--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/pdf/pdf-resources.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,139 @@
+// Copyright (C) 2004-2025 Artifex Software, Inc.
+//
+// This file is part of MuPDF.
+//
+// MuPDF is free software: you can redistribute it and/or modify it under the
+// terms of the GNU Affero General Public License as published by the Free
+// Software Foundation, either version 3 of the License, or (at your option)
+// any later version.
+//
+// MuPDF 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 Affero General Public License for more
+// details.
+//
+// You should have received a copy of the GNU Affero General Public License
+// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
+//
+// Alternative licensing terms are available from the licensor.
+// For commercial licensing, see <https://www.artifex.com/> or contact
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#include "mupdf/fitz.h"
+#include "mupdf/pdf.h"
+
+#include <string.h>
+
+static void pdf_drop_obj_as_void(fz_context *ctx, void *obj)
+{
+	pdf_drop_obj(ctx, obj);
+}
+
+/* We do need to come up with an effective way to see what is already in the
+ * file to avoid adding to what is already there. This is avoided for pdfwrite
+ * as we check as we add each font. For adding text to an existing file though
+ * it may be more problematic. */
+
+pdf_obj *
+pdf_find_font_resource(fz_context *ctx, pdf_document *doc, int type, int encoding, fz_font *item, pdf_font_resource_key *key)
+{
+	pdf_obj *res;
+
+	if (!doc->resources.fonts)
+		doc->resources.fonts = fz_new_hash_table(ctx, 4096, sizeof(*key), -1, pdf_drop_obj_as_void);
+
+	memset(key, 0, sizeof(*key));
+	fz_font_digest(ctx, item, key->digest);
+
+	key->type = type;
+	key->encoding = encoding;
+	key->local_xref = doc->local_xref_nesting > 0;
+
+	res = fz_hash_find(ctx, doc->resources.fonts, (void *)key);
+	if (res)
+		pdf_keep_obj(ctx, res);
+	return res;
+}
+
+pdf_obj *
+pdf_find_colorspace_resource(fz_context *ctx, pdf_document *doc, fz_colorspace *item, pdf_colorspace_resource_key *key)
+{
+	pdf_obj *res;
+
+	if (!doc->resources.colorspaces)
+		doc->resources.colorspaces = fz_new_hash_table(ctx, 4096, sizeof(*key), -1, pdf_drop_obj_as_void);
+
+	memset(key, 0, sizeof(*key));
+	fz_colorspace_digest(ctx, item, key->digest);
+
+	key->local_xref = doc->local_xref_nesting > 0;
+
+	res = fz_hash_find(ctx, doc->resources.colorspaces, (void *)key);
+	if (res)
+		pdf_keep_obj(ctx, res);
+	return res;
+}
+
+pdf_obj *
+pdf_insert_font_resource(fz_context *ctx, pdf_document *doc, pdf_font_resource_key *key, pdf_obj *obj)
+{
+	pdf_obj *res = fz_hash_insert(ctx, doc->resources.fonts, (void *)key, obj);
+	if (res)
+		fz_warn(ctx, "warning: font resource already present");
+	else
+		res = pdf_keep_obj(ctx, obj);
+	return pdf_keep_obj(ctx, res);
+}
+
+pdf_obj *
+pdf_insert_colorspace_resource(fz_context *ctx, pdf_document *doc, pdf_colorspace_resource_key *key, pdf_obj *obj)
+{
+	pdf_obj *res = fz_hash_insert(ctx, doc->resources.colorspaces, (void *)key, obj);
+	if (res)
+		fz_warn(ctx, "warning: colorspace resource already present");
+	else
+		res = pdf_keep_obj(ctx, obj);
+	return pdf_keep_obj(ctx, res);
+}
+
+static int purge_local_font_resource(fz_context *ctx, void *state, void *key_, int keylen, void *val)
+{
+	pdf_font_resource_key *key = key_;
+	if (key->local_xref)
+	{
+		pdf_drop_obj(ctx, val);
+		return 1;
+	}
+	return 0;
+}
+
+static int purge_local_colorspace_resource(fz_context *ctx, void *state, void *key_, int keylen, void *val)
+{
+	pdf_colorspace_resource_key *key = key_;
+	if (key->local_xref)
+	{
+		pdf_drop_obj(ctx, val);
+		return 1;
+	}
+	return 0;
+}
+
+void
+pdf_purge_local_resources(fz_context *ctx, pdf_document *doc)
+{
+	if (doc->resources.fonts)
+		fz_hash_filter(ctx, doc->resources.fonts, NULL, purge_local_font_resource);
+	if (doc->resources.colorspaces)
+		fz_hash_filter(ctx, doc->resources.colorspaces, NULL, purge_local_colorspace_resource);
+}
+
+void
+pdf_drop_resource_tables(fz_context *ctx, pdf_document *doc)
+{
+	if (doc)
+	{
+		fz_drop_hash_table(ctx, doc->resources.colorspaces);
+		fz_drop_hash_table(ctx, doc->resources.fonts);
+	}
+}