com.itextpdf.io.util

Class GhostscriptHelper

java.lang.Object

com.itextpdf.io.util.GhostscriptHelper

public class GhostscriptHelper
extends Object

A utility class that is used as an interface to run 3rd-party tool Ghostscript. Ghostscript is an interpreter for the PostScript language and PDF files, it allows to render them as images.

The Ghostscript needs to be installed independently on the system. This class provides a convenient way to run it by passing a terminal command. The command can either be specified explicitly or by a mean of environment variable GHOSTSCRIPT_ENVIRONMENT_VARIABLE.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	GhostscriptHelper.GhostscriptExecutionException Exceptions thrown when errors occur during generation and comparison of images obtained on the basis of pdf files.

Field Summary

Fields

Modifier and Type	Field and Description
static String	GHOSTSCRIPT_ENVIRONMENT_VARIABLE The name of the environment variable with the command to execute Ghostscript operations.

Constructor Summary

Constructors

Constructor and Description
GhostscriptHelper() Creates new instance that will rely on Ghostscript execution command defined by GHOSTSCRIPT_ENVIRONMENT_VARIABLE environment variable.
GhostscriptHelper(String newGsExec) Creates new instance that will rely on Ghostscript execution command defined as passed argument.

Method Summary

Modifier and Type	Method and Description
String	getCliExecutionCommand() Returns a command that is used to run the utility.
void	runGhostScriptImageGeneration(String pdf, String outDir, String image) Runs Ghostscript to render the PDF's pages as PNG images.
void	runGhostScriptImageGeneration(String pdf, String outDir, String image, String pageList) Runs Ghostscript to render the PDF's pages as PNG images.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

GHOSTSCRIPT_ENVIRONMENT_VARIABLE

public static final String GHOSTSCRIPT_ENVIRONMENT_VARIABLE

The name of the environment variable with the command to execute Ghostscript operations.

See Also:

Constant Field Values

Constructor Detail

GhostscriptHelper

public GhostscriptHelper()

Creates new instance that will rely on Ghostscript execution command defined by GHOSTSCRIPT_ENVIRONMENT_VARIABLE environment variable.

GhostscriptHelper

public GhostscriptHelper(String newGsExec)

Creates new instance that will rely on Ghostscript execution command defined as passed argument.

Parameters:

newGsExec - the Ghostscript execution command; if null - environment variables will be used instead

Method Detail

getCliExecutionCommand

public String getCliExecutionCommand()

Returns a command that is used to run the utility. This command doesn't contain command parameters. Parameters are added on specific methods invocation.

Returns:

a string command

runGhostScriptImageGeneration

public void runGhostScriptImageGeneration(String pdf,
                                          String outDir,
                                          String image)
                                   throws IOException,
                                          InterruptedException

Runs Ghostscript to render the PDF's pages as PNG images.

Note, that this method may create temporary directory and files.

Parameters:

pdf - Path to the PDF file to be rendered

outDir - Path to the output directory, in which the rendered pages will be stored

image - String which defines the name of the resultant images. This string will be concatenated with the number of the rendered page from the start of the PDF in "-%03d" format, e.g. "-011" for the eleventh rendered page and so on. This number may not correspond to the actual page number: for example, if the passed pageList equals to "5,3", then images with postfixes "-001.png" and "-002.png" will be created: the former for the third page, the latter for the fifth page. "%" sign in the passed name is prohibited.

Throws:

IOException - if there are file's reading/writing issues

InterruptedException - if there is thread interruption while executing GhostScript.

runGhostScriptImageGeneration

public void runGhostScriptImageGeneration(String pdf,
                                          String outDir,
                                          String image,
                                          String pageList)
                                   throws IOException,
                                          InterruptedException

Runs Ghostscript to render the PDF's pages as PNG images.

Note, that this method may create temporary directory and files.

Parameters:

pdf - Path to the PDF file to be rendered

outDir - Path to the output directory, in which the rendered pages will be stored

image - String which defines the name of the resultant images. This string will be concatenated with the number of the rendered page from the start of the PDF in "-%03d" format, e.g. "-011" for the eleventh rendered page and so on. This number may not correspond to the actual page number: for example, if the passed pageList equals to "5,3", then images with postfixes "-001.png" and "-002.png" will be created: the former for the third page, the latter for the fifth page. "%" sign in the passed name is prohibited.

pageList - String with numbers of the required pages to be rendered as images. This string should be formatted as a string with numbers, separated by commas, without whitespaces. Can be null, if it is required to render all the PDF's pages.

Throws:

IOException - if there are file's reading/writing issues

InterruptedException - if there is thread interruption while executing GhostScript.