public/fpdf_structtree.h

// Copyright 2016 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_STRUCTTREE_H_
#define PUBLIC_FPDF_STRUCTTREE_H_

// clang-format off
// NOLINTNEXTLINE(build/include)
#include "fpdfview.h"

#ifdef __cplusplus
extern "C" {
#endif

// Function: FPDF_StructTree_GetForPage
//          Get the structure tree for a page.
// Parameters:
//          page        -   Handle to the page, as returned by FPDF_LoadPage().
// Return value:
//          A handle to the structure tree or NULL on error.
FPDF_EXPORT FPDF_STRUCTTREE FPDF_CALLCONV
FPDF_StructTree_GetForPage(FPDF_PAGE page);

// Function: FPDF_StructTree_Close
//          Release a resource allocated by FPDF_StructTree_GetForPage().
// Parameters:
//          struct_tree -   Handle to the structure tree, as returned by
//                          FPDF_StructTree_LoadPage().
// Return value:
//          None.
FPDF_EXPORT void FPDF_CALLCONV
FPDF_StructTree_Close(FPDF_STRUCTTREE struct_tree);

// Function: FPDF_StructTree_CountChildren
//          Count the number of children for the structure tree.
// Parameters:
//          struct_tree -   Handle to the structure tree, as returned by
//                          FPDF_StructTree_LoadPage().
// Return value:
//          The number of children, or -1 on error.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructTree_CountChildren(FPDF_STRUCTTREE struct_tree);

// Function: FPDF_StructTree_GetChildAtIndex
//          Get a child in the structure tree.
// Parameters:
//          struct_tree -   Handle to the structure tree, as returned by
//                          FPDF_StructTree_LoadPage().
//          index       -   The index for the child, 0-based.
// Return value:
//          The child at the n-th index or NULL on error.
FPDF_EXPORT FPDF_STRUCTELEMENT FPDF_CALLCONV
FPDF_StructTree_GetChildAtIndex(FPDF_STRUCTTREE struct_tree, int index);

// Function: FPDF_StructElement_GetAltText
//          Get the alt text for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
//          buffer         -   A buffer for output the alt text. May be NULL.
//          buflen         -   The length of the buffer, in bytes. May be 0.
// Return value:
//          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.
// Comments:
//          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 than the required length, or |buffer| is NULL,
//          |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetAltText(FPDF_STRUCTELEMENT struct_element,
                              void* buffer,
                              unsigned long buflen);

// Experimental API.
// Function: FPDF_StructElement_GetID
//          Get the ID for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
//          buffer         -   A buffer for output the ID string. May be NULL.
//          buflen         -   The length of the buffer, in bytes. May be 0.
// Return value:
//          The number of bytes in the ID string, including the terminating NUL
//          character. The number of bytes is returned regardless of the
//          |buffer| and |buflen| parameters.
// Comments:
//          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 than the required length, or |buffer| is NULL,
//          |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetID(FPDF_STRUCTELEMENT struct_element,
                         void* buffer,
                         unsigned long buflen);

// Experimental API.
// Function: FPDF_StructElement_GetLang
//          Get the case-insensitive IETF BCP 47 language code for an element.
// Parameters:
//          struct_element -   Handle to the struct element.
//          buffer         -   A buffer for output the lang string. May be NULL.
//          buflen         -   The length of the buffer, in bytes. May be 0.
// Return value:
//          The number of bytes in the ID string, including the terminating NUL
//          character. The number of bytes is returned regardless of the
//          |buffer| and |buflen| parameters.
// Comments:
//          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 than the required length, or |buffer| is NULL,
//          |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetLang(FPDF_STRUCTELEMENT struct_element,
                           void* buffer,
                           unsigned long buflen);

// Experimental API.
// Function: FPDF_StructElement_GetStringAttribute
//          Get a struct element attribute of type "name" or "string".
// Parameters:
//          struct_element -   Handle to the struct element.
//          attr_name      -   The name of the attribute to retrieve.
//          buffer         -   A buffer for output. May be NULL.
//          buflen         -   The length of the buffer, in bytes. May be 0.
// Return value:
//          The number of bytes in the attribute value, including the
//          terminating NUL character. The number of bytes is returned
//          regardless of the |buffer| and |buflen| parameters.
// Comments:
//          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 than the required length, or |buffer| is NULL,
//          |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetStringAttribute(FPDF_STRUCTELEMENT struct_element,
                                      FPDF_BYTESTRING attr_name,
                                      void* buffer,
                                      unsigned long buflen);

// Function: FPDF_StructElement_GetMarkedContentID
//          Get the marked content ID for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
// Return value:
//          The marked content ID of the element. If no ID exists, returns
//          -1.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructElement_GetMarkedContentID(FPDF_STRUCTELEMENT struct_element);

// Function: FPDF_StructElement_GetType
//           Get the type (/S) for a given element.
// Parameters:
//           struct_element - Handle to the struct element.
//           buffer        - A buffer for output. May be NULL.
//           buflen        - The length of the buffer, in bytes. May be 0.
// Return value:
//           The number of bytes in the type, including the terminating NUL
//           character. The number of bytes is returned regardless of the
//           |buffer| and |buflen| parameters.
// Comments:
//           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 than the required length, or |buffer| is NULL,
//           |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetType(FPDF_STRUCTELEMENT struct_element,
                           void* buffer,
                           unsigned long buflen);

// Function: FPDF_StructElement_GetTitle
//           Get the title (/T) for a given element.
// Parameters:
//           struct_element - Handle to the struct element.
//           buffer         - A buffer for output. May be NULL.
//           buflen         - The length of the buffer, in bytes. May be 0.
// Return value:
//           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.
// Comments:
//           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 than the required length, or |buffer| is NULL,
//           |buffer| will not be modified.
FPDF_EXPORT unsigned long FPDF_CALLCONV
FPDF_StructElement_GetTitle(FPDF_STRUCTELEMENT struct_element,
                            void* buffer,
                            unsigned long buflen);

// Function: FPDF_StructElement_CountChildren
//          Count the number of children for the structure element.
// Parameters:
//          struct_element -   Handle to the struct element.
// Return value:
//          The number of children, or -1 on error.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructElement_CountChildren(FPDF_STRUCTELEMENT struct_element);

// Function: FPDF_StructElement_GetChildAtIndex
//          Get a child in the structure element.
// Parameters:
//          struct_tree -   Handle to the struct element.
//          index       -   The index for the child, 0-based.
// Return value:
//          The child at the n-th index or NULL on error.
// Comments:
//          If the child exists but is not an element, then this function will
//          return NULL. This will also return NULL for out of bounds indices.
FPDF_EXPORT FPDF_STRUCTELEMENT FPDF_CALLCONV
FPDF_StructElement_GetChildAtIndex(FPDF_STRUCTELEMENT struct_element,
                                   int index);

#ifdef __cplusplus
}  // extern "C"
#endif

#endif  // PUBLIC_FPDF_STRUCTTREE_H_