# Class: ElementWriter

## PDFNet. ElementWriter

#### new ElementWriter()

  ElementWriter can be used to assemble and write new content to a page, Form XObject, Type3 Glyph stream, pattern stream, or any other content stream.

### Methods

#### <static> create()

  Constructor for an ElementWriter object that can be used to assemble and write new content to a page, Form XObject, pattern stream or any other content stream.

  ##### Returns:

  A promise that resolves to Returns an ElementWriter object

  Type
    PDFNet.ElementWriter

#### begin(doc, compress)

  begin writing an Element sequence to a new stream. Use this function to write Elements to a content stream other than the page. For example, you can create Form XObjects (See Section '4.9 Form XObjects' in PDF Reference for more details) pattern streams, Type3 font glyph streams, etc.

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `doc` | PDFNet.SDFDoc | A low-level SDF/Cos document that will contain the new stream. You can access low-level document using PDFDoc::GetSDFDoc() or Obj::GetDoc() methods.
  `compress` | boolean | An optional flag indicating whether the page content stream should be compressed. This may be useful for debugging content streams. Also some applications need to do a clear text search on strings in the PDF files. By default, all content streams are compressed.

#### beginOnObj(stream_obj_to_update, compress)

  begin writing an Element sequence to a stream. Use this function to write Elements to a content stream which will replace an existing content stream in an object passed as a parameter.

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `stream_obj_to_update` | PDFNet.Obj | A low-level SDF stream object that will contain the new stream. Old stream inside that object will be discarded.
  `compress` | boolean | An optional flag indicating whether the content stream should be compressed. This may be useful for debugging content streams. Also some applications need to do a clear text search on strings in the PDF files. By default, all content streams are compressed.

#### beginOnPage(page, placement, page_coord_sys, compress)

  begin writing to the given page.

  By default, new content will be appended to the page, as foreground graphics. It is possible to add new page content as background graphics by setting the second parameter in begin method to 'true' (e.g. writer.Begin(page, true)).

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `page` | PDFNet.Page | The page to write content.
  `placement` | number/enum |
      PDFNet.ElementWriter.WriteMode = {
      	e_underlay : 0
      	e_overlay : 1
      	e_replacement : 2
      }
  An optional flag indicating whether the new content should be added as a foreground or background layer to the existing page. By default, the new content will appear on top of the existing graphics.
  `page_coord_sys` | boolean | An optional flag used to select the target coordinate system if true (default), the coordinates are relative to the lower-left corner of the page, otherwise the coordinates are defined in PDF user coordinate system (which may, or may not coincide with the page coordinates).
  `compress` | boolean | An optional flag indicating whether the page content stream should be compressed. This may be useful for debugging content streams. Also some applications need to do a clear text search on strings in the PDF files. By default, all content streams are compressed.

#### destroy()

  Frees the native memory of the object.

#### end()

  Finish writing to a page

  ##### Returns:

  A promise that resolves to a low-level stream object that was used to store Elements.

  Type
    PDFNet.Obj

#### flush()

  the Flush method flushes all pending Element writing operations. This method is typically only required to be called when intermixing direct content writing (i.e. WriteBuffer/WriteString) with Element writing.

#### writeBuffer(data, data_sz)

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `data` | string |
  `data_sz` | number |

#### writeElement(element)

  Writes the Element to the content stream.

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `element` | PDFNet.Element | The element to write to the content stream.

#### writePlacedElement(element)

  A utility function that surrounds the given Element with a graphics state Save/Restore Element (i.e. in PDF content stream represented as 'q element Q').

  The function is equivalent to calling WriteElement three times: WriteElement(eSave); WriteElement(element); WriteElement(eRestore);

  where eSave is 'e_group_begin' and eRestore is 'e_group_end' Element

  The function is useful when XObjects such as Images and Forms are drawn on the page.

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `element` | PDFNet.Element | Element object to enact function on.

#### writeString(str)

  Writes an arbitrary string to the content stream. Serves the same purpose as WriteBuffer().

  ##### Parameters:

  Name | Type | Description
  --- | --- | ---
  `str` | string | String to write to the content stream.

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