DynaPDF Manual - Page 468

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Function Reference

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GetOCUINode

Syntax:

IOCN* pdfGetOCUINode(

const PPDF* IPDF,

// Instance pointer

const IOCN* Node,

// Node pointer or NULL to get the root

struct TPDFOCUINode* OutNode) // See below

struct TPDFOCUINode

{

UI32 StructSize;

// Must be set to sizeof(TOCUINode)

const char* LabelA; // Optional label.

const UI16* LabelW; // Either the Ansi or Unicode string is set at time but never both.

UI32 LabelLength;

// Length in characters without the null-terminator.

IOCN* NextChild;

// If set, the next child node that must be loaded.

LBOOL NewNode;

// If true, a new child node must be created.

SI32 OCG;

// Optional OCG handle. -1 if not set -> GetOCG().

};

The function retrieves the most important properties of an Optional Content UI node (UI stands for

User Interface).

Notice:

If the PDF file was not already imported with ImportPDFFile() the function

ImportOCProperties() must be called to import the global Optional Content Properties.

UI nodes are part of a layer configuration. Therefore, a layer configuration must be loaded with

LoadLayerConfig() before the function can be called.

Optional Content Groups (OCGs) which are returned by this function should be visible in the user

interface of a viewer application. All other OCGs should not be shown by default.

UI nodes are stored in a single linked list. To get the pointer of the root node set the parameter Node

to NULL. The parameter OutNode will be ignored in this case but it is required otherwise.

The next node of the root is the return value of this function. If no further node is available the

return value will be NULL.

Every node can contain one or more child nodes, an optional label, or a reference to an OCG.

To achieve the same nesting as in Adobe's Acrobat or Reader the nodes must be added to a custom

tree control as shown in the following simplified algorithm (Delphi):

function GetString(const ValueA: PAnsiChar; const ValueW: PWideChar): String;

begin

// Make never a direct typecast from PAnsiChar to String because this causes a buffer overrun!

if ValueA <> nil then

Result := String(AnsiString(ValueA))

else

Result := String(WideString(ValueW));

end;

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