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 alt text, 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_GetActualText
//          Get the actual text for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
//          buffer         -   A buffer for output the actual text. May be NULL.
//          buflen         -   The length of the buffer, in bytes. May be 0.
// Return value:
//          The number of bytes in the actual text, 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_GetActualText(FPDF_STRUCTELEMENT struct_element,
                                 void* buffer,
                                 unsigned long buflen);

// 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);

// Experimental API.
// Function: FPDF_StructElement_GetObjType
//           Get the object type (/Type) 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 object 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_GetObjType(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_element -   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);

// Experimental API.
// Function: FPDF_StructElement_GetParent
//          Get the parent of the structure element.
// Parameters:
//          struct_element -   Handle to the struct element.
// Return value:
//          The parent structure element or NULL on error.
// Comments:
//          If structure element is StructTreeRoot, then this function will
//          return NULL.
FPDF_EXPORT FPDF_STRUCTELEMENT FPDF_CALLCONV
FPDF_StructElement_GetParent(FPDF_STRUCTELEMENT struct_element);

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

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

// Experimental API.
// Function: FPDF_StructElement_Attr_GetCount
//          Count the number of attributes in a structure element attribute map.
// Parameters:
//          struct_attribute - Handle to the struct element attribute.
// Return value:
//          The number of attributes, or -1 on error.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructElement_Attr_GetCount(FPDF_STRUCTELEMENT_ATTR struct_attribute);


// Experimental API.
// Function: FPDF_StructElement_Attr_GetName
//          Get the name of an attribute in a structure element attribute map.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          index              - The index of attribute in the map.
//          buffer             - A buffer for output. May be NULL. This is only
//                               modified if |buflen| is longer than the length
//                               of the key. Optional, pass null to just
//                               retrieve the size of the buffer needed.
//          buflen             - The length of the buffer.
//          out_buflen         - A pointer to variable that will receive the
//                               minimum buffer size to contain the key. Not
//                               filled if FALSE is returned.
// Return value:
//          TRUE if the operation was successful, FALSE otherwise.
FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
FPDF_StructElement_Attr_GetName(FPDF_STRUCTELEMENT_ATTR struct_attribute,
                                int index,
                                void* buffer,
                                unsigned long buflen,
                                unsigned long* out_buflen);

// Experimental API.
// Function: FPDF_StructElement_Attr_GetType
//          Get the type of an attribute in a structure element attribute map.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          name               - The attribute name.
// Return value:
//          Returns the type of the value, or FPDF_OBJECT_UNKNOWN in case of
//          failure.
FPDF_EXPORT FPDF_OBJECT_TYPE FPDF_CALLCONV
FPDF_StructElement_Attr_GetType(FPDF_STRUCTELEMENT_ATTR struct_attribute,
                                FPDF_BYTESTRING name);

// Experimental API.
// Function: FPDF_StructElement_Attr_GetBooleanValue
//          Get the value of a boolean attribute in an attribute map by name as
//          FPDF_BOOL. FPDF_StructElement_Attr_GetType() should have returned
//          FPDF_OBJECT_BOOLEAN for this property.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          name               - The attribute name.
//          out_value          - A pointer to variable that will receive the
//                               value. Not filled if false is returned.
// Return value:
//          Returns TRUE if the name maps to a boolean value, FALSE otherwise.
FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
FPDF_StructElement_Attr_GetBooleanValue(
    FPDF_STRUCTELEMENT_ATTR struct_attribute,
    FPDF_BYTESTRING name,
    FPDF_BOOL* out_value);

// Experimental API.
// Function: FPDF_StructElement_Attr_GetNumberValue
//          Get the value of a number attribute in an attribute map by name as
//          float. FPDF_StructElement_Attr_GetType() should have returned
//          FPDF_OBJECT_NUMBER for this property.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          name               - The attribute name.
//          out_value          - A pointer to variable that will receive the
//                               value. Not filled if false is returned.
// Return value:
//          Returns TRUE if the name maps to a number value, FALSE otherwise.
FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
FPDF_StructElement_Attr_GetNumberValue(FPDF_STRUCTELEMENT_ATTR struct_attribute,
                                       FPDF_BYTESTRING name,
                                       float* out_value);

// Experimental API.
// Function: FPDF_StructElement_Attr_GetStringValue
//          Get the value of a string attribute in an attribute map by name as
//          string. FPDF_StructElement_Attr_GetType() should have returned
//          FPDF_OBJECT_STRING or FPDF_OBJECT_NAME for this property.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          name               - The attribute name.
//          buffer             - A buffer for holding the returned key in
//                               UTF-16LE. This is only modified if |buflen| is
//                               longer than the length of the key. Optional,
//                               pass null to just retrieve the size of the
//                               buffer needed.
//          buflen             - The length of the buffer.
//          out_buflen         - A pointer to variable that will receive the
//                               minimum buffer size to contain the key. Not
//                               filled if FALSE is returned.
// Return value:
//          Returns TRUE if the name maps to a string value, FALSE otherwise.
FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
FPDF_StructElement_Attr_GetStringValue(FPDF_STRUCTELEMENT_ATTR struct_attribute,
                                       FPDF_BYTESTRING name,
                                       void* buffer,
                                       unsigned long buflen,
                                       unsigned long* out_buflen);

// Experimental API.
// Function: FPDF_StructElement_Attr_GetBlobValue
//          Get the value of a blob attribute in an attribute map by name as
//          string.
// Parameters:
//          struct_attribute   - Handle to the struct element attribute.
//          name               - The attribute name.
//          buffer             - A buffer for holding the returned value. This
//                               is only modified if |buflen| is at least as
//                               long as the length of the value. Optional, pass
//                               null to just retrieve the size of the buffer
//                               needed.
//          buflen             - The length of the buffer.
//          out_buflen         - A pointer to variable that will receive the
//                               minimum buffer size to contain the key. Not
//                               filled if FALSE is returned.
// Return value:
//          Returns TRUE if the name maps to a string value, FALSE otherwise.
FPDF_EXPORT FPDF_BOOL FPDF_CALLCONV
FPDF_StructElement_Attr_GetBlobValue(FPDF_STRUCTELEMENT_ATTR struct_attribute,
                                     FPDF_BYTESTRING name,
                                     void* buffer,
                                     unsigned long buflen,
                                     unsigned long* out_buflen);

// Experimental API.
// Function: FPDF_StructElement_GetMarkedContentIdCount
//          Get the count of marked content ids for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
// Return value:
//          The count of marked content ids or -1 if none exists.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructElement_GetMarkedContentIdCount(FPDF_STRUCTELEMENT struct_element);

// Experimental API.
// Function: FPDF_StructElement_GetMarkedContentIdAtIndex
//          Get the marked content id at a given index for a given element.
// Parameters:
//          struct_element -   Handle to the struct element.
//          index          -   The index of the marked content id, 0-based.
// Return value:
//          The marked content ID of the element. If no ID exists, returns
//          -1.
FPDF_EXPORT int FPDF_CALLCONV
FPDF_StructElement_GetMarkedContentIdAtIndex(FPDF_STRUCTELEMENT struct_element,
                                             int index);

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

#endif  // PUBLIC_FPDF_STRUCTTREE_H_