make tiff load and save IPCT data

we did XMP already, but add IPCT as well

see https://github.com/jcupitt/libvips/issues/332

ChangeLog

@@ -19,6 +19,7 @@
 - vips_log(), vips_log10() are zero-avoiding
 - better overlap handling for dzsave, thanks robclouth
 - add @spacing option to vips_text()
+- tiff loads and saves IPCT data
 
 7/5/15 started 8.0.3
 - dzsave and tif pyr write could fail for some image dimensions, thanks Jonas

libvips/foreign/tiff2vips.c

@@ -157,6 +157,8 @@
  * 26/2/15
  * 	- close the read down early for a header read ... this saves an
  * 	  fd during file read, handy for large numbers of input images 
+ * 29/9/15
+ * 	- load IPCT metadata
  */
 
 /*
@@ -1182,6 +1184,24 @@ parse_header( ReadTiff *rtiff, VipsImage *out )
 			(VipsCallbackFn) vips_free, data_copy, data_length );
 	}
 
+	/* Read any IPCT metadata.
+	 */
+	if( TIFFGetField( rtiff->tiff, 
+		TIFFTAG_RICHTIFFIPTC, &data_length, &data ) ) {
+		void *data_copy;
+
+		/* For no very good reason, libtiff stores IPCT as an array of
+		 * long, not byte.
+		 */
+		data_length *= 4;
+
+		if( !(data_copy = vips_malloc( NULL, data_length )) ) 
+			return( -1 );
+		memcpy( data_copy, data, data_length );
+		vips_image_set_blob( out, VIPS_META_IPCT_NAME, 
+			(VipsCallbackFn) vips_free, data_copy, data_length );
+	}
+
 	return( 0 );
 }
 

libvips/foreign/vips2tiff.c

@@ -153,6 +153,8 @@
  * 27/3/15
  * 	- squash >128 rather than >0, nicer results for shrink
  * 	- add miniswhite option
+ * 29/9/15
+ * 	- try to write IPCT metadata
  */
 
 /*
@@ -442,6 +444,41 @@ write_embed_xmp( Write *write, TIFF *tif )
 	return( 0 );
 }
 
+/* Embed any IPCT metadata. 
+ */
+static int
+write_embed_ipct( Write *write, TIFF *tif )
+{
+	void *data;
+	size_t data_length;
+
+	if( !vips_image_get_typeof( write->im, VIPS_META_IPCT_NAME ) )
+		return( 0 );
+	if( vips_image_get_blob( write->im, VIPS_META_IPCT_NAME, 
+		&data, &data_length ) )
+		return( -1 );
+
+	/* For no very good reason, libtiff stores IPCT as an array of
+	 * long, not byte.
+	 */
+	if( data_length & 3 ) {
+		vips_warn( "vips2tiff", 
+			"%s", _( "rounding up IPCT data length" ) );
+		data_length /= 4;
+		data_length += 1;
+	}
+	else
+		data_length /= 4;
+
+	TIFFSetField( tif, TIFFTAG_RICHTIFFIPTC, data_length, data );
+
+#ifdef DEBUG
+	printf( "vips2tiff: attached XMP from meta\n" );
+#endif /*DEBUG*/
+
+	return( 0 );
+}
+
 /* Write a TIFF header. width and height are the size of the VipsImage we are
  * writing (it may have been shrunk).
  */
@@ -475,9 +512,9 @@ write_tiff_header( Write *write, Layer *layer )
 	TIFFSetField( tif, TIFFTAG_YRESOLUTION, 
 		VIPS_CLIP( 0.01, write->yres, 1000000 ) );
 
-	if( write_embed_profile( write, tif ) )
+	if( write_embed_profile( write, tif ) ||
-		return( -1 );
+		write_embed_xmp( write, tif ) ||
-	if( write_embed_xmp( write, tif ) )
+		write_embed_ipct( write, tif ) )
 		return( -1 ); 
 
 	/* And colour fields.
@@ -1422,9 +1459,9 @@ write_copy_tiff( Write *write, TIFF *out, TIFF *in )
 
 	/* We can't copy profiles or xmp :( Set again from Write.
 	 */
-	if( write_embed_profile( write, out ) )
+	if( write_embed_profile( write, out ) ||
-		return( -1 );
+		write_embed_xmp( write, out ) ||
-	if( write_embed_xmp( write, out ) )
+		write_embed_ipct( write, out ) )
 		return( -1 );
 
 	buf = vips_malloc( NULL, TIFFTileSize( in ) );