public class

PDFRasterizer

extends Object
java.lang.Object
   ↳ com.pdftron.pdf.PDFRasterizer

Class Overview

PDFRasterizer is a low-level PDF rasterizer. The main purpose of this class is to convert PDF pages to raster images (or bitmaps).

* Note: 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 you may want to use PDF::PDFViewCtrl instead.

Summary

Constants
int e_postprocess_gradient_map The Constant e_postprocess_gradient_map.
int e_postprocess_invert The Constant e_postprocess_invert.
int e_postprocess_night_mode The Constant e_postprocess_night_mode.
int e_postprocess_none The Constant e_postprocess_none.
Public Constructors
PDFRasterizer()
Public Methods
void destroy()
Frees the native memory of the object.
int getColorPostProcessMode()
byte[] rasterize(Page page, int width, int height, int stride, int num_comps, boolean demult, Matrix2D device_mtx, Rect clip)
Rasterize a page into a buffer (byte array).
void rasterize(Page page, int[] buffer, int width, int height, boolean demult, Matrix2D device_mtx, Rect clip)
Rasterize a page into a buffer provided by the user.
void setAntiAliasing(boolean enable_aa)
Enable or disable anti-aliasing.
void setCaching()
Enables or disables caching.
void setCaching(boolean enabled)
Set the caching.
void setCancel(boolean cancel)
Signals the rendering thread whether to stop or not.
void setColorPostProcessColors(int white_color, int black_color)
Set the color post processing transformation.
void setColorPostProcessMapFile(Filter image_file_contents)
Set the color post processing transformation.
void setColorPostProcessMode(int mode)
Set the color post processing transformation.
void setDrawAnnotations(boolean render_annots)
Enable or disable annotation and forms rendering.
void setGamma(double exp)
Set the gamma factor used for anti-aliased rendering.
void setHighlightFields(boolean highlight_fields)
Enable or disable highlighting form fields.
void setImageSmoothing()
Enable image smoothing.
void setImageSmoothing(boolean smoothing_enabled, boolean hq_image_resampling)
Set the image smoothing.
void setImageSmoothing(boolean smoothing_enabled)
Set the image smoothing.
void setOCGContext(Context ctx)
Set the Optional Content Group (OCG) context that should be used when rendering the page.
void setOverprint(int op)
Enable or disable support for overprint.
void setPathHinting(boolean enable_ph)
Enable or disable path hinting.
void setPrintMode(boolean is_printing)
Tells the rasterizer to render the page 'print' mode.
void setThinLineAdjustment(boolean pixel_grid_fit, boolean stroke_adjust)
Set thin line adjustment parameters.
[Expand]
Inherited Methods
From class java.lang.Object

Constants

public static final int e_postprocess_gradient_map

The Constant e_postprocess_gradient_map.

Constant Value: 2 (0x00000002)

public static final int e_postprocess_invert

The Constant e_postprocess_invert.

Constant Value: 1 (0x00000001)

public static final int e_postprocess_night_mode

The Constant e_postprocess_night_mode.

Constant Value: 3 (0x00000003)

public static final int e_postprocess_none

The Constant e_postprocess_none.

Constant Value: 0 (0x00000000)

Public Constructors

public PDFRasterizer ()

Public Methods

public void destroy ()

Frees the native memory of the object. This can be explicity called to control the deallocation of native memory and avoid situations where the garbage collector does not free the object in a timely manner.

public int getColorPostProcessMode ()

Returns
  • the current color post processing mode.

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

Rasterize a page into a buffer (byte array).

Parameters
page The page to rasterize.
width The width of the target image in pixels.
height The height of the target image in pixels (the number of rows).
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.
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.
demult Specifies if the alpha is de-multiplied from the resulting color components.
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.
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
  • A buffer containing the rasterized image (in byte array).

public void rasterize (Page page, int[] buffer, int width, int height, boolean demult, Matrix2D device_mtx, Rect clip)

Rasterize a page into a buffer provided by the user.

Parameters
page The page to rasterize.
buffer The buffer into which the page will be rasterized. It has to be pre-allocated by the user and its length should be 'width*height'. It is an int array and each element stores a pixel in ARGB format.
width The width of the buffer.
height The height of the buffer.
demult The RGB components in each pixel are pre-multiplied by its alpha component. Users can set this flag to false to disable such a behavior.
device_mtx This matrix transforms page contents in PDF space into UI space.
clip Specifies a rectangular region only within which page contents will be rendered. Note that clip is specified in PDF page space.

public void setAntiAliasing (boolean enable_aa)

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.

Parameters
enable_aa whether to enable or disable anti-aliasing

public void setCaching ()

Enables or disables caching. Caching can improve the rendering performance in cases where the same page will be drawn multiple times.

public void setCaching (boolean enabled)

Set the caching.

Parameters
enabled whether to enable caching

public void setCancel (boolean cancel)

Signals the rendering thread whether to stop or not. This method can be used to signal the rendering thread to stop when passing true. When passing false the rendering thread will not be affected.

Note: This call affects only the current rendering thread.

Parameters
cancel whether to cancel or not the rendering thread

public void setColorPostProcessColors (int white_color, int black_color)

Set the color post processing transformation. This transform is applied to the rasterized bitmap as the final step in the rasterization process, and is applied directly to the resulting bitmap (disregarding any color space information). Color post processing only supported for RGBA output. This mode will map the brightness of the original rasterized bitmap to a gradient between white_color and black_color

Parameters
white_color the white color of page
black_color the black color of page

public void setColorPostProcessMapFile (Filter image_file_contents)

Set the color post processing transformation. This transform is applied to the rasterized bitmap as the final step in the rasterization process, and is applied directly to the resulting bitmap (disregarding any color space information). Color post processing only supported for RGBA output. This mode will map the brightness of the original rasterized bitmap to a gradient in image_file_contents from left to right

Parameters
image_file_contents is a filter with image file contents

public void setColorPostProcessMode (int mode)

Set the color post processing transformation. This transform is applied to the rasterized bitmap as the final step in the rasterization process, and is applied directly to the resulting bitmap (disregarding any color space information). Color post processing only supported for RGBA output.

Parameters
mode is the specific transform to be applied

public void setDrawAnnotations (boolean render_annots)

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

Parameters
render_annots True to draw annotations, false otherwise.

public void setGamma (double exp)

Set the gamma factor used for anti-aliased rendering.

Note: Gamma correction is used only in the built-in rasterizer.

Parameters
exp is the exponent value of gamma function. Typical values are in the range from 0.1 to 3. 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).

public void setHighlightFields (boolean highlight_fields)

Enable or disable highlighting form fields. Default is disabled.

Parameters
highlight_fields true to highlight, false otherwise.

public void setImageSmoothing ()

Enable 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.

Note: 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.

public void setImageSmoothing (boolean smoothing_enabled, boolean hq_image_resampling)

Set the image smoothing.

Parameters
smoothing_enabled whether to enable image smoothing
hq_image_resampling whether to use a higher quality (but slower) smoothing algorithm

public void setImageSmoothing (boolean smoothing_enabled)

Set the image smoothing.

Parameters
smoothing_enabled whether to enable image smoothing

public void setOCGContext (Context ctx)

Set 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.

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

public void setOverprint (int op)

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.

Parameters
op 0: always disabled; 1: always enabled; 2: enabled for PDF/X files only. The default is 2.

public void setPathHinting (boolean enable_ph)

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. Path hinting is enabled by default.

Parameters
enable_ph whether to enable or disable path hinting

public void setPrintMode (boolean is_printing)

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. By default, print mode flag is set to false.

Parameters
is_printing set to true if the page should be rendered in print mode.

public void setThinLineAdjustment (boolean pixel_grid_fit, boolean stroke_adjust)

Set thin line adjustment parameters.

Parameters
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 only works if path hinting is enabled.
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.