pdftron::PDF::OCG::Context Class Reference

#include <Context.h>

List of all members.

Public Types

enum  OCDrawMode { e_VisibleOC, e_AllOC, e_NoOC }
 OCDrawMode controls drawing or enumerating the page with respect to optional content. More...

Public Member Functions

 Context (const Context &context)
 Copy constructor.
Contextoperator= (const Context &g)
 Context (const class Config &config)
 Create a context object that represents an optional-content state of the document from a given configuration.
 ~Context ()
 Destructor.
bool IsValid () const
bool GetState (const class Group &group) const
void SetState (const class Group &group, bool state)
 Sets the ON-OFF states for the given optional-content group (OCG) in this context.
void ResetStates (bool all_on)
 Sets the sates of all OCGs in the context to ON or OFF.
void SetNonOCDrawing (bool draw_non_OC)
bool GetNonOCDrawing () const
void SetOCDrawMode (OCDrawMode oc_draw_mode)
 Sets the drawing and enumeration type for this context.
OCDrawMode GetOCMode () const


Detailed Description

The OCG::Context object represents an optional-content context in a document, within which document objects such as words or annotations are visible or hidden. The context keeps track of the ON-OFF states of all of the optional-content groups (OCGs) in a document. Content is or is not visible with respect to the OCG states stored in a specific context. Unlike other objects in OCG namespace, the OCG::Context does not correspond to any explicit PDF structure.

Each PDFView has a default context (PDF::GetOCGContext()) that it uses for on-screen drawing and that determines the default state for any drawing. The context has flags that control whether to draw content that is marked as optional, and whether to draw content that is not marked as optional.

When enumerating page content, OCG::Context can be passed as a parameter in ElementReader.Begin() method. When using PDFDraw, PDFRasterizer, or PDFView class to render PDF pages use ( PDFDraw::SetOCGContext() method to select an OC context.

There can be more than one Context object, representing different combinations of OCG states. You can change the states of OCGs within any context. You can build contexts with your own combination of OCG states, and issue drawing or enumeration commands using that context. For example, you can pass an optional-content context to ElementReader.Begin(). You can save the resulting state information as part of the configuration (e.g. using Config::SetInit methods), but the context itself has no corresponding PDF representation, and is not saved.


Member Enumeration Documentation

OCDrawMode controls drawing or enumerating the page with respect to optional content.

Together with the value of SetNonOCDrawing this mode controls drawing or enumerating content on a page with optional content:

  • Content that is marked as optional content is drawn or not drawn according to the OCDrawMode and the visibility state as determined by the Optional Content Groups (OCGs) and OCMDs.
  • Content that is not marked as optional content is drawn when GetNonOCDrawing() is true, and not drawn when GetNonOCDrawing() is false.
Enumerator:
e_VisibleOC  Draw or enumerate optional content that is visible, according to the current state of Optional Content Groups (OCGs) and Optional Content Membership Dictionaries (OCMDs).

This is the default mode.

e_AllOC  Draw or enumerate all optional content, regardless of its visibility state.

If the context's 'SetNonOCDrawing' is enabled, all contents of document are shown.

e_NoOC  Draw or enumerate no optional content, regardless of its visibility state.

If the context's 'SetNonOCDrawing' is not enabled, nothing is drawn, resulting in a blank page.


Constructor & Destructor Documentation

pdftron::PDF::OCG::Context::Context ( const Context context  ) 

Copy constructor.

Parameters:
context Another context from which to take initial OCG states.

pdftron::PDF::OCG::Context::Context ( const class Config config  ) 

Create a context object that represents an optional-content state of the document from a given configuration.

Parameters:
config A configuration from which to take initial OCG states.

pdftron::PDF::OCG::Context::~Context (  ) 

Destructor.


Member Function Documentation

Context& pdftron::PDF::OCG::Context::operator= ( const Context g  ) 

bool pdftron::PDF::OCG::Context::IsValid (  )  const [inline]

Returns:
true is this is a valid (non-null) context, false otherwise.

bool pdftron::PDF::OCG::Context::GetState ( const class Group group  )  const

Returns:
the ON-OFF states (true or false) for the given optional-content group (OCG) in this OC context.
Parameters:
group The optional-content group (OCG) that is queried.

void pdftron::PDF::OCG::Context::SetState ( const class Group group,
bool  state 
)

Sets the ON-OFF states for the given optional-content group (OCG) in this context.

Parameters:
group The optional-content group (OCG) that is queried.
state true for 'ON' and false for 'OFF'.

void pdftron::PDF::OCG::Context::ResetStates ( bool  all_on  ) 

Sets the sates of all OCGs in the context to ON or OFF.

Parameters:
all_on A flag used to specify whether the OCG states should be set to ON (if true), or OFF (if false).

void pdftron::PDF::OCG::Context::SetNonOCDrawing ( bool  draw_non_OC  ) 

bool pdftron::PDF::OCG::Context::GetNonOCDrawing (  )  const

Returns:
the non-OC status for this context. The flag indicates whether the content that is not marked as optional should be treated as visible. For more information, please see SetNonOCDrawing().

void pdftron::PDF::OCG::Context::SetOCDrawMode ( OCDrawMode  oc_draw_mode  ) 

Sets the drawing and enumeration type for this context.

This type, together with the visibility determined by the OCG and OCMD states, controls whether content that is marked as optional content is drawn or enumerated.

Parameters:
oc_draw_mode A flag specifying the visibility of optional content.

OCDrawMode pdftron::PDF::OCG::Context::GetOCMode (  )  const

Returns:
the drawing and enumeration type for this context. For more information, please see SetOCMode() and OCG::Context::OCDrawMode.


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