ElementReader Class

ElementReader can be used to parse and process content streams. ElementReader provides a convenient interface used to traverse the Element display list of a page. The display list representing graphical elements (such as text-runs, paths, images, shadings, forms, etc) is accessed using the intrinsic iterator. ElementReader automatically concatenates page contents spanning multiple streams and provides a mechanism to parse contents of sub-display lists (e.g. forms XObjects and Type3 fonts).

Inheritance Hierarchy

SystemObject
pdftron.PDFElementReader

Namespace: pdftron.PDF
Assembly: pdftron (in pdftron.dll) Version: 255.255.255.255

Syntax

C++

JavaScript

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public sealed class ElementReader : IClosable

Public NotInheritable Class ElementReader
	Implements IClosable

public ref class ElementReader sealed : IClosable

pdftron.PDF.ElementReader = function();

Type.createClass(
	'pdftron.PDF.ElementReader',
	null,
	Windows.Foundation.IClosable);

The ElementReader type exposes the following members.

Constructors

	Name	Description
	ElementReader	Instantiates a new element reader.

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Methods

	Name	Description
	Begin(Obj)	Begin processing given content stream. The content stream may be a Form XObject, Type3 glyph stream, pattern stream or any other content stream.
	Begin(Page)	Begin processing a page.
	Begin(Obj, Obj)	Begin processing given content stream. The content stream may be a Form XObject, Type3 glyph stream, pattern stream or any other content stream.
	Begin(Page, Context)
	Begin(Obj, Obj, Context)
	ClearChangeList	Clear the list containing identifiers of modified graphics state attributes. The list of modified attributes is then accumulated during a subsequent call(s) to ElementReader.Next().
	Close
	Current	Current.
	End	Close the current display list. If the current display list is a sub-list created using FormBegin(), PatternBegin(), or Type3FontBegin() methods, the function will end the sub-list and will return processing to the parent display list at the point where it left off before entering the sub-list.
	Equals	Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
	FormBegin	When the current element is a form XObject you have the option to skip form processing (by not calling FormBegin()) or to open the form stream and continue Element traversal into the form. To open a form XObject display list use FormBegin() method. The Next() returned Element will be the first Element in the form XObject display list. Subsequent calls to Next() will traverse form's display list until NULL is returned. At any point you can close the form sub-list using ElementReader::End() method. After the form display list is closed (using End()) the processing will return to the parent display list at the point where it left off before entering the form XObject.
	GetChangesIterator	Gets the changes iterator.
	GetColorSpace	Gets the color space.
	GetExtGState	Gets the ext g state.
	GetFont	Gets the font.
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetPattern	Gets the pattern.
	GetShading	Gets the shading.
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetXObject	Gets the x object.
	IsChanged	Checks if is changed.
	Next	Next.
	PatternBegin(Boolean)	Pattern begin.
	PatternBegin(Boolean, Boolean)	A method used to spawn the sub-display list representing the tiling pattern of the current element in the ElementReader. You can call this method at any point as long as the current element is valid.
	ToString	Returns a string that represents the current object. (Inherited from Object.)
	Type3FontBegin	A method used to spawn a sub-display list representing a Type3 Font glyph. You can call this method at any point as long as the current element in the ElementReader is a text element whose font type is type 3.

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Examples

For a full sample, please refer to ElementReader and ElementReaderAdv sample projects. A sample use case for ElementReader is given below:

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...
ElementReader reader=new ElementReader();
reader.Begin(page);
for (Element element=reader.next(); element!=null;element=reader.next()) {
Rect bbox;
if((bbox=element.getBBox())!=null) System.out.println("Bounding Box: " + bbox.getRectangle());
switch (element.getType())    {
case Element.e_path: { // Process path data...
double[] data = element.getPathPoints();
}
break;
case Element.e_text:
// ...
break;
}
}
reader.End();

Reference

pdftron.PDF Namespace