From 0bfa2ce884eed8bef83fb23cf2e25dae81a2207e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20B=C3=BCnzli?= <zeniko@gmail.com>
Date: Fri, 3 Jan 2014 12:15:09 +0100
Subject: 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.
---
 source/fitz/filter-jbig2.c | 56 +++++++++++++++++++++++++++++++++-------------
 source/pdf/pdf-stream.c    | 38 ++++++++++++++++++++++++++++---
 2 files changed, 75 insertions(+), 19 deletions(-)

(limited to 'source')

diff --git a/source/fitz/filter-jbig2.c b/source/fitz/filter-jbig2.c
index 2771d070..592f7ab6 100644
--- a/source/fitz/filter-jbig2.c
+++ b/source/fitz/filter-jbig2.c
@@ -4,15 +4,27 @@
 
 typedef struct fz_jbig2d_s fz_jbig2d;
 
+struct fz_jbig2_globals_s
+{
+	fz_storable storable;
+	Jbig2GlobalCtx *gctx;
+};
+
 struct fz_jbig2d_s
 {
 	fz_stream *chain;
 	Jbig2Ctx *ctx;
-	Jbig2GlobalCtx *gctx;
+	fz_jbig2_globals *gctx;
 	Jbig2Image *page;
 	int idx;
 };
 
+static void
+fz_drop_jbig2_globals(fz_context *ctx, fz_jbig2_globals *globals)
+{
+	fz_drop_storable(ctx, &globals->storable);
+}
+
 static void
 close_jbig2d(fz_context *ctx, void *state_)
 {
@@ -20,7 +32,7 @@ close_jbig2d(fz_context *ctx, void *state_)
 	if (state->page)
 		jbig2_release_page(state->ctx, state->page);
 	if (state->gctx)
-		jbig2_global_ctx_free(state->gctx);
+		fz_drop_jbig2_globals(ctx, state->gctx);
 	jbig2_ctx_free(state->ctx);
 	fz_close(state->chain);
 	fz_free(ctx, state);
@@ -81,8 +93,30 @@ error_callback(void *data, const char *msg, Jbig2Severity severity, int32_t seg_
 	return 0;
 }
 
+fz_jbig2_globals *
+fz_load_jbig2_globals(fz_context *ctx, unsigned char *data, int size)
+{
+	fz_jbig2_globals *globals = fz_malloc_struct(ctx, fz_jbig2_globals);
+
+	Jbig2Ctx *jctx = jbig2_ctx_new(NULL, JBIG2_OPTIONS_EMBEDDED, NULL, error_callback, ctx);
+	jbig2_data_in(jctx, data, size);
+
+	FZ_INIT_STORABLE(globals, 1, fz_free_jbig2_globals_imp);
+	globals->gctx = jbig2_make_global_ctx(jctx);
+
+	return globals;
+}
+
+void
+fz_free_jbig2_globals_imp(fz_context *ctx, fz_storable *globals_)
+{
+	fz_jbig2_globals *globals = (fz_jbig2_globals *)globals_;
+	jbig2_global_ctx_free(globals->gctx);
+	fz_free(ctx, globals);
+}
+
 fz_stream *
-fz_open_jbig2d(fz_stream *chain, fz_buffer *globals)
+fz_open_jbig2d(fz_stream *chain, fz_jbig2_globals *globals)
 {
 	fz_jbig2d *state = NULL;
 	fz_context *ctx = chain->ctx;
@@ -93,34 +127,24 @@ fz_open_jbig2d(fz_stream *chain, fz_buffer *globals)
 	{
 		state = fz_malloc_struct(chain->ctx, fz_jbig2d);
 		state->ctx = NULL;
-		state->gctx = NULL;
+		state->gctx = globals;
 		state->chain = chain;
-		state->ctx = jbig2_ctx_new(NULL, JBIG2_OPTIONS_EMBEDDED, NULL, error_callback, ctx);
+		state->ctx = jbig2_ctx_new(NULL, JBIG2_OPTIONS_EMBEDDED, globals ? globals->gctx : NULL, error_callback, ctx);
 		state->page = NULL;
 		state->idx = 0;
-
-		if (globals)
-		{
-			jbig2_data_in(state->ctx, globals->data, globals->len);
-			state->gctx = jbig2_make_global_ctx(state->ctx);
-			state->ctx = jbig2_ctx_new(NULL, JBIG2_OPTIONS_EMBEDDED, state->gctx, error_callback, ctx);
-		}
 	}
 	fz_catch(ctx)
 	{
 		if (state)
 		{
-			if (state->gctx)
-				jbig2_global_ctx_free(state->gctx);
+			fz_drop_jbig2_globals(ctx, state->gctx);
 			if (state->ctx)
 				jbig2_ctx_free(state->ctx);
 		}
-		fz_drop_buffer(ctx, globals);
 		fz_free(ctx, state);
 		fz_close(chain);
 		fz_rethrow(ctx);
 	}
-	fz_drop_buffer(ctx, globals);
 
 	return fz_new_stream(ctx, state, read_jbig2d, close_jbig2d, rebind_jbig2d);
 }
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);
 	}
-- 
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