPS_EXTEND_BACKGROUND; 
+
 	switch( embed->extend ) {
 	case VIPS_EXTEND_REPEAT:
 {
@@ -398,6 +422,7 @@ vips_embed_build( VipsObject *object )
 
 	case VIPS_EXTEND_BLACK:
 	case VIPS_EXTEND_WHITE:
+	case VIPS_EXTEND_BACKGROUND:
 	case VIPS_EXTEND_COPY:
 		if( vips_image_copy_fields( conversion->out, embed->in ) )
 			return( -1 );
@@ -559,13 +584,22 @@ vips_embed_class_init( VipsEmbedClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsEmbed, extend ),
 		VIPS_TYPE_EXTEND, VIPS_EXTEND_BLACK );
+
+	VIPS_ARG_BOXED( class, "background", 12, 
+		_( "Background" ), 
+		_( "Colour for background pixels" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsEmbed, background ),
+		VIPS_TYPE_ARRAY_DOUBLE );
 }
 
 static void
 vips_embed_init( VipsEmbed *embed )
 {
-	/* Init our instance fields.
-	 */
+	embed->extend = VIPS_EXTEND_BLACK;
+	embed->background = 
+		vips_area_new_array( G_TYPE_DOUBLE, sizeof( double ), 1 ); 
+	((double *) (embed->background->data))[0] = 0;
 }
 
 /**
@@ -581,6 +615,7 @@ vips_embed_init( VipsEmbed *embed )
  * Optional arguments:
  *
  * @extend: how to generate the edge pixels
+ * @background: colour for edge pixels
  *
  * The opposite of vips_extract_area(): embed @in within an image of size 
  * @width by @height at position @x, @y.  @extend

libvips/foreign/dzsave.c

@@ -24,6 +24,8 @@
  * 	- remove filename options from format string in .dzi (thanks Martin)
  * 3/10/12
  * 	- add zoomify and google maps output
+ * 10/10/12
+ * 	- add @background option
  */
 
 /*
@@ -131,6 +133,7 @@ struct _VipsForeignSaveDz {
 	int overlap;
 	int tile_size;
 	VipsForeignDzLayout layout;
+	VipsArea *background;
 
 	Layer *layer;			/* x2 shrink pyr layer */
 
@@ -703,7 +706,7 @@ strip_work( VipsThreadState *state, void *a )
 		VipsImage *z;
 
 		if( vips_embed( x, &z, 0, 0, dz->tile_size, dz->tile_size,
-			"extend", VIPS_EXTEND_WHITE,
+			"background", dz->background,
 			NULL ) ) {
 			g_object_unref( x );
 			return( -1 );
@@ -1133,6 +1136,13 @@ vips_foreign_save_dz_class_init( VipsForeignSaveDzClass *class )
 		G_STRUCT_OFFSET( VipsForeignSaveDz, tile_size ),
 		1, 1024, 256 );
 
+	VIPS_ARG_BOXED( class, "background", 12, 
+		_( "Background" ), 
+		_( "Colour for background pixels" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignSaveDz, background ),
+		VIPS_TYPE_ARRAY_DOUBLE );
+
 	/* How annoying. We stupidly had these in earlier versions.
 	 */
 
@@ -1167,6 +1177,9 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
 	dz->overlap = 1;
 	dz->tile_size = 256;
 	dz->tile_count = 0;
+	dz->background = 
+		vips_area_new_array( G_TYPE_DOUBLE, sizeof( double ), 1 ); 
+	((double *) (dz->background->data))[0] = 255;
 }
 
 /**
@@ -1181,6 +1194,7 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
  * @suffix: suffix for tile tiles 
  * @overlap; set tile overlap 
  * @tile_size; set tile size 
+ * @background: background colour
  *
  * Save an image as a set of tiles at various resolutions. By default dzsave
  * uses DeepZoom layout -- use @layout to pick other conventions.
@@ -1194,6 +1208,10 @@ vips_foreign_save_dz_init( VipsForeignSaveDz *dz )
  *
  * You can set @suffix to something like ".jpg[Q=85]" to set the tile write
  * options. 
+ * 
+ * In Google layout mode, edge tiles are expanded to @tile_size by @tile_size 
+ * pixels. Normally they are filled with white, but you can set another colour
+ * with @background.
  *
  * You can set the size and overlap of tiles with @tile_size and @overlap.
  * They default to the correct settings for the selected @layout. 

libvips/include/vips/conversion.h

@@ -44,6 +44,7 @@ extern "C" {
  * @VIPS_EXTEND_REPEAT: repeat the whole image
  * @VIPS_EXTEND_MIRROR: mirror the whole image
  * @VIPS_EXTEND_WHITE: extend with white (all bits set) pixels
+ * @VIPS_EXTEND_BACKGROUND: extend with colour from the @background property
  *
  * See vips_embed(), vips_conv(), vips_affine() and so on.
  *
@@ -61,6 +62,8 @@ extern "C" {
  * edges
  *
  * #VIPS_EXTEND_WHITE --- new pixels are white, ie. all bits are set
+
+ * #VIPS_EXTEND_BACKGROUND --- colour set from the @background property
  *
  * We have to specify the exact value of each enum member since we have to 
  * keep these frozen for back compat with vips7.
@@ -68,12 +71,13 @@ extern "C" {
  * See also: vips_embed().
  */
 typedef enum {
-	VIPS_EXTEND_BLACK = 0,
-	VIPS_EXTEND_COPY = 1,
-	VIPS_EXTEND_REPEAT = 2,
-	VIPS_EXTEND_MIRROR = 3,
-	VIPS_EXTEND_WHITE = 4,
-	VIPS_EXTEND_LAST = 5
+	VIPS_EXTEND_BLACK,
+	VIPS_EXTEND_COPY,
+	VIPS_EXTEND_REPEAT,
+	VIPS_EXTEND_MIRROR,
+	VIPS_EXTEND_WHITE,
+	VIPS_EXTEND_BACKGROUND,
+	VIPS_EXTEND_LAST
 } VipsExtend;
 
 /** 

libvips/iofuncs/enumtypes.c

@@ -137,6 +137,7 @@ vips_extend_get_type( void )
 			{VIPS_EXTEND_REPEAT, "VIPS_EXTEND_REPEAT", "repeat"},
 			{VIPS_EXTEND_MIRROR, "VIPS_EXTEND_MIRROR", "mirror"},
 			{VIPS_EXTEND_WHITE, "VIPS_EXTEND_WHITE", "white"},
+			{VIPS_EXTEND_BACKGROUND, "VIPS_EXTEND_BACKGROUND", "background"},
 			{VIPS_EXTEND_LAST, "VIPS_EXTEND_LAST", "last"},
 			{0, NULL, NULL}
 		};