LaTeX to PDF | Aspose.TeX for Java

How to convert LaTeX to PDF

Let’s take a closer look at the Java code providing the simplest way to convert LaTeX to PDF format.

1// Create conversion options for Object LaTeX format upon Object TeX engine extension.
2TeXOptions options = TeXOptions.consoleAppOptions(TeXConfig.objectLaTeX());
3// Specify a file system working directory for the output.
4options.setOutputWorkingDirectory(new OutputFileSystemDirectory(Utils.getOutputDirectory()));
5// Initialize the options for saving in PDF format.
6options.setSaveOptions(new PdfSaveOptions());
7// Run LaTeX to PDF conversion.
8new TeXJob(Utils.getInputDirectory() +  "hello-world.ltx", new PdfDevice(), options).run();

So, the first thing we need to do (sometimes not the very first, as we will find out later) is to create an instance of the TeXOptions class. The only static method that does this is consoleAppOptions(), so let’s not bother with the meaning of its name. The method takes an instance of the TeXConfig class, which is exactly suitable for converting a LaTeX file. This configuration instructs the Object TeX engine to load the Object LaTeX format and to be ready to accept the LaTeX file. The object LaTeX format is just the LaTeX format, except that it uses Object TeX specific primitives to set up the page metrics.

The first of the required options is OutputWorkingDirectory which defines the space, or area, where the TeX output will be written. Here are the details about the output directory concept in Aspose.TeX for Java. In this example, we use the OutputFileSystemDirectory class, which allows us to write the output to the specified directory, or folder.

The second option is a SaveOptions class instance which will control the transformation of the object model to the target format. Since we are converting LaTeX to PDF, it’s the PdfSaveOptions class instance.

Then we need to create an instance of the TeXJob class. Wanting to convert a LaTeX file stored in the file system, we use this version of the constructor. We should specify the full path to the file. Otherwise, the engine will look for it in the current directory (which is defined here) and most likely will not find it. Nevertheless, we may omit the extension if our file has the .tex one. The engine will append it automatically. The second argument of the constructor is a Device class instance. Since we are converting LaTeX to PDF, it’s an PdfDevice class instance. As the last argument, we pass the recently prepared conversion options.

All that we have to do now is to run the job.

Regardless of whether the run was successful or not, the first result that we’ll see will be the terminal output. In case of success, it looks something like this:

 1This is ObjectTeX, Version 3.1415926-1.0 (Aspose.TeX 21.8)
 2entering extended mode
 3
 4(<input_directory>\hello-world.ltx
 5LaTeX2e <2011/06/27>
 6(article.cls
 7Document Class: article 2007/10/19 v1.4h Standard LaTeX document class
 8(size10.clo))
 9No file hello-world.aux.
10[1]
11(<output_directory>\hello-world.aux) )
12Output written on hello-world.pdf (1 page).
13Transcript written on hello-world.log.

We will find other products of the engine’s run in the folder that we specified as the output directory. Those will be the transcript (.log) file and, Voila!, the main output PDF file.

An alternative way to write the main output PDF file

There’s another constructor of the PdfDevice class, which lets us get the resulting PDF file in an alternative way.

 1// Create the stream to write the PDF file to.
 2final OutputStream pdfStream = new FileOutputStream(Utils.getOutputDirectory() + "any-name.pdf");
 3try {
 4  // Create conversion options for Object LaTeX format upon Object TeX engine extension.
 5  ...
 6    // Run LaTeX to PDF conversion.
 7    new TeXJob(Utils.getInputDirectory() + "hello-world.ltx", new PdfDevice(pdfStream), options).run();
 8} finally {
 9  if (pdfStream != null)
10    pdfStream.close();
11}

The any-name.pdf file in the specified directory will be our main output PDF file. At the same time, unlike image output, we will not find any PDF files in the output directory defined by the conversion options. Exception: any-name.pdf is located (by its path) in the same file system directory that is assigned to OutputWorkingDirectory option using OutputFileSystemDirectory.

About input options

In case our main input file requires dependencies, for example, packages, that are not included in the basic LaTeX system and supported packages, we MUST set the RequiredInputDirectory option the similar way we set the OutputWorkingDirectory option and put the dependencies in that directory. Dependencies may be arbitrarily organized in subdirectories. In case we have our own files to include along the typesetting process, say external graphics files, we MUST also set the InputWorkingDirectory using the path to the location where those files are collected. We may also place the main input file somewhere inside the input directory and specify the relative path in the run() method (or specify no path at all if the main input file is in the root). Here are the details about the input directory concept in Aspose.TeX for Java and provided implementations.

Other TeX job options are discussed here.

You may also check out the free LaTeX-to-PDF conversion web app built based on Aspose.TeX for .NET API. Here is the Java version page.

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