flag to save bmp with bitdepth 1 (libvips#2)

configure.ac

@@ -624,7 +624,7 @@ if test x"$magick6" = x"yes"; then
   LIBS="$LIBS $MAGICK_LIBS"
   CFLAGS="$CFLAGS $MAGICK_CFLAGS"
 
-  AC_CHECK_FUNCS([InheritException AcquireExceptionInfo SetImageProperty SetImageExtent AcquireImage GetVirtualPixels ResetImageProfileIterator ResetImageAttributeIterator ResetImagePropertyIterator MagickCoreGenesis SetImageOption BlobToStringInfo OptimizePlusImageLayers OptimizeImageTransparency])
+  AC_CHECK_FUNCS([InheritException AcquireExceptionInfo SetImageProperty SetImageExtent AcquireImage GetVirtualPixels ResetImageProfileIterator ResetImageAttributeIterator ResetImagePropertyIterator MagickCoreGenesis SetImageOption BlobToStringInfo OptimizePlusImageLayers OptimizeImageTransparency SetImageType])
 
   LIBS="$save_LIBS"
   CFLAGS="$save_CFLAGS"

libvips/foreign/magick.c

@@ -846,4 +846,14 @@ magick_set_magick_profile( Image *image,
 	return( 0 );
 }
 
+int
+magick_set_image_type( Image *images,
+	ImageType image_type, ExceptionInfo *exception )
+{
+//	SetImageDepth( images, 1, exception);
+	SetImageType( images, image_type, exception );
+
+	return( exception->severity == UndefinedException );
+}
+
 #endif /*defined(HAVE_MAGICK6) || defined(HAVE_MAGICK7)*/

libvips/foreign/magick.h

@@ -88,6 +88,8 @@ int magick_optimize_image_layers( Image **images, ExceptionInfo *exception );
 int magick_optimize_image_transparency( const Image *images,
     ExceptionInfo *exception );
 
+int magick_set_image_type( Image *images, ImageType image_type, ExceptionInfo *exception );
+
 gboolean magick_ismagick( const unsigned char *bytes, size_t length );
 
 #endif /*HAVE_MAGICK6*/

libvips/foreign/vips2magick.c

@@ -69,6 +69,7 @@ typedef struct _VipsForeignSaveMagick {
 	char *filename;		/* NULL during buffer output */
 	char *format;
 	int quality;
+	gboolean bmp_bitdepth_1;
 	gboolean optimize_gif_frames;
 	gboolean optimize_gif_transparency;
 
@@ -406,6 +407,17 @@ vips_foreign_save_magick_build( VipsObject *object )
 			return( -1 );
 		}
 	}
+
+	if( magick->bmp_bitdepth_1 ) {
+		if( !magick_set_image_type( magick->images,
+			BilevelType, magick->exception ) ) {
+			magick_inherit_exception( magick->exception, 
+				magick->images );
+			magick_vips_error( class->nickname, magick->exception );
+
+			return( -1 );
+		}
+	}
 
 	return( 0 );
 }
@@ -493,6 +505,13 @@ vips_foreign_save_magick_class_init( VipsForeignSaveMagickClass *class )
 		G_STRUCT_OFFSET( VipsForeignSaveMagick, 
 			optimize_gif_transparency ),
 		FALSE );
+
+	VIPS_ARG_BOOL( class, "bmp_bitdepth_1", 6,
+		_( "BMP bithdepth 1" ),
+		_( "BMP file bitdepth 1`" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignSaveMagick, bmp_bitdepth_1 ),
+		FALSE );
 }
 
 static void

meson.build

@@ -186,7 +186,7 @@ if not get_option('magick').disabled() and magick_dep.found()
         if cc.has_member('struct _ImageInfo', 'number_scenes', prefix: '#include <magick/api.h>', dependencies: magick_dep)
             cfg_var.set('HAVE_NUMBER_SCENES', '1')
         endif
-        func_names = [ 'InheritException', 'AcquireExceptionInfo', 'SetImageProperty', 'SetImageExtent', 'AcquireImage', 'GetVirtualPixels', 'ResetImageProfileIterator', 'ResetImageAttributeIterator', 'ResetImagePropertyIterator', 'MagickCoreGenesis', 'SetImageOption', 'BlobToStringInfo', 'OptimizePlusImageLayers', 'OptimizeImageTransparency' ]
+        func_names = [ 'InheritException', 'AcquireExceptionInfo', 'SetImageProperty', 'SetImageExtent', 'AcquireImage', 'GetVirtualPixels', 'ResetImageProfileIterator', 'ResetImageAttributeIterator', 'ResetImagePropertyIterator', 'MagickCoreGenesis', 'SetImageOption', 'BlobToStringInfo', 'OptimizePlusImageLayers', 'OptimizeImageTransparency', 'SetImageType' ]
         foreach func_name : func_names
             if cc.has_function(func_name, prefix: '#include <magick/api.h>', dependencies: magick_dep)
                 cfg_var.set('HAVE_' + func_name.to_upper(), '1')