Remove margin from listings in beamer

Question

I am including some code in my beamer document. I would like to get rid of all margins, so I can include as much code as possible. This is the code I am trying:

\documentclass[]{beamer}
\usepackage[spanish]{babel}
\usepackage[utf8]{inputenc} 
\usepackage{listings} 
\usepackage{caption}  
\usepackage{color}
\definecolor{comentaryGreen}{rgb}{0,0.6,0}
\lstset{
         basicstyle=\tiny  ,
         numbers=none,              
         tabsize=1,
         extendedchars=true,         
         breaklines=true,
         language=Java,                              
         keywordstyle=\color{blue},       
         commentstyle=\color{comentaryGreen},
         rulecolor=\color{black},         
         showspaces=false,  
         showtabs=false,   
         showstringspaces=false, 
         xleftmargin=0pt,
         framexleftmargin=0pt,
         framexrightmargin=0pt,
         framexbottommargin=0pt,
 }
 \lstloadlanguages{
         Java
 } 
\usetheme{Antibes}
\usecolortheme{dolphin}

\begin{frame}
    \lstinputlisting[linerange={529-550}]{source/cGaussianBlur.java}
\end{frame}

\end{document}

(the code I used is available in http://imagej.nih.gov/ij/source/ij/plugin/filter/GaussianBlur.java)

This is the result:

How can I get rid of those margins?

Answer 1

As pointed out by dcmst in his (her?) comment, you can follow, for instance, Paul Gaborit's approach to locally increase the text width:

\begin{frame}
  \begin{columns}
    \column{\dimexpr\paperwidth-10pt}
      \lstinputlisting{cGaussianBlur.java}
  \end{columns}
\end{frame}

However, there will still be some whitespace on the left:

Why? Because the lines in your source file are indented, and listings will include that indentation in the output; it will/can not remove it.

Actually, listings does provide a gobble key for removing a specified number of spaces at the beginning of each line of a listing. Besides, Martin Scharrer's lstautogobble package improved upon that by providing a key called autogobble, which automatically measures the number of spaces that need to be gobbled, so that you don't have to specify that number yourself, as mentioned in MaxNoe's answer.

However, those two approaches are only compatible with "embedded" listings, i.e. listings that live within your .tex file, inside an lstlisting environment (or the likes of it). They do not work for external listings, i.e. those living in external files and inserted with the \lstinpulisting macro.

To solve this problem, I wrote, a while back, a little package called lstautodedent. It defines a key called autodedent, which works very similarly to how lstautogobble's autogobble key works. The main difference is that it works for both embedded listings and external listings. Only one caveat: it doesn't play well with tab characters.

I haven't submitted that package on CTAN yet, but you can already grab the .sty file from my GitHub account.

To use it, load lstautodedent in your preamble, set the autodedent key as you would any other Boolean listings key, and (assuming your source code is indented with space characters, not tabs) you won't get any whitespace on the left:

Complete code

\documentclass[]{beamer}

\usepackage{lstautodedent}

% this is only to write a fraction of your source file to 
% an external file and make my answer self-contained
\usepackage{filecontents}
\begin{filecontents*}{cGaussianBlur.java}
    public float[][] makeGaussianKernel(final double sigma, final double accuracy, int maxRadius) {
        int kRadius = (int)Math.ceil(sigma*Math.sqrt(-2*Math.log(accuracy)))+1;
        if (maxRadius < 50) maxRadius = 50;         // too small maxRadius would result in inaccurate sum.
        if (kRadius > maxRadius) kRadius = maxRadius;
        float[][] kernel = new float[2][kRadius];
        for (int i=0; i<kRadius; i++)               // Gaussian function
            kernel[0][i] = (float)(Math.exp(-0.5*i*i/sigma/sigma));
        if (kRadius < maxRadius && kRadius > 3) {   // edge correction
            double sqrtSlope = Double.MAX_VALUE;
            int r = kRadius;
            while (r > kRadius/2) {
                r--;
                double a = Math.sqrt(kernel[0][r])/(kRadius-r);
                if (a < sqrtSlope)
                    sqrtSlope = a;
                else
                    break;
            }
            for (int r1 = r+2; r1 < kRadius; r1++)
                kernel[0][r1] = (float)((kRadius-r1)*(kRadius-r1)*sqrtSlope*sqrtSlope);
        }
\end{filecontents*}


\usepackage{listings} 
\usepackage{color}
\definecolor{comentaryGreen}{rgb}{0,0.6,0}
\lstset{
         basicstyle=\tiny  ,
         numbers=none,              
         tabsize=1,
         extendedchars=true,         
         breaklines=true,
         language=Java,                              
         keywordstyle=\color{blue},       
         commentstyle=\color{comentaryGreen},
         rulecolor=\color{black},         
         showspaces=false,  
         showtabs=false,   
         showstringspaces=false, 
         xleftmargin=0pt,
         framexleftmargin=0pt,
         framexrightmargin=0pt,
         framexbottommargin=0pt,
         autodedent,
 }
 \lstloadlanguages{
         Java
 } 
\usetheme{Antibes}
\usecolortheme{dolphin}

\begin{document}

\begin{frame}
  \begin{columns}
    \column{\dimexpr\paperwidth-10pt}
      \lstinputlisting{cGaussianBlur.java}
  \end{columns}
\end{frame}

\end{document}

Answer 2

Your "problem" is your proper indentation of your code. lstlisting is a verbatim-environment and as such it typesets the tabs of your indentation.

The solution for this problem is delivered by the lstautogobble-package:

\usepackage{listings}
\usepackage{lstautogobble}

\lstset{autogobble,
        ...,
        ...,
    }

It subtracts the right amount of tabs so your LaTeX-code-indentation is not taken into account.