Add ImageMagick buffer support

This commits adds buffer support for the ImageMagick backend, using the Blob
API.

cplusplus/include/vips/vips-operators.h

@@ -226,6 +226,8 @@ static VImage openslideload( char * filename , VOption *options = 0 )
     throw( VError );
 static VImage magickload( char * filename , VOption *options = 0 )
     throw( VError );
+static VImage magickload_buffer( VipsBlob * buffer , VOption *options = 0 )
+    throw( VError );
 static VImage fitsload( char * filename , VOption *options = 0 )
     throw( VError );
 static VImage openexrload( char * filename , VOption *options = 0 )

cplusplus/vips-operators.cpp

@@ -1567,6 +1567,19 @@ VImage VImage::magickload( char * filename , VOption *options )
     return( out );
 }
 
+VImage VImage::magickload_buffer( VipsBlob * buffer , VOption *options )
+    throw( VError )
+{
+    VImage out;
+
+    call( "magickload_buffer" ,
+        (options ? options : VImage::option()) ->
+            set( "buffer", buffer ) ->
+            set( "out", &out ) );
+
+    return( out );
+}
+
 VImage VImage::fitsload( char * filename , VOption *options )
     throw( VError )
 {

doc/function-list.xml

@@ -641,6 +641,11 @@
   <entry>load file with ImageMagick</entry>
   <entry>vips_magickload()</entry>
 </row>
+<row>
+  <entry>magickload_buffer</entry>
+  <entry>load image from buffer with ImageMagick</entry>
+  <entry>vips_magickload_buffer()</entry>
+</row>
 <row>
   <entry>fitsload</entry>
   <entry>load a FITS image</entry>

libvips/foreign/foreign.c

@@ -1546,6 +1546,7 @@ vips_foreign_operation_init( void )
 	extern GType vips_foreign_save_raw_get_type( void ); 
 	extern GType vips_foreign_save_raw_fd_get_type( void ); 
 	extern GType vips_foreign_load_magick_get_type( void ); 
+	extern GType vips_foreign_load_magick_buffer_get_type( void ); 
 	extern GType vips_foreign_save_dz_get_type( void ); 
 	extern GType vips_foreign_load_webp_file_get_type( void ); 
 	extern GType vips_foreign_load_webp_buffer_get_type( void ); 
@@ -1610,6 +1611,7 @@ vips_foreign_operation_init( void )
 
 #ifdef HAVE_MAGICK
 	vips_foreign_load_magick_get_type(); 
+	vips_foreign_load_magick_buffer_get_type(); 
 #endif /*HAVE_MAGICK*/
 
 #ifdef HAVE_CFITSIO
@@ -1668,6 +1670,48 @@ vips_magickload( const char *filename, VipsImage **out, ... )
 	return( result );
 }
 
+/**
+ * vips_magickload_buffer:
+ * @buf: memory area to load
+ * @len: size of memory area
+ * @out: decompressed image
+ * @...: %NULL-terminated list of optional named arguments
+ *
+ * Optional arguments:
+ *
+ * @all_frames: %gboolean, load all frames in sequence
+ * @density: string, canvas resolution for rendering vector formats like SVG
+ *
+ * Read an image memory block using libMagick into a VIPS image. Exactly as
+ * vips_magickload(), but read from a memory source. 
+ *
+ * You must not free the buffer while @out is active. The 
+ * #VipsObject::postclose signal on @out is a good place to free. 
+ *
+ * See also: vips_magickload().
+ *
+ * Returns: 0 on success, -1 on error.
+ */
+int
+vips_magickload_buffer( void *buf, size_t len, VipsImage **out, ... )
+{
+	va_list ap;
+	VipsBlob *blob;
+	int result;
+
+	/* We don't take a copy of the data or free it.
+	 */
+	blob = vips_blob_new( NULL, buf, len );
+
+	va_start( ap, out );
+	result = vips_call_split( "magickload_buffer", ap, blob, out );
+	va_end( ap );
+
+	vips_area_unref( VIPS_AREA( blob ) );
+
+	return( result );
+}
+
 /**
  * vips_tiffload:
  * @filename: file to load

libvips/foreign/magick.h

@@ -40,6 +40,11 @@ int vips__magick_read( const char *filename,
 int vips__magick_read_header( const char *filename, 
 	VipsImage *out, gboolean all_frames, const char *density );
 
+int vips__magick_read_buffer( const void *buf, const size_t len,
+	VipsImage *out, gboolean all_frames, const char *density );
+int vips__magick_read_buffer_header( const void *buf, const size_t len,
+	VipsImage *out, gboolean all_frames, const char *density );
+
 #ifdef __cplusplus
 }
 #endif /*__cplusplus*/

libvips/foreign/magick2vips.c

@@ -160,7 +160,7 @@ read_new( const char *filename, VipsImage *im, gboolean all_frames,
 
 	if( !(read = VIPS_NEW( im, Read )) )
 		return( NULL );
-	read->filename = g_strdup( filename );
+	read->filename = filename ? g_strdup( filename ) : NULL;
 	read->all_frames = all_frames;
 	read->im = im;
 	read->image = NULL;
@@ -176,7 +176,9 @@ read_new( const char *filename, VipsImage *im, gboolean all_frames,
 	if( !read->image_info ) 
 		return( NULL );
 
-	vips_strncpy( read->image_info->filename, filename, MaxTextExtent );
+	if (filename) {
+		vips_strncpy( read->image_info->filename, filename, MaxTextExtent );
+	}
 
 	/* Canvas resolution for rendering vector formats like SVG.
 	 */
@@ -740,5 +742,86 @@ vips__magick_read_header( const char *filename, VipsImage *im,
 	return( 0 );
 }
 
+int
+vips__magick_read_buffer( const void *buf, const size_t len, VipsImage *out,
+	gboolean all_frames, const char *density )
+{
+	Read *read;
+
+#ifdef DEBUG
+	printf( "magick2vips: vips__magick_read_buffer: %p %zu\n", buf, len );
+#endif /*DEBUG*/
+
+	if( !(read = read_new( NULL, out, all_frames, density )) )
+		return( -1 );
+
+#ifdef HAVE_SETIMAGEOPTION
+	/* When reading DICOM images, we want to ignore any
+	 * window_center/_width setting, since it may put pixels outside the
+	 * 0-65535 range and lose data. 
+	 *
+	 * These window settings are attached as vips metadata, so our caller
+	 * can interpret them if it wants.
+	 */
+  	SetImageOption( read->image_info, "dcm:display-range", "reset" );
+#endif /*HAVE_SETIMAGEOPTION*/
+
+#ifdef DEBUG
+	printf( "magick2vips: calling BlobToImage() ...\n" );
+#endif /*DEBUG*/
+
+	read->image = BlobToImage( read->image_info, buf, len, &read->exception );
+	if( !read->image ) {
+		vips_error( "magick2vips", _( "unable to read buffer\n"
+			"libMagick error: %s %s" ),
+			read->exception.reason, read->exception.description );
+		return( -1 );
+	}
+
+	if( parse_header( read ) )
+		return( -1 );
+	if( vips_image_generate( out, 
+		NULL, magick_fill_region, NULL, read, NULL ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+int
+vips__magick_read_buffer_header( const void *buf, const size_t len,
+	VipsImage *im, gboolean all_frames, const char *density )
+{
+	Read *read;
+
+#ifdef DEBUG
+	printf( "vips__magick_read_buffer_header: %p %zu\n", buf, len );
+#endif /*DEBUG*/
+
+	if( !(read = read_new( NULL, im, all_frames, density )) )
+		return( -1 );
+
+#ifdef DEBUG
+	printf( "vips__magick_read_buffer_header: pinging blob ...\n" );
+#endif /*DEBUG*/
+
+	read->image = PingBlob( read->image_info, buf, len, &read->exception );
+	if( !read->image ) {
+		vips_error( "magick2vips", _( "unable to ping blob\n"
+			"libMagick error: %s %s" ),
+			read->exception.reason, read->exception.description );
+		return( -1 );
+	}
+
+	if( parse_header( read ) ) 
+		return( -1 );
+
+	if( im->Xsize <= 0 || im->Ysize <= 0 ) {
+		vips_error( "magick2vips", "%s", _( "bad image size" ) );
+		return( -1 );
+	}
+
+	return( 0 );
+}
+
 #endif /*HAVE_MAGICK*/
 

libvips/foreign/magickload.c

@@ -175,4 +175,114 @@ vips_foreign_load_magick_init( VipsForeignLoadMagick *magick )
 {
 }
 
+typedef struct _VipsForeignLoadMagickBuffer {
+	VipsForeignLoad parent_object;
+
+	VipsArea *buf;
+	gboolean all_frames;
+	char *density;
+
+} VipsForeignLoadMagickBuffer;
+
+typedef VipsForeignLoadClass VipsForeignLoadMagickBufferClass;
+
+G_DEFINE_TYPE( VipsForeignLoadMagickBuffer, vips_foreign_load_magick_buffer, 
+	VIPS_TYPE_FOREIGN_LOAD );
+
+static gboolean
+vips_foreign_load_magick_buffer_is_a_buffer ( void* buf, size_t len )
+{
+	VipsImage *t;
+	int result;
+
+	t = vips_image_new();
+	vips_error_freeze();
+	result = vips__magick_read_buffer_header( buf, len, t, FALSE, NULL );
+	g_object_unref( t );
+	vips_error_thaw();
+
+	return( result == 0 );
+}
+
+static VipsForeignFlags
+vips_foreign_load_magick_buffer_get_flags( VipsForeignLoad *load )
+{
+	return( VIPS_FOREIGN_PARTIAL );
+}
+
+static int
+vips_foreign_load_magick_buffer_header( VipsForeignLoad *load )
+{
+	VipsForeignLoadMagickBuffer *magick = (VipsForeignLoadMagickBuffer *) load;
+
+	if( vips__magick_read_buffer_header( magick->buf->data, magick->buf->length, 
+		load->out, magick->all_frames, magick->density ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static int
+vips_foreign_load_magick_buffer_load( VipsForeignLoad *load )
+{
+	VipsForeignLoadMagickBuffer *magick = (VipsForeignLoadMagickBuffer *) load;
+
+	if( vips__magick_read_buffer( magick->buf->data, magick->buf->length, 
+		load->real, magick->all_frames, magick->density ) )
+		return( -1 );
+
+	return( 0 );
+}
+
+static void
+vips_foreign_load_magick_buffer_class_init( VipsForeignLoadMagickBufferClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *object_class = (VipsObjectClass *) class;
+	VipsForeignClass *foreign_class = (VipsForeignClass *) class;
+	VipsForeignLoadClass *load_class = (VipsForeignLoadClass *) class;
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	object_class->nickname = "magickload_buffer";
+	object_class->description = _( "load buffer with ImageMagick" );
+
+	/* We need to be well to the back of the queue since the vips's
+	 * dedicated loaders are usually preferable.
+	 */
+	foreign_class->priority = -100;
+
+	load_class->is_a_buffer = vips_foreign_load_magick_buffer_is_a_buffer;
+	load_class->get_flags = vips_foreign_load_magick_buffer_get_flags;
+	load_class->header = vips_foreign_load_magick_buffer_header;
+	load_class->load = vips_foreign_load_magick_buffer_load;
+
+	VIPS_ARG_BOXED( class, "buffer", 1, 
+		_( "Buffer" ),
+		_( "Buffer to load from" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT, 
+		G_STRUCT_OFFSET( VipsForeignLoadMagickBuffer, buf ),
+		VIPS_TYPE_BLOB );
+
+	VIPS_ARG_BOOL( class, "all_frames", 3, 
+		_( "all_frames" ), 
+		_( "Read all frames from an image" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignLoadMagickBuffer, all_frames ),
+		FALSE );
+
+	VIPS_ARG_STRING( class, "density", 4,
+		_( "Density" ),
+		_( "Canvas resolution for rendering vector formats like SVG" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignLoadMagickBuffer, density ),
+		NULL );
+}
+
+static void
+vips_foreign_load_magick_buffer_init( VipsForeignLoadMagickBuffer *buffer )
+{
+}
+
 #endif /*HAVE_MAGICK*/

libvips/include/vips/foreign.h

@@ -435,6 +435,8 @@ int vips_matrixprint( VipsImage *in, ... )
 
 int vips_magickload( const char *filename, VipsImage **out, ... )
 	__attribute__((sentinel));
+int vips_magickload_buffer( void *buf, size_t len, VipsImage **out, ... )
+	__attribute__((sentinel));
 
 /**
  * VipsForeignPngFilter:

python/Vips.py

@@ -993,6 +993,7 @@ class_methods = [
                     "tiffload_buffer",
                     "openslideload",
                     "magickload",
+                    "magickload_buffer",
                     "fitsload",
                     "openexrload"]