Class PDFDraw

PDFDraw contains methods for converting PDF pages to images and to Bitmap objects. Utility methods are provided to export PDF pages to various raster formats as well as to convert pages to GDI+ bitmaps for further manipulation or drawing.

Inheritance

System.Object

PDFDraw

Namespace: pdftron.PDF

Assembly: PDFNetAndroid.dll

Syntax

public class PDFDraw : IDisposable

Remarks

This class is available on all platforms supported by PDFNet.

Constructors

PDFDraw()

PDFDraw constructor and destructor.

Declaration

public PDFDraw()

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

PDFDraw(Double)

Instantiates a new pDF draw.

Declaration

public PDFDraw(double dpi)

Parameters

Type	Name	Description
System.Double	dpi	the dpi

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

Methods

Destroy()

Declaration

public void Destroy()

Dispose()

Declaration

public void Dispose()

Dispose(Boolean)

Declaration

protected virtual void Dispose(bool disposing)

Parameters

Type	Name	Description
System.Boolean	disposing

Export(Page, String)

A utility method to export the given PDF page to an image file.

Declaration

public void Export(Page page, string filename)

Parameters

Type	Name	Description
Page	page	The source PDF page.
System.String	filename	The name of the output image file. The filename should include the extension suffix (e.g. 'c:/output/myimage.png').

Remarks

By default, the function exports to PNG.. The file format of the output image. Currently supported formats are:

• "RAW" RAW format. There are four possibilities: e_rgba - if transparent and color page; e_gray_alpha - if transparent and gray page; e_rgb - if opaque and color page; e_gray - if opaque and gray page.
• "BMP" Bitmap image format (BMP)
• "JPEG" Joint Photographic Experts Group (JPEG) image format
• "PNG" 24-bit W3C Portable Network Graphics (PNG) image format
• "PNG8" 8-bit, palettized PNG format. The exported file size should be smaller than the one generated using "PNG", possibly at the expense of some image quality.
• "TIFF" Tag Image File Format (TIFF) image format.
• "TIFF8" Tag Image File Format (TIFF) image format (with 8-bit pallete).

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

Export(Page, String, String)

Export.

Declaration

public void Export(Page page, string filename, string format)

Parameters

Type	Name	Description
Page	page	the page
System.String	filename	the filename
System.String	format	the format

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

Export(Page, String, String, Obj)

Export.

Declaration

public void Export(Page page, string filename, string format, Obj encoder_hints)

Parameters

Type	Name	Description
Page	page	the page
System.String	filename	the filename
System.String	format	the format
Obj	encoder_hints	the encoder_params

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

Finalize()

Releases all resources used by the PDFDraw

Declaration

protected void Finalize()

GetBitmap(Page)

Declaration

public Android.Graphics.Bitmap GetBitmap(Page page)

Parameters

Type	Name	Description
Page	page

Returns

Type	Description
Android.Graphics.Bitmap

GetBitmap(Page, PDFDraw.PixelFormat, Boolean)

Declaration

public BitmapInfo GetBitmap(Page page, PDFDraw.PixelFormat pix_fmt, bool demult)

Parameters

Type	Name	Description
Page	page
PDFDraw.PixelFormat	pix_fmt
System.Boolean	demult

Returns

Type	Description
BitmapInfo

GetBitmapInfo(Page)

Declaration

public BitmapInfo GetBitmapInfo(Page page)

Parameters

Type	Name	Description
Page	page

Returns

Type	Description
BitmapInfo

SetAntiAliasing(Boolean)

Enable or disable anti-aliasing. Anti-Aliasing is a technique used to improve the visual quality of images when displaying them on low resolution devices (for example, low DPI computer monitors). Anti-aliasing is enabled by default.

Declaration

public void SetAntiAliasing(bool enable_aa)

Parameters

Type	Name	Description
System.Boolean	enable_aa	whether to enable anti-aliasing

SetCaching(Boolean)

Sets the caching.

Declaration

public void SetCaching(bool enabled)

Parameters

Type	Name	Description
System.Boolean	enabled	the new caching

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetClipRect(Rect)

Clip the render region to the provided rect (in page space)

Declaration

public void SetClipRect(Rect clip_rect)

Parameters

Type	Name	Description
Rect	clip_rect	Clipping rect. By default, PDFDraw will rasterize the entire page box.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetDefaultPageColor(Byte, Byte, Byte)

Sets the default color of the page backdrop.

Declaration

public void SetDefaultPageColor(byte r, byte g, byte b)

Parameters

Type	Name	Description
System.Byte	r
System.Byte	g
System.Byte	b

SetDPI(Double)

Sets the output image resolution.

DPI stands for Dots Per Inch. This parameter is used to specify the output image size and quality. A typical screen resolution for monitors these days is 92 DPI, but printers could use 200 DPI or more.

Declaration

public void SetDPI(double dpi)

Parameters

Type	Name	Description
System.Double	dpi	the new dPI

Remarks

The size of resulting image is a function of DPI and the dimensions of the source PDF page. For example, is DPI is 92 and page is 8 inches wide, the output bitmap will have 92*8 = 736 pixels per line. If you know the dimensions of the destination bitmap, but don't care about DPI of the image you can use pdfdraw.SetImageSize() instead.

if you would like to rasterize extremely large bitmaps (e.g. with resolutions of 2000 DPI or more) it is not practical to use PDFDraw directly because of the memory required to store the entire image. In this case, you can use PDFRasterizer directly to generate the rasterized image in stripes or tiles.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetDrawAnnotations(Boolean)

Enable or disable annotation and forms rendering. By default, all annotations and form fields are rendered.

Declaration

public void SetDrawAnnotations(bool render_annots)

Parameters

Type	Name	Description
System.Boolean	render_annots	True to draw annotations, false otherwise.

SetFlipYAxis(Boolean)

Flips the vertical (i.e. Y) axis of the image.

Declaration

public void SetFlipYAxis(bool flip_y)

Parameters

Type	Name	Description
System.Boolean	flip_y	true to flip the Y axis, false otherwise. For compatibility with most raster formats 'flip_y' is true by default.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetGamma(Double)

Sets the gamma factor used for anti-aliased rendering.

Declaration

public void SetGamma(double exp)

Parameters

Type	Name	Description
System.Double	exp	exponent value of gamma function. Typical values are in the range from 0.1 to 3.

Remarks

Gamma correction can be used to improve the quality of anti-aliased image output and can (to some extent) decrease the appearance common anti-aliasing artifacts (such as pixel width lines between polygons). Gamma correction is used only in the built-in rasterizer.

SetHighlightFields(Boolean)

Enable or disable highlighting form fields. Default is disabled.

Declaration

public void SetHighlightFields(bool highlight_fields)

Parameters

Type	Name	Description
System.Boolean	highlight_fields	true to highlight, false otherwise.

SetImageSize(Int32, Int32)

SetImageSize can be used instead of SetDPI() to adjust page scaling so that image fits into a buffer of given dimensions.

If this function is used, DPI will be calculated dynamically for each page so that every page fits into the buffer of given dimensions.

Declaration

public void SetImageSize(int width, int height)

Parameters

Type	Name	Description
System.Int32	width	The width of the image, in pixels/samples.
System.Int32	height	The height of the image, in pixels/samples.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetImageSize(Int32, Int32, Boolean)

Sets the image size.

Declaration

public void SetImageSize(int width, int height, bool preserve_aspect_ratio)

Parameters

Type	Name	Description
System.Int32	width	the width
System.Int32	height	the height
System.Boolean	preserve_aspect_ratio	the preserve_aspect_ratio

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetImageSmoothing(Boolean, Boolean)

Enable or disable image smoothing.
The rasterizer allows a tradeoff between rendering quality and rendering speed. This function can be used to indicate the preference between rendering speed and quality. image smoothing is enabled by default.

Declaration

public void SetImageSmoothing(bool smoothing_enabled, bool hq_image_resampling)

Parameters

Type	Name	Description
System.Boolean	smoothing_enabled	whether to enable image smoothing
System.Boolean	hq_image_resampling	whether to use a higher quality (but slower) smoothing algorithm

Remarks

image smoothing option has effect only if the source image has higher resolution that the output resolution of the image on the rasterized page. PDFNet automatically controls at what resolution/zoom factor, 'image smoothing' needs to take effect.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetOCGContext(Context)

Sets the Optional Content Group (OCG) context that should be used when rendering the page. This function can be used to selectively render optional content (such as PDF layers) based on the states of optional content groups in the given context.

Declaration

public void SetOCGContext(Context ctx)

Parameters

Type	Name	Description
Context	ctx	Optional Content Group (OCG) context, or NULL if the rasterizer should render all content on the page.

SetOverprint(PDFRasterizer.OverprintPreviewMode)

Enable or disable support for overprint. Overprint is a device dependent feature and the results will vary depending on the output color space and supported colorants (i.e. CMYK, CMYK+spot, RGB, etc). By default overprint is enabled for only PDF/X files.

Declaration

public void SetOverprint(PDFRasterizer.OverprintPreviewMode op)

Parameters

Type	Name	Description
PDFRasterizer.OverprintPreviewMode	op	e_op_on: always enabled; e_op_off: always disabled; e_op_pdfx_on: enabled for PDF/X files only.

SetPageBox(Page.Box)

Selects the page box/region to rasterize.

Declaration

public void SetPageBox(Page.Box region)

Parameters

Type	Name	Description
Page.Box	region	Page box to rasterize. By default, PDFDraw will rasterize page crop box.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetPageTransparent(Boolean)

Sets the page color to transparent. By default, PDFDraw assumes that the page is imposed directly on an opaque white surface. Some applications may need to impose the page on a different backdrop. In this case any pixels that are not covered during rendering will be transparent.

Declaration

public void SetPageTransparent(bool is_transp)

Parameters

Type	Name	Description
System.Boolean	is_transp	If true, page's backdrop color will be transparent. If false, the page's backdrop will be a opaque white.

Remarks

If true, page's backdrop color will be transparent. If false, the page's backdrop will be a opaque white.

SetPathHinting(Boolean)

Enable or disable path hinting. 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.

Declaration

public void SetPathHinting(bool enable_ph)

Parameters

Type	Name	Description
System.Boolean	enable_ph	whether to enable path hinting.

SetPrintMode(Boolean)

Tells the rasterizer to render the page 'print' mode. Certain page elements (such as annotations or OCG-s) are meant to be visible either on the screen or on the printed paper but not both. A common example, is the "Submit" button on electronic forms.

Declaration

public void SetPrintMode(bool is_printing)

Parameters

Type	Name	Description
System.Boolean	is_printing	set to true if the page should be rendered in print mode. By default, print mode flag is set to false.

SetRasterizerType(PDFRasterizer.Type)

Sets the core graphics library used for rasterization and rendering. Using this method it is possible to quickly switch between different implementations. By default, PDFDraw uses the built-in, platform independent rasterizer.

Declaration

public void SetRasterizerType(PDFRasterizer.Type type)

Parameters

Type	Name	Description
PDFRasterizer.Type	type	Rasterizer type.

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetRotate(Page.Rotate)

Sets the rotation value for this page.

Declaration

public void SetRotate(Page.Rotate r)

Parameters

Type	Name	Description
Page.Rotate	r	the new rotate

Remarks

This method is used only for drawing purposes and it does not modify the document (unlike Page.SetRotate()).

Exceptions

Type	Condition
PDFNetException	PDFNetException the PDFNet exception

SetThinLineAdjustment(Boolean, Boolean)

Set thin line adjustment parameters.

Declaration

public void SetThinLineAdjustment(bool pixel_grid_fit, bool stroke_adjust)

Parameters

Type	Name	Description
System.Boolean	pixel_grid_fit	if true (horizontal/vertical) thin lines will be snapped to integer pixel positions. This helps make thin lines look sharper and clearer. This option is turned off by default and it only works if path hinting is enabled.
System.Boolean	stroke_adjust	if true auto stroke adjustment is enabled. Currently, this would make lines with sub-pixel width to be one-pixel wide. This option is turned on by default.