From da50c6f300e565c8eedf4ce252c44b5ddbb95cee Mon Sep 17 00:00:00 2001
From: Robin Watts <robin.watts@artifex.com>
Date: Wed, 9 Nov 2016 17:41:43 +0000
Subject: Add pdf_layer configuration API.

Add API to:

 * allow enumeration of layer configs (OCCDs) within PDF files.

 * allow selection of layer configs.

 * allow enumeration of the "UI" (or "Human readable") form of layer
   configs.

 * allow selection/toggling of entries in the UI.
---
 include/mupdf/pdf/document.h   | 125 ++++++-
 include/mupdf/pdf/interpret.h  |   4 +-
 include/mupdf/pdf/page.h       |   7 +-
 platform/win32/libmupdf.vcproj |   8 +
 resources/pdf/names.txt        |   3 +
 source/pdf/pdf-imp.h           |   9 +
 source/pdf/pdf-interpret.c     | 226 +------------
 source/pdf/pdf-layer.c         | 715 +++++++++++++++++++++++++++++++++++++++++
 source/pdf/pdf-op-run.c        |   4 +-
 source/pdf/pdf-run.c           |  20 +-
 source/pdf/pdf-xref.c          | 161 +---------
 11 files changed, 879 insertions(+), 403 deletions(-)
 create mode 100644 source/pdf/pdf-imp.h
 create mode 100644 source/pdf/pdf-layer.c

diff --git a/include/mupdf/pdf/document.h b/include/mupdf/pdf/document.h
index 5b9632ff..4cb4c819 100644
--- a/include/mupdf/pdf/document.h
+++ b/include/mupdf/pdf/document.h
@@ -119,20 +119,125 @@ int pdf_lookup_metadata(fz_context *ctx, pdf_document *doc, const char *key, cha
 
 fz_outline *pdf_load_outline(fz_context *ctx, pdf_document *doc);
 
-typedef struct pdf_ocg_entry_s pdf_ocg_entry;
+/*
+	pdf_count_layer_configs: Get the number of layer
+	configurations defined in this document.
+
+	doc: The document in question.
+*/
+int pdf_count_layer_configs(fz_context *ctx, pdf_document *doc);
 
-struct pdf_ocg_entry_s
+typedef struct
 {
-	int num;
-	int state;
-};
+	const char *name;
+	const char *creator;
+} pdf_layer_config;
+
+/*
+	pdf_layer_config_info: Fetch the name (and
+	optionally creator) of the given layer config.
+
+	doc: The document in question.
+
+	config_num: A value in the 0..n-1 range, where n is the
+	value returned from pdf_count_layer_configs.
+
+	info: Pointer to structure to fill in. Pointers within
+	this structure may be set to NULL if no information is
+	available.
+*/
+void pdf_layer_config_info(fz_context *ctx, pdf_document *doc, int config_num, pdf_layer_config *info);
+
+/*
+	pdf_select_layer_config: Set the current configuration.
+	This updates the visibility of the optional content groups
+	within the document.
+
+	doc: The document in question.
+
+	config_num: A value in the 0..n-1 range, where n is the
+	value returned from pdf_count_layer_configs.
+*/
+void pdf_select_layer_config(fz_context *ctx, pdf_document *doc, int config_num);
+
+/*
+	pdf_count_layer_config_ui: Returns the number of entries in the
+	'UI' for this layer configuration.
+
+	doc: The document in question.
+*/
+int pdf_count_layer_config_ui(fz_context *ctx, pdf_document *doc);
+
+/*
+	pdf_select_layer_ui: Select a checkbox/radiobox
+	within the 'UI' for this layer configuration.
+
+	Selecting a UI entry that is a radiobox may disable
+	other UI entries.
+
+	doc: The document in question.
 
-struct pdf_ocg_descriptor_s
+	ui: A value in the 0..m-1 range, where m is the value
+	returned by pdf_count_layer_config_ui.
+*/
+void pdf_select_layer_config_ui(fz_context *ctx, pdf_document *doc, int ui);
+
+/*
+	pdf_deselect_layer_ui: Select a checkbox/radiobox
+	within the 'UI' for this layer configuration.
+
+	doc: The document in question.
+
+	ui: A value in the 0..m-1 range, where m is the value
+	returned by pdf_count_layer_config_ui.
+*/
+void pdf_deselect_layer_config_ui(fz_context *ctx, pdf_document *doc, int ui);
+
+/*
+	pdf_toggle_layer_config_ui: Toggle a checkbox/radiobox
+	within the 'UI' for this layer configuration.
+
+	Toggling a UI entry that is a radiobox may disable
+	other UI entries.
+
+	doc: The document in question.
+
+	ui: A value in the 0..m-1 range, where m is the value
+	returned by pdf_count_layer_config_ui.
+*/
+void pdf_toggle_layer_config_ui(fz_context *ctx, pdf_document *doc, int ui);
+
+typedef enum
 {
-	int len;
-	pdf_ocg_entry *ocgs;
-	pdf_obj *intent;
-};
+	PDF_LAYER_UI_LABEL = 0,
+	PDF_LAYER_UI_CHECKBOX = 1,
+	PDF_LAYER_UI_RADIOBOX = 2
+} pdf_layer_config_ui_type;
+
+typedef struct
+{
+	const char *text;
+	int depth;
+	pdf_layer_config_ui_type type;
+	int selected;
+	int locked;
+} pdf_layer_config_ui;
+
+/*
+	pdf_layer_config_ui_info: Get the info for a given
+	entry in the layer config ui.
+
+	doc: The document in question.
+
+	ui: A value in the 0..m-1 range, where m is the value
+	returned by pdf_count_layer_config_ui.
+
+	info: Pointer to a structure to fill in with information
+	about the requested ui entry.
+*/
+void pdf_layer_config_ui_info(fz_context *ctx, pdf_document *doc, int ui, pdf_layer_config_ui *info);
+
+int pdf_is_hidden_ocg(fz_context *ctx, pdf_ocg_descriptor *desc, pdf_obj *rdb, const char *usage, pdf_obj *ocg);
 
 /*
 	pdf_update_page: update a page for the sake of changes caused by a call
diff --git a/include/mupdf/pdf/interpret.h b/include/mupdf/pdf/interpret.h
index 07460221..b7b85fff 100644
--- a/include/mupdf/pdf/interpret.h
+++ b/include/mupdf/pdf/interpret.h
@@ -127,7 +127,7 @@ struct pdf_processor_s
 	void (*op_END)(fz_context *ctx, pdf_processor *proc);
 
 	/* interpreter state that persists across content streams */
-	const char *event;
+	const char *usage;
 	int hidden;
 };
 
@@ -155,7 +155,7 @@ struct pdf_csi_s
 };
 
 /* Functions to set up pdf_process structures */
-pdf_processor *pdf_new_run_processor(fz_context *ctx, fz_device *dev, const fz_matrix *ctm, const char *event, pdf_gstate *gstate, int nested);
+pdf_processor *pdf_new_run_processor(fz_context *ctx, fz_device *dev, const fz_matrix *ctm, const char *usage, pdf_gstate *gstate, int nested);
 pdf_processor *pdf_new_buffer_processor(fz_context *ctx, fz_buffer *buffer, int ahxencode);
 pdf_processor *pdf_new_filter_processor(fz_context *ctx, pdf_processor *chain, pdf_document *doc, pdf_obj *old_res, pdf_obj *new_res);
 
diff --git a/include/mupdf/pdf/page.h b/include/mupdf/pdf/page.h
index a5a60be8..407fcc09 100644
--- a/include/mupdf/pdf/page.h
+++ b/include/mupdf/pdf/page.h
@@ -65,7 +65,7 @@ fz_rect *pdf_bound_page(fz_context *ctx, pdf_page *page, fz_rect *);
 void pdf_run_page(fz_context *ctx, pdf_page *page, fz_device *dev, const fz_matrix *ctm, fz_cookie *cookie);
 
 /*
-	pdf_run_page: Interpret a loaded page and render it on a device.
+	pdf_run_page_with_usage: Interpret a loaded page and render it on a device.
 
 	page: A page loaded by pdf_load_page.
 
@@ -74,10 +74,13 @@ void pdf_run_page(fz_context *ctx, pdf_page *page, fz_device *dev, const fz_matr
 	ctm: A transformation matrix applied to the objects on the page,
 	e.g. to scale or rotate the page contents as desired.
 
+	usage: The 'usage' for displaying the file (typically
+	'View', 'Print' or 'Export'). NULL means 'View'.
+
 	cookie: A pointer to an optional fz_cookie structure that can be used
 	to track progress, collect errors etc.
 */
-void pdf_run_page_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, char *event, fz_cookie *cookie);
+void pdf_run_page_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, const char *usage, fz_cookie *cookie);
 
 /*
 	pdf_run_page_contents: Interpret a loaded page and render it on a device.
diff --git a/platform/win32/libmupdf.vcproj b/platform/win32/libmupdf.vcproj
index f7134220..69193a9a 100644
--- a/platform/win32/libmupdf.vcproj
+++ b/platform/win32/libmupdf.vcproj
@@ -2030,6 +2030,10 @@
 				RelativePath="..\..\source\pdf\pdf-image.c"
 				>
 			</File>
+			<File
+				RelativePath="..\..\source\pdf\pdf-imp.h"
+				>
+			</File>
 			<File
 				RelativePath="..\..\source\pdf\pdf-interpret-imp.h"
 				>
@@ -2046,6 +2050,10 @@
 				RelativePath="..\..\source\pdf\pdf-js.c"
 				>
 			</File>
+			<File
+				RelativePath="..\..\source\pdf\pdf-layer.c"
+				>
+			</File>
 			<File
 				RelativePath="..\..\source\pdf\pdf-lex.c"
 				>
diff --git a/resources/pdf/names.txt b/resources/pdf/names.txt
index 57228c15..30f4f60d 100644
--- a/resources/pdf/names.txt
+++ b/resources/pdf/names.txt
@@ -214,6 +214,7 @@ Limits
 Line
 Linearized
 Link
+Locked
 Luminosity
 M
 MK
@@ -249,6 +250,7 @@ Of
 Off
 OpenType
 Opt
+Order
 Ordering
 Outlines
 P
@@ -275,6 +277,7 @@ Push
 Q
 QuadPoints
 R
+RBGroups
 RGB
 RI
 RL
diff --git a/source/pdf/pdf-imp.h b/source/pdf/pdf-imp.h
new file mode 100644
index 00000000..37605c51
--- /dev/null
+++ b/source/pdf/pdf-imp.h
@@ -0,0 +1,9 @@
+#ifndef MUPDF_PDF_IMP_H
+#define MUPDF_PDF_IMP_H
+
+#include "mupdf/pdf.h"
+
+void pdf_read_ocg(fz_context *ctx, pdf_document *doc);
+void pdf_drop_ocg(fz_context *ctx, pdf_document *doc);
+
+#endif
diff --git a/source/pdf/pdf-interpret.c b/source/pdf/pdf-interpret.c
index 58999373..4a8a2a46 100644
--- a/source/pdf/pdf-interpret.c
+++ b/source/pdf/pdf-interpret.c
@@ -81,220 +81,6 @@ load_font_or_hail_mary(fz_context *ctx, pdf_document *doc, pdf_obj *rdb, pdf_obj
 	return desc;
 }
 
-static int
-ocg_intents_include(fz_context *ctx, pdf_ocg_descriptor *desc, char *name)
-{
-	int i, len;
-
-	if (strcmp(name, "All") == 0)
-		return 1;
-
-	/* In the absence of a specified intent, it's 'View' */
-	if (!desc->intent)
-		return (strcmp(name, "View") == 0);
-
-	if (pdf_is_name(ctx, desc->intent))
-	{
-		char *intent = pdf_to_name(ctx, desc->intent);
-		if (strcmp(intent, "All") == 0)
-			return 1;
-		return (strcmp(intent, name) == 0);
-	}
-	if (!pdf_is_array(ctx, desc->intent))
-		return 0;
-
-	len = pdf_array_len(ctx, desc->intent);
-	for (i=0; i < len; i++)
-	{
-		char *intent = pdf_to_name(ctx, pdf_array_get(ctx, desc->intent, i));
-		if (strcmp(intent, "All") == 0)
-			return 1;
-		if (strcmp(intent, name) == 0)
-			return 1;
-	}
-	return 0;
-}
-
-static int
-pdf_is_hidden_ocg(fz_context *ctx, pdf_ocg_descriptor *desc, pdf_obj *rdb, const char *event, pdf_obj *ocg)
-{
-	char event_state[16];
-	pdf_obj *obj, *obj2, *type;
-
-	/* Avoid infinite recursions */
-	if (pdf_obj_marked(ctx, ocg))
-		return 0;
-
-	/* If no event, everything is visible */
-	if (!event)
-		return 0;
-
-	/* If no ocg descriptor, everything is visible */
-	if (!desc)
-		return 0;
-
-	/* If we've been handed a name, look it up in the properties. */
-	if (pdf_is_name(ctx, ocg))
-	{
-		ocg = pdf_dict_get(ctx, pdf_dict_get(ctx, rdb, PDF_NAME_Properties), ocg);
-	}
-	/* If we haven't been given an ocg at all, then we're visible */
-	if (!ocg)
-		return 0;
-
-	fz_strlcpy(event_state, event, sizeof event_state);
-	fz_strlcat(event_state, "State", sizeof event_state);
-
-	type = pdf_dict_get(ctx, ocg, PDF_NAME_Type);
-
-	if (pdf_name_eq(ctx, type, PDF_NAME_OCG))
-	{
-		/* An Optional Content Group */
-		int default_value = 0;
-		int num = pdf_to_num(ctx, ocg);
-		int len = desc->len;
-		int i;
-		pdf_obj *es;
-
-		/* by default an OCG is visible, unless it's explicitly hidden */
-		for (i = 0; i < len; i++)
-		{
-			if (desc->ocgs[i].num == num)
-			{
-				default_value = desc->ocgs[i].state == 0;
-				break;
-			}
-		}
-
-		/* Check Intents; if our intent is not part of the set given
-		 * by the current config, we should ignore it. */
-		obj = pdf_dict_get(ctx, ocg, PDF_NAME_Intent);
-		if (pdf_is_name(ctx, obj))
-		{
-			/* If it doesn't match, it's hidden */
-			if (ocg_intents_include(ctx, desc, pdf_to_name(ctx, obj)) == 0)
-				return 1;
-		}
-		else if (pdf_is_array(ctx, obj))
-		{
-			int match = 0;
-			len = pdf_array_len(ctx, obj);
-			for (i=0; i<len; i++) {
-				match |= ocg_intents_include(ctx, desc, pdf_to_name(ctx, pdf_array_get(ctx, obj, i)));
-				if (match)
-					break;
-			}
-			/* If we don't match any, it's hidden */
-			if (match == 0)
-				return 1;
-		}
-		else
-		{
-			/* If it doesn't match, it's hidden */
-			if (ocg_intents_include(ctx, desc, "View") == 0)
-				return 1;
-		}
-
-		/* FIXME: Currently we do a very simple check whereby we look
-		 * at the Usage object (an Optional Content Usage Dictionary)
-		 * and check to see if the corresponding 'event' key is on
-		 * or off.
-		 *
-		 * Really we should only look at Usage dictionaries that
-		 * correspond to entries in the AS list in the OCG config.
-		 * Given that we don't handle Zoom or User, or Language
-		 * dicts, this is not really a problem. */
-		obj = pdf_dict_get(ctx, ocg, PDF_NAME_Usage);
-		if (!pdf_is_dict(ctx, obj))
-			return default_value;
-		/* FIXME: Should look at Zoom (and return hidden if out of
-		 * max/min range) */
-		/* FIXME: Could provide hooks to the caller to check if
-		 * User is appropriate - if not return hidden. */
-		obj2 = pdf_dict_gets(ctx, obj, event);
-		es = pdf_dict_gets(ctx, obj2, event_state);
-		if (pdf_name_eq(ctx, es, PDF_NAME_OFF))
-		{
-			return 1;
-		}
-		if (pdf_name_eq(ctx, es, PDF_NAME_ON))
-		{
-			return 0;
-		}
-		return default_value;
-	}
-	else if (pdf_name_eq(ctx, type, PDF_NAME_OCMD))
-	{
-		/* An Optional Content Membership Dictionary */
-		pdf_obj *name;
-		int combine, on;
-
-		obj = pdf_dict_get(ctx, ocg, PDF_NAME_VE);
-		if (pdf_is_array(ctx, obj)) {
-			/* FIXME: Calculate visibility from array */
-			return 0;
-		}
-		name = pdf_dict_get(ctx, ocg, PDF_NAME_P);
-		/* Set combine; Bit 0 set => AND, Bit 1 set => true means
-		 * Off, otherwise true means On */
-		if (pdf_name_eq(ctx, name, PDF_NAME_AllOn))
-		{
-			combine = 1;
-		}
-		else if (pdf_name_eq(ctx, name, PDF_NAME_AnyOff))
-		{
-			combine = 2;
-		}
-		else if (pdf_name_eq(ctx, name, PDF_NAME_AllOff))
-		{
-			combine = 3;
-		}
-		else /* Assume it's the default (AnyOn) */
-		{
-			combine = 0;
-		}
-
-		if (pdf_mark_obj(ctx, ocg))
-			return 0; /* Should never happen */
-		fz_try(ctx)
-		{
-			obj = pdf_dict_get(ctx, ocg, PDF_NAME_OCGs);
-			on = combine & 1;
-			if (pdf_is_array(ctx, obj)) {
-				int i, len;
-				len = pdf_array_len(ctx, obj);
-				for (i = 0; i < len; i++)
-				{
-					int hidden = pdf_is_hidden_ocg(ctx, desc, rdb, event, pdf_array_get(ctx, obj, i));
-					if ((combine & 1) == 0)
-						hidden = !hidden;
-					if (combine & 2)
-						on &= hidden;
-					else
-						on |= hidden;
-				}
-			}
-			else
-			{
-				on = pdf_is_hidden_ocg(ctx, desc, rdb, event, obj);
-				if ((combine & 1) == 0)
-					on = !on;
-			}
-		}
-		fz_always(ctx)
-		{
-			pdf_unmark_obj(ctx, ocg);
-		}
-		fz_catch(ctx)
-		{
-			fz_rethrow(ctx);
-		}
-		return !on;
-	}
-	/* No idea what sort of object this is - be visible */
-	return 0;
-}
-
 static fz_image *
 parse_inline_image(fz_context *ctx, pdf_csi *csi, fz_stream *stm)
 {
@@ -530,7 +316,7 @@ pdf_process_Do(fz_context *ctx, pdf_processor *proc, pdf_csi *csi)
 	if (!pdf_is_name(ctx, subtype))
 		fz_throw(ctx, FZ_ERROR_GENERIC, "no XObject subtype specified");
 
-	if (pdf_is_hidden_ocg(ctx, csi->doc->ocg, csi->rdb, proc->event, pdf_dict_get(ctx, xobj, PDF_NAME_OC)))
+	if (pdf_is_hidden_ocg(ctx, csi->doc->ocg, csi->rdb, proc->usage, pdf_dict_get(ctx, xobj, PDF_NAME_OC)))
 		return;
 
 	if (pdf_name_eq(ctx, subtype, PDF_NAME_Form))
@@ -726,7 +512,7 @@ pdf_process_BDC(fz_context *ctx, pdf_processor *proc, pdf_csi *csi)
 	if (!pdf_name_eq(ctx, pdf_dict_get(ctx, cooked, PDF_NAME_Type), PDF_NAME_OCG))
 		return;
 
-	if (pdf_is_hidden_ocg(ctx, csi->doc->ocg, csi->rdb, proc->event, cooked))
+	if (pdf_is_hidden_ocg(ctx, csi->doc->ocg, csi->rdb, proc->usage, cooked))
 		++proc->hidden;
 }
 
@@ -1263,18 +1049,18 @@ pdf_process_annot(fz_context *ctx, pdf_processor *proc, pdf_document *doc, pdf_p
 	if (flags & (PDF_ANNOT_IS_INVISIBLE | PDF_ANNOT_IS_HIDDEN))
 		return;
 
-	if (proc->event)
+	if (proc->usage)
 	{
-		if (!strcmp(proc->event, "Print") && !(flags & PDF_ANNOT_IS_PRINT))
+		if (!strcmp(proc->usage, "Print") && !(flags & PDF_ANNOT_IS_PRINT))
 			return;
-		if (!strcmp(proc->event, "View") && (flags & PDF_ANNOT_IS_NO_VIEW))
+		if (!strcmp(proc->usage, "View") && (flags & PDF_ANNOT_IS_NO_VIEW))
 			return;
 	}
 
 	/* TODO: NoZoom and NoRotate */
 
 	/* XXX what resources, if any, to use for this check? */
-	if (pdf_is_hidden_ocg(ctx, doc->ocg, NULL, proc->event, pdf_dict_get(ctx, annot->obj, PDF_NAME_OC)))
+	if (pdf_is_hidden_ocg(ctx, doc->ocg, NULL, proc->usage, pdf_dict_get(ctx, annot->obj, PDF_NAME_OC)))
 		return;
 
 	if (proc->op_q && proc->op_cm && proc->op_Do_form && proc->op_Q && annot->ap)
diff --git a/source/pdf/pdf-layer.c b/source/pdf/pdf-layer.c
new file mode 100644
index 00000000..70dfcd50
--- /dev/null
+++ b/source/pdf/pdf-layer.c
@@ -0,0 +1,715 @@
+#include "mupdf/fitz.h"
+#include "pdf-imp.h"
+
+/*
+	Notes on OCGs etc.
+
+	PDF Documents may contain Optional Content Groups. Which of
+	these is shown at any given time is dependent on which
+	Optional Content Configuration Dictionary is in force at the
+	time.
+
+	A pdf_document, once loaded, contains some state saying which
+	OCGs are enabled/disabled, and which 'Intent' (or 'Intents')
+	a file is being used for. This information is held outside of
+	the actual PDF file.
+
+	An Intent (just 'View' or 'Design' or 'All', according to
+	PDF 2.0, but theoretically more) says which OCGs to consider
+	or ignore in calculating the visibility of content. The
+	Intent (or Intents, for there can be an array) is set by the
+	current OCCD.
+
+	When first loaded, we turn all OCGs on, then load the default
+	OCCD. This may turn some OCGs off, and sets the document Intent.
+
+	Callers can ask how many OCCDs there are, read the names/creators
+	for each, and then select any one of them. That updates which
+	OCGs are selected, and resets the Intent.
+
+	Once an OCCD has been selected, a caller can enumerate the
+	'displayable configuration'. This is a list of labels/radio
+	buttons/check buttons that can be used to enable/disable
+	given OCGs. The caller can then enable/disable OCGs by
+	asking to select (or toggle) given entries in that list.
+
+	Thus the handling of radio button groups, and 'locked'
+	elements is kept within the core of MuPDF.
+
+	Finally, the caller can set the 'usage' for a document. This
+	can be 'View', 'Print', or 'Export'.
+*/
+
+typedef struct
+{
+	pdf_obj *obj;
+	int state;
+} pdf_ocg_entry;
+
+typedef struct
+{
+	int ocg;
+	const char *name;
+	int depth;
+	unsigned int button_flags : 2;
+	unsigned int locked : 1;
+} pdf_ocg_ui;
+
+struct pdf_ocg_descriptor_s
+{
+	int current;
+	int num_configs;
+
+	int len;
+	pdf_ocg_entry *ocgs;
+
+	pdf_obj *intent;
+	char *usage;
+
+	int num_ui_entries;
+	pdf_ocg_ui *ui;
+};
+
+int
+pdf_count_layer_configs(fz_context *ctx, pdf_document *doc)
+{
+	/* If no OCProperties, then no OCGs */
+	if (!doc || !doc->ocg)
+		return 0;
+	return doc->ocg->num_configs;
+}
+
+
+static int
+count_entries(fz_context *ctx, pdf_obj *obj)
+{
+	int len = pdf_array_len(ctx, obj);
+	int i;
+	int count = 0;
+
+	for (i = 0; i < len; i++)
+	{
+		pdf_obj *o = pdf_array_get(ctx, obj, i);
+		count += (pdf_is_array(ctx, o) ? count_entries(ctx, o) : 1);
+	}
+	return count;
+}
+
+static pdf_ocg_ui *
+populate_ui(fz_context *ctx, pdf_ocg_descriptor *desc, pdf_ocg_ui *ui, pdf_obj *order, int depth, pdf_obj *rbgroups, pdf_obj *locked)
+{
+	int len = pdf_array_len(ctx, order);
+	int i, j;
+
+	for (i = 0; i < len; i++)
+	{
+		pdf_obj *o = pdf_array_get(ctx, order, i);
+		if (pdf_is_array(ctx, o))
+		{
+			ui = populate_ui(ctx, desc, ui, o, depth+1, rbgroups, locked);
+			continue;
+		}
+		ui->depth = depth;
+		if (pdf_is_string(ctx, o))
+		{
+			ui->ocg = -1;
+			ui->name = pdf_to_str_buf(ctx, o);
+			ui->button_flags = PDF_LAYER_UI_LABEL;
+			ui->locked = 1;
+			ui++;
+			continue;
+		}
+
+		for (j = 0; j < desc->len; j++)
+		{
+			if (!pdf_objcmp_resolve(ctx, o, desc->ocgs[j].obj))
+				break;
+		}
+		if (j == desc->len)
+			continue; /* OCG not found in main list! Just ignore it */
+		ui->ocg = j;
+		ui->name = pdf_to_str_buf(ctx, pdf_dict_get(ctx, o, PDF_NAME_Name));
+		ui->button_flags = pdf_array_contains(ctx, o, rbgroups) ? PDF_LAYER_UI_RADIOBOX : PDF_LAYER_UI_CHECKBOX;
+		ui->locked = pdf_array_contains(ctx, o, locked);
+		ui++;
+	}
+	return ui;
+}
+
+static void
+drop_ui(fz_context *ctx, pdf_ocg_descriptor *desc)
+{
+	if (!desc)
+		return;
+
+	fz_free(ctx, desc->ui);
+	desc->ui = NULL;
+}
+
+static void
+load_ui(fz_context *ctx, pdf_ocg_descriptor *desc, pdf_obj *ocprops, pdf_obj *occg)
+{
+	pdf_obj *order;
+	pdf_obj *rbgroups;
+	pdf_obj *locked;
+	int count;
+
+	/* Count the number of entries */
+	order = pdf_dict_get(ctx, occg, PDF_NAME_Order);
+	count = count_entries(ctx, order);
+	rbgroups = pdf_dict_get(ctx, occg, PDF_NAME_RBGroups);
+	locked = pdf_dict_get(ctx, occg, PDF_NAME_Locked);
+
+	desc->num_ui_entries = count;
+	desc->ui = Memento_label(fz_calloc(ctx, count, sizeof(pdf_ocg_ui)), "pdf_ocg_ui");
+	fz_try(ctx)
+	{
+		(void)populate_ui(ctx, desc, desc->ui, order, 0, rbgroups, locked);
+	}
+	fz_catch(ctx)
+	{
+		drop_ui(ctx, desc);
+		fz_rethrow(ctx);
+	}
+}
+
+void
+pdf_select_layer_config(fz_context *ctx, pdf_document *doc, int config)
+{
+	int i, j, len, len2;
+	pdf_ocg_descriptor *desc = doc->ocg;
+	pdf_obj *obj, *cobj;
+	pdf_obj *name;
+
+	obj = pdf_dict_get(ctx, pdf_dict_get(ctx, pdf_trailer(ctx, doc), PDF_NAME_Root), PDF_NAME_OCProperties);
+	if (!obj)
+	{
+		if (config == 0)
+			return;
+		else
+			fz_throw(ctx, FZ_ERROR_GENERIC, "Unknown Layer config (None known!)");
+	}
+
+	cobj = pdf_array_get(ctx, pdf_dict_get(ctx, obj, PDF_NAME_Configs), config);
+	if (!cobj)
+	{
+		if (config != 0)
+			fz_throw(ctx, FZ_ERROR_GENERIC, "Illegal Layer config");
+		cobj = pdf_dict_get(ctx, obj, PDF_NAME_D);
+		if (!cobj)
+			fz_throw(ctx, FZ_ERROR_GENERIC, "No default Layer config");
+	}
+
+	pdf_drop_obj(ctx, desc->intent);
+	desc->intent = pdf_keep_obj(ctx, pdf_dict_get(ctx, cobj, PDF_NAME_Intent));
+
+	len = desc->len;
+	name = pdf_dict_get(ctx, cobj, PDF_NAME_BaseState);
+	if (pdf_name_eq(ctx, name, PDF_NAME_Unchanged))
+	{
+		/* Do nothing */
+	}
+	else if (pdf_name_eq(ctx, name, PDF_NAME_OFF))
+	{
+		for (i = 0; i < len; i++)
+		{
+			desc->ocgs[i].state = 0;
+		}
+	}
+	else /* Default to ON */
+	{
+		for (i = 0; i < len; i++)
+		{
+			desc->ocgs[i].state = 1;
+		}
+	}
+
+	obj = pdf_dict_get(ctx, cobj, PDF_NAME_ON);
+	len2 = pdf_array_len(ctx, obj);
+	for (i = 0; i < len2; i++)
+	{
+		pdf_obj *o = pdf_array_get(ctx, obj, i);
+		for (j=0; j < len; j++)
+		{
+			if (!pdf_objcmp_resolve(ctx, desc->ocgs[j].obj, o))
+			{
+				desc->ocgs[j].state = 1;
+				break;
+			}
+		}
+	}
+
+	obj = pdf_dict_get(ctx, cobj, PDF_NAME_OFF);
+	len2 = pdf_array_len(ctx, obj);
+	for (i = 0; i < len2; i++)
+	{
+		pdf_obj *o = pdf_array_get(ctx, obj, i);
+		for (j=0; j < len; j++)
+		{
+			if (!pdf_objcmp_resolve(ctx, desc->ocgs[j].obj, o))
+			{
+				desc->ocgs[j].state = 0;
+				break;
+			}
+		}
+	}
+
+	desc->current = config;
+
+	drop_ui(ctx, desc);
+	load_ui(ctx, desc, obj, cobj);
+}
+
+void
+pdf_layer_config_info(fz_context *ctx, pdf_document *doc, int config_num, pdf_layer_config *info)
+{
+	pdf_obj *ocprops;
+	pdf_obj *obj;
+
+	if (!info)
+		return;
+
+	info->name = NULL;
+	info->creator = NULL;
+
+	if (doc == NULL || doc->ocg == NULL)
+		return;
+	if (config_num < 0 || config_num >= doc->ocg->num_configs)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid layer config number");
+
+	ocprops = pdf_dict_getp(ctx, pdf_trailer(ctx, doc), "Root/OCProperties");
+	if (!ocprops)
+		return;
+
+	obj = pdf_dict_get(ctx, ocprops, PDF_NAME_Configs);
+	if (pdf_is_array(ctx, obj))
+		obj = pdf_array_get(ctx, obj, config_num);
+	else if (config_num == 0)
+		obj = pdf_dict_get(ctx, ocprops, PDF_NAME_D);
+	else
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid layer config number");
+
+	info->creator = pdf_to_str_buf(ctx, pdf_dict_get(ctx, obj, PDF_NAME_Creator));
+	info->name = pdf_to_str_buf(ctx, pdf_dict_get(ctx, obj, PDF_NAME_Name));
+}
+
+void
+pdf_drop_ocg(fz_context *ctx, pdf_document *doc)
+{
+	pdf_ocg_descriptor *desc;
+	int i;
+
+	if (!doc)
+		return;
+	desc = doc->ocg;
+	if (!desc)
+		return;
+
+	pdf_drop_obj(ctx, desc->intent);
+	for (i = 0; i < desc->len; i++)
+		pdf_drop_obj(ctx, desc->ocgs[i].obj);
+	fz_free(ctx, desc->ocgs);
+	fz_free(ctx, desc);
+}
+
+static void
+clear_radio_group(fz_context *ctx, pdf_document *doc, pdf_obj *ocg)
+{
+	pdf_obj *rbgroups = pdf_dict_getp(ctx, pdf_trailer(ctx, doc), "Root/OCProperties/RBGroups");
+	int len, i;
+
+	len = pdf_array_len(ctx, rbgroups);
+	for (i = 0; i < len; i++)
+	{
+		pdf_obj *group = pdf_array_get(ctx, rbgroups, i);
+
+		if (pdf_array_contains(ctx, ocg, group))
+		{
+			int len2 = pdf_array_len(ctx, group);
+			int j;
+
+			for (j = 0; j < len2; j++)
+			{
+				pdf_obj *g = pdf_array_get(ctx, group, j);
+				int k;
+				for (k = 0; k < doc->ocg->len; k++)
+				{
+					pdf_ocg_entry *s = &doc->ocg->ocgs[k];
+
+					if (!pdf_objcmp_resolve(ctx, s->obj, g))
+						s->state = 0;
+				}
+			}
+		}
+	}
+}
+
+int pdf_count_layer_config_ui(fz_context *ctx, pdf_document *doc)
+{
+	if (doc == NULL || doc->ocg == NULL)
+		return 0;
+
+	return doc->ocg->num_ui_entries;
+}
+
+void pdf_select_layer_config_ui(fz_context *ctx, pdf_document *doc, int ui)
+{
+	pdf_ocg_ui *entry;
+
+	if (doc == NULL || doc->ocg == NULL)
+		return;
+
+	if (ui < 0 || ui >= doc->ocg->num_ui_entries)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Out of range UI entry selected");
+
+	entry = &doc->ocg->ui[ui];
+	if (entry->button_flags != PDF_LAYER_UI_RADIOBOX &&
+		entry->button_flags != PDF_LAYER_UI_CHECKBOX)
+		return;
+	if (entry->locked)
+		return;
+
+	if (entry->button_flags == PDF_LAYER_UI_RADIOBOX)
+		clear_radio_group(ctx, doc, doc->ocg->ocgs[entry->ocg].obj);
+
+	doc->ocg->ocgs[entry->ocg].state = 1;
+}
+
+void pdf_toggle_layer_config_ui(fz_context *ctx, pdf_document *doc, int ui)
+{
+	pdf_ocg_ui *entry;
+	int selected;
+
+	if (doc == NULL || doc->ocg == NULL)
+		return;
+
+	if (ui < 0 || ui >= doc->ocg->num_ui_entries)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Out of range UI entry toggled");
+
+	entry = &doc->ocg->ui[ui];
+	if (entry->button_flags != PDF_LAYER_UI_RADIOBOX &&
+		entry->button_flags != PDF_LAYER_UI_CHECKBOX)
+		return;
+	if (entry->locked)
+		return;
+
+	selected = doc->ocg->ocgs[entry->ocg].state;
+
+	if (entry->button_flags == PDF_LAYER_UI_RADIOBOX)
+		clear_radio_group(ctx, doc, doc->ocg->ocgs[entry->ocg].obj);
+
+	doc->ocg->ocgs[entry->ocg].state = !selected;
+}
+
+void pdf_deselect_layer_ui(fz_context *ctx, pdf_document *doc, int ui)
+{
+	pdf_ocg_ui *entry;
+
+	if (doc == NULL || doc->ocg == NULL)
+		return;
+
+	if (ui < 0 || ui >= doc->ocg->num_ui_entries)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Out of range UI entry deselected");
+
+	entry = &doc->ocg->ui[ui];
+	if (entry->button_flags != PDF_LAYER_UI_RADIOBOX &&
+		entry->button_flags != PDF_LAYER_UI_CHECKBOX)
+		return;
+	if (entry->locked)
+		return;
+
+	doc->ocg->ocgs[entry->ocg].state = 0;
+}
+
+void
+pdf_layer_config_ui_info(fz_context *ctx, pdf_document *doc, int ui, pdf_layer_config_ui *info)
+{
+	pdf_ocg_ui *entry;
+
+	if (!info)
+		return;
+
+	info->depth = 0;
+	info->locked = 0;
+	info->selected = 0;
+	info->text = NULL;
+	info->type = 0;
+
+	if (doc == NULL || doc->ocg == NULL)
+		return;
+
+	if (ui < 0 || ui >= doc->ocg->num_ui_entries)
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Out of range UI entry selected");
+
+	entry = &doc->ocg->ui[ui];
+	info->type = entry->button_flags;
+	info->depth = entry->depth;
+	info->selected = doc->ocg->ocgs[entry->ocg].state;
+	info->locked = entry->locked;
+	info->text = entry->name;
+}
+
+static int
+ocg_intents_include(fz_context *ctx, pdf_ocg_descriptor *desc, char *name)
+{
+	int i, len;
+
+	if (strcmp(name, "All") == 0)
+		return 1;
+
+	/* In the absence of a specified intent, it's 'View' */
+	if (!desc->intent)
+		return (strcmp(name, "View") == 0);
+
+	if (pdf_is_name(ctx, desc->intent))
+	{
+		char *intent = pdf_to_name(ctx, desc->intent);
+		if (strcmp(intent, "All") == 0)
+			return 1;
+		return (strcmp(intent, name) == 0);
+	}
+	if (!pdf_is_array(ctx, desc->intent))
+		return 0;
+
+	len = pdf_array_len(ctx, desc->intent);
+	for (i=0; i < len; i++)
+	{
+		char *intent = pdf_to_name(ctx, pdf_array_get(ctx, desc->intent, i));
+		if (strcmp(intent, "All") == 0)
+			return 1;
+		if (strcmp(intent, name) == 0)
+			return 1;
+	}
+	return 0;
+}
+
+int
+pdf_is_hidden_ocg(fz_context *ctx, pdf_ocg_descriptor *desc, pdf_obj *rdb, const char *usage, pdf_obj *ocg)
+{
+	char event_state[16];
+	pdf_obj *obj, *obj2, *type;
+
+	/* Avoid infinite recursions */
+	if (pdf_obj_marked(ctx, ocg))
+		return 0;
+
+	/* If no usage, everything is visible */
+	if (!usage)
+		return 0;
+
+	/* If no ocg descriptor, everything is visible */
+	if (!desc)
+		return 0;
+
+	/* If we've been handed a name, look it up in the properties. */
+	if (pdf_is_name(ctx, ocg))
+	{
+		ocg = pdf_dict_get(ctx, pdf_dict_get(ctx, rdb, PDF_NAME_Properties), ocg);
+	}
+	/* If we haven't been given an ocg at all, then we're visible */
+	if (!ocg)
+		return 0;
+
+	fz_strlcpy(event_state, usage, sizeof event_state);
+	fz_strlcat(event_state, "State", sizeof event_state);
+
+	type = pdf_dict_get(ctx, ocg, PDF_NAME_Type);
+
+	if (pdf_name_eq(ctx, type, PDF_NAME_OCG))
+	{
+		/* An Optional Content Group */
+		int default_value = 0;
+		int len = desc->len;
+		int i;
+		pdf_obj *es;
+
+		/* by default an OCG is visible, unless it's explicitly hidden */
+		for (i = 0; i < len; i++)
+		{
+			if (!pdf_objcmp_resolve(ctx, desc->ocgs[i].obj, ocg))
+			{
+				default_value = !desc->ocgs[i].state;
+				break;
+			}
+		}
+
+		/* Check Intents; if our intent is not part of the set given
+		 * by the current config, we should ignore it. */
+		obj = pdf_dict_get(ctx, ocg, PDF_NAME_Intent);
+		if (pdf_is_name(ctx, obj))
+		{
+			/* If it doesn't match, it's hidden */
+			if (ocg_intents_include(ctx, desc, pdf_to_name(ctx, obj)) == 0)
+				return 1;
+		}
+		else if (pdf_is_array(ctx, obj))
+		{
+			int match = 0;
+			len = pdf_array_len(ctx, obj);
+			for (i=0; i<len; i++) {
+				match |= ocg_intents_include(ctx, desc, pdf_to_name(ctx, pdf_array_get(ctx, obj, i)));
+				if (match)
+					break;
+			}
+			/* If we don't match any, it's hidden */
+			if (match == 0)
+				return 1;
+		}
+		else
+		{
+			/* If it doesn't match, it's hidden */
+			if (ocg_intents_include(ctx, desc, "View") == 0)
+				return 1;
+		}
+
+		/* FIXME: Currently we do a very simple check whereby we look
+		 * at the Usage object (an Optional Content Usage Dictionary)
+		 * and check to see if the corresponding 'event' key is on
+		 * or off.
+		 *
+		 * Really we should only look at Usage dictionaries that
+		 * correspond to entries in the AS list in the OCG config.
+		 * Given that we don't handle Zoom or User, or Language
+		 * dicts, this is not really a problem. */
+		obj = pdf_dict_get(ctx, ocg, PDF_NAME_Usage);
+		if (!pdf_is_dict(ctx, obj))
+			return default_value;
+		/* FIXME: Should look at Zoom (and return hidden if out of
+		 * max/min range) */
+		/* FIXME: Could provide hooks to the caller to check if
+		 * User is appropriate - if not return hidden. */
+		obj2 = pdf_dict_gets(ctx, obj, usage);
+		es = pdf_dict_gets(ctx, obj2, event_state);
+		if (pdf_name_eq(ctx, es, PDF_NAME_OFF))
+		{
+			return 1;
+		}
+		if (pdf_name_eq(ctx, es, PDF_NAME_ON))
+		{
+			return 0;
+		}
+		return default_value;
+	}
+	else if (pdf_name_eq(ctx, type, PDF_NAME_OCMD))
+	{
+		/* An Optional Content Membership Dictionary */
+		pdf_obj *name;
+		int combine, on;
+
+		obj = pdf_dict_get(ctx, ocg, PDF_NAME_VE);
+		if (pdf_is_array(ctx, obj)) {
+			/* FIXME: Calculate visibility from array */
+			return 0;
+		}
+		name = pdf_dict_get(ctx, ocg, PDF_NAME_P);
+		/* Set combine; Bit 0 set => AND, Bit 1 set => true means
+		 * Off, otherwise true means On */
+		if (pdf_name_eq(ctx, name, PDF_NAME_AllOn))
+		{
+			combine = 1;
+		}
+		else if (pdf_name_eq(ctx, name, PDF_NAME_AnyOff))
+		{
+			combine = 2;
+		}
+		else if (pdf_name_eq(ctx, name, PDF_NAME_AllOff))
+		{
+			combine = 3;
+		}
+		else /* Assume it's the default (AnyOn) */
+		{
+			combine = 0;
+		}
+
+		if (pdf_mark_obj(ctx, ocg))
+			return 0; /* Should never happen */
+		fz_try(ctx)
+		{
+			obj = pdf_dict_get(ctx, ocg, PDF_NAME_OCGs);
+			on = combine & 1;
+			if (pdf_is_array(ctx, obj)) {
+				int i, len;
+				len = pdf_array_len(ctx, obj);
+				for (i = 0; i < len; i++)
+				{
+					int hidden = pdf_is_hidden_ocg(ctx, desc, rdb, usage, pdf_array_get(ctx, obj, i));
+					if ((combine & 1) == 0)
+						hidden = !hidden;
+					if (combine & 2)
+						on &= hidden;
+					else
+						on |= hidden;
+				}
+			}
+			else
+			{
+				on = pdf_is_hidden_ocg(ctx, desc, rdb, usage, obj);
+				if ((combine & 1) == 0)
+					on = !on;
+			}
+		}
+		fz_always(ctx)
+		{
+			pdf_unmark_obj(ctx, ocg);
+		}
+		fz_catch(ctx)
+		{
+			fz_rethrow(ctx);
+		}
+		return !on;
+	}
+	/* No idea what sort of object this is - be visible */
+	return 0;
+}
+
+void
+pdf_read_ocg(fz_context *ctx, pdf_document *doc)
+{
+	pdf_obj *obj, *ocg, *configs;
+	int len, i, num_configs;
+	pdf_ocg_descriptor *desc;
+
+	fz_var(desc);
+
+	obj = pdf_dict_get(ctx, pdf_dict_get(ctx, pdf_trailer(ctx, doc), PDF_NAME_Root), PDF_NAME_OCProperties);
+	if (!obj)
+		return;
+
+	configs = pdf_dict_get(ctx, obj, PDF_NAME_Configs);
+	if (configs == NULL)
+		num_configs = 1;
+	else if (!pdf_is_array(ctx, configs))
+		fz_throw(ctx, FZ_ERROR_GENERIC, "Invalid Configs value");
+	else
+		num_configs = pdf_array_len(ctx, configs);
+
+	ocg = pdf_dict_get(ctx, obj, PDF_NAME_OCGs);
+	if (!ocg || !pdf_is_array(ctx, ocg))
+		/* Not ever supposed to happen, but live with it. */
+		return;
+	len = pdf_array_len(ctx, ocg);
+	fz_try(ctx)
+	{
+		desc = fz_malloc_struct(ctx, pdf_ocg_descriptor);
+		desc->num_configs = num_configs;
+		desc->len = len;
+		desc->ocgs = fz_calloc(ctx, len, sizeof(*desc->ocgs));
+		desc->intent = NULL;
+		for (i=0; i < len; i++)
+		{
+			pdf_obj *o = pdf_array_get(ctx, ocg, i);
+			desc->ocgs[i].obj = pdf_keep_obj(ctx, o);
+			desc->ocgs[i].state = 1;
+		}
+		doc->ocg = desc;
+	}
+	fz_catch(ctx)
+	{
+		if (desc)
+			fz_free(ctx, desc->ocgs);
+		fz_free(ctx, desc);
+		fz_rethrow(ctx);
+	}
+
+	pdf_select_layer_config(ctx, doc, 0);
+}
diff --git a/source/pdf/pdf-op-run.c b/source/pdf/pdf-op-run.c
index 89bbf008..00d1957d 100644
--- a/source/pdf/pdf-op-run.c
+++ b/source/pdf/pdf-op-run.c
@@ -2018,11 +2018,11 @@ pdf_drop_run_processor(fz_context *ctx, pdf_processor *proc)
 }
 
 pdf_processor *
-pdf_new_run_processor(fz_context *ctx, fz_device *dev, const fz_matrix *ctm, const char *event, pdf_gstate *gstate, int nested)
+pdf_new_run_processor(fz_context *ctx, fz_device *dev, const fz_matrix *ctm, const char *usage, pdf_gstate *gstate, int nested)
 {
 	pdf_run_processor *proc = pdf_new_processor(ctx, sizeof *proc);
 	{
-		proc->super.event = event;
+		proc->super.usage = usage;
 
 		proc->super.drop_processor = pdf_drop_run_processor;
 
diff --git a/source/pdf/pdf-run.c b/source/pdf/pdf-run.c
index f806b120..ba8b30b7 100644
--- a/source/pdf/pdf-run.c
+++ b/source/pdf/pdf-run.c
@@ -1,7 +1,7 @@
 #include "mupdf/pdf.h"
 
 static void
-pdf_run_annot_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, pdf_annot *annot, fz_device *dev, const fz_matrix *ctm, char *event, fz_cookie *cookie)
+pdf_run_annot_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, pdf_annot *annot, fz_device *dev, const fz_matrix *ctm, const char *usage, fz_cookie *cookie)
 {
 	fz_matrix local_ctm, page_ctm;
 	fz_rect mediabox;
@@ -10,7 +10,7 @@ pdf_run_annot_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, pdf
 	pdf_page_transform(ctx, page, &mediabox, &page_ctm);
 	fz_concat(&local_ctm, &page_ctm, ctm);
 
-	proc = pdf_new_run_processor(ctx, dev, &local_ctm, event, NULL, 0);
+	proc = pdf_new_run_processor(ctx, dev, &local_ctm, usage, NULL, 0);
 	fz_try(ctx)
 		pdf_process_annot(ctx, proc, doc, page, annot, cookie);
 	fz_always(ctx)
@@ -19,7 +19,8 @@ pdf_run_annot_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, pdf
 		fz_rethrow(ctx);
 }
 
-static void pdf_run_page_contents_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, char *event, fz_cookie *cookie)
+static void
+pdf_run_page_contents_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, const char *usage, fz_cookie *cookie)
 {
 	fz_matrix local_ctm, page_ctm;
 	pdf_obj *resources;
@@ -36,7 +37,7 @@ static void pdf_run_page_contents_with_usage(fz_context *ctx, pdf_document *doc,
 	if (page->transparency)
 		fz_begin_group(ctx, dev, fz_transform_rect(&mediabox, &local_ctm), 1, 0, 0, 1);
 
-	proc = pdf_new_run_processor(ctx, dev, &local_ctm, event, NULL, 0);
+	proc = pdf_new_run_processor(ctx, dev, &local_ctm, usage, NULL, 0);
 	fz_try(ctx)
 		pdf_process_contents(ctx, proc, doc, resources, contents, cookie);
 	fz_always(ctx)
@@ -100,7 +101,8 @@ void pdf_run_annot(fz_context *ctx, pdf_annot *annot, fz_device *dev, const fz_m
 		fz_throw(ctx, FZ_ERROR_TRYLATER, "incomplete rendering");
 }
 
-static void pdf_run_page_annots_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, char *event, fz_cookie *cookie)
+static void
+pdf_run_page_annots_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, const char *usage, fz_cookie *cookie)
 {
 	pdf_annot *annot;
 
@@ -122,12 +124,12 @@ static void pdf_run_page_annots_with_usage(fz_context *ctx, pdf_document *doc, p
 			cookie->progress++;
 		}
 
-		pdf_run_annot_with_usage(ctx, doc, page, annot, dev, ctm, event, cookie);
+		pdf_run_annot_with_usage(ctx, doc, page, annot, dev, ctm, usage, cookie);
 	}
 }
 
 void
-pdf_run_page_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, char *event, fz_cookie *cookie)
+pdf_run_page_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_device *dev, const fz_matrix *ctm, const char *usage, fz_cookie *cookie)
 {
 	int nocache = !!(dev->hints & FZ_NO_CACHE);
 
@@ -135,8 +137,8 @@ pdf_run_page_with_usage(fz_context *ctx, pdf_document *doc, pdf_page *page, fz_d
 		pdf_mark_xref(ctx, doc);
 	fz_try(ctx)
 	{
-		pdf_run_page_contents_with_usage(ctx, doc, page, dev, ctm, event, cookie);
-		pdf_run_page_annots_with_usage(ctx, doc, page, dev, ctm, event, cookie);
+		pdf_run_page_contents_with_usage(ctx, doc, page, dev, ctm, usage, cookie);
+		pdf_run_page_annots_with_usage(ctx, doc, page, dev, ctm, usage, cookie);
 	}
 	fz_always(ctx)
 	{
diff --git a/source/pdf/pdf-xref.c b/source/pdf/pdf-xref.c
index 41dd9984..1af2d391 100644
--- a/source/pdf/pdf-xref.c
+++ b/source/pdf/pdf-xref.c
@@ -1,4 +1,4 @@
-#include "mupdf/pdf.h"
+#include "pdf-imp.h"
 #include "mupdf/fitz/document.h"
 
 #undef DEBUG_PROGESSIVE_ADVANCE
@@ -241,7 +241,7 @@ pdf_xref_entry *pdf_get_populating_xref_entry(fz_context *ctx, pdf_document *doc
  * xref. */
 pdf_xref_entry *pdf_get_xref_entry(fz_context *ctx, pdf_document *doc, int i)
 {
-	pdf_xref *xref;
+	pdf_xref *xref = NULL;
 	pdf_xref_subsec *sub;
 	int j;
 
@@ -1277,161 +1277,6 @@ pdf_load_linear(fz_context *ctx, pdf_document *doc)
 	}
 }
 
-void
-pdf_ocg_set_config(fz_context *ctx, pdf_document *doc, int config)
-{
-	int i, j, len, len2;
-	pdf_ocg_descriptor *desc = doc->ocg;
-	pdf_obj *obj, *cobj;
-	pdf_obj *name;
-
-	obj = pdf_dict_get(ctx, pdf_dict_get(ctx, pdf_trailer(ctx, doc), PDF_NAME_Root), PDF_NAME_OCProperties);
-	if (!obj)
-	{
-		if (config == 0)
-			return;
-		else
-			fz_throw(ctx, FZ_ERROR_GENERIC, "Unknown OCG config (None known!)");
-	}
-	if (config == 0)
-	{
-		cobj = pdf_dict_get(ctx, obj, PDF_NAME_D);
-		if (!cobj)
-			fz_throw(ctx, FZ_ERROR_GENERIC, "No default OCG config");
-	}
-	else
-	{
-		cobj = pdf_array_get(ctx, pdf_dict_get(ctx, obj, PDF_NAME_Configs), config);
-		if (!cobj)
-			fz_throw(ctx, FZ_ERROR_GENERIC, "Illegal OCG config");
-	}
-
-	pdf_drop_obj(ctx, desc->intent);
-	desc->intent = pdf_dict_get(ctx, cobj, PDF_NAME_Intent);
-	if (desc->intent)
-		pdf_keep_obj(ctx, desc->intent);
-
-	len = desc->len;
-	name = pdf_dict_get(ctx, cobj, PDF_NAME_BaseState);
-	if (pdf_name_eq(ctx, name, PDF_NAME_Unchanged))
-	{
-		/* Do nothing */
-	}
-	else if (pdf_name_eq(ctx, name, PDF_NAME_OFF))
-	{
-		for (i = 0; i < len; i++)
-		{
-			desc->ocgs[i].state = 0;
-		}
-	}
-	else /* Default to ON */
-	{
-		for (i = 0; i < len; i++)
-		{
-			desc->ocgs[i].state = 1;
-		}
-	}
-
-	obj = pdf_dict_get(ctx, cobj, PDF_NAME_ON);
-	len2 = pdf_array_len(ctx, obj);
-	for (i = 0; i < len2; i++)
-	{
-		pdf_obj *o = pdf_array_get(ctx, obj, i);
-		int n = pdf_to_num(ctx, o);
-		for (j=0; j < len; j++)
-		{
-			if (desc->ocgs[j].num == n)
-			{
-				desc->ocgs[j].state = 1;
-				break;
-			}
-		}
-	}
-
-	obj = pdf_dict_get(ctx, cobj, PDF_NAME_OFF);
-	len2 = pdf_array_len(ctx, obj);
-	for (i = 0; i < len2; i++)
-	{
-		pdf_obj *o = pdf_array_get(ctx, obj, i);
-		int n = pdf_to_num(ctx, o);
-		for (j=0; j < len; j++)
-		{
-			if (desc->ocgs[j].num == n)
-			{
-				desc->ocgs[j].state = 0;
-				break;
-			}
-		}
-	}
-
-	/* FIXME: Should make 'num configs' available in the descriptor. */
-	/* FIXME: Should copy out 'Intent' here into the descriptor, and remove
-	 * csi->intent in favour of that. */
-	/* FIXME: Should copy 'AS' into the descriptor, and visibility
-	 * decisions should respect it. */
-	/* FIXME: Make 'Order' available via the descriptor (when we have an
-	 * app that needs it) */
-	/* FIXME: Make 'ListMode' available via the descriptor (when we have
-	 * an app that needs it) */
-	/* FIXME: Make 'RBGroups' available via the descriptor (when we have
-	 * an app that needs it) */
-	/* FIXME: Make 'Locked' available via the descriptor (when we have
-	 * an app that needs it) */
-}
-
-static void
-pdf_read_ocg(fz_context *ctx, pdf_document *doc)
-{
-	pdf_obj *obj, *ocg;
-	int len, i;
-	pdf_ocg_descriptor *desc;
-
-	fz_var(desc);
-
-	obj = pdf_dict_get(ctx, pdf_dict_get(ctx, pdf_trailer(ctx, doc), PDF_NAME_Root), PDF_NAME_OCProperties);
-	if (!obj)
-		return;
-	ocg = pdf_dict_get(ctx, obj, PDF_NAME_OCGs);
-	if (!ocg || !pdf_is_array(ctx, ocg))
-		/* Not ever supposed to happen, but live with it. */
-		return;
-	len = pdf_array_len(ctx, ocg);
-	fz_try(ctx)
-	{
-		desc = fz_malloc_struct(ctx, pdf_ocg_descriptor);
-		desc->len = len;
-		desc->ocgs = fz_calloc(ctx, len, sizeof(*desc->ocgs));
-		desc->intent = NULL;
-		for (i=0; i < len; i++)
-		{
-			pdf_obj *o = pdf_array_get(ctx, ocg, i);
-			desc->ocgs[i].num = pdf_to_num(ctx, o);
-			desc->ocgs[i].state = 1;
-		}
-		doc->ocg = desc;
-	}
-	fz_catch(ctx)
-	{
-		if (desc)
-			fz_free(ctx, desc->ocgs);
-		fz_free(ctx, desc);
-		fz_rethrow(ctx);
-	}
-
-	pdf_ocg_set_config(ctx, doc, 0);
-}
-
-static void
-pdf_drop_ocg(fz_context *ctx, pdf_ocg_descriptor *desc)
-{
-	if (!desc)
-		return;
-
-	pdf_drop_obj(ctx, desc->intent);
-	fz_free(ctx, desc->ocgs);
-	fz_free(ctx, desc);
-}
-
 /*
  * Initialize and load xref tables.
  * If password is not null, try to decrypt.
@@ -1631,7 +1476,7 @@ pdf_drop_document_imp(fz_context *ctx, pdf_document *doc)
 		}
 		fz_free(ctx, doc->type3_fonts);
 
-		pdf_drop_ocg(ctx, doc->ocg);
+		pdf_drop_ocg(ctx, doc);
 
 		pdf_empty_store(ctx, doc);
 
-- 
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