create output images in _build()

new idea: output image get made in _build(), we copy them out after
calling the operation's build, see TODO

vips_image_new() param removed, it just always makes "p" images now

libvips/arithmetic/arithmetic.c

@@ -71,13 +71,16 @@ G_DEFINE_ABSTRACT_TYPE( VipsArithmetic, vips_arithmetic, VIPS_TYPE_OPERATION );
 static int
 vips_arithmetic_build( VipsObject *object )
 {
-#ifdef DEBUG
 	VipsArithmetic *arithmetic = VIPS_ARITHMETIC( object );
-#endif /*DEBUG*/
+    VipsImage *out;
 
 	if( VIPS_OBJECT_CLASS( vips_arithmetic_parent_class )->build( object ) )
 		return( -1 );
 
+    if( !(out = vips_image_new()) )
+		return( -1 );
+    g_object_set( arithmetic, "out", out, NULL );
+
 	/* Should we _generate() here? We should keep the params in the object
 	 * ready to be dropped in.
 	 *

libvips/deprecated/vips7compat.c

@@ -192,7 +192,7 @@ im_init( const char *filename )
 {
 	VipsImage *image;
 
-	image = vips_image_new( "p" );
+	image = vips_image_new();
 	VIPS_SETSTR( image->filename, filename );
 
 	return( image );

libvips/format/fits.c

@@ -475,14 +475,14 @@ im_fits2vips( const char *filename, VipsImage *out )
 	 * separately then join them.
 	 */
 
-	if( !(t = vips_image_new( "p" )) ||
+	if( !(t = vips_image_new()) ||
 		vips_object_local( out, t ) ||
 		fits2vips_header( filename, t ) )
 		return( -1 );
 	n_bands = t->Bands;
 
 	if( n_bands == 1 ) {
-		if( !(t = vips_image_new( "p" )) ||
+		if( !(t = vips_image_new()) ||
 			vips_object_local( out, t ) ||
 			fits2vips( filename, t, 0 ) )
 			return( -1 );
@@ -493,7 +493,7 @@ im_fits2vips( const char *filename, VipsImage *out )
 
 		acc = NULL;
 		for( i = 0; i < n_bands; i++ ) {
-			if( !(t = vips_image_new( "p" )) ||
+			if( !(t = vips_image_new()) ||
 				vips_object_local( out, t ) ||
 				fits2vips( filename, t, i ) )
 				return( -1 );
@@ -503,7 +503,7 @@ im_fits2vips( const char *filename, VipsImage *out )
 			else {
 				VipsImage *t2;
 
-				if( !(t2 = vips_image_new( "p" )) ||
+				if( !(t2 = vips_image_new()) ||
 					vips_object_local( out, t2 ) ||
 					im_bandjoin( acc, t, t2 ) )
 					return( -1 );
@@ -582,7 +582,7 @@ vips_fits_new_write( VipsImage *in, const char *filename )
 
 	/* Cast to a supported format.
 	 */
-	if( !(type = vips_image_new( "p" )) ||
+	if( !(type = vips_image_new()) ||
 		vips_object_local( in, type ) ||
 		im_clip2fmt( in, type, vips_fits_bandfmt[in->BandFmt] ) )
 		return( NULL );
@@ -590,7 +590,7 @@ vips_fits_new_write( VipsImage *in, const char *filename )
 
 	/* FITS has (0,0) in the bottom left, we need to flip.
 	 */
-	if( !(flip = vips_image_new( "p" )) ||
+	if( !(flip = vips_image_new()) ||
 		vips_object_local( in, flip ) ||
 		im_flipver( in, flip ) )
 		return( NULL );

libvips/include/vips/image.h

@@ -285,7 +285,7 @@ typedef struct _VipsImageClass {
 	void (*posteval)( VipsImage *image, VipsProgress *progress );
 
 	/* An image has been written to. 
-	 * Used by eg. vips_image_new_from_file("x.jpg", "w") to do the 
+	 * Used by eg. vips_image_open("x.jpg", "w") to do the 
 	 * final write to jpeg.
 	 * Set *result to non-zero to indicate an error on write.
 	 */
@@ -355,7 +355,7 @@ void vips_image_set_progress( VipsImage *image, gboolean progress );
 gboolean vips_image_get_kill( VipsImage *image );
 void vips_image_set_kill( VipsImage *image, gboolean kill );
 
-VipsImage *vips_image_new( const char *mode );
+VipsImage *vips_image_new( void );
 int vips_image_new_array( VipsObject *parent, VipsImage **images, int n );
 VipsImage *vips_image_new_from_file( const char *filename, const char *mode );
 VipsImage *vips_image_new_from_file_raw( const char *filename, 

libvips/iofuncs/image.c

@@ -673,7 +673,7 @@ lazy_real_image( Lazy *lazy )
 	/* Otherwise, fall back to a "p".
 	 */
 	if( !real && 
-		!(real = vips_image_new( "p" )) )
+		!(real = vips_image_new()) )
 		return( NULL );
 
 	return( real );
@@ -897,7 +897,7 @@ vips_image_build( VipsObject *object )
 			else {
 				VipsImage *x;
 
-				if( !(x = vips_image_new( "p" )) )
+				if( !(x = vips_image_new()) )
 					return( -1 );
 				vips_object_local( image, x );
 				if( vips_image_open_input( x ) )
@@ -1431,38 +1431,23 @@ vips_image_temp_name( void )
 
 /**
  * vips_image_new:
- * @mode: mode to open with
  *
- * vips_image_new() examines the mode string and creates an 
- * appropriate #VipsImage.
+ * vips_image_new() creates a "glue" descriptor you can use to join two image 
+ * processing operations together. 
  *
- * <itemizedlist>
- *   <listitem> 
- *     <para>
- *       <emphasis>"t"</emphasis>
- *       creates a temporary memory buffer image.
- *     </para>
- *   </listitem>
- *   <listitem> 
- *     <para>
- *       <emphasis>"p"</emphasis>
- *       creates a "glue" descriptor you can use to join two image 
- *       processing operations together.
- *     </para>
- *   </listitem>
- * </itemizedlist>
+ * It is the equivalent of vips_image_new_from_file("xxx", "p").
  *
  * Returns: the new #VipsImage, or %NULL on error.
  */
 VipsImage *
-vips_image_new( const char *mode )
+vips_image_new( void )
 {
 	VipsImage *image;
 
 	image = VIPS_IMAGE( g_object_new( VIPS_TYPE_IMAGE, NULL ) );
 	g_object_set( image,
 		"filename", vips_image_temp_name(),
-		"mode", mode,
+		"mode", "p",
 		NULL );
 	if( vips_object_build( VIPS_OBJECT( image ) ) ) {
 		VIPS_UNREF( image );
@@ -1505,7 +1490,7 @@ vips_image_new_array( VipsObject *parent, VipsImage **images, int n )
 	int i;
 
 	for( i = 0; i < n; i++ ) {
-		if( !(images[i] = vips_image_new( "p" )) ) 
+		if( !(images[i] = vips_image_new()) ) 
 			return( -1 );
 		vips_object_local( parent, images[i] );
 	}
@@ -1524,6 +1509,19 @@ vips_image_new_array( VipsObject *parent, VipsImage **images, int n )
  * <itemizedlist>
  *   <listitem> 
  *     <para>
+ *       <emphasis>"t"</emphasis>
+ *       creates a temporary memory buffer image.
+ *     </para>
+ *   </listitem>
+ *   <listitem> 
+ *     <para>
+ *       <emphasis>"p"</emphasis>
+ *       creates a "glue" descriptor you can use to join operations, see also
+ *       vips_image_new().
+ *     </para>
+ *   </listitem>
+ *   <listitem> 
+ *     <para>
  *       <emphasis>"r"</emphasis>
  *       opens the named file for reading. If the file is not in the native 
  *       VIPS format for your machine, vips_image_new_from_file() 
@@ -2006,7 +2004,7 @@ vips_image_wio_input( VipsImage *image )
 		/* Change to VIPS_IMAGE_SETBUF. First, make a memory 
 		 * buffer and copy into that.
 		 */
-		if( !(t1 = vips_image_new( "t" )) ) 
+		if( !(t1 = vips_image_new_from_file( "vips_image_wio_input", "t" )) ) 
 			return( -1 );
 		if( im_copy( image, t1 ) ) {
 			g_object_unref( t1 );

libvips/iofuncs/sink.c

@@ -227,7 +227,7 @@ sink_init( Sink *sink,
 	sink->a = a;
 	sink->b = b;
 
-	if( !(sink->t = vips_image_new( "p" )) ||
+	if( !(sink->t = vips_image_new()) ||
 		im_copy( sink->sink_base.im, sink->t ) ) {
 		sink_free( sink );
 		return( -1 );