Merge pull request #190 from lovell/png-set-filter

Expose ability to control libpng's row filter

libvips/foreign/foreign.c

@@ -2487,6 +2487,7 @@ vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
  * @compression: compression level
  * @interlace: interlace image
  * @profile: ICC profile to embed
+ * @filter: libpng row filter flag(s)
  *
  * Write a VIPS image to a file as PNG.
  *
@@ -2506,6 +2507,8 @@ vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )
  * contains an ICC profile named VIPS_META_ICC_NAME ("icc-profile-data"), the
  * profile from the VIPS header will be attached.
  *
+ * Use @filter to specify one or more filters (instead of adaptive filtering).
+ *
  * The image is automatically converted to RGB, RGBA, Monochrome or Mono +
  * alpha before saving. Images with more than one byte per band element are
  * saved as 16-bit PNG, others are saved as 8-bit PNG.
@@ -2539,6 +2542,7 @@ vips_pngsave( VipsImage *in, const char *filename, ... )
  * @compression: compression level
  * @interlace: interlace image
  * @profile: ICC profile to embed
+ * @filter: libpng row filter flag(s)
  *
  * As vips_pngsave(), but save to a memory buffer. 
  *

libvips/foreign/pngsave.c

@@ -59,6 +59,7 @@ typedef struct _VipsForeignSavePng {
 	int compression;
 	gboolean interlace;
 	char *profile;
+	VipsForeignPngFilter filter;
 } VipsForeignSavePng;
 
 typedef VipsForeignSaveClass VipsForeignSavePngClass;
@@ -124,12 +125,21 @@ vips_foreign_save_png_class_init( VipsForeignSavePngClass *class )
 		G_STRUCT_OFFSET( VipsForeignSavePng, profile ),
 		NULL );
 
+	VIPS_ARG_FLAGS( class, "filter", 12,
+		_( "Filter" ),
+		_( "libpng row filter flag(s)" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignSavePng, filter ),
+		VIPS_TYPE_FOREIGN_PNG_FILTER,
+		VIPS_FOREIGN_PNG_FILTER_ALL );
+
 }
 
 static void
 vips_foreign_save_png_init( VipsForeignSavePng *png )
 {
 	png->compression = 6;
+	png->filter = VIPS_FOREIGN_PNG_FILTER_ALL;
 }
 
 typedef struct _VipsForeignSavePngFile {
@@ -155,7 +165,7 @@ vips_foreign_save_png_file_build( VipsObject *object )
 		return( -1 );
 
 	if( vips__png_write( save->ready, png_file->filename,
-		png->compression, png->interlace, png->profile ) ) 
+		png->compression, png->interlace, png->profile, png->filter ) )
 		return( -1 );
 
 	return( 0 );
@@ -213,7 +223,7 @@ vips_foreign_save_png_buffer_build( VipsObject *object )
 		return( -1 );
 
 	if( vips__png_write_buf( save->ready, &obuf, &olen,
-		png->compression, png->interlace, png->profile ) )
+		png->compression, png->interlace, png->profile, png->filter ) )
 		return( -1 );
 
 	blob = vips_blob_new( (VipsCallbackFn) vips_free, obuf, olen );

libvips/foreign/vipspng.c

@@ -783,7 +783,8 @@ write_png_block( VipsRegion *region, VipsRect *area, void *a )
 /* Write a VIPS image to PNG.
  */
 static int
-write_vips( Write *write, int compress, int interlace, const char *profile )
+write_vips( Write *write, int compress, int interlace, const char *profile,
+	VipsForeignPngFilter filter )
 {
 	VipsImage *in = write->in;
 
@@ -824,6 +825,10 @@ write_vips( Write *write, int compress, int interlace, const char *profile )
 	 */
 	png_set_compression_level( write->pPng, compress );
 
+	/* Set row filter.
+	 */
+	png_set_filter( write->pPng, 0, filter );
+
 	bit_depth = in->BandFmt == VIPS_FORMAT_UCHAR ? 8 : 16;
 
 	switch( in->Bands ) {
@@ -921,7 +926,8 @@ write_vips( Write *write, int compress, int interlace, const char *profile )
 
 int
 vips__png_write( VipsImage *in, const char *filename, 
-	int compress, int interlace, const char *profile )
+	int compress, int interlace, const char *profile,
+	VipsForeignPngFilter filter )
 {
 	Write *write;
 
@@ -940,7 +946,7 @@ vips__png_write( VipsImage *in, const char *filename,
 
 	/* Convert it!
 	 */
-	if( write_vips( write, compress, interlace, profile ) ) {
+	if( write_vips( write, compress, interlace, profile, filter ) ) {
 		vips_error( "vips2png", 
 			_( "unable to write \"%s\"" ), filename );
 
@@ -1027,7 +1033,7 @@ 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,
-	const char *profile )
+	const char *profile, VipsForeignPngFilter filter )
 {
 	WriteBuf *wbuf;
 	Write *write;
@@ -1043,7 +1049,7 @@ vips__png_write_buf( VipsImage *in,
 
 	/* Convert it!
 	 */
-	if( write_vips( write, compression, interlace, profile ) ) {
+	if( write_vips( write, compression, interlace, profile, filter ) ) {
 		write_buf_free( wbuf );
 		vips_error( "vips2png", 
 			"%s", _( "unable to write to buffer" ) );

libvips/foreign/vipspng.h

@@ -46,10 +46,11 @@ 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, const char *profile );
+	int compress, int interlace, const char *profile,
+	VipsForeignPngFilter filter );
 int vips__png_write_buf( VipsImage *in, 
 	void **obuf, size_t *olen, int compression, int interlace, 
-	const char *profile );
+	const char *profile, VipsForeignPngFilter filter );
 
 #ifdef __cplusplus
 }

libvips/include/vips/enumtypes.h

@@ -17,6 +17,8 @@ GType vips_foreign_tiff_predictor_get_type (void) G_GNUC_CONST;
 #define VIPS_TYPE_FOREIGN_TIFF_PREDICTOR (vips_foreign_tiff_predictor_get_type())
 GType vips_foreign_tiff_resunit_get_type (void) G_GNUC_CONST;
 #define VIPS_TYPE_FOREIGN_TIFF_RESUNIT (vips_foreign_tiff_resunit_get_type())
+GType vips_foreign_png_filter_get_type (void) G_GNUC_CONST;
+#define VIPS_TYPE_FOREIGN_PNG_FILTER (vips_foreign_png_filter_get_type())
 GType vips_foreign_dz_layout_get_type (void) G_GNUC_CONST;
 #define VIPS_TYPE_FOREIGN_DZ_LAYOUT (vips_foreign_dz_layout_get_type())
 GType vips_foreign_dz_depth_get_type (void) G_GNUC_CONST;

libvips/include/vips/foreign.h

@@ -436,6 +436,28 @@ int vips_matrixprint( VipsImage *in, ... )
 int vips_magickload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));
 
+/**
+ * VipsForeignPngFilter:
+ * @VIPS_FOREIGN_PNG_FILTER_NONE
+ * @VIPS_FOREIGN_PNG_FILTER_SUB
+ * @VIPS_FOREIGN_PNG_FILTER_UP
+ * @VIPS_FOREIGN_PNG_FILTER_AVG
+ * @VIPS_FOREIGN_PNG_FILTER_PAETH
+ * @VIPS_FOREIGN_PNG_FILTER_ALL
+ *
+ * http://www.w3.org/TR/PNG-Filters.html
+ * The values mirror those of png.h in libpng.
+ */
+typedef enum /*< flags >*/ {
+	VIPS_FOREIGN_PNG_FILTER_NONE = 0x08,
+	VIPS_FOREIGN_PNG_FILTER_SUB = 0x10,
+	VIPS_FOREIGN_PNG_FILTER_UP = 0x20,
+	VIPS_FOREIGN_PNG_FILTER_AVG = 0x40,
+	VIPS_FOREIGN_PNG_FILTER_PAETH = 0x80,
+	VIPS_FOREIGN_PNG_FILTER_ALL = 0xEA,
+	VIPS_FOREIGN_PNG_FILTER_LAST = 0xFF
+} VipsForeignPngFilter;
+
 int vips_pngload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));
 int vips_pngload_buffer( void *buf, size_t len, VipsImage **out, ... )

libvips/iofuncs/enumtypes.c

@@ -106,6 +106,28 @@ vips_foreign_tiff_resunit_get_type( void )
 	return( etype );
 }
 GType
+vips_foreign_png_filter_get_type( void )
+{
+	static GType etype = 0;
+
+	if( etype == 0 ) {
+		static const GFlagsValue values[] = {
+			{VIPS_FOREIGN_PNG_FILTER_NONE, "VIPS_FOREIGN_PNG_FILTER_NONE", "none"},
+			{VIPS_FOREIGN_PNG_FILTER_SUB, "VIPS_FOREIGN_PNG_FILTER_SUB", "sub"},
+			{VIPS_FOREIGN_PNG_FILTER_UP, "VIPS_FOREIGN_PNG_FILTER_UP", "up"},
+			{VIPS_FOREIGN_PNG_FILTER_AVG, "VIPS_FOREIGN_PNG_FILTER_AVG", "avg"},
+			{VIPS_FOREIGN_PNG_FILTER_PAETH, "VIPS_FOREIGN_PNG_FILTER_PAETH", "paeth"},
+			{VIPS_FOREIGN_PNG_FILTER_ALL, "VIPS_FOREIGN_PNG_FILTER_ALL", "all"},
+			{VIPS_FOREIGN_PNG_FILTER_LAST, "VIPS_FOREIGN_PNG_FILTER_LAST", "last"},
+			{0, NULL, NULL}
+		};
+
+		etype = g_flags_register_static( "VipsForeignPngFilter", values );
+	}
+
+	return( etype );
+}
+GType
 vips_foreign_dz_layout_get_type( void )
 {
 	static GType etype = 0;