Class: Flattener

PDFNet. Flattener


new Flattener()

Flattener is a optional PDFNet add-on that can be used to simplify and optimize existing PDF's to render faster on devices with lower memory and speeds.

PDF documents can frequently contain very complex page description (e.g. thousands of paths, different shadings, color spaces, blend modes, large images etc.) that may not be suitable for interactive viewing on mobile devices. Flattener can be used to speed-up PDF rendering on mobile devices and on the Web by simplifying page content (e.g. flattening complex graphics into images) while maintaining vector text whenever possible.

By using the FlattenMode::e_simple option each page in the PDF will be reduced to a single background image, with the remaining text over top in vector format. Some text may still get flattened, in particular any text that is clipped, or underneath, other content that will be flattened.

On the other hand the FlattenMode::e_fast will not flatten simple content, such as simple straight lines, nor will it flatten Type3 fonts.

Methods


<static> create()

Flattener constructor

Returns:

A promise that resolves to an object of type: "Flattener"

Type
PDFNet.Flattener

destroy()

Frees the native memory of the object.


process(doc, mode)

Process each page in the PDF, flattening content that matches the mode criteria.

Parameters:
Name Type Description
doc PDFNet.PDFDoc

the document to flatten.

mode number/enum
PDFNet.Flattener.Mode = {
	e_mode_simple : 0
	e_mode_fast : 1
}

indicates the criteria for which elements are flattened.


processPage(page, mode)

Process the given page, flattening content that matches the mode criteria.

Parameters:
Name Type Description
page PDFNet.Page

the page to flatten.

mode number/enum
PDFNet.Flattener.Mode = {
	e_mode_simple : 0
	e_mode_fast : 1
}

indicates the criteria for which elements are flattened.


setDPI(dpi)

The output resolution, from 1 to 1000, in Dots Per Inch (DPI) at which to render elements which cannot be directly converted. the default value is 150 Dots Per Inch

Parameters:
Name Type Description
dpi number

the resolution in Dots Per Inch


setJPGQuality(quality)

Specifies the compression quality to use when generating JPEG images.

Parameters:
Name Type Description
quality number

the JPEG compression quality, from 0(highest compression) to 100(best quality).


setMaximumImagePixels(max_pixels)

Specifies the maximum image size in pixels.

Parameters:
Name Type Description
max_pixels number

the maximum number of pixels an image can have.


setPathHinting(hinting)

Enable or disable path hinting.

Parameters:
Name Type Description
hinting boolean

if true path hinting is enabled. Path hinting is used to slightly adjust paths in order to avoid or alleviate artifacts of hair line cracks between certain graphical elements. This option is turned on by default.


setPreferJPG(jpg)

Specifies whether to leave images in existing compression, or as JPEG.

Parameters:
Name Type Description
jpg boolean

if true PDF will contain all JPEG images.


setThreshold(threshold)

Used to control how precise or relaxed text flattening is. When some text is preserved (not flattened to image) the visual appearance of the document may be altered.

Parameters:
Name Type Description
threshold number/enum
PDFNet.Flattener.Threshold = {
	e_threshold_very_strict : 0
	e_threshold_strict : 1
	e_threshold_default : 2
	e_threshold_keep_most : 3
	e_threshold_keep_all : 4
}

the threshold setting to use.