From a5a3b062fc3aed2c6efa115ce840765ba6a41917 Mon Sep 17 00:00:00 2001
From: John Cupitt <jcupitt@gmail.com>
Date: Fri, 17 Apr 2015 16:59:28 +0100
Subject: [PATCH] support saving 1 and 2 band images to webp

see https://github.com/jcupitt/libvips/issues/267

libwebp does not supportG and GA images

make a new SAVEABLE type for savers which only do RGB and RGBA
---
 libvips/foreign/foreign.c      | 32 +++++++++++++++++++++++++++++++-
 libvips/foreign/webpsave.c     |  2 +-
 libvips/include/vips/foreign.h |  3 ++-
 libvips/iofuncs/enumtypes.c    |  1 +
 4 files changed, 35 insertions(+), 3 deletions(-)

diff --git a/libvips/foreign/foreign.c b/libvips/foreign/foreign.c
index be2dff69..ac14d649 100644
--- a/libvips/foreign/foreign.c
+++ b/libvips/foreign/foreign.c
@@ -1132,6 +1132,7 @@ vips_foreign_convert_saveable( VipsForeignSave *save )
 		vips_colourspace_issupported( in ) &&
 		(class->saveable == VIPS_SAVEABLE_RGB ||
 		 class->saveable == VIPS_SAVEABLE_RGBA ||
+		 class->saveable == VIPS_SAVEABLE_RGBA_ONLY ||
 		 class->saveable == VIPS_SAVEABLE_RGB_CMYK) ) { 
 		VipsImage *out;
 		VipsInterpretation interpretation;
@@ -1154,6 +1155,34 @@ vips_foreign_convert_saveable( VipsForeignSave *save )
 		in = out;
 	}
 
+	/* VIPS_SAVEABLE_RGBA_ONLY does not support 1 or 2 bands ... convert 
+	 * to sRGB. 
+	 */
+	if( !class->coding[VIPS_CODING_RAD] &&
+		in->Bands < 3 &&
+		vips_colourspace_issupported( in ) &&
+		class->saveable == VIPS_SAVEABLE_RGBA_ONLY ) { 
+		VipsImage *out;
+		VipsInterpretation interpretation;
+
+		/* Do we make RGB or RGB16? We don't want to squash a 16-bit
+		 * RGB down to 8 bits if the saver supports 16. 
+		 */
+		if( vips_band_format_is8bit( 
+			class->format_table[in->BandFmt] ) )
+			interpretation = VIPS_INTERPRETATION_sRGB;
+		else
+			interpretation = VIPS_INTERPRETATION_RGB16;
+
+		if( vips_colourspace( in, &out, interpretation, NULL ) ) {
+			g_object_unref( in );
+			return( -1 );
+		}
+		g_object_unref( in );
+
+		in = out;
+	}
+
 	/* Get the bands right. We must do this after all colourspace
 	 * transforms, since they can change the number of bands. 
 	 */
@@ -1211,7 +1240,8 @@ vips_foreign_convert_saveable( VipsForeignSave *save )
 		else if( in->Bands > 4 && 
 			((class->saveable == VIPS_SAVEABLE_RGB_CMYK &&
 			  in->Type == VIPS_INTERPRETATION_CMYK) ||
-			 class->saveable == VIPS_SAVEABLE_RGBA) ) {
+			 class->saveable == VIPS_SAVEABLE_RGBA ||
+			 class->saveable == VIPS_SAVEABLE_RGBA_ONLY) ) {
 			VipsImage *out;
 
 			if( vips_extract_band( in, &out, 0, 
diff --git a/libvips/foreign/webpsave.c b/libvips/foreign/webpsave.c
index b61a3f74..03120c0d 100644
--- a/libvips/foreign/webpsave.c
+++ b/libvips/foreign/webpsave.c
@@ -92,7 +92,7 @@ vips_foreign_save_webp_class_init( VipsForeignSaveWebpClass *class )
 
 	foreign_class->suffs = vips__webp_suffs;
 
-	save_class->saveable = VIPS_SAVEABLE_RGBA;
+	save_class->saveable = VIPS_SAVEABLE_RGBA_ONLY;
 	save_class->format_table = bandfmt_webp;
 
 	VIPS_ARG_INT( class, "Q", 10, 
diff --git a/libvips/include/vips/foreign.h b/libvips/include/vips/foreign.h
index adc9f259..4a22920d 100644
--- a/libvips/include/vips/foreign.h
+++ b/libvips/include/vips/foreign.h
@@ -239,7 +239,7 @@ gboolean vips_foreign_is_a_buffer( const char *loader, void *data, size_t size )
  * VipsSaveable:
  * @VIPS_SAVEABLE_MONO: 1 band (eg. CSV)
  * @VIPS_SAVEABLE_RGB: 1 or 3 bands (eg. PPM) 
- * @VIPS_SAVEABLE_RGBA: 1, 2, 3 or 4 bands (eg. PNG)
+ * @VIPS_SAVEABLE_RGBA_ONLY: 3 or 4 bands (eg. WEBP)
  * @VIPS_SAVEABLE_RGB_CMYK: 1, 3 or 4 bands (eg. JPEG)
  * @VIPS_SAVEABLE_ANY: any number of bands (eg. TIFF)
  *
@@ -249,6 +249,7 @@ typedef enum {
 	VIPS_SAVEABLE_MONO,
 	VIPS_SAVEABLE_RGB,
 	VIPS_SAVEABLE_RGBA,
+	VIPS_SAVEABLE_RGBA_ONLY,
 	VIPS_SAVEABLE_RGB_CMYK,
 	VIPS_SAVEABLE_ANY,
 	VIPS_SAVEABLE_LAST
diff --git a/libvips/iofuncs/enumtypes.c b/libvips/iofuncs/enumtypes.c
index 586c18de..ccdd9796 100644
--- a/libvips/iofuncs/enumtypes.c
+++ b/libvips/iofuncs/enumtypes.c
@@ -35,6 +35,7 @@ vips_saveable_get_type( void )
 			{VIPS_SAVEABLE_MONO, "VIPS_SAVEABLE_MONO", "mono"},
 			{VIPS_SAVEABLE_RGB, "VIPS_SAVEABLE_RGB", "rgb"},
 			{VIPS_SAVEABLE_RGBA, "VIPS_SAVEABLE_RGBA", "rgba"},
+			{VIPS_SAVEABLE_RGBA_ONLY, "VIPS_SAVEABLE_RGBA_ONLY", "rgba-only"},
 			{VIPS_SAVEABLE_RGB_CMYK, "VIPS_SAVEABLE_RGB_CMYK", "rgb-cmyk"},
 			{VIPS_SAVEABLE_ANY, "VIPS_SAVEABLE_ANY", "any"},
 			{VIPS_SAVEABLE_LAST, "VIPS_SAVEABLE_LAST", "last"},