add ".pnm" save

see https://github.com/libvips/libvips/issues/3016

ChangeLog

@@ -10,6 +10,7 @@ master
 - require libjxl 0.7+
 - add "interlace" option to GIF save [dloebl]
 - magick load sets "magick-format" metadata [aksdb]
+- add ".pnm", save as image format [ewelot]
 
 24/7/22 started 8.13.1
 - fix im7 feature detection in meson

libvips/foreign/pforeign.h

@@ -131,6 +131,7 @@ extern const char *vips__save_pbm_suffs[];
 extern const char *vips__save_pgm_suffs[];
 extern const char *vips__save_ppm_suffs[];
 extern const char *vips__save_pfm_suffs[];
+extern const char *vips__save_pnm_suffs[];
 
 int vips__ppm_save_target( VipsImage *in, VipsTarget *target,
 	gboolean ascii, gboolean squash );

libvips/foreign/ppmload.c

@@ -141,11 +141,14 @@ static char *magic_names[] = {
 
 /* Shared with ppmsave.
  */
-const char *vips__ppm_suffs[] = { ".pbm", ".pgm", ".ppm", ".pfm", NULL };
+const char *vips__ppm_suffs[] = { 
+        ".pbm", ".pgm", ".ppm", ".pfm", ".pnm", NULL 
+};
 const char *vips__save_pbm_suffs[] = { ".pbm", NULL };
 const char *vips__save_pgm_suffs[] = { ".pgm", NULL };
 const char *vips__save_ppm_suffs[] = { ".ppm", NULL };
 const char *vips__save_pfm_suffs[] = { ".pfm", NULL };
+const char *vips__save_pnm_suffs[] = { ".pnm", NULL };
 
 static gboolean
 vips_foreign_load_ppm_is_a_source( VipsSource *source )

libvips/foreign/ppmsave.c

@@ -14,6 +14,8 @@
  * 	- don't add date with @strip [ewelot]
  * 28/10/21
  * 	- add @format, default type by filename
+ * 30/8/22
+ *      - add ".pnm", save as image format [ewelot]
  */
 
 /*
@@ -239,6 +241,7 @@ vips_foreign_save_ppm_build( VipsObject *object )
 	 *   pgm ... 1 band many bit
 	 *   ppm ... 3 band many bit
 	 *   pfm ... 1 or 3 bands, 32 bit
+	 *   pnm ... pick from input
 	 */
 	switch( ppm->format ) {
 	case VIPS_FOREIGN_PPM_FORMAT_PBM:
@@ -265,8 +268,9 @@ vips_foreign_save_ppm_build( VipsObject *object )
 		target_format = VIPS_FORMAT_FLOAT;
 		break;
 
+	case VIPS_FOREIGN_PPM_FORMAT_PNM:
 	default:
-		/* Harmless.
+		/* Just use the input format and interpretation.
 		 */
 		break;
 	}
@@ -527,6 +531,8 @@ vips_foreign_save_ppm_file_build( VipsObject *object )
 		ppm->format = VIPS_FOREIGN_PPM_FORMAT_PGM;
 	else if( vips_iscasepostfix( file->filename, ".pfm" ) )
 		ppm->format = VIPS_FOREIGN_PPM_FORMAT_PFM;
+	else if( vips_iscasepostfix( file->filename, ".pnm" ) )
+		ppm->format = VIPS_FOREIGN_PPM_FORMAT_PNM;
 
 	return( VIPS_OBJECT_CLASS( vips_foreign_save_ppm_file_parent_class )->
 		build( object ) );
@@ -716,6 +722,38 @@ vips_foreign_save_pfm_target_init( VipsForeignSavePfmTarget *target )
 	ppm->format = VIPS_FOREIGN_PPM_FORMAT_PFM;
 }
 
+typedef VipsForeignSavePpmTarget VipsForeignSavePnmTarget;
+typedef VipsForeignSavePpmTargetClass VipsForeignSavePnmTargetClass;
+
+G_DEFINE_TYPE( VipsForeignSavePnmTarget, vips_foreign_save_pnm_target, 
+	vips_foreign_save_ppm_target_get_type() );
+
+static void
+vips_foreign_save_pnm_target_class_init( 
+	VipsForeignSavePfmTargetClass *class )
+{
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
+	VipsOperationClass *operation_class = (VipsOperationClass *) class;
+
+	object_class->nickname = "pnmsave_target";
+	object_class->description = _( "save image in pnm format" );
+
+	foreign_class->suffs = vips__save_pnm_suffs;
+
+	/* Hide from UI.
+	 */
+	operation_class->flags |= VIPS_OPERATION_DEPRECATED;
+}
+
+static void
+vips_foreign_save_pnm_target_init( VipsForeignSavePfmTarget *target )
+{
+	VipsForeignSavePpm *ppm = (VipsForeignSavePpm *) target;
+
+	ppm->format = VIPS_FOREIGN_PPM_FORMAT_PNM;
+}
+
 #endif /*HAVE_PPM*/
 
 /**

libvips/include/vips/foreign.h

@@ -715,6 +715,7 @@ int vips_pngsave_buffer( VipsImage *in, void **buf, size_t *len, ... )
  * @VIPS_FOREIGN_PPM_FORMAT_PGM: portable greymap
  * @VIPS_FOREIGN_PPM_FORMAT_PPM: portable pixmap
  * @VIPS_FOREIGN_PPM_FORMAT_PFM: portable float map
+ * @VIPS_FOREIGN_PPM_FORMAT_PNM: portable anymap
  *
  * The netpbm file format to save as.
  *
@@ -725,12 +726,17 @@ int vips_pngsave_buffer( VipsImage *in, void **buf, size_t *len, ... )
  * #VIPS_FOREIGN_PPM_FORMAT_PPM images are 8, 16, or 32-bits, three bands.
  *
  * #VIPS_FOREIGN_PPM_FORMAT_PFM images are 32-bit float pixels.
+ *
+ * #VIPS_FOREIGN_PPM_FORMAT_PNM images are anymap images -- the image format
+ * is used to pick the saver.
+ *
  */
 typedef enum {
 	VIPS_FOREIGN_PPM_FORMAT_PBM,
 	VIPS_FOREIGN_PPM_FORMAT_PGM,
 	VIPS_FOREIGN_PPM_FORMAT_PPM,
 	VIPS_FOREIGN_PPM_FORMAT_PFM,
+	VIPS_FOREIGN_PPM_FORMAT_PNM,
 	VIPS_FOREIGN_PPM_FORMAT_LAST
 } VipsForeignPpmFormat;