Provided by: wml_2.0.12ds1-9build1_amd64 
NAME
GD.pm - Interface to Gd Graphics Library
SYNOPSIS
use GD;
# create a new image
$im = new GD::Image(100,100);
# allocate some colors
$white = $im->colorAllocate(255,255,255);
$black = $im->colorAllocate(0,0,0);
$red = $im->colorAllocate(255,0,0);
$blue = $im->colorAllocate(0,0,255);
# make the background transparent and interlaced
$im->transparent($white);
$im->interlaced('true');
# Put a black frame around the picture
$im->rectangle(0,0,99,99,$black);
# Draw a blue oval
$im->arc(50,50,95,75,0,360,$blue);
# And fill it with red
$im->fill(50,50,$red);
# make sure we are writing to a binary stream
binmode STDOUT;
# Convert the image to PNG and print it on standard output
print $im->png;
DESCRIPTION
GD.pm is a port of Thomas Boutell's gd graphics library (see below). GD allows you to
create color drawings using a large number of graphics primitives, and emit the drawings
as PNG files.
GD defines the following three classes:
"GD::Image"
An image class, which holds the image data and accepts graphic primitive method
calls.
"GD::Font"
A font class, which holds static font information and used for text rendering.
"GD::Polygon"
A simple polygon object, used for storing lists of vertices prior to rendering a
polygon into an image.
A Simple Example:
#!/usr/local/bin/perl
use GD;
# create a new image
$im = new GD::Image(100,100);
# allocate some colors
$white = $im->colorAllocate(255,255,255);
$black = $im->colorAllocate(0,0,0);
$red = $im->colorAllocate(255,0,0);
$blue = $im->colorAllocate(0,0,255);
# make the background transparent and interlaced
$im->transparent($white);
$im->interlaced('true');
# Put a black frame around the picture
$im->rectangle(0,0,99,99,$black);
# Draw a blue oval
$im->arc(50,50,95,75,0,360,$blue);
# And fill it with red
$im->fill(50,50,$red);
# make sure we are writing to a binary stream
binmode STDOUT;
# Convert the image to PNG and print it on standard output
print $im->png;
Notes:
1. To create a new, empty image, send a new() message to GD::Image, passing it the width
and height of the image you want to create. An image object will be returned. Other
class methods allow you to initialize an image from a preexisting PNG, GD or XBM file.
2. Next you will ordinarily add colors to the image's color table. colors are added using
a colorAllocate() method call. The three parameters in each call are the red, green and
blue (rgb) triples for the desired color. The method returns the index of that color in
the image's color table. You should store these indexes for later use.
3. Now you can do some drawing! The various graphics primitives are described below. In
this example, we do some text drawing, create an oval, and create and draw a polygon.
4. Polygons are created with a new() message to GD::Polygon. You can add points to the
returned polygon one at a time using the addPt() method. The polygon can then be passed to
an image for rendering.
5. When you're done drawing, you can convert the image into PNG format by sending it a
png() message. It will return a (potentially large) scalar value containing the binary
data for the image. Ordinarily you will print it out at this point or write it to a file.
To ensure portability to platforms that differentiate between text and binary files, be
sure to call "binmode()" on the file you are writing the image to.
Method Calls
Creating and Saving Images
"new"
"GD::Image->new(width,height)" class method
To create a new, blank image, send a new() message to the GD::Image class. For
example:
$myImage = new GD::Image(100,100) || die;
This will create an image that is 100 x 100 pixels wide. If you don't specify the
dimensions, a default of 64 x 64 will be chosen. If something goes wrong (e.g.
insufficient memory), this call will return undef.
"newFromPng"
"GD::Image->newFromPng(FILEHANDLE)" class method
This will create an image from a PNG file read in through the provided filehandle.
The filehandle must previously have been opened on a valid PNG file or pipe. If
successful, this call will return an initialized image which you can then manipulate
as you please. If it fails, which usually happens if the thing at the other end of
the filehandle is not a valid PNG file, the call returns undef. Notice that the call
doesn't automatically close the filehandle for you. But it does call
"binmode(FILEHANDLE)" for you, on platforms where this matters.
To get information about the size and color usage of the information, you can call
the image query methods described below.
Example usage:
open (PNG,"barnswallow.png") || die;
$myImage = newFromPng GD::Image(PNG) || die;
close PNG;
"newFromXbm"
"GD::Image->newFromXbm(FILEHANDLE)" class method
This works in exactly the same way as "newFromPng", but reads the contents of an X
Bitmap (black & white) file:
open (XBM,"coredump.xbm") || die;
$myImage = newFromXbm GD::Image(XBM) || die;
close XBM;
Note that this function also calls "binmode(FILEHANDLE)" before reading from the
filehandle.
"newFromXpm"
"GD::Image->newFromXpm($filename)" class method
This creates a new GD::Image object starting from a filename. This is unlike the
other newFrom() functions because it does not take a filehandle. This difference
comes from an inconsistency in the underlying gd library.
$myImage = newFromXpm GD::Image('earth.xpm') || die;
This function is only available if libgd was compiled with XPM support.
NOTE: As of version 1.7.3 of the libgd library, I can't get the underlying
createFromXpm() function to return a valid image -- I just get black.
"newFromGd2"
"GD::Image->newFromGd2(FILEHANDLE)" class method
This works in exactly the same way as "newFromgd()", but uses the new compressed GD2
image format.
"newFromGd"
"GD::Image->newFromGd(FILEHANDLE)" class method
This works in exactly the same way as "newFromPng", but reads the contents of a GD
file. GD is Tom Boutell's disk-based storage format, intended for the rare case when
you need to read and write the image to disk quickly. It's not intended for regular
use, because, unlike PNG or JPEG, no image compression is performed and these files
can become BIG.
open (GDF,"godzilla.gd") || die;
$myImage = newFromGd GD::Image(GDF) || die;
close GDF;
Note that this function also calls "binmode(FILEHANDLE)" before reading from the
supplied filehandle.
"newFromGd2"
"GD::Image->newFromGd2(FILEHANDLE)" class method
This works in exactly the same way as "newFromgd()", but uses the new compressed GD2
image format.
"newFromGd2Part"
"GD::Image->newFromGd2Part(FILEHANDLE,srcX,srcY,width,height)" class method
This class method allows you to read in just a portion of a GD version 2 image file.
In additionto a filehandle, it accepts the top-left corner and dimensions
(width,height) of the region of the image to read. For example:
open (GDF,"godzilla.gd2") || die;
$myImage = GD::Image->newFromGd2Part(GDF,10,20,100,100) || die;
close GDF;
This reads a 100x100 square portion of the image starting from position (10,20).
"png"
"$image->png" object method
This returns the image data in PNG format. You can then print it, pipe it to a
display program, or write it to a file. Example:
$png_data = $myImage->png;
open (DISPLAY,"| display -") || die;
binmode DISPLAY;
print DISPLAY $png_data;
close DISPLAY;
Note the use of "binmode()". This is crucial for portability to DOSish platforms.
"gd" "$image->gd" object method
This returns the image data in GD format. You can then print it, pipe it to a
display program, or write it to a file. Example:
binmode MYOUTFILE;
print MYOUTFILE $myImage->gd;
"gd2"
"$image->gd2" object method
Same as gd(), except that it returns the data in compressed GD2 format.
Color Control
"colorAllocate"
"$image->colorAllocate(red,green,blue)" object method
This allocates a color with the specified red, green and blue components and returns
its index in the color table, if specified. The first color allocated in this way
becomes the image's background color. (255,255,255) is white (all pixels on).
(0,0,0) is black (all pixels off). (255,0,0) is fully saturated red. (127,127,127)
is 50% gray. You can find plenty of examples in /usr/X11/lib/X11/rgb.txt.
If no colors are allocated, then this function returns -1.
Example:
$white = $myImage->colorAllocate(0,0,0); #background color
$black = $myImage->colorAllocate(255,255,255);
$peachpuff = $myImage->colorAllocate(255,218,185);
"colorDeallocate"
"$image->colorDeallocate(colorIndex)" object method
This marks the color at the specified index as being ripe for reallocation. The next
time colorAllocate is used, this entry will be replaced. You can call this method
several times to deallocate multiple colors. There's no function result from this
call.
Example:
$myImage->colorDeallocate($peachpuff);
$peachy = $myImage->colorAllocate(255,210,185);
"colorClosest"
"$image->colorClosest(red,green,blue)" object method
This returns the index of the color closest in the color table to the red green and
blue components specified. If no colors have yet been allocated, then this call
returns -1.
Example:
$apricot = $myImage->colorClosest(255,200,180);
"colorExact"
"$image->colorExact(red,green,blue)" object method
This returns the index of a color that exactly matches the specified red green and
blue components. If such a color is not in the color table, this call returns -1.
$rosey = $myImage->colorExact(255,100,80);
warn "Everything's coming up roses.\n" if $rosey >= 0;
"colorResolve"
"$image->colorResolve(red,green,blue)" object method
This returns the index of a color that exactly matches the specified red green and
blue components. If such a color is not in the color table and there is room, then
this method allocates the color in the color table and returns its index.
$rosey = $myImage->colorResolve(255,100,80);
warn "Everything's coming up roses.\n" if $rosey >= 0;
"colorsTotal"
"$image->colorsTotal)" object method
This returns the total number of colors allocated in the object.
$maxColors = $myImage->colorsTotal;
"getPixel"
"$image->getPixel(x,y)" object method
This returns the color table index underneath the specified point. It can be
combined with rgb() to obtain the rgb color underneath the pixel.
Example:
$index = $myImage->getPixel(20,100);
($r,$g,$b) = $myImage->rgb($index);
"rgb"
"$image->rgb(colorIndex)" object method
This returns a list containing the red, green and blue components of the specified
color index.
Example:
@RGB = $myImage->rgb($peachy);
"transparent"
"$image->transparent(colorIndex)" object method
This marks the color at the specified index as being transparent. Portions of the
image drawn in this color will be invisible. This is useful for creating
paintbrushes of odd shapes, as well as for making PNG backgrounds transparent for
displaying on the Web. Only one color can be transparent at any time. To disable
transparency, specify -1 for the index.
If you call this method without any parameters, it will return the current index of
the transparent color, or -1 if none.
Example:
open(PNG,"test.png");
$im = newFromPng GD::Image(PNG);
$white = $im->colorClosest(255,255,255); # find white
$im->transparent($white);
binmode STDOUT;
print $im->png;
Special Colors
GD implements a number of special colors that can be used to achieve special effects.
They are constants defined in the GD:: namespace, but automatically exported into your
namespace when the GD module is loaded.
"setBrush"
"gdBrushed"
"$image->setBrush( )" and "GD::gdBrushed"
You can draw lines and shapes using a brush pattern. Brushes are just images that
you can create and manipulate in the usual way. When you draw with them, their
contents are used for the color and shape of the lines.
To make a brushed line, you must create or load the brush first, then assign it to
the image using "setBrush". You can then draw in that with that brush using the
"gdBrushed" special color. It's often useful to set the background of the brush to
transparent so that the non-colored parts don't overwrite other parts of your image.
Example:
# Create a brush at an angle
$diagonal_brush = new GD::Image(5,5);
$white = $diagonal_brush->allocateColor(255,255,255);
$black = $diagonal_brush->allocateColor(0,0,0);
$diagonal_brush->transparent($white);
$diagonal_brush->line(0,4,4,0,$black); # NE diagonal
# Set the brush
$myImage->setBrush($diagonal_brush);
# Draw a circle using the brush
$myImage->arc(50,50,25,25,0,360,gdBrushed);
"setStyle"
"gdStyled"
"$image->setStyle(@colors)" and "GD::gdStyled"
Styled lines consist of an arbitrary series of repeated colors and are useful for
generating dotted and dashed lines. To create a styled line, use "setStyle" to
specify a repeating series of colors. It accepts an array consisting of one or more
color indexes. Then draw using the "gdStyled" special color. Another special color,
"gdTransparent" can be used to introduce holes in the line, as the example shows.
Example:
# Set a style consisting of 4 pixels of yellow,
# 4 pixels of blue, and a 2 pixel gap
$myImage->setStyle($yellow,$yellow,$yellow,$yellow,
$blue,$blue,$blue,$blue,
gdTransparent,gdTransparent);
$myImage->arc(50,50,25,25,0,360,gdStyled);
To combine the "gdStyled" and "gdBrushed" behaviors, you can specify
"gdStyledBrushed". In this case, a pixel from the current brush pattern is rendered
wherever the color specified in setStyle() is neither gdTransparent nor 0.
"gdTiled"
Draw filled shapes and flood fills using a pattern. The pattern is just another
image. The image will be tiled multiple times in order to fill the required space,
creating wallpaper effects. You must call "setTile" in order to define the
particular tile pattern you'll use for drawing when you specify the gdTiled color.
details.
"gdStyled"
The gdStyled color is used for creating dashed and dotted lines. A styled line can
contain any series of colors and is created using the "setStyled" command.
Drawing Commands
"setPixel"
"$image->setPixel(x,y,color)" object method
This sets the pixel at (x,y) to the specified color index. No value is returned from
this method. The coordinate system starts at the upper left at (0,0) and gets larger
as you go down and to the right. You can use a real color, or one of the special
colors gdBrushed, gdStyled and gdStyledBrushed can be specified.
Example:
# This assumes $peach already allocated
$myImage->setPixel(50,50,$peach);
"line"
"$image->line(x1,y1,x2,y2,color)" object method
This draws a line from (x1,y1) to (x2,y2) of the specified color. You can use a real
color, or one of the special colors gdBrushed, gdStyled and gdStyledBrushed.
Example:
# Draw a diagonal line using the currently defind
# paintbrush pattern.
$myImage->line(0,0,150,150,gdBrushed);
"dashedLine"
"$image->dashedLine(x1,y1,x2,y2,color)" object method
This draws a dashed line from (x1,y1) to (x2,y2) in the specified color. A more
powerful way to generate arbitrary dashed and dotted lines is to use the setStyle()
method described below and to draw with the special color gdStyled.
Example:
$myImage->dashedLine(0,0,150,150,$blue);
"rectangle"
"GD::Image::rectangle(x1,y1,x2,y2,color)" object method
This draws a rectangle with the specified color. (x1,y1) and (x2,y2) are the upper
left and lower right corners respectively. Both real color indexes and the special
colors gdBrushed, gdStyled and gdStyledBrushed are accepted.
Example:
$myImage->rectangle(10,10,100,100,$rose);
"filledRectangle"
"$image->filledRectangle(x1,y1,x2,y2,color)" object method
This draws a rectangle filed with the specified color. You can use a real color, or
the special fill color gdTiled to fill the polygon with a pattern.
Example:
# read in a fill pattern and set it
open(PNG,"happyface.png") || die;
$tile = newFromPng GD::Image(PNG);
$myImage->setTile($tile);
# draw the rectangle, filling it with the pattern
$myImage->filledRectangle(10,10,150,200,gdTiled);
"polygon"
"$image->polygon(polygon,color)" object method
This draws a polygon with the specified color. The polygon must be created first
(see below). The polygon must have at least three vertices. If the last vertex
doesn't close the polygon, the method will close it for you. Both real color indexes
and the special colors gdBrushed, gdStyled and gdStyledBrushed can be specified.
Example:
$poly = new GD::Polygon;
$poly->addPt(50,0);
$poly->addPt(99,99);
$poly->addPt(0,99);
$myImage->polygon($poly,$blue);
"filledPolygon"
"$image->filledPolygon(poly,color)" object method
This draws a polygon filled with the specified color. You can use a real color, or
the special fill color gdTiled to fill the polygon with a pattern.
Example:
# make a polygon
$poly = new GD::Polygon;
$poly->addPt(50,0);
$poly->addPt(99,99);
$poly->addPt(0,99);
# draw the polygon, filling it with a color
$myImage->filledPolygon($poly,$peachpuff);
"arc"
"$image->arc(cx,cy,width,height,start,end,color)" object method
This draws arcs and ellipses. (cx,cy) are the center of the arc, and (width,height)
specify the width and height, respectively. The portion of the ellipse covered by
the arc are controlled by start and end, both of which are given in degrees from 0 to
360. Zero is at the top of the ellipse, and angles increase clockwise. To specify a
complete ellipse, use 0 and 360 as the starting and ending angles. To draw a circle,
use the same value for width and height.
You can specify a normal color or one of the special colors gdBrushed, gdStyled, or
gdStyledBrushed.
Example:
# draw a semicircle centered at 100,100
$myImage->arc(100,100,50,50,0,180,$blue);
"fill"
"$image->fill(x,y,color)" object method
This method flood-fills regions with the specified color. The color will spread
through the image, starting at point (x,y), until it is stopped by a pixel of a
different color from the starting pixel (this is similar to the "paintbucket" in many
popular drawing toys). You can specify a normal color, or the special color gdTiled,
to flood-fill with patterns.
Example:
# Draw a rectangle, and then make its interior blue
$myImage->rectangle(10,10,100,100,$black);
$myImage->fill(50,50,$blue);
"$image->fillToBorder(x,y,bordercolor,color)" object method
Like "fill", this method flood-fills regions with the specified color, starting at
position (x,y). However, instead of stopping when it hits a pixel of a different
color than the starting pixel, flooding will only stop when it hits the color
specified by bordercolor. You must specify a normal indexed color for the
bordercolor. However, you are free to use the gdTiled color for the fill.
Example:
# This has the same effect as the previous example
$myImage->rectangle(10,10,100,100,$black);
$myImage->fillToBorder(50,50,$black,$blue);
Image Copying Commands
Two methods are provided for copying a rectangular region from one image to another. One
method copies a region without resizing it. The other allows you to stretch the region
during the copy operation.
With either of these methods it is important to know that the routines will attempt to
flesh out the destination image's color table to match the colors that are being copied
from the source. If the destination's color table is already full, then the routines will
attempt to find the best match, with varying results.
"copy"
"$image->copy(sourceImage,dstX,dstY,srcX,srcY,width,height)" object method
This is the simplest of the several copy operations, copying the specified region
from the source image to the destination image (the one performing the method call).
(srcX,srcY) specify the upper left corner of a rectangle in the source image, and
(width,height) give the width and height of the region to copy. (dstX,dstY) control
where in the destination image to stamp the copy. You can use the same image for
both the source and the destination, but the source and destination regions must not
overlap or strange things will happen.
Example:
$myImage = new GD::Image(100,100);
... various drawing stuff ...
$srcImage = new GD::Image(50,50);
... more drawing stuff ...
# copy a 25x25 pixel region from $srcImage to
# the rectangle starting at (10,10) in $myImage
$myImage->copy($srcImage,10,10,0,0,25,25);
"clone"
"$image->clone()" object method
Make a copy of the image and return it as a new object. The new image will look
identical. However, it may differ in the size of the color palette and other
nonessential details.
Example:
$myImage = new GD::Image(100,100);
... various drawing stuff ...
$copy = $myImage->clone;
"$image->copyMerge(sourceImage,dstX,dstY,srcX,srcY,width,height,percent)" object
method
This copies the indicated rectangle from the source image to the destination image,
merging the colors to the extent specified by percent (an integer between 0 and 100).
Specifying 100% has the same effect as copy() -- replacing the destination pixels
with the source image. This is most useful for highlighting an area by merging in a
solid rectangle.
Example:
$myImage = new GD::Image(100,100);
... various drawing stuff ...
$redImage = new GD::Image(50,50);
... more drawing stuff ...
# copy a 25x25 pixel region from $srcImage to
# the rectangle starting at (10,10) in $myImage, merging 50%
$myImage->copyMerge($srcImage,10,10,0,0,25,25,50);
"$image->copyMergeGray(sourceImage,dstX,dstY,srcX,srcY,width,height,percent)" object
method
This is identical to copyMerge() except that it preserves the hue of the source by
converting all the pixels of the destination rectangle to grayscale before merging.
"copyResized"
"$image->copyResized(sourceImage,dstX,dstY,srcX,srcY,destW,destH,srcW,srcH)" object
method
This method is similar to copy() but allows you to choose different sizes for the
source and destination rectangles. The source and destination rectangle's are
specified independently by (srcW,srcH) and (destW,destH) respectively. copyResized()
will stretch or shrink the image to accommodate the size requirements.
Example:
$myImage = new GD::Image(100,100);
... various drawing stuff ...
$srcImage = new GD::Image(50,50);
... more drawing stuff ...
# copy a 25x25 pixel region from $srcImage to
# a larger rectangle starting at (10,10) in $myImage
$myImage->copyResized($srcImage,10,10,0,0,50,50,25,25);
Character and String Drawing
Gd allows you to draw characters and strings, either in normal horizontal orientation or
rotated 90 degrees. These routines use a GD::Font object, described in more detail below.
There are four built-in fonts, available in global variables gdGiantFont, gdLargeFont,
gdMediumBoldFont, gdSmallFont and gdTinyFont. Currently there is no way of dynamically
creating your own fonts.
"string"
"$image->string(font,x,y,string,color)" Object Method
This method draws a string startin at position (x,y) in the specified font and color.
Your choices of fonts are gdSmallFont, gdMediumBoldFont, gdTinyFont, gdLargeFont and
gdGiantFont.
Example:
$myImage->string(gdSmallFont,2,10,"Peachy Keen",$peach);
"stringUp"
"$image->stringUp(font,x,y,string,color)" Object Method
Just like the previous call, but draws the text rotated counterclockwise 90 degrees.
"char"
"charUp"
"$image->char(font,x,y,char,color)" Object Method
"$image->charUp(font,x,y,char,color)" Object Method
These methods draw single characters at position (x,y) in the specified font and
color. They're carry-overs from the C interface, where there is a distinction
between characters and strings. Perl is insensible to such subtle distinctions.
"stringTTF"
"@bounds = $image->stringTTF(fgcolor,fontname,ptsize,angle,x,y,string)" Object Method
"@bounds = GD::Image->stringTTF(fgcolor,fontname,ptsize,angle,x,y,string)" Class
Method
This method uses TrueType to draw a scaled, antialiased string using the TrueType
vector font of your choice. It requires that libgd to have been compiled with
TrueType support, and for the appropriate TrueType font to be installed on your
system.
The arguments are as follows:
fgcolor Color index to draw the string in
fontname An absolute or relative path to the TrueType (.ttf) font file
ptsize The desired point size (may be fractional)
angle The rotation angle, in radians
x,y X and Y coordinates to start drawing the string
string The string itself
If successful, the method returns an eight-element list giving the boundaries of the
rendered string:
@bounds[0,1] Lower left corner (x,y)
@bounds[2,3] Lower right corner (x,y)
@bounds[4,5] Upper right corner (x,y)
@bounds[6,7] Upper left corner (x,y)
In case of an error (such as the font not being available, or TTF support not being
available), the method returns an empty list and sets $@ to the error message.
You may also call this method from the GD::Image class name, in which case it doesn't
do any actual drawing, but returns the bounding box using an inexpensive operation.
You can use this to perform layout operations prior to drawing.
Miscellaneous Image Methods
"interlaced"
"$image->interlaced( )" "$image->interlaced(1)" Object method
This method sets or queries the image's interlaced setting. Interlace produces a
cool venetian blinds effect on certain viewers. Provide a true parameter to set the
interlace attribute. Provide undef to disable it. Call the method without
parameters to find out the current setting.
"getBounds"
"$image->getBounds( )" Object method
This method will return a two-member list containing the width and height of the
image. You query but not not change the size of the image once it's created.
"compare"
"$image1->compare($image2)"
Compare two images and return a bitmap describing the differenes found, if any. The
return value must be logically ANDed with one or more constants in order to determine
the differences. The following constants are available:
GD_CMP_IMAGE The two images look different
GD_CMP_NUM_COLORS The two images have different numbers of colors
GD_CMP_COLOR The two images' palettes differ
GD_CMP_SIZE_X The two images differ in the horizontal dimension
GD_CMP_SIZE_Y The two images differ in the vertical dimension
GD_CMP_TRANSPARENT The two images have different transparency
GD_CMP_BACKGROUND The two images have different background colors
GD_CMP_INTERLACE The two images differ in their interlace
The most important of these is GD_CMP_IMAGE, which will tell you whether the two
images will look different, ignoring differences in the order of colors in the color
palette and other invisible changes. The constants are not imported by default, but
must be imported individually or by importing the :cmp tag. Example:
use GD qw(:DEFAULT :cmp);
# get $image1 from somewhere
# get $image2 from somewhere
if ($image1->compare($image2) & GD_CMP_IMAGE) {
warn "images differ!";
}
Polygon Methods
A few primitive polygon creation and manipulation methods are provided. They aren't part
of the Gd library, but I thought they might be handy to have around (they're borrowed from
my qd.pl Quickdraw library).
"new"
"GD::Polygon->new" class method
Create an empty polygon with no vertices.
$poly = new GD::Polygon;
"addPt"
"$poly->addPt(x,y)" object method
Add point (x,y) to the polygon.
$poly->addPt(0,0);
$poly->addPt(0,50);
$poly->addPt(25,25);
$myImage->fillPoly($poly,$blue);
"getPt"
"$poly->getPt(index)" object method
Retrieve the point at the specified vertex.
($x,$y) = $poly->getPt(2);
"setPt"
"$poly->setPt(index,x,y)" object method
Change the value of an already existing vertex. It is an error to set a vertex that
isn't already defined.
$poly->setPt(2,100,100);
"deletePt"
"$poly->deletePt(index)" object method
Delete the specified vertex, returning its value.
($x,$y) = $poly->deletePt(1);
"toPt"
"$poly->toPt(dx,dy)" object method
Draw from current vertex to a new vertex, using relative (dx,dy) coordinates. If
this is the first point, act like addPt().
$poly->addPt(0,0);
$poly->toPt(0,50);
$poly->toPt(25,-25);
$myImage->fillPoly($poly,$blue);
"length"
"$poly->length" object method
Return the number of vertices in the polygon.
$points = $poly->length;
"vertices"
"$poly->vertices" object method
Return a list of all the verticies in the polygon object. Each membver of the list
is a reference to an (x,y) array.
@vertices = $poly->vertices;
foreach $v (@vertices)
print join(",",@$v),"\n";
}
"bounds"
"$poly->bounds" object method
Return the smallest rectangle that completely encloses the polygon. The return value
is an array containing the (left,top,right,bottom) of the rectangle.
($left,$top,$right,$bottom) = $poly->bounds;
"offset"
"$poly->offset(dx,dy)" object method
Offset all the vertices of the polygon by the specified horizontal (dh) and vertical
(dy) amounts. Positive numbers move the polygon down and to the right.
$poly->offset(10,30);
"map"
"$poly->map(srcL,srcT,srcR,srcB,destL,dstT,dstR,dstB)" object method
Map the polygon from a source rectangle to an equivalent position in a destination
rectangle, moving it and resizing it as necessary. See polys.pl for an example of
how this works. Both the source and destination rectangles are given in
(left,top,right,bottom) coordinates. For convenience, you can use the polygon's own
bounding box as the source rectangle.
# Make the polygon really tall
$poly->map($poly->bounds,0,0,50,200);
"scale"
"$poly->scale(sx,sy)" object method
Scale each vertex of the polygon by the X and Y factors indicated by sx and sy. For
example scale(2,2) will make the polygon twice as large. For best results, move the
center of the polygon to position (0,0) before you scale, then move it back to its
previous position.
"transform"
"$poly->transform(sx,rx,sy,ry,tx,ty)" object method
Run each vertex of the polygon through a transformation matrix, where sx and sy are
the X and Y scaling factors, rx and ry are the X and Y rotation factors, and tx and
ty are X and Y offsets. See the Adobe PostScript Reference, page 154 for a full
explanation, or experiment.
Font Utilities
The libgd library (used by the Perl GD library) has built-in support for about half a
dozen fonts, which were converted from public-domain X Windows fonts. For more fonts,
compile libgd with TrueType support and use the stringTTF() call.
If you wish to add more built-in fonts, the directory bdf_scripts contains two contributed
utilities that may help you convert X-Windows BDF-format fonts into the format that libgd
uses internally. However these scripts were written for earlier versions of GD which
included its own mini-gd library. These scripts will have to be adapted for use with
libgd, and the libgd library itself will have to be recompiled and linked! Please do not
contact me for help with these scripts: they are unsupported.
"gdSmallFont"
"GD::Font->Small" constant
This is the basic small font, "borrowed" from a well known public domain 6x12 font.
"gdLargeFont"
"GD::Font->Large" constant
This is the basic large font, "borrowed" from a well known public domain 8x16 font.
"gdMediumBoldFont"
"GD::Font->MediumBold" constant
This is a bold font intermediate in size between the small and large fonts, borrowed
from a public domain 7x13 font;
"gdTinyFont"
"GD::Font->Tiny" constant
This is a tiny, almost unreadable font, 5x8 pixels wide.
"gdGiantFont"
"GD::Font->Giant" constant
This is a 9x15 bold font converted by Jan Pazdziora from a sans serif X11 font.
"nchars"
"$font->nchars" object method
This returns the number of characters in the font.
print "The large font contains ",gdLargeFont->nchars," characters\n";
"offset"
"$font->offset" object method
This returns the ASCII value of the first character in the font
"width"
"height"
"$font->width" "GD::Font::height" object methods
These return the width and height of the font.
($w,$h) = (gdLargeFont->width,gdLargeFont->height);
Obtaining the C-language version of gd
libgd, the C-language version of gd, can be obtained at URL http://www.boutell.com/gd/.
Directions for installing and using it can be found at that site. Please do not contact
me for help with libgd.
Copyright Information
The GD.pm interface is copyright 1995-1999, 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
http://stein.cshl.org/WWW/software/GD