add format option to magickload

Some magick coders (eg. ICO) don't sniff the filetype from the data, so
when you try to load from a string, imagemagick is unable to pick the
right decode path.

Add a @format option so callers can hint the filetype.

see https://github.com/jcupitt/pyvips/issues/39

ChangeLog

@@ -15,6 +15,7 @@
 - use O_TMPFILE, if available [Alexander--]
 - set "interlaced=1" for interlaced JPG and PNG images
 - add PDFium PDF loader
+- add @format option to magickload
 
 12/3/18 started 8.6.4
 - better fitting of fonts with overhanging edges [Adrià]

libvips/foreign/magick.c

@@ -216,7 +216,7 @@ magick_genesis_cb( void *client )
 	printf( "magick_genesis_cb:\n" ); 
 #endif /*DEBUG*/
 
-#ifdef HAVE_MAGICKCOREGENESIS
+#if defined(HAVE_MAGICKCOREGENESIS) || defined(HAVE_MAGICK7) 
 	MagickCoreGenesis( vips_get_argv0(), MagickFalse );
 #else /*!HAVE_MAGICKCOREGENESIS*/
 	InitializeMagick( "" );

libvips/foreign/magick2vips.c

@@ -55,6 +55,8 @@
  * 	- remove @all_frames, add @n
  * 23/2/17
  * 	- try using GetImageChannelDepth() instead of ->depth
+ * 24/4/18
+ * 	- add format hint
  */
 
 /*
@@ -172,7 +174,7 @@ read_close( VipsImage *im, Read *read )
 
 static Read *
 read_new( const char *filename, VipsImage *im, 
-	const char *density, int page, int n )
+	const char *format, const char *density, int page, int n )
 {
 	Read *read;
 	static int inited = 0;
@@ -215,6 +217,12 @@ read_new( const char *filename, VipsImage *im,
 		vips_strncpy( read->image_info->filename, 
 			filename, MaxTextExtent );
 
+	/* The file format hint, eg. "ICO".
+	 */
+	if( format ) 
+		vips_strncpy( read->image_info->magick, 
+			format, MaxTextExtent );
+
 	/* Canvas resolution for rendering vector formats like SVG.
 	 */
 	VIPS_SETSTR( read->image_info->density, density );
@@ -743,7 +751,8 @@ magick_fill_region( VipsRegion *out,
 
 int
 vips__magick_read( const char *filename, 
-	VipsImage *out, const char *density, int page, int n )
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n )
 {
 	Read *read;
 
@@ -751,7 +760,7 @@ vips__magick_read( const char *filename,
 	printf( "magick2vips: vips__magick_read: %s\n", filename );
 #endif /*DEBUG*/
 
-	if( !(read = read_new( filename, out, density, page, n )) )
+	if( !(read = read_new( filename, out, format, density, page, n )) )
 		return( -1 );
 
 #ifdef DEBUG
@@ -782,7 +791,8 @@ vips__magick_read( const char *filename,
  */
 int
 vips__magick_read_header( const char *filename, 
-	VipsImage *out, const char *density, int page, int n )
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n )
 {
 	Read *read;
 
@@ -790,7 +800,7 @@ vips__magick_read_header( const char *filename,
 	printf( "vips__magick_read_header: %s\n", filename );
 #endif /*DEBUG*/
 
-	if( !(read = read_new( filename, out, density, page, n )) )
+	if( !(read = read_new( filename, out, format, density, page, n )) )
 		return( -1 );
 
 #ifdef DEBUG
@@ -824,7 +834,8 @@ vips__magick_read_header( const char *filename,
 
 int
 vips__magick_read_buffer( const void *buf, const size_t len, 
-	VipsImage *out, const char *density, int page, int n )
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n )
 {
 	Read *read;
 
@@ -832,7 +843,7 @@ vips__magick_read_buffer( const void *buf, const size_t len,
 	printf( "magick2vips: vips__magick_read_buffer: %p %zu\n", buf, len );
 #endif /*DEBUG*/
 
-	if( !(read = read_new( NULL, out, density, page, n )) )
+	if( !(read = read_new( NULL, out, format, density, page, n )) )
 		return( -1 );
 
 #ifdef DEBUG
@@ -859,7 +870,8 @@ vips__magick_read_buffer( const void *buf, const size_t len,
 
 int
 vips__magick_read_buffer_header( const void *buf, const size_t len, 
-	VipsImage *out, const char *density, int page, int n )
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n )
 {
 	Read *read;
 
@@ -867,7 +879,7 @@ vips__magick_read_buffer_header( const void *buf, const size_t len,
 	printf( "vips__magick_read_buffer_header: %p %zu\n", buf, len );
 #endif /*DEBUG*/
 
-	if( !(read = read_new( NULL, out, density, page, n )) )
+	if( !(read = read_new( NULL, out, format, density, page, n )) )
 		return( -1 );
 
 #ifdef DEBUG

libvips/foreign/magick7load.c

@@ -4,6 +4,8 @@
  * 	- from magickload
  * 25/11/16
  * 	- add @n, deprecate @all_frames (just sets n = -1)
+ * 24/4/18
+ * 	- add format hint
  */
 
 /*
@@ -56,6 +58,8 @@
 
 #include <MagickCore/MagickCore.h>
 
+#include "magick.h"
+
 typedef struct _VipsForeignLoadMagick7 {
 	VipsForeignLoad parent_object;
 
@@ -63,6 +67,7 @@ typedef struct _VipsForeignLoadMagick7 {
 	 */
 	gboolean all_frames;
 
+	char *format;			/* Format hint */
 	char *density;			/* Load at this resolution */
 	int page;			/* Load this page (frame) */
 	int n;				/* Load this many pages */
@@ -307,7 +312,7 @@ vips_foreign_load_magick7_build( VipsObject *object )
 	printf( "vips_foreign_load_magick7_build: %p\n", object ); 
 #endif /*DEBUG*/
 
-	vips_foreign_load_magick7_genesis();
+	magick_genesis();
 
 	magick7->image_info = CloneImageInfo( NULL );
 	magick7->exception = AcquireExceptionInfo();
@@ -319,6 +324,12 @@ vips_foreign_load_magick7_build( VipsObject *object )
 	if( magick7->all_frames )
 		magick7->n = -1;
 
+	/* The file format hint, eg. "ICO".
+	 */
+	if( magick7->format ) 
+		vips_strncpy( magick7->image_info->magick, 
+			magick7->format, MaxTextExtent );
+
 	/* Canvas resolution for rendering vector formats like SVG.
 	 */
 	VIPS_SETSTR( magick7->image_info->density, magick7->density );
@@ -377,12 +388,12 @@ vips_foreign_load_magick7_class_init( VipsForeignLoadMagick7Class *class )
 		vips_foreign_load_magick7_get_flags_filename;
 	load_class->get_flags = vips_foreign_load_magick7_get_flags;
 
-	VIPS_ARG_BOOL( class, "all_frames", 3, 
-		_( "all_frames" ), 
-		_( "Read all frames from an image" ),
-		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
-		G_STRUCT_OFFSET( VipsForeignLoadMagick7, all_frames ),
-		FALSE );
+	VIPS_ARG_STRING( class, "format", 3,
+		_( "Format" ),
+		_( "Image format hint" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignLoadMagick7, format ),
+		NULL );
 
 	VIPS_ARG_STRING( class, "density", 4,
 		_( "Density" ),
@@ -405,6 +416,13 @@ vips_foreign_load_magick7_class_init( VipsForeignLoadMagick7Class *class )
 		G_STRUCT_OFFSET( VipsForeignLoadMagick7, n ),
 		-1, 100000, 1 );
 
+	VIPS_ARG_BOOL( class, "all_frames", 7, 
+		_( "all_frames" ), 
+		_( "Read all frames from an image" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
+		G_STRUCT_OFFSET( VipsForeignLoadMagick7, all_frames ),
+		FALSE );
+
 }
 
 static void
@@ -579,7 +597,7 @@ vips_foreign_load_magick7_parse( VipsForeignLoadMagick7 *magick7,
 	return( 0 );
 }
 
-/* We don't bother with GetPixelReadMask((), assume it's everywhere. Don't
+/* We don't bother with GetPixelReadMask(), assume it's everywhere. Don't
  * bother with traits, assume taht's always update.
  *
  * We do skip index channels. Palette images add extra index channels

libvips/foreign/magickload.c

@@ -12,6 +12,8 @@
  * 	- add @n, deprecate @all_frames (just sets n = -1)
  * 8/9/17
  * 	- don't cache magickload
+ * 24/4/18
+ * 	- add format hint
  */
 
 /*
@@ -72,6 +74,7 @@ typedef struct _VipsForeignLoadMagick {
 	gboolean all_frames;
 
 	char *density;			/* Load at this resolution */
+	char *format;			/* Load format hint */
 	int page;			/* Load this page (frame) */
 	int n;				/* Load this many pages */
 
@@ -122,28 +125,35 @@ vips_foreign_load_magick_class_init( VipsForeignLoadMagickClass *class )
 		vips_foreign_load_magick_get_flags_filename;
 	load_class->get_flags = vips_foreign_load_magick_get_flags;
 
-	VIPS_ARG_BOOL( class, "all_frames", 3, 
+	VIPS_ARG_STRING( class, "format", 3,
+		_( "Format" ),
+		_( "Image format hint" ),
+		VIPS_ARGUMENT_OPTIONAL_INPUT,
+		G_STRUCT_OFFSET( VipsForeignLoadMagick, format ),
+		NULL );
+
+	VIPS_ARG_BOOL( class, "all_frames", 4, 
 		_( "all_frames" ), 
 		_( "Read all frames from an image" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT | VIPS_ARGUMENT_DEPRECATED,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick, all_frames ),
 		FALSE );
 
-	VIPS_ARG_STRING( class, "density", 4,
+	VIPS_ARG_STRING( class, "density", 5,
 		_( "Density" ),
 		_( "Canvas resolution for rendering vector formats like SVG" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick, density ),
 		NULL );
 
-	VIPS_ARG_INT( class, "page", 5,
+	VIPS_ARG_INT( class, "page", 6,
 		_( "Page" ),
 		_( "Load this page from the file" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
 		G_STRUCT_OFFSET( VipsForeignLoadMagick, page ),
 		0, 100000, 0 );
 
-	VIPS_ARG_INT( class, "n", 6,
+	VIPS_ARG_INT( class, "n", 7,
 		_( "n" ),
 		_( "Load this many pages" ),
 		VIPS_ARGUMENT_OPTIONAL_INPUT,
@@ -177,7 +187,7 @@ ismagick( const char *filename )
 
 	t = vips_image_new();
 	vips_error_freeze();
-	result = vips__magick_read_header( filename, t, NULL, 0, 1 );
+	result = vips__magick_read_header( filename, t, NULL, NULL, 0, 1 );
 	g_object_unref( t );
 	vips_error_thaw();
 
@@ -202,7 +212,8 @@ vips_foreign_load_magick_file_header( VipsForeignLoad *load )
 		magick->n = -1;
 
 	if( vips__magick_read( magick_file->filename, 
-		load->out, magick->density, magick->page, magick->n ) )
+		load->out, magick->format, magick->density, 
+		magick->page, magick->n ) )
 		return( -1 );
 
 	VIPS_SETSTR( load->out->filename, magick_file->filename );
@@ -262,7 +273,8 @@ vips_foreign_load_magick_buffer_is_a_buffer( const void *buf, size_t len )
 
 	t = vips_image_new();
 	vips_error_freeze();
-	result = vips__magick_read_buffer_header( buf, len, t, NULL, 0, 1 );
+	result = vips__magick_read_buffer_header( buf, len, t, 
+		NULL, NULL, 0, 1 );
 	g_object_unref( t );
 	vips_error_thaw();
 
@@ -288,7 +300,8 @@ vips_foreign_load_magick_buffer_header( VipsForeignLoad *load )
 
 	if( vips__magick_read_buffer( 
 		magick_buffer->buf->data, magick_buffer->buf->length, 
-		load->out, magick->density, magick->page, magick->n ) )
+		load->out, magick->format, magick->density, magick->page, 
+		magick->n ) )
 		return( -1 );
 
 	return( 0 );
@@ -338,6 +351,7 @@ vips_foreign_load_magick_buffer_init( VipsForeignLoadMagickBuffer *buffer )
  *
  * Optional arguments:
  *
+ * * @format: string, format hint, eg. "JPG"
  * * @page: %gint, load from this page
  * * @n: %gint, load this many pages
  * * @density: string, canvas resolution for rendering vector formats like SVG
@@ -352,6 +366,10 @@ vips_foreign_load_magick_buffer_init( VipsForeignLoadMagickBuffer *buffer )
  * The reader should also work with most versions of GraphicsMagick. See the
  * "--with-magickpackage" configure option.
  *
+ * The file format is usually guessed from the filename suffix. You can 
+ * override this with @format -- for example `"ICO"` selects Windows icon
+ * format. See the ImageMagick documentation for a list of format names. 
+ *
  * Normally it will only load the first image in a many-image sequence (such
  * as a GIF or a PDF). Use @page and @n to set the start page and number of
  * pages to load. Set @n to -1 to load all pages from @page onwards.
@@ -387,6 +405,7 @@ vips_magickload( const char *filename, VipsImage **out, ... )
  *
  * Optional arguments:
  *
+ * * @format: string, format hint, eg. "JPG"
  * * @page: %gint, load from this page
  * * @n: %gint, load this many pages
  * * @density: string, canvas resolution for rendering vector formats like SVG
@@ -394,6 +413,12 @@ vips_magickload( const char *filename, VipsImage **out, ... )
  * Read an image memory block using libMagick into a VIPS image. Exactly as
  * vips_magickload(), but read from a memory source. 
  *
+ * The file format is usually guessed from the buffer contents, but this does
+ * not work for all image formats. You can 
+ * set the format explicitly with @format -- for example `"ICO"` selects 
+ * Windows icon
+ * format. See the ImageMagick documentation for a list of format names. 
+ *
  * You must not free the buffer while @out is active. The 
  * #VipsObject::postclose signal on @out is a good place to free. 
  *

libvips/foreign/pforeign.h

@@ -123,14 +123,18 @@ int vips__fits_read( const char *filename, VipsImage *out );
 int vips__fits_write( VipsImage *in, const char *filename );
 
 int vips__magick_read( const char *filename, 
-	VipsImage *out, const char *density, int page, int n );
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n );
 int vips__magick_read_header( const char *filename, 
-	VipsImage *out, const char *density, int page, int n );
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n );
 
 int vips__magick_read_buffer( const void *buf, const size_t len,
-	VipsImage *out, const char *density, int page, int n );
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n );
 int vips__magick_read_buffer_header( const void *buf, const size_t len,
-	VipsImage *out, const char *density, int page, int n );
+	VipsImage *out, const char *format, const char *density, 
+	int page, int n );
 
 extern const char *vips__mat_suffs[];
 
@@ -162,12 +166,14 @@ int vips__jpeg_write_file( VipsImage *in,
 	const char *filename, int Q, const char *profile, 
 	gboolean optimize_coding, gboolean progressive, gboolean strip,
 	gboolean no_subsample, gboolean trellis_quant,
-	gboolean overshoot_deringing, gboolean optimize_scans, int quant_table );
+	gboolean overshoot_deringing, gboolean optimize_scans, 
+	int quant_table );
 int vips__jpeg_write_buffer( VipsImage *in, 
 	void **obuf, size_t *olen, int Q, const char *profile, 
 	gboolean optimize_coding, gboolean progressive, gboolean strip,
 	gboolean no_subsample, gboolean trellis_quant,
-	gboolean overshoot_deringing, gboolean optimize_scans, int quant_table );
+	gboolean overshoot_deringing, gboolean optimize_scans, 
+	int quant_table );
 
 int vips__isjpeg_buffer( const void *buf, size_t len );
 int vips__isjpeg( const char *filename );