Add private PPAPI interfaces for PDFium accessibility.

ppapi/c/private/ppb_pdf.h

Index: ppapi/c/private/ppb_pdf.h
diff --git a/ppapi/c/private/ppb_pdf.h b/ppapi/c/private/ppb_pdf.h
index a4c49c3e114315d46e9319bbc11a2c6aae3a68c6..ce6221e07aaf5b30d6126674e06a2cbd87e50a19 100644
--- a/ppapi/c/private/ppb_pdf.h
+++ b/ppapi/c/private/ppb_pdf.h
@@ -9,6 +9,8 @@
 
 #include "ppapi/c/pp_bool.h"
 #include "ppapi/c/pp_instance.h"
+#include "ppapi/c/pp_point.h"
+#include "ppapi/c/pp_rect.h"
 #include "ppapi/c/pp_resource.h"
 #include "ppapi/c/pp_var.h"
 #include "ppapi/c/private/pp_private_font_charset.h"
@@ -31,6 +33,46 @@ struct PP_PrivateFindResult {
   int length;
 };
 
+struct PP_PrivateAccessibilityViewportInfo {
+  double zoom;
+  struct PP_Point scroll;
+  struct PP_Point offset;
+};
+
+struct PP_PrivateAccessibilityDocInfo {
+  uint32_t page_count;
+  PP_Bool text_accessible;
+  PP_Bool text_copyable;
+};
+
+typedef enum {
+  PP_PRIVATEDIRECTION_NONE = 0,
+  PP_PRIVATEDIRECTION_LTR = 1,
+  PP_PRIVATEDIRECTION_RTL = 2,
+  PP_PRIVATEDIRECTION_TTB = 3,
+  PP_PRIVATEDIRECTION_BTT = 4,
+  PP_PRIVATEDIRECTION_LAST = PP_PRIVATEDIRECTION_BTT
+} PP_PrivateDirection;
+
+struct PP_PrivateAccessibilityPageInfo {
+  uint32_t page_index;
+  struct PP_Rect bounds;
+  uint32_t text_run_count;
+  uint32_t char_count;
+};
+
+struct PP_PrivateAccessibilityTextRunInfo {
+  uint32_t len;
+  double font_size;
+  struct PP_FloatRect bounds;
+  PP_PrivateDirection direction;
+};
+
+struct PP_PrivateAccessibilityCharInfo {
+  uint32_t unicode_character;
+  double char_width;

[raymes, 2016/05/30 04:17:37]

Would it be any more performant to split these two things into parallel arrays.
e.g. would it be useful to directly have a uint32_t array of characters without
having to unpack them on the renderer side?

[dmazzoni, 2016/05/31 21:45:01]

I agree there are some advantages to having parallel arrays, but I'm positive
this won't be a bottleneck - the total amount of text on a page is not that
large.

The main reason I prefer this design is that I think there's a chance
I'd want to add another per-character field at some point in the
future, and it seems like it'd be a lot easier with this design.

[raymes, 2016/06/01 00:05:53]

sgtm

+};
+
 struct PPB_PDF {
   // Returns a resource identifying a font file corresponding to the given font
   // request after applying the browser-specific fallback.
@@ -95,6 +137,27 @@ struct PPB_PDF {
                                     int* natives_size_out,
                                     const char** snapshot_data_out,
                                     int* snapshot_size_out);
+
+  // Sends information about the viewport to the renderer for accessibility
+  // support.
+  void (*SetAccessibilityViewportInfo)(
+      PP_Instance instance,
+      struct PP_PrivateAccessibilityViewportInfo* viewport_info);
+
+  // Sends information about the PDF document to the renderer for accessibility
+  // support.
+  void (*SetAccessibilityDocInfo)(
+      PP_Instance instance,
+      struct PP_PrivateAccessibilityDocInfo* doc_info);
+
+  // Sends information about one page in a PDF document to the renderer for
+  // accessibility support.
+  void (*SetAccessibilityPageInfo)(
+      PP_Instance instance,
+      struct PP_PrivateAccessibilityPageInfo* page_info,
+      struct PP_PrivateAccessibilityTextRunInfo text_runs[],
+      struct PP_PrivateAccessibilityCharInfo chars[]);
+
 };
 
 #endif  // PPAPI_C_PRIVATE_PPB_PDF_H_