add @profile option to pngsave

tiff and jpeg save both have a @profile option, this patch adds one to png as
well, see

https://github.com/jcupitt/libvips/issues/180

ChangeLog

@@ -5,6 +5,7 @@
 - fix vipsthumbnail with both input cmyk and output rgb profiles specified
 - vipsthumbnail retries with specified input profile if embedded profile is
   broken
+- add @profile option to pngsave, matching tiff and jpeg
 
 8/9/14 started 7.40.8
 - fix configure on rhel6 [Lovell]

libvips/foreign/foreign.c

@@ -2498,6 +2498,7 @@ vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
  *
  * @compression: compression level
  * @interlace: interlace image
+ * @profile: ICC profile to embed
  *
  * Write a VIPS image to a file as PNG.
  *
@@ -2508,7 +2509,12 @@ vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
  * than an interlaced PNG can be up to 7 times slower to write than a
  * non-interlaced image.
  *
- * If the VIPS header 
+ * Use @profile to give the filename of a profile to be embedded in the PNG.
+ * This does not affect the pixels which are written, just the way 
+ * they are tagged. You can use the special string "none" to mean 
+ * "don't attach a profile".
+ *
+ * If @profile is specified and the VIPS header 
  * contains an ICC profile named VIPS_META_ICC_NAME ("icc-profile-data"), the
  * profile from the VIPS header will be attached.
  *
@@ -2544,6 +2550,7 @@ vips_pngsave( VipsImage *in, const char *filename, ... )
  *
  * @compression: compression level
  * @interlace: interlace image
+ * @profile: ICC profile to embed
  *
  * As vips_pngsave(), but save to a memory buffer. 
  *

libvips/foreign/pngsave.c

@@ -58,6 +58,7 @@ typedef struct _VipsForeignSavePng {
 
 	int compression;
 	gboolean interlace;
+	char *profile;
 } VipsForeignSavePng;
 
 typedef VipsForeignSaveClass VipsForeignSavePngClass;
@@ -115,6 +116,14 @@ vips_foreign_save_png_class_init( VipsForeignSavePngClass *class )
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignSavePng, interlace ),
 		FALSE );
+
+	VIPS_ARG_STRING( class, "profile", 11, 
+		_( "Profile" ), 
+		_( "ICC profile to embed" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignSavePng, profile ),
+		NULL );
+
 }
 
 static void
@@ -146,7 +155,7 @@ vips_foreign_save_png_file_build( VipsObject *object )
 		return( -1 );
 
 	if( vips__png_write( save->ready, png_file->filename,
-		png->compression, png->interlace ) ) 
+		png->compression, png->interlace, png->profile ) ) 
 		return( -1 );
 
 	return( 0 );
@@ -204,7 +213,7 @@ vips_foreign_save_png_buffer_build( VipsObject *object )
 		return( -1 );
 
 	if( vips__png_write_buf( save->ready, &obuf, &olen,
-		png->compression, png->interlace ) )
+		png->compression, png->interlace, png->profile ) )
 		return( -1 );
 
 	area = vips_area_new_blob( (VipsCallbackFn) vips_free, obuf, olen );

libvips/foreign/vipspng.c

@@ -783,7 +783,7 @@ write_png_block( VipsRegion *region, Rect *area, void *a )
 /* Write a VIPS image to PNG.
  */
 static int
-write_vips( Write *write, int compress, int interlace )
+write_vips( Write *write, int compress, int interlace, const char *profile )
 {
 	VipsImage *in = write->in;
 
@@ -854,21 +854,42 @@ write_vips( Write *write, int compress, int interlace )
 
 	/* Set ICC Profile.
 	 */
-	if( vips_image_get_typeof( in, VIPS_META_ICC_NAME ) ) {
-		void *profile;
-		size_t profile_length;
+	if( profile ) {
+		if( strcmp( profile, "none" ) != 0 ) { 
+			void *data;
+			unsigned int length;
+
+			if( !(data = 
+				vips__file_read_name( profile, VIPS_ICC_DIR, 
+				&length )) ) 
+				return( -1 );
+
+#ifdef DEBUG
+			printf( "write_vips: "
+				"attaching %d bytes of ICC profile\n",
+				length );
+#endif /*DEBUG*/
+
+			png_set_iCCP( write->pPng, write->pInfo, "icc", 
+				PNG_COMPRESSION_TYPE_BASE, 
+				data, length );
+		}
+	}
+	else if( vips_image_get_typeof( in, VIPS_META_ICC_NAME ) ) {
+		void *data;
+		size_t length;
 
 		if( vips_image_get_blob( in, VIPS_META_ICC_NAME, 
-			&profile, &profile_length ) ) 
+			&data, &length ) ) 
 			return( -1 ); 
 
 #ifdef DEBUG
 		printf( "write_vips: attaching %zd bytes of ICC profile\n",
-			profile_length );
+			length );
 #endif /*DEBUG*/
 
 		png_set_iCCP( write->pPng, write->pInfo, "icc", 
-			PNG_COMPRESSION_TYPE_BASE, profile, profile_length );
+			PNG_COMPRESSION_TYPE_BASE, data, length );
 	}
 
 	png_write_info( write->pPng, write->pInfo ); 
@@ -902,7 +923,7 @@ write_vips( Write *write, int compress, int interlace )
 
 int
 vips__png_write( VipsImage *in, const char *filename, 
-	int compress, int interlace )
+	int compress, int interlace, const char *profile )
 {
 	Write *write;
 
@@ -921,7 +942,7 @@ vips__png_write( VipsImage *in, const char *filename,
 
 	/* Convert it!
 	 */
-	if( write_vips( write, compress, interlace ) ) {
+	if( write_vips( write, compress, interlace, profile ) ) {
 		vips_error( "vips2png", 
 			_( "unable to write \"%s\"" ), filename );
 
@@ -1007,7 +1028,8 @@ user_write_data( png_structp png_ptr, png_bytep data, png_size_t length )
 
 int
 vips__png_write_buf( VipsImage *in, 
-	void **obuf, size_t *olen, int compression, int interlace )
+	void **obuf, size_t *olen, int compression, int interlace,
+	const char *profile )
 {
 	WriteBuf *wbuf;
 	Write *write;
@@ -1023,7 +1045,7 @@ vips__png_write_buf( VipsImage *in,
 
 	/* Convert it!
 	 */
-	if( write_vips( write, compression, interlace ) ) {
+	if( write_vips( write, compression, interlace, profile ) ) {
 		write_buf_free( wbuf );
 		vips_error( "vips2png", 
 			"%s", _( "unable to write to buffer" ) );

libvips/foreign/vipspng.h

@@ -46,9 +46,10 @@ int vips__png_read_buffer( char *buffer, size_t length, VipsImage *out,
 int vips__png_header_buffer( char *buffer, size_t length, VipsImage *out );
 
 int vips__png_write( VipsImage *in, const char *filename, 
-	int compress, int interlace );
+	int compress, int interlace, const char *profile );
 int vips__png_write_buf( VipsImage *in, 
-	void **obuf, size_t *olen, int compression, int interlace );
+	void **obuf, size_t *olen, int compression, int interlace, 
+	const char *profile );
 
 #ifdef __cplusplus
 }