Class PDFRasterizer

PDFRasterizer is a low-level PDF rasterizer. The main purpose of this class is to convert PDF pages to raster images (or bitmaps). PDFRasterizer is a relatively low-level class. If you need to convert PDF page to an image format or a Bitmap, consider using PDF.PDFDraw. Similarly, if you are building an interactive PDF viewing application use PDF.PDFViewCtrl instead.

Inheritance

System.Object

PDFRasterizer

Implements

System.IDisposable

Inherited Members

System.Object.Equals(System.Object)

System.Object.Equals(System.Object, System.Object)

System.Object.GetHashCode()

System.Object.GetType()

System.Object.MemberwiseClone()

System.Object.ToString()

System.Object.ReferenceEquals(System.Object, System.Object)

Namespace: pdftron.PDF

Assembly: PDFNetAndroid.dll

Syntax

public class PDFRasterizer : IDisposable

Constructors

PDFRasterizer()

empty PDFRasterizer constructor

Declaration

public PDFRasterizer()

PDFRasterizer(PDFRasterizer.Type)

instantiates PDFRasterizer with specified type

Declaration

[Obsolete("Deprecated, will be removed in the next update.")]
public PDFRasterizer(PDFRasterizer.Type type)

Parameters

Type	Name	Description
PDFRasterizer.Type	type	PDFRasterizer type

Methods

CancelRendering()

Cancel the rendering in progress.

Declaration

public void CancelRendering()

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

Finalize()

Releases all resources used by the PDFRasterizer

Declaration

protected void Finalize()

GetRasterizerType()

Gets the type of current rasterizer.

Declaration

[Obsolete("Deprecated, will be removed in the next update.")]
public PDFRasterizer.Type GetRasterizerType()

Returns

Type	Description
PDFRasterizer.Type	the type of current rasterizer.

Rasterize(Page, Int32, Int32, Int32, Int32, Boolean, Matrix2D)

Draws the page into a given memory buffer.

Declaration

public byte[] Rasterize(Page page, int width, int height, int stride, int num_comps, bool demult, Matrix2D device_mtx)

Parameters

Type	Name	Description
Page	page	The page to rasterize.
System.Int32	width	The width of the target image in pixels.
System.Int32	height	The height of the target image in pixels (the number of rows).
System.Int32	stride	Stride determines the physical width (in bytes) of one row in memory. If this value is negative the direction of the Y axis is inverted. The absolute value of stride is of importance, because it allows rendering in buffers where rows are padded in memory (e.g. in Windows bitmaps are padded on 4 byte boundaries). Besides allowing rendering on the whole buffer stride parameter can be used for rendering in a rectangular subset of a buffer.
System.Int32	num_comps	The number (4 or 5) representing the number of color components in the device color space. For BGR+Alpha set this parameter to 4, and for CMYK+Alpha use 5. If other values are set, exceptions will be thrown.
System.Boolean	demult	Specifies if the alpha is de-multiplied from the resulting color components.
Matrix2D	device_mtx	Device transformation matrix that maps PDF page from PDF user space into device coordinate space (e.g. pixel space). PDF user space is represented in page units, where one unit corresponds to 1/72 of an inch.

Returns

Type	Description
System.Byte[]

Rasterize(Page, Int32, Int32, Int32, Int32, Boolean, Matrix2D, Rect)

Draws the page into a given memory buffer.

Declaration

public byte[] Rasterize(Page page, int width, int height, int stride, int num_comps, bool demult, Matrix2D device_mtx, Rect clip)

Parameters

Type	Name	Description
Page	page	The page to rasterize.
System.Int32	width	The width of the target image in pixels.
System.Int32	height	The height of the target image in pixels (the number of rows).
System.Int32	stride	Stride determines the physical width (in bytes) of one row in memory. If this value is negative the direction of the Y axis is inverted. The absolute value of stride is of importance, because it allows rendering in buffers where rows are padded in memory (e.g. in Windows bitmaps are padded on 4 byte boundaries). Besides allowing rendering on the whole buffer stride parameter can be used for rendering in a rectangular subset of a buffer.
System.Int32	num_comps	The number (4 or 5) representing the number of color components in the device color space. For BGR+Alpha set this parameter to 4, and for CMYK+Alpha use 5. If other values are set, exceptions will be thrown.
System.Boolean	demult	Specifies if the alpha is de-multiplied from the resulting color components.
Matrix2D	device_mtx	Device transformation matrix that maps PDF page from PDF user space into device coordinate space (e.g. pixel space). PDF user space is represented in page units, where one unit corresponds to 1/72 of an inch.
Rect	clip	Optional parameter defining the clip region for the page. If the parameter is null or is not specified, PDFRasterizer uses page's crop box as a default clip region.

Returns

Type	Description
System.Byte[]

Examples

float drawing_scale = 2: 
Common.Matrix2D mtx(drawing_scale, 0, 0, drawing_scale, 0, 0);
PDF.Rect bbox(page.GetMediaBox());
bbox.Normalize();
int width = int(bbox.Width() * drawing_scale); 
int height = int(bbox.Height() * drawing_scale);

// Stride is represented in bytes and is aligned on 4 byte 
// boundary so that you can render directly to GDI bitmap.
// A negative value for stride can be used to flip the image 
// upside down.
int comps = 4;  // for BGRA
int stride = ((width * comps + 3) / 4) * 4;
// buf is a memory buffer containing at least (stride*height) bytes.
     memset(ptr, 0xFF, height*stride);  // Clear the background to opaque white paper color.
PDFRasterizer rast;
   rast.Rasterize(page, buf, width, height, stride, 4, false, mtx);

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	true 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

SetDrawAnnotations(Boolean)

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

Declaration

public void SetDrawAnnotations(bool render_annots)

Parameters

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

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.

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.

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 is the page should be rendered in print mode. By default, print mode flag is set to false.

SetRasterizerType(PDFRasterizer.Type)

Sets rasterizer to the specified type

Declaration

[Obsolete("Deprecated, will be removed in the next update.")]
public void SetRasterizerType(PDFRasterizer.Type type)

Parameters

Type	Name	Description
PDFRasterizer.Type	type	PDFRasterizer type

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.

Implements

System.IDisposable