Don't dispose of GpMetafile if a GpGraphics is using it

src/graphics-private.h

@@ -126,6 +126,7 @@ typedef struct _Graphics {
 	float			aa_offset_y;
 	/* metafile-specific stuff */
 	EmfType			emf_type;
+	BOOL			own_metafile;	/* true when metafile is owned by the graphics instance */
 	GpMetafile		*metafile;
 	cairo_surface_t		*metasurface;	/* bogus surface to satisfy some API calls */
 	/* common-stuff */

src/graphics.c

@@ -201,6 +201,11 @@ gdip_graphics_metafile_init (GpGraphics *graphics, GpMetafile *metafile)
 	graphics->metasurface = cairo_image_surface_create (CAIRO_FORMAT_A1, 1, 1);
 	graphics->ct = cairo_create (graphics->metasurface);
 	graphics->metafile = metafile;
+	graphics->own_metafile = FALSE;
+
+	g_assert (metafile->graphics == NULL);
+	/* Track the graphics instance in the metafile */
+	metafile->graphics = graphics;
 
 	gdip_graphics_common_init (graphics);
 }
@@ -455,8 +460,15 @@ GdipDeleteGraphics (GpGraphics *graphics)
 
 	if (graphics->backend == GraphicsBackEndMetafile) {
 		/* if recording this is where we save the metafile (stream or file) */
-		if (graphics->metafile->recording)
+		if (graphics->metafile && graphics->metafile->recording)
 			gdip_metafile_stop_recording (graphics->metafile);
+		/* break the link to the metafile */
+		if (graphics->metafile)
+			graphics->metafile->graphics = NULL;
+		if (graphics->own_metafile)
+			gdip_metafile_dispose (graphics->metafile);
+		graphics->metafile = NULL;
+		graphics->own_metafile = FALSE;
 		cairo_surface_destroy (graphics->metasurface);
 		graphics->metasurface = NULL;
 	}

src/image.c

@@ -295,6 +295,9 @@ GdipGetImageGraphicsContext (GpImage *image, GpGraphics **graphics)
 		GpMetafile *mf = (GpMetafile*)image;
 		if (!mf->recording)
 			return OutOfMemory;
+		/* creating more than one graphics instance for a metafile is not supported */
+		if (mf->graphics)
+			return OutOfMemory;
 		*graphics = gdip_metafile_graphics_new (mf);
 		return *graphics ? Ok : OutOfMemory;
 	}

src/metafile-private.h

@@ -68,6 +68,7 @@ struct _Metafile {
 	BOOL recording;		/* recording into memory (data), file (fp) or user stream (stream) */
 	FILE *fp;
 	void *stream;
+	GpGraphics *graphics;	/* set if GdipGetImageGraphicsContext was called */
 };
 
 typedef struct {

src/metafile.c

@@ -918,6 +918,7 @@ gdip_metafile_create ()
 		mf->recording = FALSE;
 		mf->fp = NULL;
 		mf->stream = NULL;
+		mf->graphics = NULL;
 	}
 	return mf;
 }
@@ -970,6 +971,13 @@ gdip_metafile_dispose (GpMetafile *metafile)
 	if (!metafile)
 		return InvalidParameter;
 
+	if (metafile->graphics) {
+		g_assert (!metafile->graphics->own_metafile);
+		g_assert (metafile->graphics->metafile == metafile);
+		/* Transfer responsiblity to the graphics instance that outlives this metafile instance */
+		metafile->graphics->own_metafile = TRUE;
+		return Ok;
+	}
 	/* TODO deal with "delete" flag */
 	metafile->length = 0;
 	if (metafile->data) {
@@ -980,6 +988,9 @@ gdip_metafile_dispose (GpMetafile *metafile)
 	if (metafile->recording)
 		gdip_metafile_stop_recording (metafile);
 
+	/* if there was a graphics instance, it should already be cleaned up */
+	g_assert (metafile->graphics == NULL);
+
 	GdipFree (metafile);
 	return Ok;
 }