GD::Simple(3pm) User Contributed Perl Documentation GD::Simple(3pm)
NAME
GD::Simple - Simplified interface to GD library
SYNOPSIS
For a nice tutorial on using this module, see Gabor Szabo's article at
http://perlmaven.com/drawing-images-using-gd-simple.
use GD::Simple;
# create a new image
$img = GD::Simple->new(400,250);
# draw a red rectangle with blue borders
$img->bgcolor('red');
$img->fgcolor('blue');
$img->rectangle(10,10,50,50);
# draw an empty rectangle with green borders
$img->bgcolor(undef);
$img->fgcolor('green');
$img->rectangle(30,30,100,100);
# move to (80,80) and draw a green line to (100,190)
$img->moveTo(80,80);
$img->lineTo(100,190);
# draw a solid orange ellipse
$img->moveTo(110,100);
$img->bgcolor('orange');
$img->fgcolor('orange');
$img->ellipse(40,40);
# draw a black filled arc
$img->moveTo(150,150);
$img->fgcolor('black');
$img->arc(50,50,0,100,gdNoFill|gdEdged);
# draw a string at (10,180) using the default
# built-in font
$img->moveTo(10,180);
$img->string('This is very simple');
# draw a string at (280,210) using 20 point
# times italic, angled upward 90 degrees
$img->moveTo(280,210);
$img->font('Times:italic');
$img->fontsize(20);
$img->angle(-90);
$img->string('This is very fancy');
# some turtle graphics
$img->moveTo(300,100);
$img->penSize(3,3);
$img->angle(0);
$img->line(20); # 20 pixels going to the right
$img->turn(30); # set turning angle to 30 degrees
$img->line(20); # 20 pixel line
$img->line(20);
$img->line(20);
$img->turn(-90); # set turning angle to -90 degrees
$img->line(50); # 50 pixel line
# draw a cyan polygon edged in blue
my $poly = GD::Polygon->new;
$poly->addPt(150,100);
$poly->addPt(199,199);
$poly->addPt(100,199);
$img->bgcolor('cyan');
$img->fgcolor('blue');
$img->penSize(1,1);
$img->polygon($poly);
# convert into png data
print $img->png;
DESCRIPTION
GD::Simple is a subclass of the GD library that shortens many of the
long GD method calls by storing information about the pen color, size
and position in the GD object itself. It also adds a small number of
"turtle graphics" style calls for those who prefer to work in polar
coordinates. In addition, the library allows you to use symbolic names
for colors, such as "chartreuse", and will manage the colors for you.
The Pen
GD::Simple maintains a "pen" whose settings are used for line- and
shape-drawing operations. The pen has the following properties:
fgcolor
The pen foreground color is the color of lines and the borders of
filled and unfilled shapes.
bgcolor
The pen background color is the color of the contents of filled
shapes.
pensize
The pen size is the width of the pen. Larger sizes draw thicker
lines.
position
The pen position is its current position on the canvas in (X,Y)
coordinates.
angle
When drawing in turtle mode, the pen angle determines the current
direction of lines of relative length.
turn
When drawing in turtle mode, the turn determines the clockwise or
counterclockwise angle that the pen will turn before drawing the
next line.
font
The font to use when drawing text. Both built-in bitmapped fonts
and TrueType fonts are supported.
fontsize
The size of the font to use when drawing with TrueType fonts.
One sets the position and properties of the pen and then draws. As the
drawing progresses, the position of the pen is updated.
Methods
GD::Simple introduces a number of new methods, a few of which have the
same name as GD::Image methods, and hence change their behavior. In
addition to these new methods, GD::Simple objects support all of the
GD::Image methods. If you make a method call that isn't directly
supported by GD::Simple, it refers the request to the underlying
GD::Image object. Hence one can load a JPEG image into GD::Simple and
declare it to be TrueColor by using this call, which is effectively
inherited from GD::Image:
my $img = GD::Simple->newFromJpeg('./myimage.jpg',1);
The rest of this section describes GD::Simple-specific methods.
$img = GD::Simple->new($x,$y [,$truecolor])
$img = GD::Simple->new($gd)
Create a new GD::Simple object. There are two forms of new(). In
the first form, pass the width and height of the desired canvas,
and optionally a boolean flag to request a truecolor image. In the
second form, pass a previously-created GD::Image object.
GD::Simple->class('GD');
GD::Simple->class('GD::SVG');
Select whether new() should use GD or GD::SVG internally. Call
GD::Simple->class('GD::SVG') before calling new() if you wish to
generate SVG images.
If future GD subclasses are created, this method will subport them.
$img->moveTo($x,$y)
This call changes the position of the pen without drawing. It moves
the pen to position ($x,$y) on the drawing canvas.
$img->move($dx,$dy)
$img->move($dr)
This call changes the position of the pen without drawing. When
called with two arguments it moves the pen $dx pixels to the right
and $dy pixels downward. When called with one argument it moves
the pen $dr pixels along the vector described by the current pen
angle.
$img->lineTo($x,$y)
The lineTo() call simultaneously draws and moves the pen. It draws
a line from the current pen position to the position defined by
($x,$y) using the current pen size and color. After drawing, the
position of the pen is updated to the new position.
$img->line($x1,$y1,$x2,$y2 [,$color])
$img->line($dx,$dy)
$img->line($dr)
The line() call simultaneously draws and moves the pen. When called
with two arguments it draws a line from the current position of the
pen to the position $dx pixels to the right and $dy pixels down.
When called with one argument, it draws a line $dr pixels long
along the angle defined by the current pen angle.
When called with four or five arguments, line() behaves like
GD::Image->line().
$img->clear
This method clears the canvas by painting over it with the current
background color.
$img->rectangle($x1,$y1,$x2,$y2)
This method draws the rectangle defined by corners ($x1,$y1),
($x2,$y2). The rectangle's edges are drawn in the foreground color
and its contents are filled with the background color. To draw a
solid rectangle set bgcolor equal to fgcolor. To draw an unfilled
rectangle (transparent inside), set bgcolor to undef.
$img->ellipse($width,$height)
This method draws the ellipse centered at the current location with
width $width and height $height. The ellipse's border is drawn in
the foreground color and its contents are filled with the
background color. To draw a solid ellipse set bgcolor equal to
fgcolor. To draw an unfilled ellipse (transparent inside), set
bgcolor to undef.
$img->arc([$cx,$cy,] $width,$height,$start,$end [,$style])
This method draws filled and unfilled arcs, at the current
position, with the current fore- and background colors. See GD for
a description of the arguments. To draw a solid arc (such as a pie
wedge) set bgcolor equal to fgcolor. To draw an unfilled arc, set
bgcolor to undef.
$img->polygon($poly)
This method draws filled and unfilled polygon using the current
settings of fgcolor for the polygon border and bgcolor for the
polygon fill color. See GD for a description of creating polygons.
To draw a solid polygon set bgcolor equal to fgcolor. To draw an
unfilled polygon, set bgcolor to undef.
$img->polyline($poly)
This method draws polygons without closing the first and last
vertices (similar to GD::Image->unclosedPolygon()). It uses the
fgcolor to draw the line.
$img->string($string)
This method draws the indicated string starting at the current
position of the pen. The pen is moved to the end of the drawn
string. Depending on the font selected with the font() method,
this will use either a bitmapped GD font or a TrueType font. The
angle of the pen will be consulted when drawing the text. For
TrueType fonts, any angle is accepted. For GD bitmapped fonts, the
angle can be either 0 (draw horizontal) or -90 (draw upwards).
For consistency between the TrueType and GD font behavior, the
string is always drawn so that the current position of the pen
corresponds to the bottom left of the first character of the text.
This is different from the GD behavior, in which the first
character of bitmapped fonts hangs down from the pen point.
This method returns a polygon indicating the bounding box of the
rendered text. If an error occurred (such as invalid font
specification) it returns undef and an error message in $@.
$metrics = $img->fontMetrics
($metrics,$width,$height) =
GD::Simple->fontMetrics($font,$fontsize,$string)
This method returns information about the current font, most
commonly a TrueType font. It can be invoked as an instance method
(on a previously-created GD::Simple object) or as a class method
(on the 'GD::Simple' class).
When called as an instance method, fontMetrics() takes no arguments
and returns a single hash reference containing the metrics that
describe the currently selected font and size. The hash reference
contains the following information:
xheight the base height of the font from the bottom to the top of
a lowercase 'm'
ascent the length of the upper stem of the lowercase 'd'
descent the length of the lower step of the lowercase 'j'
lineheight the distance from the bottom of the 'j' to the top of
the 'd'
leading the distance between two adjacent lines
This description and code was changed with 2.75.
($delta_x,$delta_y)= $img->stringBounds($string)
This method indicates the X and Y offsets (which may be negative)
that will occur when the given string is drawn using the current
font, fontsize and angle. When the string is drawn horizontally, it
gives the width and height of the string's bounding box.
$delta_x = $img->stringWidth($string)
This method indicates the width of the string given the current
font, fontsize and angle. It is the same as
($img->stringBounds($string))[0]
($x,$y) = $img->curPos
Return the current position of the pen. Set the current position
using moveTo().
$font = $img->font([$newfont] [,$newsize])
Get or set the current font. Fonts can be GD::Font objects,
TrueType font file paths, or fontconfig font patterns like
"Times:italic" (see fontconfig). The latter feature requires that
you have the fontconfig library installed and are using libgd
version 2.0.33 or higher.
As a shortcut, you may pass two arguments to set the font and the
fontsize simultaneously. The fontsize is only valid when drawing
with TrueType fonts.
$size = $img->fontsize([$newfontsize])
Get or set the current font size. This is only valid for TrueType
fonts.
$size = $img->penSize([$newpensize])
Get or set the current pen width for use during line drawing
operations.
$angle = $img->angle([$newangle])
Set the current angle for use when calling line() or move() with a
single argument.
Here is an example of using turn() and angle() together to draw an
octagon. The first line drawn is the downward-slanting top right
edge. The last line drawn is the horizontal top of the octagon.
$img->moveTo(200,50);
$img->angle(0);
$img->turn(360/8);
for (1..8) { $img->line(50) }
$angle = $img->turn([$newangle])
Get or set the current angle to turn prior to drawing lines. This
value is only used when calling line() or move() with a single
argument. The turning angle will be applied to each call to line()
or move() just before the actual drawing occurs.
Angles are in degrees. Positive values turn the angle clockwise.
$color = $img->fgcolor([$newcolor])
Get or set the pen's foreground color. The current pen color can
be set by (1) using an (r,g,b) triple; (2) using a previously-
allocated color from the GD palette; or (3) by using a symbolic
color name such as "chartreuse." The list of color names can be
obtained using color_names(). The special color name 'transparent'
will create a completely transparent color.
$color = $img->bgcolor([$newcolor])
Get or set the pen's background color. The current pen color can
be set by (1) using an (r,g,b) triple; (2) using a previously-
allocated color from the GD palette; or (3) by using a symbolic
color name such as "chartreuse." The list of color names can be
obtained using color_names(). The special color name 'transparent'
will create a completely transparent color.
$index = $img->translate_color(@args)
Translates a color into a GD palette or TrueColor index. You may
pass either an (r,g,b) triple or a symbolic color name. If you pass
a previously-allocated index, the method will return it unchanged.
$index = $img->alphaColor(@args,$alpha)
Creates an alpha color. You may pass either an (r,g,b) triple or a
symbolic color name, followed by an integer indicating its opacity.
The opacity value ranges from 0 (fully opaque) to 127 (fully
transparent).
@names = GD::Simple->color_names
$translate_table = GD::Simple->color_names
Called in a list context, color_names() returns the list of
symbolic color names recognized by this module. Called in a scalar
context, the method returns a hash reference in which the keys are
the color names and the values are array references containing
[r,g,b] triples.
$gd = $img->gd
Return the internal GD::Image object. Usually you will not need to
call this since all GD methods are automatically referred to this
object.
($red,$green,$blue) = GD::Simple->HSVtoRGB($hue,$saturation,$value)
Convert a Hue/Saturation/Value (HSV) color into an RGB triple. The
hue, saturation and value are integers from 0 to 255.
($hue,$saturation,$value) = GD::Simple->RGBtoHSV($red,$green,$blue)
Convert a Red/Green/Blue (RGB) value into a Hue/Saturation/Value
(HSV) triple. The hue, saturation and value are integers from 0 to
255.
COLORS
This script will create an image showing all the symbolic colors.
#!/usr/bin/perl
use strict;
use GD::Simple;
my @color_names = GD::Simple->color_names;
my $cols = int(sqrt(@color_names));
my $rows = int(@color_names/$cols)+1;
my $cell_width = 100;
my $cell_height = 50;
my $legend_height = 16;
my $width = $cols * $cell_width;
my $height = $rows * $cell_height;
my $img = GD::Simple->new($width,$height);
$img->font(gdSmallFont);
for (my $c=0; $c<$cols; $c++) {
for (my $r=0; $r<$rows; $r++) {
my $color = $color_names[$c*$rows + $r] or next;
my @topleft = ($c*$cell_width,$r*$cell_height);
my @botright = ($topleft[0]+$cell_width,$topleft[1]+$cell_height-$legend_height);
$img->bgcolor($color);
$img->fgcolor($color);
$img->rectangle(@topleft,@botright);
$img->moveTo($topleft[0]+2,$botright[1]+$legend_height-2);
$img->fgcolor('black');
$img->string($color);
}
}
print $img->png;
AUTHOR
The GD::Simple module is copyright 2004, Lincoln D. Stein. It is
distributed under the same terms as Perl itself. See the "Artistic
License" in the Perl source code distribution for licensing terms.
The latest versions of GD.pm are available at
https://github.com/lstein/Perl-GD
SEE ALSO
GD, GD::Polyline, GD::SVG, Image::Magick
perl v5.36.0 2022-10-19 GD::Simple(3pm)
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