reuse JBIG2Globals

Certain optimized documents use a rather large common symbol dictionary
for all JBIG2 images. Caching these JBIG2Globals speeds up loading and
rendering of such documents.

1 files changed, 35 insertions, 3 deletions

diff --git a/source/pdf/pdf-stream.c b/source/pdf/pdf-stream.c
index bf7f64f2..f747a54b 100644
--- a/source/pdf/pdf-stream.c
+++ b/source/pdf/pdf-stream.c
@@ -46,6 +46,38 @@ pdf_stream_has_crypt(fz_context *ctx, pdf_obj *stm)
 	return 0;
 }
 
+static fz_jbig2_globals *
+pdf_load_jbig2_globals(pdf_document *doc, pdf_obj *dict)
+{
+	fz_jbig2_globals *globals;
+	fz_context *ctx = doc->ctx;
+	fz_buffer *buf = NULL;
+
+	fz_var(buf);
+
+	if ((globals = pdf_find_item(ctx, fz_free_jbig2_globals_imp, dict)) != NULL)
+	{
+		return globals;
+	}
+
+	fz_try(ctx)
+	{
+		buf = pdf_load_stream(doc, pdf_to_num(dict), pdf_to_gen(dict));
+		globals = fz_load_jbig2_globals(ctx, buf->data, buf->len);
+		pdf_store_item(ctx, dict, globals, buf->len);
+	}
+	fz_always(ctx)
+	{
+		fz_drop_buffer(ctx, buf);
+	}
+	fz_catch(ctx)
+	{
+		fz_rethrow(ctx);
+	}
+
+	return globals;
+}
+
 /*
  * Create a filter given a name and param dictionary.
  */
@@ -161,10 +193,10 @@ build_filter(fz_stream *chain, pdf_document *doc, pdf_obj *f, pdf_obj *p, int nu
 
 	else if (!strcmp(s, "JBIG2Decode"))
 	{
-		fz_buffer *globals = NULL;
+		fz_jbig2_globals *globals = NULL;
 		pdf_obj *obj = pdf_dict_gets(p, "JBIG2Globals");
-		if (obj)
-			globals = pdf_load_stream(doc, pdf_to_num(obj), pdf_to_gen(obj));
+		if (pdf_is_indirect(obj))
+			globals = pdf_load_jbig2_globals(doc, obj);
 		/* fz_open_jbig2d takes possession of globals */
 		return fz_open_jbig2d(chain, globals);
 	}