add "seed" param to perlin, worley and gaussnoise

see https://github.com/libvips/libvips/issues/1884

ChangeLog

@@ -8,6 +8,7 @@
 - have a lock just for pdfium [DarthSim]
 - get pdfium load building again [Projkt-James]
 - add _source load support for pdfium
+- add "seed" param to perlin, worley and gaussnoise
 
 18/10/20 started 8.10.3
 - relax heic is_a rules [hisham]

libvips/create/gaussnoise.c

@@ -75,7 +75,8 @@ typedef struct _VipsGaussnoise {
 	double mean;
 	double sigma;
 
-	/* Per-image seed. 
+	/* Per-image seed. Each pixel is seeded by this plus the (x,
+	 * y) coordinate.
 	 */
 	guint32 seed;
 } VipsGaussnoise;
@@ -138,11 +139,6 @@ vips_gaussnoise_build( VipsObject *object )
 	vips_image_pipelinev( create->out, 
 		VIPS_DEMAND_STYLE_ANY, NULL );
 
-	/* The seed for this image. Each pixel is seeded by this plus the (x,
-	 * y) coordinate.
-	 */
-	gaussnoise->seed = UINT_MAX * g_random_double(); 
-
 	if( vips_image_generate( create->out, 
 		NULL, vips_gaussnoise_gen, NULL, gaussnoise, NULL ) )
 		return( -1 );
@@ -196,6 +192,13 @@ vips_gaussnoise_class_init( VipsGaussnoiseClass *class )
 		G_STRUCT_OFFSET( VipsGaussnoise, sigma ),
 		0, 100000, 30 );
 
+	VIPS_ARG_INT( class, "seed", 7, 
+		_( "Seed" ), 
+		_( "Random number seed" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsGaussnoise, seed ),
+		INT_MIN, INT_MAX, 0 );
+
 }
 
 static void
@@ -203,6 +206,7 @@ vips_gaussnoise_init( VipsGaussnoise *gaussnoise )
 {
 	gaussnoise->mean = 128.0;
 	gaussnoise->sigma = 30.0;
+	gaussnoise->seed = UINT_MAX * g_random_double(); 
 }
 
 /**

libvips/create/perlin.c

@@ -244,8 +244,6 @@ vips_perlin_build( VipsObject *object )
 		VIPS_ROUND_UP( perlin->height, perlin->cell_size ) / 
 		perlin->cell_size;
 
-	perlin->seed = g_random_double() * 0xffffffffu;
-
 	vips_image_init_fields( create->out,
 		perlin->width, perlin->height, 1,
 		perlin->uchar ? VIPS_FORMAT_UCHAR : VIPS_FORMAT_FLOAT, 
@@ -321,12 +319,20 @@ vips_perlin_class_init( VipsPerlinClass *class )
 		G_STRUCT_OFFSET( VipsPerlin, uchar ),
 		FALSE );
 
+	VIPS_ARG_INT( class, "seed", 5, 
+		_( "Seed" ), 
+		_( "Random number seed" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsPerlin, seed ),
+		INT_MIN, INT_MAX, 0 );
+
 }
 
 static void
 vips_perlin_init( VipsPerlin *perlin )
 {
 	perlin->cell_size = 256;
+	perlin->seed = UINT_MAX * g_random_double();
 }
 
 /**

libvips/create/worley.c

@@ -277,8 +277,6 @@ vips_worley_build( VipsObject *object )
 		VIPS_ROUND_UP( worley->height, worley->cell_size ) / 
 		worley->cell_size;
 
-	worley->seed = g_random_double() * 0xffffffffu;
-
 	vips_image_init_fields( create->out,
 		worley->width, worley->height, 1,
 		VIPS_FORMAT_FLOAT, VIPS_CODING_NONE, 
@@ -328,12 +326,20 @@ vips_worley_class_init( VipsWorleyClass *class )
 		G_STRUCT_OFFSET( VipsWorley, cell_size ),
 		1, VIPS_MAX_COORD, 256 );
 
+	VIPS_ARG_INT( class, "seed", 4, 
+		_( "Seed" ), 
+		_( "Random number seed" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsWorley, seed ),
+		INT_MIN, INT_MAX, 0 );
+
 }
 
 static void
 vips_worley_init( VipsWorley *worley )
 {
 	worley->cell_size = 256;
+	worley->seed = UINT_MAX * g_random_double();
 }
 
 /**