- NAME
- SYNOPSIS
- DESCRIPTION
- INTERFACE

- new
- image_type
- image_data

- SEE ALSO
- MAINTAINER
- COPYRIGHT
- VERSION

# NAME

GT::Image::Security - Using the GD module, creates an image with text.

# SYNOPSIS

        use GT::Image::Security;

        my $sec_image  = GT::Image::Security->new(
            fonts_path => "/home/aki/public_html/fonts",
            text       => "Hello World"
        ) or die $GT::Image::Security::error;

        # some versions have gif, others png
        my $img_type = $sec_image->image_type();

        print "Content-type: image/$img_type\n\n";
        print $sec_image->image_data;

# DESCRIPTION

Creates an image with specified text with mild alterations to rendered text and background to reduce machine legibility. Whenever it can, it will attempt to use TrueType fonts as the internal fonts tend to be difficult to read and very limited in the number of transformations possible.

# INTERFACE

## new

Creates a new security image handler with all options populated but does not initialize the image. While most option are set by default or automatically, certain behaviours can be forced quite easily by passing in a new value.

new will return undef if the GD module cannot be loaded. The exact details of the error can be retreived from $GT::Image::Security::error or through the normal GT::Base error function mechanism.

The following is a list of attributes that can be used to customize the output.

text

  Required. The string to be rendered in the image.

fonts_path

  Optional. Required only if TrueType support is desired, it should be the path to the directory that holds .TTF files.

height

  Optional. Typically automatically calculated, setting this will force the image to the specified height. (Output will be clipped if not tall enough)

width

  Optional. Typically automatically calculated, setting this will force the image to the specified width. (Output will be clipped if not wide enough)

image_type

  Optional. Set to png/jpeg/gif if the output format is important. If GD does not support the rendering method for the type of image, image_data will return undef and an error will be set.

exclude_fonts

  Optional. Arrayref of filenames to ignore when scanning fonts for reasons such as illegibility. By default, the settings have been configured to work with the Bitstream Vera selection of fonts.

colour_steps

  Optional. The number of steps between 0..255 in relation to the brightness of a single colour channel. By default, it has been set to 5 as older GD modules only support 256 colours.

invert

  Optional. Typically automatically chosen, it will invert the colour selections so instead of dark colours for the foreground, brighter colours will be chosen instead. Similarly for the background, from bright, dark colours will be chosen instead.

max_x_wobble

  Optional. Maximum number of pixels to randomly offset characters from ideal position along the horizontal axis.

max_y_wobble

  Optional. Maximum number of pixels to randomly offset characters from ideal position along the vertical axis.

max_ang_wobble

  Optional. Only affects TrueType fonts, internal fonts will not use this feature. The maximum amount of random angular rotation for each character in the text.

base_pt

  Optional. Only affects TrueType fonts, internal fonts will not use this feature. This sets the base point size of the font.

max_pt_wobble

  Optional. Only affects TrueType fonts, internal fonts will not use this feature. The maximum amount of random deviation from the base_pt size for each chacter rendered.

max_obfuscates

  Optional. Usually set automatically, this sets the number of times the obfuscate_image action will be called uon the image. The action randomly draws a line or a rectangle on the image to provide chaff for any attempt to use OCR type software to extract the text from the image.

padding

  Optional. The amount of extra pixel space that should be around the text.

display_chars

  Optional. Typically shouldn't be used. However, it may be useful in situations where you would like to reproduce the image. After image_data has been called, squirrel away the value of $obj->{display_chars} and it will contain all the settings to be able to regenerate the image's core parts. Note: it does not store colour information so while the positions and size of the image would be the same, the colours would be different.

## image_type

Returns the type of image the module will attempt to produce. The results can be ``png'', ``gif'', and ``jpeg'', fit for inserting into a mimetype header.

If an error occurs in the testing or no rendering methods could be found, the function will return undef. The details on the error can be retrieved through $obj->error

## image_data

Returns a scalar with binary data which comprise the image. The image type can be preset via the ``image_type'' attribute or accertained by the `image_type()` method.

If an error occurs in the testing or no rendering methods could be found, the function will return undef. The details on the error can be retrieved through $obj->error

# SEE ALSO

GD, http://stein.cshl.org/WWW/software/GD/

# MAINTAINER

Aki Mimoto

# COPYRIGHT

Copyright (c) 2004 Gossamer Threads Inc. All Rights Reserved. http://www.gossamer-threads.com

# VERSION

Revision: $Id: Security.pm,v 1.3 2006/11/03 18:55:35 brewt Exp $