Ghost4J

https://github.com/zippy1978/ghost4j
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Ghost4J is a Java wrapper for the Ghostscript C API, providing high-level APIs to process PDF and...
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### PS to PDF Conversion Example

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/index.md

This snippet demonstrates how to load a PostScript document, set PDF conversion options, and convert it to a PDF file using Ghost4J.

```java
//load PostScript document
        PSDocument document = new PSDocument();
        document.load(new File("input.ps"));

        //create OutputStream
        fos = new FileOutputStream(new File("rendition.pdf"));

        //create converter
        PDFConverter converter = new PDFConverter();

        //set options
        converter.setPDFSettings(PDFConverter.OPTION_PDFSETTINGS_PREPRESS);

        //convert
        converter.convert(document, fos);
```

--------------------------------

### Convert Postscript to PDF

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/coreapisamples.md

This example demonstrates how to convert a Postscript file to a PDF file using the Ghostscript library. It sets up the necessary interpreter arguments and executes the conversion.

```java
package org.ghost4j.example;

import org.ghost4j.Ghostscript;
import org.ghost4j.GhostscriptException;

/**
 * Example showing how to convert a Postscript file to PDF.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class PDFConvertExample {

     public static void main(String[] args) {

        //get Ghostscript instance
        Ghostscript gs = Ghostscript.getInstance();

        //prepare Ghostscript interpreter parameters
        //refer to Ghostscript documentation for parameter usage
        String[] gsArgs = new String[10];
        gsArgs[0] = "-ps2pdf";
        gsArgs[1] = "-dNOPAUSE";
        gsArgs[2] = "-dBATCH";
        gsArgs[3] = "-dSAFER";
        gsArgs[4] = "-sDEVICE=pdfwrite";
        gsArgs[5] = "-sOutputFile=output.pdf";
        gsArgs[6] = "-c";
        gsArgs[7] = ".setpdfwrite";
        gsArgs[8] = "-f";
        gsArgs[9] = "input.ps";

        //execute and exit interpreter
        try {

            gs.initialize(gsArgs);
            gs.exit();

        } catch (GhostscriptException e) {
            System.out.println("ERROR: " + e.getMessage());
        }
     }

}
```

--------------------------------

### PS to PDF Conversion Example

Source: https://github.com/zippy1978/ghost4j/blob/master/README.md

This Java code snippet demonstrates how to convert a PostScript file to a PDF document using Ghost4J. Ensure the necessary file I/O streams are properly handled.

```java
//load PostScript document
PSDocument document = new PSDocument();
document.load(new File("input.ps"));

//create OutputStream
fos = new FileOutputStream(new File("rendition.pdf"));

//create converter
PDFConverter converter = new PDFConverter();

//set options
converter.setPDFSettings(PDFConverter.OPTION_PDFSETTINGS_PREPRESS);

//convert
converter.convert(document, fos);
```

--------------------------------

### Handle Display Callback for Image Output

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/coreapisamples.md

This example shows how to set up a display callback to capture page rasters as images during Ghostscript processing. It uses an ImageWriterDisplayCallback to save each page as a PNG file.

```java
package org.ghost4j.example;

import java.awt.image.RenderedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;

import org.ghost4j.Ghostscript;
import org.ghost4j.GhostscriptException;
import org.ghost4j.display.ImageWriterDisplayCallback;

/**
 * Example showing how to setup a display callback (to interract with the display) for the Ghostscript interpreter.
 * In this example, a simple ImageWriterDisplayCallback is used as callback: it converts page rasters into images and stores them.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class DisplayCallbackExample {

    public static void main(String[] args) {

        //get Ghostscript instance
        Ghostscript gs = Ghostscript.getInstance();

        //create display callback (capture display output pages as images)
        ImageWriterDisplayCallback displayCallback = new ImageWriterDisplayCallback();

        //set display callback
        gs.setDisplayCallback(displayCallback);

        //prepare Ghostscript interpreter parameters with display device
        String[] gsArgs = new String[7];
        gsArgs[0] = "-dQUIET";
        gsArgs[1] = "-dNOPAUSE";
        gsArgs[2] = "-dBATCH";
        gsArgs[3] = "-dSAFER";
        gsArgs[4] = "-sDEVICE=display";
        gsArgs[5] = "-sDisplayHandle=0";
        gsArgs[6] = "-dDisplayFormat=16#804";

        //run PostScript (also works with PDF) and exit interpreter
        try {

            gs.initialize(gsArgs);
            gs.runFile("input.ps");
            gs.exit();

        } catch (GhostscriptException e) {
            System.out.println("ERROR: " + e.getMessage());
        }

        //write images captured by the display callback to the disk in PNG format
        try {
            for (int i = 0; i < displayCallback.getImages().size(); i++) {
                ImageIO.write((RenderedImage) displayCallback.getImages().get(i), "png", new File((i + 1) + ".png"));
            }
        } catch (IOException e) {
            System.out.println("ERROR: " + e.getMessage());
        }

    }
}
```

--------------------------------

### File Header for Source Files

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/contributing.md

All source files in the project must include this standard header comment.

```java
/*
 * Ghost4J: a Java wrapper for Ghostscript API.
 * 
 * Distributable under LGPL license.
 * See terms of license at http://www.gnu.org/licenses/lgpl.html. 
 */
```

--------------------------------

### Maven Configuration for Ghost4J

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/index.md

This snippet shows the Maven repository and dependency configuration required to include Ghost4J in your project. Note that since version 1.0.0, artifacts are available from Maven Central.

```xml
<repositories>
	... 
	<repository>
		<id>org.ghost4j.repository.releases</id>
		<name>Ghost4J releases</name>
		<url>http://repo.ghost4j.org/maven2/releases</url>
	</repository>
	<repository>
		<id>org.ghost4j.repository.snapshots</id>
		<name>Ghost4J snapshots</name>
		<url>http://repo.ghost4j.org/maven2/snapshots</url>
	</repository>
	...
</repositories>

<dependencies>
	... 
	<dependency>
		<groupId>org.ghost4j</groupId>
		<artifactId>ghost4j</artifactId>
		<version>1.0.0</version>
	</dependency>
	...
</dependencies>
```

--------------------------------

### Analyze Ink Coverage of PostScript Document

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Demonstrates how to analyze the ink coverage of a PostScript document using the InkAnalyzer. This method also works for PDF documents. Ensure 'input-2pages.ps' exists in the same directory.

```java
package org.ghost4j.example;

import java.io.File;
import java.util.List;

import org.ghost4j.analyzer.AnalysisItem;
import org.ghost4j.analyzer.InkAnalyzer;
import org.ghost4j.document.PSDocument;

/**
 * Example showing how to analyze ink coverage of a PS (works with PDF as well)
 * document using the high level API.
 * 
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class InkAnalyzerExample {

    public static void main(String[] args) {

	try {

	    // load PS document
	    PSDocument document = new PSDocument();
	    document.load(new File("input-2pages.ps"));

	    // create analyzer
	    InkAnalyzer analyzer = new InkAnalyzer();

	    // analyze
	    List<AnalysisItem> coverageData = analyzer.analyze(document);

	    // print result
	    for (AnalysisItem analysisItem : coverageData) {
		System.out.println(analysisItem);

	    }

	} catch (Exception e) {
	    System.out.println("ERROR: " + e.getMessage());
	}

    }

}
```

--------------------------------

### Render PDF Document to Images

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Renders pages of a PDF document into images using SimpleRenderer. Sets resolution to 300 DPI and saves each page as a PNG file. Requires input.pdf.

```java
package org.ghost4j.example;

import java.awt.Image;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.IOException;
import java.util.List;

import javax.imageio.ImageIO;

import org.ghost4j.analyzer.AnalysisItem;
import org.ghost4j.analyzer.FontAnalyzer;
import org.ghost4j.document.PDFDocument;
import org.ghost4j.renderer.SimpleRenderer;


/**
 * Example showing how to render pages of a PDF document using the high level API.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class SimpleRendererExample {

	public static void main(String[] args) {

		try {

			// load PDF document
			PDFDocument document = new PDFDocument();
			document.load(new File("input.pdf"));

			// create renderer
			SimpleRenderer renderer = new SimpleRenderer();
			
			// set resolution (in DPI)
			renderer.setResolution(300);

			// render
			List<Image> images = renderer.render(document);

			// write images to files to disk as PNG
	        try {
	            for (int i = 0; i < images.size(); i++) {
	                ImageIO.write((RenderedImage) images.get(i), "png", new File((i + 1) + ".png"));
	            }
	        } catch (IOException e) {
	            System.out.println("ERROR: " + e.getMessage());
	        }

		} catch (Exception e) {
			System.out.println("ERROR: " + e.getMessage());
		}

	}
}
```

--------------------------------

### Maven Repositories for Older Releases

Source: https://github.com/zippy1978/ghost4j/blob/master/README.md

Include these repositories in your Maven configuration if you are using a release prior to 1.0.0.

```xml
<repositories>

	...
	
	<repository>
		<id>org.ghost4j.repository.releases</id>
		<name>Ghost4J releases</name>
		<url>http://repo.ghost4j.org/maven2/releases</url>
	</repository>
	<repository>
		<id>org.ghost4j.repository.snapshots</id>
		<name>Ghost4J snapshots</name>
		<url>http://repo.ghost4j.org/maven2/snapshots</url>
	</repository>
	
	...

</repositories>
```

--------------------------------

### Convert PostScript to PDF

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Converts a PostScript file to a PDF document using PDFConverter. Ensure input.ps exists and specify output file path. Uses PDFConverter.OPTION_PDFSETTINGS_PREPRESS for conversion settings.

```java
package org.ghost4j.example;

import java.io.File;
import java.io.FileOutputStream;
import org.apache.commons.io.IOUtils;
import org.ghost4j.converter.PDFConverter;
import org.ghost4j.document.PSDocument;

/**
 * Example showing how to convert a Postscript document to PDF using the high level API.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class PDFConverterExample {

    public static void main(String[] args) {

        FileOutputStream fos = null;
        try{

            //load PostScript document
            PSDocument document = new PSDocument();
            document.load(new File("input.ps"));

            //create OutputStream
            fos = new FileOutputStream(new File("rendition.pdf"));

            //create converter
            PDFConverter converter = new PDFConverter();

            //set options
            converter.setPDFSettings(PDFConverter.OPTION_PDFSETTINGS_PREPRESS);

            //convert
            converter.convert(document, fos);

        } catch (Exception e) {
            System.out.println("ERROR: " + e.getMessage());
        } finally{
            IOUtils.closeQuietly(fos);
        }


    }
}
```

--------------------------------

### Append PDF to PostScript Document

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Demonstrates how to append a PDF document to an existing PostScript document using the SafeAppenderModifier. Ensure both input files ('input.ps' and 'input.pdf') exist in the same directory as the program.

```java
package org.ghost4j.example;

import java.io.File;
import java.io.Serializable;
import java.util.HashMap;
import java.util.Map;

import org.ghost4j.document.Document;
import org.ghost4j.document.PDFDocument;
import org.ghost4j.document.PSDocument;
import org.ghost4j.modifier.SafeAppenderModifier;

/**
 * Example showing how to append a PostScript document to a PDF document.
 * 
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class SafeAppenderModifierExample {

    public static void main(String[] args) {

	try {
	    // load PS document
	    PSDocument psDocument = new PSDocument();
	    psDocument.load(new File("input.ps"));

	    // load PDF document
	    PDFDocument pdfDocument = new PDFDocument();
	    pdfDocument.load(new File("input.pdf"));

	    // prepare modifier
	    SafeAppenderModifier modifier = new SafeAppenderModifier();

	    // prepare modifier parameters
	    Map<String, Serializable> parameters = new HashMap<String, Serializable>();
	    parameters.put(SafeAppenderModifier.PARAMETER_APPEND_DOCUMENT,
		    pdfDocument);

	    // run modifier
	    Document result = modifier.modify(psDocument, parameters);

	    // write resulting document to file
	    result.write(new File("merged.ps"));

	} catch (Exception e) {
	    System.out.println("ERROR: " + e.getMessage());
	}
    }

}
```

--------------------------------

### Count Pages of a PostScript Document

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Counts the number of pages in a PostScript file using PSDocument. Requires the input.ps file to be present.

```java
package org.ghost4j.example;

import java.io.File;

import org.ghost4j.document.PSDocument;

/**
 * Example showing how to count pages of a PostScript.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class PSPageCountExample {

    public static void main(String[] args) {
        try {

            PSDocument psDocument = new PSDocument();
            psDocument.load(new File("input.ps"));
            System.out.println("Page count is : " + psDocument.getPageCount());

        } catch (Exception e) {
            System.out.println("ERROR: " + e.getMessage());
        }
    }
}
```

--------------------------------

### Author Tag in Class Documentation

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/contributing.md

The initial author of each source file must be specified in the class documentation comment using the @author tag.

```java
@author Gilles Grousset (gi.grousset@gmail.com)
```

--------------------------------

### Maven Dependency for Ghost4J

Source: https://github.com/zippy1978/ghost4j/blob/master/README.md

Add this dependency to your Maven project to include the Ghost4J library.

```xml
<dependencies>

	...

	<dependency>
		<groupId>org.ghost4j</groupId>
		<artifactId>ghost4j</artifactId>
		<version>1.0.1</version>
	</dependency>
	
	...
	
</dependencies>
```

--------------------------------

### Destroy Ghostscript Instance

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/encoding.md

Call this method before changing the ghost4j.encoding system property at runtime to ensure the change is applied. This is crucial when working with multiple JVMs or when reconfiguring encoding.

```java
Ghostscript.deleteInstance();
```

--------------------------------

### Setting Max Process Count for PDFConverter

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/threadsafetyandmultithreading.md

Configures a PDFConverter component to enable multi-threading by setting the maximum number of concurrent 'slave' JVMs. A value of 0 disables multi-threading.

```java
//create converter
PDFConverter converter = new PDFConverter();

//set multi-threading
converter.setMaxProcessCount(2);
```

--------------------------------

### List Fonts in a PDF Document

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/highlevelapisamples.md

Analyzes a PDF document to list all embedded fonts using FontAnalyzer. The input.pdf file must exist. The output is a list of AnalysisItem objects.

```java
package org.ghost4j.example;

import java.io.File;
import java.util.List;

import org.ghost4j.analyzer.AnalysisItem;
import org.ghost4j.analyzer.FontAnalyzer;
import org.ghost4j.document.PDFDocument;


/**
 * Example showing how to list fonts of a PDF document using the high level API.
 * @author Gilles Grousset (gi.grousset@gmail.com)
 */
public class FontAnalyzerExample {

	public static void main(String[] args) {

		try {

			// load PDF document
			PDFDocument document = new PDFDocument();
			document.load(new File("input.pdf"));

			// create analyzer
			FontAnalyzer analyzer = new FontAnalyzer();

			// analyze
			List<AnalysisItem> fonts = analyzer.analyze(document);

			// print result
			for (AnalysisItem analysisItem : fonts) {
				System.out.println(analysisItem);

			}

		} catch (Exception e) {
			System.out.println("ERROR: " + e.getMessage());
		}

	}
}
```

--------------------------------

### Synchronized Ghostscript Instance Access

Source: https://github.com/zippy1978/ghost4j/blob/master/src/site/markdown/threadsafetyandmultithreading.md

Ensures thread safety when calling Ghostscript interpreter operations by synchronizing access to the shared Ghostscript instance. Always use this pattern for thread-safe operations.

```java
Ghostscript gs = Ghostscript.getInstance();
  
try {

synchronized(gs){
    
    //call interpreter operations here
																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																																													. 1. The Ghostscript API can only have one interpreter instance in the same native process. This means that when writing a program using the API, operations called on the interpreter instance must be synchronous. To make sure a Ghostscript process is thread safe when using Ghost4J, always call it like this:

```
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