/ 
Image-Base-GD-5
River stage zero No dependents
/ Image::Base::GD

NAME

Image::Base::GD -- draw PNG format images

SYNOPSIS

use Image::Base::GD;
my $image = Image::Base::GD->new (-width => 100,
                                  -height => 100);
$image->rectangle (0,0, 99,99, 'white');
$image->xy (20,20, 'black');
$image->line (50,50, 70,70, '#FF00FF');
$image->line (50,50, 70,70, '#0000AAAA9999');
$image->save ('/some/filename.png');

CLASS HIERARCHY

Image::Base::GD is a subclass of Image::Base,

Image::Base
  Image::Base::GD

DESCRIPTION

Image::Base::GD extends Image::Base to create or update PNG format image files using the GD module and library (version 2 or higher).

Colour names for drawing are taken from the GD::Simple color_table(), plus hex "#RRGGBB" or "#RRRRGGGGBBBB". Special colour "None" means transparent. Colours are allocated when first used. 4-digit "#RRRRGGGGBBBB" forms are truncated to the high 2 digits since GD works in 8-bit components.

FUNCTIONS

$image = Image::Base::GD->new (key=>value,...)

Create and return a new image object. A new image can be started with -width and -height,

$image = Image::Base::GD->new (-width => 200, -height => 100);

Or an existing file can be read,

$image = Image::Base::GD->new (-file => '/some/filename.png');

Or a GD::Image object can be given,

$image = Image::Base::GD->new (-gd => $gdimageobject);
$new_image = $image->new (key=>value,...)

Create and return a copy of $image. The GD within $image is cloned (per $gd->clone). The optional parameters are applied to the new image as per set.

# copy image, new compression level
my $new_image = $image->new (zlib_compression => 9);
$colour = $image->xy ($x, $y)
$image->xy ($x, $y, $colour)

Get or set an individual pixel.

Currently colours returned are in hex "#RRGGBB" form, or "None" for a fully transparent pixel. Partly transparent pixels are returned as a colour.

$image->rectangle ($x1,$y1, $x2,$y2, $colour, $fill)

Draw a rectangle with corners at $x1,$y1 and $x2,$y2. If $fill is true then it's filled, otherwise just the outline.

GD library 2.0.36 has a bug when drawing 1-pixel high $y1 == $y2 unfilled rectangles where it adds 3-pixel high sides to the result. Image::Base::GD has a workaround to avoid that. The intention isn't to second guess GD, but this fix is easy to apply and makes the output consistent with other Image::Base modules.

$image->ellipse ($x1,$y1, $x2,$y2, $colour)

Draw an ellipse within the rectangle bounded by $x1,$y1 and $x2,$y2.

In the current implementation ellipses with odd length sides (when $x2-$x1+1 and $y2-$y1+1 are both odd numbers) are drawn with GD and the rest go to Image::Base since GD doesn't seem to draw even widths very well. This different handling is a bit inconsistent though.

$image->add_colours ($name, $name, ...)

Add colours to the GD palette. Colour names are the same as to the drawing functions.

$image->add_colours ('red', 'green', '#FF00FF');

The drawing functions automatically add a colour if it doesn't already exist so add_colours in not needed, but it can be used to initialize the palette with particular desired colours.

For a truecolor GD add_colours does nothing since in that case each pixel has RGBA component values, rather than an index into a palette.

ATTRIBUTES

-width (integer, read-only)
-height (integer, read-only)

The size of a GD image cannot be changed once created.

-ncolours (integer, read-only)

The number of colours allocated in the palette, or undef on a truecolor GD (which doesn't have a palette).

This count is similar to the -ncolours of Image::Xpm.

-zlib_compression (integer 0-9 or -1)

The amount of data compression to apply when saving. The value is Zlib style 0 for no compression up to 9 for maximum effort. -1 means Zlib's default level.

-gd

The underlying GD::Image object.

BUGS

Putting colour "None" into pixels requires GD "alpha blending" turned off. Image::Base::GD turns off blending for GD objects it creates, but currently if you pass in a -gd then you must set the blending yourself if you're going to use None. Is that the best way? The ideal might be to save and restore while drawing None, but there's no apparent way to read the blending setting out of a GD to later restore. Alternately maybe turn blending off and leave it off on first drawing any None.

SEE ALSO

Image::Base, GD, GD::Simple, Image::Base::PNGwriter, Image::Xpm

HOME PAGE

http://user42.tuxfamily.org/image-base-gd/index.html

LICENSE

Image-Base-GD is Copyright 2010 Kevin Ryde

Image-Base-GD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

Image-Base-GD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.

You should have received a copy of the GNU General Public License along with Image-Base-GD. If not, see <http://www.gnu.org/licenses/>.