From 1bbde93ba39613877ded2015965aaab2341d3d36 Mon Sep 17 00:00:00 2001
From: Michael Vrhel <michael.vrhel@artifex.com>
Date: Tue, 15 Mar 2016 16:33:22 -0700
Subject: Add mutool merge

This commit adds a page merging tool.  The tool demonstrates the
use of object grafting.  The object grafting function recursively
goes through the object to add all referenced objects.  A map is
maintained to ensure that objects that have already been copied are
not copied again.
---
 source/pdf/pdf-graft.c | 163 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 163 insertions(+)
 create mode 100644 source/pdf/pdf-graft.c

(limited to 'source/pdf')

diff --git a/source/pdf/pdf-graft.c b/source/pdf/pdf-graft.c
new file mode 100644
index 00000000..bbe5e17b
--- /dev/null
+++ b/source/pdf/pdf-graft.c
@@ -0,0 +1,163 @@
+#include "mupdf/pdf.h"
+
+pdf_graft_map *
+pdf_new_graft_map(fz_context *ctx, pdf_document *src)
+{
+	pdf_graft_map *map = NULL;
+
+	map = fz_malloc_struct(ctx, pdf_graft_map);
+
+	fz_try(ctx)
+	{
+		map->len = pdf_xref_len(ctx, src);
+		map->dst_from_src = fz_calloc(ctx, map->len, sizeof(int));
+	}
+	fz_catch(ctx)
+	{
+		fz_free(ctx, map);
+		fz_rethrow(ctx);
+	}
+	map->refs = 1;
+	return map;
+}
+
+pdf_graft_map *
+fz_keep_graft_map(fz_context *ctx, pdf_graft_map *map)
+{
+	if (map)
+		++map->refs;
+	return map;
+}
+
+void
+pdf_drop_graft_map(fz_context *ctx, pdf_graft_map *map)
+{
+	if (map && --map->refs == 0)
+	{
+		fz_free(ctx, map->dst_from_src);
+		fz_free(ctx, map);
+	}
+}
+
+/* Graft object from dst to source */
+pdf_obj *
+pdf_graft_object(fz_context *ctx, pdf_document *dst, pdf_document *src, pdf_obj *obj_ref, pdf_graft_map *map)
+{
+	pdf_obj *val, *key;
+	pdf_obj *new_obj = NULL;
+	pdf_obj *new_dict = NULL;
+	pdf_obj *new_array = NULL;
+	pdf_obj *ref = NULL;
+	fz_buffer *buffer = NULL;
+	pdf_graft_map *drop_map = NULL;
+	int new_num, src_num, len, i;
+
+	if (map == NULL)
+		drop_map = map = pdf_new_graft_map(ctx, src);
+
+	if (pdf_is_indirect(ctx, obj_ref))
+	{
+		src_num = pdf_to_num(ctx, obj_ref);
+
+		/* Check if we have done this one.  If yes, then drop map (if allocated)
+		 * and return our indirect ref */
+		if (map->dst_from_src[src_num] != 0)
+		{
+			int dest_num = map->dst_from_src[src_num];
+			pdf_drop_graft_map(ctx, drop_map);
+			return pdf_new_indirect(ctx, dst, dest_num, 0);
+		}
+
+		fz_var(buffer);
+		fz_var(ref);
+
+		fz_try(ctx)
+		{
+			/* Create new slot for our src object, set the mapping and call again
+			 * using the resolved indirect reference */
+			new_num = pdf_create_object(ctx, dst);
+			map->dst_from_src[src_num] = new_num;
+			new_obj = pdf_graft_object(ctx, dst, src, pdf_resolve_indirect(ctx, obj_ref), map);
+
+			/* Return a ref to the new_obj making sure to attach any stream */
+			pdf_update_object(ctx, dst, new_num, new_obj);
+			pdf_drop_obj(ctx, new_obj);
+			ref = pdf_new_indirect(ctx, dst, new_num, 0);
+			if (pdf_is_stream(ctx, obj_ref))
+			{
+				buffer = pdf_load_raw_stream(ctx, src, src_num, 0);
+				pdf_update_stream(ctx, dst, ref, buffer, 1);
+			}
+		}
+		fz_always(ctx)
+		{
+			fz_drop_buffer(ctx, buffer);
+			pdf_drop_graft_map(ctx, drop_map);
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, ref);
+			fz_rethrow(ctx);
+		}
+		return ref;
+	}
+	else if (pdf_is_dict(ctx, obj_ref))
+	{
+		fz_var(new_dict);
+
+		fz_try(ctx)
+		{
+			len = pdf_dict_len(ctx, obj_ref);
+			new_dict = pdf_new_dict(ctx, dst, len);
+
+			for (i = 0; i < len; i++)
+			{
+				key = pdf_dict_get_key(ctx, obj_ref, i);
+				val = pdf_dict_get_val(ctx, obj_ref, i);
+				pdf_dict_put_drop(ctx, new_dict, key, pdf_graft_object(ctx, dst, src, val, map));
+			}
+		}
+		fz_always(ctx)
+		{
+			pdf_drop_graft_map(ctx, drop_map);
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, new_dict);
+			fz_rethrow(ctx);
+		}
+		return new_dict;
+	}
+	else if (pdf_is_array(ctx, obj_ref))
+	{
+		fz_var(new_array);
+
+		fz_try(ctx)
+		{
+			/* Step through the array items handling indirect refs */
+			len = pdf_array_len(ctx, obj_ref);
+			new_array = pdf_new_array(ctx, dst, len);
+
+			for (i = 0; i < len; i++)
+			{
+				val = pdf_array_get(ctx, obj_ref, i);
+				pdf_array_push_drop(ctx, new_array, pdf_graft_object(ctx, dst, src, val, map));
+			}
+		}
+		fz_always(ctx)
+		{
+			pdf_drop_graft_map(ctx, drop_map);
+		}
+		fz_catch(ctx)
+		{
+			pdf_drop_obj(ctx, new_array);
+			fz_rethrow(ctx);
+		}
+		return new_array;
+	}
+	else
+	{
+		pdf_drop_graft_map(ctx, drop_map);
+		return pdf_keep_obj(ctx, obj_ref);;
+	}
+}
-- 
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