Cleanup fpdf_edit.h and fpdf_doc.h documentation.

public/fpdf_doc.h

 // Copyright 2014 PDFium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Original code copyright 2014 Foxit Software Inc. http://www.foxitsoftware.com
 
 #ifndef PUBLIC_FPDF_DOC_H_
 #define PUBLIC_FPDF_DOC_H_
 
 #include "fpdfview.h"
 
-// Exported Functions
 #ifdef __cplusplus
 extern "C" {
-#endif
-
-// Function: FPDFBookmark_GetFirstChild
-//          Get the first child of a bookmark item, or the first top level
-//          bookmark item.
-// Parameters:
-//          document    -   Handle to the document. Returned by
-//          FPDF_LoadDocument or FPDF_LoadMemDocument.
-//          bookmark    -   Handle to the current bookmark. Can be NULL if you
-//          want to get the first top level item.
-// Return value:
-//          Handle to the first child or top level bookmark item. NULL if no
-//          child or top level bookmark found.
-//
-DLLEXPORT FPDF_BOOKMARK STDCALL
-FPDFBookmark_GetFirstChild(FPDF_DOCUMENT document, FPDF_BOOKMARK bookmark);
-
-// Function: FPDFBookmark_GetNextSibling
-//          Get next bookmark item at the same level.
-// Parameters:
-//          document    -   Handle to the document. Returned by
-//          FPDF_LoadDocument or FPDF_LoadMemDocument.
-//          bookmark    -   Handle to the current bookmark. Cannot be NULL.
-// Return value:
-//          Handle to the next bookmark item at the same level. NULL if this is
-//          the last bookmark at this level.
-//
-DLLEXPORT FPDF_BOOKMARK STDCALL
-FPDFBookmark_GetNextSibling(FPDF_DOCUMENT document, FPDF_BOOKMARK bookmark);
-
-// Function: FPDFBookmark_GetTitle
-//          Get title of a bookmark.
-// Parameters:
-//          bookmark    -   Handle to the bookmark.
-//          buffer      -   Buffer for the title. Can be NULL.
-//          buflen      -   The length of the buffer in bytes. Can be 0.
-// Return value:
-//          Number of bytes the title consumes, including trailing zeros.
-// Comments:
-//          Regardless of the platform, the title is always in UTF-16LE
-//          encoding. That means the buffer
-//          can be treated as an array of WORD (on Intel and compatible CPUs),
-//          each WORD representing the Unicode of
-//          a character(some special Unicode may take 2 WORDs).The string is
-//          followed by two bytes of zero
-//          indicating the end of the string.
-//
-//          The return value always indicates the number of bytes required for
-//          the buffer, even if no buffer is specified
-//          or the buffer size is less then required. In these cases, the buffer
-//          will not be modified.
-//
-DLLEXPORT unsigned long STDCALL FPDFBookmark_GetTitle(FPDF_BOOKMARK bookmark,
-                                                      void* buffer,
-                                                      unsigned long buflen);
-
-// Function: FPDFBookmark_Find
-//          Find a bookmark in the document, using the bookmark title.
-// Parameters:
-//          document    -   Handle to the document. Returned by
-//          FPDF_LoadDocument or FPDF_LoadMemDocument.
-//          title       -   The UTF-16LE encoded Unicode string for the bookmark
-//          title to be searched. Can't be NULL.
-// Return value:
-//          Handle to the found bookmark item. NULL if the title can't be found.
-// Comments:
-//          It always returns the first found bookmark if more than one
-//          bookmarks have the same title.
-//
-DLLEXPORT FPDF_BOOKMARK STDCALL FPDFBookmark_Find(FPDF_DOCUMENT document,
-                                                  FPDF_WIDESTRING title);
-
-// Function: FPDFBookmark_GetDest
-//          Get the destination associated with a bookmark item.
-// Parameters:
-//          document    -   Handle to the document.
-//          bookmark    -   Handle to the bookmark.
-// Return value:
-//          Handle to the destination data. NULL if no destination is associated
-//          with this bookmark.
-//
-DLLEXPORT FPDF_DEST STDCALL FPDFBookmark_GetDest(FPDF_DOCUMENT document,
-                                                 FPDF_BOOKMARK bookmark);
-
-// Function: FPDFBookmark_GetAction
-//          Get the action associated with a bookmark item.
-// Parameters:
-//          bookmark    -   Handle to the bookmark.
-// Return value:
-//          Handle to the action data. NULL if no action is associated with this
-//          bookmark. In this case, the
-//          application should try FPDFBookmark_GetDest.
-//
-DLLEXPORT FPDF_ACTION STDCALL FPDFBookmark_GetAction(FPDF_BOOKMARK bookmark);
-
-#define PDFACTION_UNSUPPORTED 0  // Unsupported action type.
-#define PDFACTION_GOTO 1         // Go to a destination within current document.
-#define PDFACTION_REMOTEGOTO 2   // Go to a destination within another document.
-#define PDFACTION_URI 3          // Universal Resource Identifier, including web
-                                 // pages and other Internet based resources.
-#define PDFACTION_LAUNCH 4       // Launch an application or open a file.
-
-// Function: FPDFAction_GetType
-//          Get type of an action.
-// Parameters:
-//          action      -   Handle to the action.
-// Return value:
-//          A type number as defined above.
-//
-DLLEXPORT unsigned long STDCALL FPDFAction_GetType(FPDF_ACTION action);
-
-// Function: FPDFAction_GetDest
-//          Get destination of an action.
-// Parameters:
-//          document    -   Handle to the document.
-//          action      -   Handle to the action. It must be a GOTO or
-//          REMOTEGOTO action.
-// Return value:
-//          Handle to the destination data.
-// Comments:
-//          In case of remote goto action, the application should first use
-//          FPDFAction_GetFilePath to
-//          get file path, then load that particular document, and use its
-//          document handle to call this
-//          function.
-//
-DLLEXPORT FPDF_DEST STDCALL FPDFAction_GetDest(FPDF_DOCUMENT document,
-                                               FPDF_ACTION action);
-
-// Function: FPDFAction_GetFilePath
-//          Get file path of a remote goto action.
-// Parameters:
-//          action    -   Handle to the action. Must be a REMOTEGOTO or
-//                        LAUNCH action.
-//          buffer    -   A buffer for output the path string. Can be NULL.
-//          buflen    -   The length of the buffer, number of bytes. Can be 0.
-// Return value:
-//          Number of bytes the file path consumes, including trailing zero.
-//
-// Comments:
-//          The file path is UTF-8 encoded. The return value is the number of

[Lei Zhang, 2017/06/09 01:49:28]

UTF-8

-//          bytes required for the buffer, even when there is no buffer
-//          specified, or the buffer size is less then required. In this case,
-//          the buffer will not be modified.
-//
-DLLEXPORT unsigned long STDCALL
-FPDFAction_GetFilePath(FPDF_ACTION action, void* buffer, unsigned long buflen);
-
-// Function: FPDFAction_GetURIPath
-//          Get URI path of a URI action.
-// Parameters:
-//          document    -   Handle to the document.
-//          action      -   Handle to the action. Must be a URI action.
-//          buffer      -   A buffer for output the path string. Can be NULL.
-//          buflen      -   The length of the buffer, number of bytes. Can be 0.
-// Return value:
-//          Number of bytes the URI path consumes, including trailing zeros.
-// Comments:
-//          The URI path is always encoded in 7-bit ASCII.
-//
-//          The return value is the number of bytes required for the buffer,
-//          even when there is no buffer specified, or the buffer size is less
-//          then required. In this case, the buffer will not be modified.
-//
-DLLEXPORT unsigned long STDCALL FPDFAction_GetURIPath(FPDF_DOCUMENT document,
-                                                      FPDF_ACTION action,
-                                                      void* buffer,
-                                                      unsigned long buflen);
-
-// Function: FPDFDest_GetPageIndex
-//          Get page index of a destination.
-// Parameters:
-//          document    -   Handle to the document.
-//          dest        -   Handle to the destination.
-// Return value:
-//          The page index. Starting from 0 for the first page.
-//
-DLLEXPORT unsigned long STDCALL FPDFDest_GetPageIndex(FPDF_DOCUMENT document,
-                                                      FPDF_DEST dest);
-
-// Function: FPDFLink_GetLinkAtPoint
-//     Find a link at specified point on a document page.
-// Parameters:
-//     page        -   Handle to the document page.
-//     x           -   The x coordinate of the point, specified in page
-//                     coordinate system.
-//     y           -   The y coordinate of the point, specified in page
-//                     coordinate system.
-// Return value:
-//     Handle to the link. NULL if no link found at that point.
-// Comments:
-//     The point coordinates are specified in page coordinate system. You can
-//     convert coordinates from screen system to page system using
-//     FPDF_DeviceToPage().
-//
-DLLEXPORT FPDF_LINK STDCALL FPDFLink_GetLinkAtPoint(FPDF_PAGE page,
-                                                    double x,
-                                                    double y);
-
-// Function: FPDFLink_GetLinkZOrderAtPoint
-//     Find the z-order of a link at specified point on a document page.
-// Parameters:
-//     page        -   Handle to the document page.
-//     x           -   The x coordinate of the point, specified in page
-//                     coordinate system.
-//     y           -   The y coordinate of the point, specified in page
-//                     coordinate system.
-// Return value:
-//     Z-order of the link, or -1 if no link found at that point.
-//     Higher numbers are closer to the front.
-// Comments:
-//     The point coordinates are specified in page coordinate system. You can
-//     convert coordinates from screen system to page system using
-//     FPDF_DeviceToPage().
-//
-DLLEXPORT int STDCALL
-FPDFLink_GetLinkZOrderAtPoint(FPDF_PAGE page, double x, double y);
-
-// Function: FPDFLink_GetDest
-//          Get destination info of a link.
-// Parameters:
-//          document    -   Handle to the document.
-//          link        -   Handle to the link. Returned by
-//          FPDFLink_GetLinkAtPoint.
-// Return value:
-//          Handle to the destination. NULL if there is no destination
-//          associated with the link, in this case
-//          the application should try FPDFLink_GetAction.
-//
-DLLEXPORT FPDF_DEST STDCALL FPDFLink_GetDest(FPDF_DOCUMENT document,
-                                             FPDF_LINK link);
-
-// Function: FPDFLink_GetAction
-//          Get action info of a link.
-// Parameters:
-//          link        -   Handle to the link.
-// Return value:
-//          Handle to the action. NULL if there is no action associated with the
-//          link.
-//
-DLLEXPORT FPDF_ACTION STDCALL FPDFLink_GetAction(FPDF_LINK link);
-
-// Function: FPDFLink_Enumerate
-//          This function would enumerate all the link annotations in a single
-//          PDF page.
-// Parameters:
-//          page[in]            -   Handle to the page.
-//          startPos[in,out]    -   The start position to enumerate the link
-//          annotations, which should be specified to start from
-//                              -   0 for the first call, and would receive the
-//                              next position for enumerating to start from.
-//          linkAnnot[out]      -   Receive the link handle.
-// Return value:
-//          TRUE if succceed, else False;
-//
-DLLEXPORT FPDF_BOOL STDCALL FPDFLink_Enumerate(FPDF_PAGE page,
-                                               int* startPos,
-                                               FPDF_LINK* linkAnnot);
-
-// Function: FPDFLink_GetAnnotRect
-//          Get the annotation rectangle. (Specified by the |Rect| entry of
-//          annotation dictionary).
-// Parameters:
-//          linkAnnot[in]       -   Handle to the link annotation.
-//          rect[out]           -   The annotation rect.
-// Return value:
-//          TRUE if succceed, else False;
-//
-DLLEXPORT FPDF_BOOL STDCALL FPDFLink_GetAnnotRect(FPDF_LINK linkAnnot,
-                                                  FS_RECTF* rect);
-
-// Function: FPDFLink_CountQuadPoints
-//          Get the count of quadrilateral points to the link annotation.
-// Parameters:
-//          linkAnnot[in]       -   Handle to the link annotation.
-// Return value:
-//          The count of quadrilateral points.
-//
-DLLEXPORT int STDCALL FPDFLink_CountQuadPoints(FPDF_LINK linkAnnot);
-
-/* _FS_DEF_STRUCTURE_QUADPOINTSF_ */
-#ifndef _FS_DEF_STRUCTURE_QUADPOINTSF_
-#define _FS_DEF_STRUCTURE_QUADPOINTSF_
+#endif  // __cplusplus
+
+// Unsupported action type.
+#define PDFACTION_UNSUPPORTED 0
+// Go to a destination within current document.
+#define PDFACTION_GOTO 1
+// Go to a destination within another document.
+#define PDFACTION_REMOTEGOTO 2
+// URI, including web pages and other Internet resources.
+#define PDFACTION_URI 3
+// Launch an application or open a file.
+#define PDFACTION_LAUNCH 4
+
 typedef struct _FS_QUADPOINTSF {
   FS_FLOAT x1;
   FS_FLOAT y1;
   FS_FLOAT x2;
   FS_FLOAT y2;
   FS_FLOAT x3;
   FS_FLOAT y3;
   FS_FLOAT x4;
   FS_FLOAT y4;
 } FS_QUADPOINTSF;
-#endif /* _FS_DEF_STRUCTURE_QUADPOINTSF_ */
-
-// Function: FPDFLink_GetQuadPoints
-//          Get the quadrilateral points for the specified index in the link
-//          annotation.
-// Parameters:
-//          linkAnnot[in]       -   Handle to the link annotation.
-//          quadIndex[in]       -   The specified quad points index.
-//          quadPoints[out]     -   Receive the quadrilateral points.
-// Return value:
-//          True if succeed, else False.
-//
+
+// Get the first child of |bookmark|, or the first top-level bookmark item.
+//
+//   document - handle to the document.
+//   bookmark - handle to the current bookmark. Pass NULL for the first top
+//              level item.
+//
+// Returns a handle to the first child of |bookmark| or the first top-level
+// bookmark item. NULL if no child or top-level bookmark found.
+DLLEXPORT FPDF_BOOKMARK STDCALL
+FPDFBookmark_GetFirstChild(FPDF_DOCUMENT document, FPDF_BOOKMARK bookmark);
+
+// Get the next sibling of |bookmark|.
+//
+//   document - handle to the document.
+//   bookmark - handle to the current bookmark.
+//
+// Returns a handle to the next sibling of |bookmark|, or NULL if this is the
+// last bookmark at this level.
+DLLEXPORT FPDF_BOOKMARK STDCALL
+FPDFBookmark_GetNextSibling(FPDF_DOCUMENT document, FPDF_BOOKMARK bookmark);
+
+// Get the title of |bookmark|.
+//
+//   bookmark - handle to the bookmark.
+//   buffer   - buffer for the title. May be NULL.
+//   buflen   - the length of the buffer in bytes. May be 0.
+//
+// Returns the number of bytes in the title, including the terminating NUL
+// character. The number of bytes is returned regardless of the |buffer| and
+// |buflen| parameters.
+//
+// Regardless of the platform, the |buffer| is always in UTF-16LE encoding. The
+// string is terminated by a UTF16 NUL character. If |buflen| is less then the
+// required length, or |buffer| is NULL, |buffer| will not be modified.
+DLLEXPORT unsigned long STDCALL FPDFBookmark_GetTitle(FPDF_BOOKMARK bookmark,
+                                                      void* buffer,
+                                                      unsigned long buflen);
+
+// Find the bookmark with |title| in |document|.
+//
+//   document - handle to the document.
+//   title    - the UTF-16LE encoded Unicode title for which to search.
+//
+// Returns the handle to the bookmark, or NULL if |title| can't be found.
+//
+// |FPDFBookmark_Find| will always return the first bookmark found even if
+// multiple bookmarks have the same |title|.
+DLLEXPORT FPDF_BOOKMARK STDCALL FPDFBookmark_Find(FPDF_DOCUMENT document,
+                                                  FPDF_WIDESTRING title);
+
+// Get the destination associated with |bookmark|.
+//
+//   document - handle to the document.
+//   bookmark - handle to the bookmark.
+//
+// Returns the handle to the destination data,  NULL if no destination is
+// associated with |bookmark|.
+DLLEXPORT FPDF_DEST STDCALL FPDFBookmark_GetDest(FPDF_DOCUMENT document,
+                                                 FPDF_BOOKMARK bookmark);
+
+// Get the action associated with |bookmark|.
+//
+//   bookmark - handle to the bookmark.
+//
+// Returns the handle to the action data, or NULL if no action is associated
+// with |bookmark|. When NULL is returned, |FPDFBookmark_GetDest| should be
+// called to get the |bookmark| destination data.
+DLLEXPORT FPDF_ACTION STDCALL FPDFBookmark_GetAction(FPDF_BOOKMARK bookmark);
+
+// Get the type of |action|.
+//
+//   action - handle to the action.
+//
+// Returns one of:
+//   PDFACTION_UNSUPPORTED
+//   PDFACTION_GOTO
+//   PDFACTION_REMOTEGOTO
+//   PDFACTION_URI
+//   PDFACTION_LAUNCH
+DLLEXPORT unsigned long STDCALL FPDFAction_GetType(FPDF_ACTION action);
+
+// Get the destination of |action|.
+//
+//   document - handle to the document.
+//   action   - handle to the action. |action| must be a |PDFACTION_GOTO| or
+//              |PDFACTION_REMOTEGOTO|.
+//
+// Returns a handle to the destination data.
+//
+// In the case of |PDFACTION_REMOTEGOTO|, you should first call
+// |FPDFAction_GetFilePath| then load that document, the document handle from
+// that document should pass as |document| to |FPDFAction_GetDest|.
+DLLEXPORT FPDF_DEST STDCALL FPDFAction_GetDest(FPDF_DOCUMENT document,
+                                               FPDF_ACTION action);
+
+// Get file path of a |PDFACTION_REMOTEGOTO| |action|.
+//
+//   action - handle to the action. |action| must be a |PDFACTION_LAUNCH| or
+//            |PDFACTION_REMOTEGOTO|
+//   buffer - a buffer for output the path string. May be NULL.
+//   buflen - the length of the buffer, in bytes. May be 0.
+//
+// Returns the number of bytes in the file path, including the trailing UTF16
+// NUL character.
+//
+// Regardless of the platform, the |buffer| is always in UTF-16LE encoding.

[Lei Zhang, 2017/06/09 01:49:28]

UTF-16LE?

+// If |buflen| is less then the returned length, or |buffer| is NULL, |buffer|
+// will not be modified.
+DLLEXPORT unsigned long STDCALL
+FPDFAction_GetFilePath(FPDF_ACTION action, void* buffer, unsigned long buflen);
+
+// Get the URI path of a |PDFACTION_URI| |action|.
+//
+//   document - handle to the document.
+//   action   - handle to the action. Must be a |PDFACTION_URI|.
+//   buffer   - a buffer for the path string. May be NULL.
+//   buflen   - the length of the buffer, in bytes. May be 0.
+//
+// Returns the number of bytes in the URI path, including trailing zeros.
+//
+// The |buffer| is always encoded in 7-bit ASCII. If |buflen| is less then the
+// returned length, or |buffer| is NULL, |buffer| will not be modified.
+DLLEXPORT unsigned long STDCALL FPDFAction_GetURIPath(FPDF_DOCUMENT document,
+                                                      FPDF_ACTION action,
+                                                      void* buffer,
+                                                      unsigned long buflen);
+
+// Get the page index of |dest|.
+//
+//   document - handle to the document.
+//   dest     - handle to the destination.
+//
+// Returns the page index containing |dest|. Page indices start from 0.
+DLLEXPORT unsigned long STDCALL FPDFDest_GetPageIndex(FPDF_DOCUMENT document,
+                                                      FPDF_DEST dest);
+
+// Find a link at point (|x|,|y|) on |page|.
+//
+//   page - handle to the document page.
+//   x    - the x coordinate, in the page coordinate system.
+//   y    - the y coordinate, in the page coordinate system.
+//
+// Returns a handle to the link, or NULL if no link found at the given point.
+//
+// You can convert coordinates from screen coordinates to page coordinates using
+// |FPDF_DeviceToPage|.
+DLLEXPORT FPDF_LINK STDCALL FPDFLink_GetLinkAtPoint(FPDF_PAGE page,
+                                                    double x,
+                                                    double y);
+
+// Find the Z-order of link at point (|x|,|y|) on |page|.
+//
+//   page - handle to the document page.
+//   x    - the x coordinate, in the page coordinate system.
+//   y    - the y coordinate, in the page coordinate system.
+//
+// Returns the Z-order of the link, or -1 if no link found at the given point.
+// Larger Z-order numbers are closer to the front.
+//
+// You can convert coordinates from screen coordinates to page coordinates using
+// |FPDF_DeviceToPage|.
+DLLEXPORT int STDCALL
+FPDFLink_GetLinkZOrderAtPoint(FPDF_PAGE page, double x, double y);
+
+// Get destination info for |link|.
+//
+//   document - handle to the document.
+//   link     - handle to the link.
+//
+// Returns a handle to the destination, or NULL if there is no destination
+// associated with the link. In this case, you should call |FPDFLink_GetAction|
+// to retrieve the action associated with |link|.
+DLLEXPORT FPDF_DEST STDCALL FPDFLink_GetDest(FPDF_DOCUMENT document,
+                                             FPDF_LINK link);
+
+// Get action info for |link|.
+//
+//   link - handle to the link.
+//
+// Returns a handle to the action associated to |link|, or NULL if no action.
+DLLEXPORT FPDF_ACTION STDCALL FPDFLink_GetAction(FPDF_LINK link);
+
+// Enumerates all the link annotations in |page|.
+//
+//   page      - handle to the page.
+//   startPos  - the start position, should initially be 0 and is updated with
+//               the next start position on return.
+//   linkAnnot - the link handle for |startPos|.
+//
+// Returns TRUE on success.
+DLLEXPORT FPDF_BOOL STDCALL FPDFLink_Enumerate(FPDF_PAGE page,
+                                               int* startPos,
+                                               FPDF_LINK* linkAnnot);
+
+// Get the rectangle for |linkAnnot|.
+//
+//   linkAnnot - handle to the link annotation.
+//   rect      - the annotation rectangle.
+//
+// Returns true on success.
+DLLEXPORT FPDF_BOOL STDCALL FPDFLink_GetAnnotRect(FPDF_LINK linkAnnot,
+                                                  FS_RECTF* rect);
+
+// Get the count of quadrilateral points to the |linkAnnot|.
+//
+//   linkAnnot - handle to the link annotation.
+//
+// Returns the count of quadrilateral points.
+DLLEXPORT int STDCALL FPDFLink_CountQuadPoints(FPDF_LINK linkAnnot);
+
+// Get the quadrilateral points for the specified |quadIndex| in |linkAnnot|.
+//
+//   linkAnnot  - handle to the link annotation.
+//   quadIndex  - the specified quad point index.
+//   quadPoints - receives the quadrilateral points.
+//
+// Returns true on success.
 DLLEXPORT FPDF_BOOL STDCALL FPDFLink_GetQuadPoints(FPDF_LINK linkAnnot,
                                                    int quadIndex,
                                                    FS_QUADPOINTSF* quadPoints);
 
-// Function: FPDF_GetMetaText
-//          Get a text from meta data of the document. Result is encoded in
-//          UTF-16LE.
-// Parameters:
-//          doc         -   Handle to a document
-//          tag         -   The tag for the meta data. Currently, It can be
-//          "Title", "Author",
-//                          "Subject", "Keywords", "Creator", "Producer",
-//                          "CreationDate", or "ModDate".
-//                          For detailed explanation of these tags and their
-//                          respective values,
-//                          please refer to PDF Reference 1.6, section 10.2.1,
-//                          "Document Information Dictionary".
-//          buffer      -   A buffer for output the title. Can be NULL.
-//          buflen      -   The length of the buffer, number of bytes. Can be 0.
-// Return value:
-//          Number of bytes the title consumes, including trailing zeros.
-// Comments:
-//          No matter on what platform, the title is always output in UTF-16LE
-//          encoding, which means the buffer
-//          can be regarded as an array of WORD (on Intel and compatible CPUs),
-//          each WORD represent the Unicode of
-//          a character (some special Unicode may take 2 WORDs). The string is
-//          followed by two bytes of zero
-//          indicating end of the string.
-//
-//          The return value always indicated number of bytes required for the
-//          buffer, even when there is
-//          no buffer specified, or the buffer size is less then required. In
-//          this case, the buffer will not
-//          be modified.
-//
+// Get meta-data |tag| content from |document|.
+//
+//   doc    - handle to the document
+//   tag    - the tag to retrieve. The tag can be one of:
+//              Title, Author, Subject, Keywords, Creator, Producer,
+//              CreationDate, or ModDate.
+//            For detailed explanations of these tags and their respective
+//            values, please refer to PDF Reference 1.6, section 10.2.1,
+//            'Document Information Dictionary'.
+//   buffer - a buffer for the title. May be NULL.
+//   buflen - the length of the buffer, in bytes. May be 0.
+//
+// Returns the number of bytes in the title, including trailing zeros.
+//
+// The |buffer| is always encoded in UTF-16LE. The |buffer| is followed by two
+// bytes of zeros indicating the end of the string.  If |buflen| is less then
+// the returned length, or |buffer| is NULL, |buffer| will not be modified.
 DLLEXPORT unsigned long STDCALL FPDF_GetMetaText(FPDF_DOCUMENT doc,
                                                  FPDF_BYTESTRING tag,
                                                  void* buffer,
                                                  unsigned long buflen);
 
 #ifdef __cplusplus
-}
-#endif
+}  // extern "C"
+#endif  // __cplusplus
 
 #endif  // PUBLIC_FPDF_DOC_H_