add sourceginput

This is a source which wraps a GInputStream. You can use this to eg.
efficiently load a PNG file from a GFile object.

ChangeLog

@@ -9,6 +9,7 @@
 - get pdfium load building again [Projkt-James]
 - add _source load support for pdfium
 - add "seed" param to perlin, worley and gaussnoise
+- add vips_source_g_input_stream_new() to load images from a GInputStream
 
 22/12/20 start 8.10.6
 - don't seek on bad file descriptors [kleisauke]

libvips/include/vips/connection.h

@@ -265,8 +265,8 @@ typedef struct _VipsSourceCustomClass {
 GType vips_source_custom_get_type( void );
 VipsSourceCustom *vips_source_custom_new( void );
 
-/* A GInputStream that's actually a VipsSource under the hood. This lets us
+/* A GInputStream that wraps a VipsSource. This lets us eg. 
- * hook librsvg up to libvips using the GInputStream interface.
+ * hook librsvg up to libvips using their GInputStream interface.
  */
 
 #define VIPS_TYPE_G_INPUT_STREAM (vips_g_input_stream_get_type())
@@ -284,8 +284,6 @@ VipsSourceCustom *vips_source_custom_new( void );
 	(G_TYPE_INSTANCE_GET_CLASS( (obj), \
 	VIPS_TYPE_G_INPUT_STREAM, VipsGInputStreamClass ))
 
-/* GInputStream <--> VipsSource
- */
 typedef struct _VipsGInputStream {
 	GInputStream parent_instance;
 
@@ -304,6 +302,43 @@ typedef struct _VipsGInputStreamClass {
 
 GInputStream *vips_g_input_stream_new_from_source( VipsSource *source );
 
+/* A VipsSource that wraps a GInputStream. This lets us eg. load PNGs from 
+ * GFile objects.
+ */
+
+#define VIPS_TYPE_SOURCE_G_INPUT_STREAM (vips_source_g_input_stream_get_type())
+#define VIPS_SOURCE_G_INPUT_STREAM( obj ) \
+	(G_TYPE_CHECK_INSTANCE_CAST( (obj), \
+	VIPS_TYPE_SOURCE_G_INPUT_STREAM, VipsSourceGInputStream ))
+#define VIPS_SOURCE_G_INPUT_STREAM_CLASS( klass ) \
+	(G_TYPE_CHECK_CLASS_CAST( (klass), \
+	VIPS_TYPE_SOURCE_G_INPUT_STREAM, VipsSourceGInputStreamClass))
+#define VIPS_IS_SOURCE_G_INPUT_STREAM( obj ) \
+	(G_TYPE_CHECK_INSTANCE_TYPE( (obj), VIPS_TYPE_SOURCE_G_INPUT_STREAM ))
+#define VIPS_IS_SOURCE_G_INPUT_STREAM_CLASS( klass ) \
+	(G_TYPE_CHECK_CLASS_TYPE( (klass), VIPS_TYPE_SOURCE_G_INPUT_STREAM ))
+#define VIPS_SOURCE_G_INPUT_STREAM_GET_CLASS( obj ) \
+	(G_TYPE_INSTANCE_GET_CLASS( (obj), \
+	VIPS_TYPE_SOURCE_G_INPUT_STREAM, VipsSourceGInputStreamClass ))
+
+typedef struct _VipsSourceGInputStream {
+	VipsSource parent_instance;
+
+	/*< private >*/
+
+	/* The GInputStream we wrap.
+	 */
+	GInputStream *stream;
+
+} VipsSourceGInputStream;
+
+typedef struct _VipsSourceGInputStreamClass {
+	VipsSourceClass parent_class;
+
+} VipsSourceGInputStreamClass;
+
+VipsSourceGInputStream *vips_source_g_input_stream_new( GInputStream *stream );
+
 #define VIPS_TYPE_TARGET (vips_target_get_type())
 #define VIPS_TARGET( obj ) \
 	(G_TYPE_CHECK_INSTANCE_CAST( (obj), \

libvips/iofuncs/Makefile.am

@@ -2,6 +2,7 @@ noinst_LTLIBRARIES = libiofuncs.la
 
 libiofuncs_la_SOURCES = \
 	ginputsource.c \
+	sourceginput.c \
 	connection.c \
 	source.c \
 	sourcecustom.c \

libvips/iofuncs/source.c

@@ -354,7 +354,8 @@ vips_source_seek_real( VipsSource *source, gint64 offset, int whence )
 	 * vips__seek() wrapper so we can seek long files on Windows.
 	 */
 	if( connection->descriptor != -1 )
-		return( vips__seek_no_error( connection->descriptor, offset, whence ) );
+		return( vips__seek_no_error( connection->descriptor, 
+			offset, whence ) );
 
 	return( -1 );
 }

libvips/iofuncs/sourceginput.c

@@ -0,0 +1,198 @@
+/* A Source subclass with signals you can easily hook up to other input
+ * sources.
+ * 
+ * J.Cupitt, 21/11/19
+ */
+
+/*
+
+    This file is part of VIPS.
+    
+    VIPS is free software; you can redistribute it and/or modify
+    it under the terms of the GNU Lesser General Public License as published by
+    the Free Software Foundation; either version 2 of the License, or
+    (at your option) any later version.
+
+    This program is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU Lesser General Public License for more details.
+
+    You should have received a copy of the GNU Lesser General Public License
+    along with this program; if not, write to the Free Software
+    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+    02110-1301  USA
+
+ */
+
+/*
+
+    These files are distributed with VIPS - http://www.vips.ecs.soton.ac.uk
+
+ */
+
+/*
+ */
+#define VIPS_DEBUG
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif /*HAVE_CONFIG_H*/
+#include <vips/intl.h>
+
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_UNISTD_H
+#include <unistd.h>
+#endif /*HAVE_UNISTD_H*/
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <vips/vips.h>
+#include <vips/internal.h>
+#include <vips/debug.h>
+
+#include "vipsmarshal.h"
+
+G_DEFINE_TYPE( VipsSourceGInputStream, vips_source_g_input_stream, 
+	VIPS_TYPE_SOURCE );
+
+/* TODO:
+ * 	- can get get a fileno out? it'd be useful if we could make
+ * 	  vips_source_map() work for eg. vips or ppm images
+ */
+
+static gint64
+vips_source_g_input_stream_read( VipsSource *source, 
+	void *buffer, size_t length )
+{
+	VipsSourceGInputStream *source_ginput = 
+		VIPS_SOURCE_G_INPUT_STREAM( source );
+	GError *error = NULL;
+
+	gint64 bytes_read;
+
+	VIPS_DEBUG_MSG( "vips_source_g_input_stream_read: %zd bytes\n", 
+		length );
+
+	/* Do we need to loop on this call? The docs are unclear.
+	 */
+	if( (bytes_read = g_input_stream_read( source_ginput->stream, 
+		buffer, length, NULL, &error )) < 0 ) {
+		VIPS_DEBUG_MSG( "    %s\n", error->message );
+		vips_g_error( &error );
+		return( -1 );
+	}
+
+	VIPS_DEBUG_MSG( "    (returned %zd bytes)\n", bytes_read );
+
+	return( bytes_read );
+}
+
+static GSeekType
+lseek_to_seek_type( int whence )
+{
+	switch( whence ) {
+	default:
+	case SEEK_CUR:
+		return( G_SEEK_CUR );
+	case SEEK_SET:
+		return( G_SEEK_SET );
+	case SEEK_END:
+		return( G_SEEK_END );
+	}
+}
+
+static gint64
+vips_source_g_input_stream_seek( VipsSource *source, gint64 offset, int whence )
+{
+	VipsSourceGInputStream *source_ginput = 
+		VIPS_SOURCE_G_INPUT_STREAM( source );
+	GSeekType type = lseek_to_seek_type( whence );
+	GError *error = NULL;
+
+	GSeekable *seekable;
+	gint64 new_position;
+
+	VIPS_DEBUG_MSG( "vips_source_g_input_stream_seek: "
+		"offset = %zd, whence = %d\n", offset, whence );
+
+	if( !G_IS_SEEKABLE( source_ginput->stream ) ) 
+		return( -1 );
+	seekable = G_SEEKABLE( source_ginput->stream );
+	if( !g_seekable_can_seek( seekable ) )
+		return( -1 );
+
+	if( !g_seekable_seek( seekable, offset, type, NULL, &error ) ) {
+		vips_g_error( &error );
+		return( -1 );
+	}
+
+	new_position = g_seekable_tell( seekable );
+
+	VIPS_DEBUG_MSG( "  (new position = %zd)\n", new_position );
+
+	return( new_position );
+}
+
+static void
+vips_source_g_input_stream_class_init( VipsSourceGInputStreamClass *class )
+{
+	GObjectClass *gobject_class = G_OBJECT_CLASS( class );
+	VipsObjectClass *object_class = VIPS_OBJECT_CLASS( class );
+	VipsSourceClass *source_class = VIPS_SOURCE_CLASS( class );
+
+	gobject_class->set_property = vips_object_set_property;
+	gobject_class->get_property = vips_object_get_property;
+
+	object_class->nickname = "source_g_input_stream";
+	object_class->description = _( "GInputStream source" );
+
+	source_class->read = vips_source_g_input_stream_read;
+	source_class->seek = vips_source_g_input_stream_seek;
+
+	VIPS_ARG_OBJECT( class, "stream", 3, 
+		_( "stream" ),
+		_( "GInputStream to read from" ),
+		VIPS_ARGUMENT_REQUIRED_INPUT, 
+		G_STRUCT_OFFSET( VipsSourceGInputStream, stream ),
+		G_TYPE_INPUT_STREAM );
+
+}
+
+static void
+vips_source_g_input_stream_init( VipsSourceGInputStream *source )
+{
+}
+
+/**
+ * vips_source_g_input_stream_new:
+ * @stream: read from this stream
+ *
+ * Create a #VipsSourceGInputStream which wraps @stream.
+ *
+ * Returns: the new source.
+ */
+VipsSourceGInputStream *
+vips_source_g_input_stream_new( GInputStream *stream )
+{
+	VipsSourceGInputStream *source;
+
+	VIPS_DEBUG_MSG( "vips_source_g_input_stream_new:\n" );
+
+	source = VIPS_SOURCE_G_INPUT_STREAM( 
+		g_object_new( VIPS_TYPE_SOURCE_G_INPUT_STREAM, 
+			"stream", stream,
+			NULL ) );
+
+	if( vips_object_build( VIPS_OBJECT( source ) ) ) {
+		VIPS_UNREF( source );
+		return( NULL );
+	}
+
+	return( source ); 
+}