|
|
| |
GD(3) |
User Contributed Perl Documentation |
GD(3) |
GD.pm - Interface to Gd Graphics Library
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;
GD.pm is a Perl interface to Thomas Boutell's gd graphics library
(version 2.01 or higher; 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 four 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.
- "GD::Simple"
- A "simple" class that simplifies the GD::Image API and then adds
a set of object-oriented drawing methods using turtle graphics, simplified
font handling, ability to work in polar coordinates, HSV color spaces, and
human-readable color names like "lightblue". Please see
GD::Simple for a description of these methods.
A Simple Example:
#!/usr/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 JPG, PNG, GD, GD2 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.
The following class methods allow you to create new GD::Image objects.
- $image =
GD::Image->new([$width,$height],[$truecolor])
- $image = GD::Image->new(*FILEHANDLE)
- $image = GD::Image->new($filename)
- $image = GD::Image->new($data)
- The new() method is the main constructor for the GD::Image class.
Called with two integer arguments, it creates a new blank image of the
specified width and height. 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.
The optional third argument,
$truecolor, tells new() to create a
truecolor GD::Image object. Truecolor images have 24 bits of color data
(eight bits each in the red, green and blue channels respectively),
allowing for precise photograph-quality color usage. If not specified,
the image will use an 8-bit palette for compatibility with older
versions of libgd.
Alternatively, you may create a GD::Image object based on an
existing image by providing an open filehandle, a filename, or the image
data itself. The image formats automatically recognized and accepted
are: PNG, JPEG, XPM and GD2. Other formats, including WBMP, and GD
version 1, cannot be recognized automatically at this time.
If something goes wrong (e.g. insufficient memory), this call
will return undef.
- $image = GD::Image->trueColor([0,1])
- For backwards compatibility with scripts previous versions of GD, new
images created from scratch (width, height) are palette based by default.
To change this default to create true color images use:
GD::Image->trueColor(1);
before creating new images. To switch back to palette based by
default, use:
GD::Image->trueColor(0);
- $image =
GD::Image->newPalette([$width,$height])
- $image =
GD::Image->newTrueColor([$width,$height])
- The newPalette() and newTrueColor() methods can be used to
explicitly create an palette based or true color image regardless of the
current setting of trueColor().
- $image = GD::Image->newFromPng($file,
[$truecolor])
- $image = GD::Image->newFromPngData($data,
[$truecolor])
- The newFromPng() method will create an image from a PNG file read
in through the provided filehandle or file path. 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.
You may use any of the following as the argument:
1) a simple filehandle, such as STDIN
2) a filehandle glob, such as *PNG
3) a reference to a glob, such as \*PNG
4) an IO::Handle object
5) the pathname of a file
In the latter case, newFromPng() will attempt to open
the file for you and read the PNG information from it.
Example1:
open (PNG,"barnswallow.png") || die;
$myImage = newFromPng GD::Image(\*PNG) || die;
close PNG;
Example2:
$myImage = newFromPng GD::Image('barnswallow.png');
To get information about the size and color usage of the
information, you can call the image query methods described below.
Images created by reading PNG images will be truecolor if the image file
itself is truecolor. To force the image to be palette-based, pass a
value of 0 in the optional $truecolor
argument.
The newFromPngData() method will create a new GD::Image
initialized with the PNG format data contained in
$data.
- $image = GD::Image->newFromJpeg($file,
[$truecolor])
- $image = GD::Image->newFromJpegData($data,
[$truecolor])
- These methods will create an image from a JPEG file. They work just like
newFromPng() and newFromPngData(), and will accept the same
filehandle and pathname arguments.
Images created by reading JPEG images will always be
truecolor. To force the image to be palette-based, pass a value of 0 in
the optional $truecolor argument.
- $image = GD::Image->newFromGif($file,
[$truecolor])
- $image = GD::Image->newFromGifData($data)
- These methods will create an image from a GIF file. They work just like
newFromPng() and newFromPngData(), and will accept the same
filehandle and pathname arguments.
Images created from GIFs are always 8-bit palette images. To
convert to truecolor, you must create a truecolor image and then perform
a copy.
- $image = GD::Image->newFromXbm($file,
[$truecolor])
- 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;
There is no newFromXbmData() function, because there is
no corresponding function in the gd library.
- $image = GD::Image->newFromWBMP($file,
[$truecolor])
- This works in exactly the same way as
"newFromPng", but reads the contents of
an Windows BMP Bitmap file:
open (BMP,"coredump.bmp") || die;
$myImage = newFromWBMP GD::Image(\*BMP) || die;
close BMP;
There is no newFromWBMPData() function, because there
is no corresponding function in the gd library.
- $image = GD::Image->newFromGd($file)
- $image = GD::Image->newFromGdData($data)
- These methods initialize a GD::Image from a Gd file, filehandle, or data.
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.
$myImage = newFromGd GD::Image("godzilla.gd") || die;
close GDF;
- $image = GD::Image->newFromGd2($file)
- $image = GD::Image->newFromGd2Data($data)
- This works in exactly the same way as
"newFromGd()" and newFromGdData, but use
the new compressed GD2 image format.
- $image =
GD::Image->newFromGd2Part($file,srcX,srcY,width,height)
- This class method allows you to read in just a portion of a GD2 image
file. In addition to 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).
- $image = GD::Image->newFromXpm($filename)
- 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: The libgd library is unable to read certain XPM files,
returning an all-black image instead.
- $bool = GD::supportsFileType($filename,
$is_writing)
- This returns a TRUE or FALSE value, if libgd supports reading or when the
2nd argument is 1, if libgd supports writing the given filetype, depending
on the filename extension. Only with libgd versions >= gd-2.1.1.
Assuming LibGD is compiled with support for these image types,
the following extensions are supported:
.gif
.gd, .gd2
.wbmp
.bmp
.xbm
.tga
.png
.jpg, .jpeg
.tiff, .tif
.webp
.xpm
Filenames are parsed case-insensitively.
Once a GD::Image object is created, you can draw with it, copy it, and merge two
images. When you are finished manipulating the object, you can convert it into
a standard image file format to output or save to a file.
The following methods convert the internal drawing format into standard output
file formats.
- $pngdata =
$image->png([$compression_level])
- 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.
The optional $compression_level
argument controls the amount of compression to apply to the output PNG
image. Values range from 0-9, where 0 means no compression (largest
files, highest quality) and 9 means maximum compression (smallest files,
worst quality). A compression level of -1 uses the default compression
level selected when zlib was compiled on your system, and is the same as
calling png() with no argument. Be careful not to confuse this
argument with the jpeg() quality argument, which ranges from
0-100 and has the opposite meaning from compression (higher numbers give
higher quality).
- $gifdata =
$image->gifanimbegin([$GlobalCM [,
$Loops]])
- For libgd version 2.0.33 and higher, this call begins an animated GIF by
returning the data that comprises animated gif image file header. After
you call this method, call gifanimadd() one or more times to add
the frames of the image. Then call gifanimend(). Each frame must be
the same width and height.
A typical sequence will look like this:
my $gifdata = $image->gifanimbegin;
$gifdata .= $image->gifanimadd; # first frame
for (1..100) {
# make a frame of right size
my $frame = GD::Image->new($image->getBounds);
add_frame_data($frame); # add the data for this frame
$gifdata .= $frame->gifanimadd; # add frame
}
$gifdata .= $image->gifanimend; # finish the animated GIF
print $gifdata; # write animated gif to STDOUT
If you do not wish to store the data in memory, you can print
it to stdout or a file.
The image that you call gifanimbegin on is used to set the
image size, color resolution and color map. If argument
$GlobalCM is 1, the image color map becomes the
GIF89a global color map. If $Loops is given and
>= 0, the NETSCAPE2.0 application extension is created, with looping
count. Looping count 0 means forever.
- $gifdata = $image->gifanimadd([$LocalCM
[, $LeftOfs [, $TopOfs [, $Delay
[, $Disposal [, $previm]]]]]])
- Returns the data that comprises one animated gif image frame. You can then
print it, pipe it to a display program, or write it to a file. With
$LeftOfs and $TopOfs you
can place this frame in different offset than (0,0) inside the image
screen. Delay between the previous frame and this frame is in 1/100s
units. Disposal is usually and by default 1. Compression is activated by
giving the previous image as a parameter. This function then compares the
images and only writes the changed pixels to the new frame in animation.
The Disposal parameter for optimized animations must be set to 1, also for
the first frame. $LeftOfs and
$TopOfs parameters are ignored for optimized
frames.
- $gifdata =
$image->gifanimend()
- Returns the data for end segment of animated gif file. It always returns
string ';'. This string must be printed to an animated gif file after all
image frames to properly terminate it according to GIF file syntax. Image
object is not used at all in this method.
- $jpegdata =
$image->jpeg([$quality])
- This returns the image data in JPEG format. You can then print it, pipe it
to a display program, or write it to a file. You may pass an optional
quality score to jpeg() in order to control the JPEG quality. This
should be an integer between 0 and 100. Higher quality scores give larger
files and better image quality. If you don't specify the quality,
jpeg() will choose a good default.
- $gifdata =
$image->gif().
- This returns the image data in GIF format. You can then print it, pipe it
to a display program, or write it to a file.
- $gddata = $image->gd
- 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;
- $gd2data = $image->gd2
- Same as gd(), except that it returns the data in compressed GD2
format.
- $wbmpdata =
$image->wbmp([$foreground])
- This returns the image data in WBMP format, which is a black-and-white
image format. Provide the index of the color to become the foreground
color. All other pixels will be considered background.
- $success =
$image->_file($filename)
- Writes an image to a file in the format indicated by the filename, with
libgd versions >= gd-2.1.1.
File type is determined by the extension of the file name. See
"supportsFiletype" for an overview of
the parsing.
For file types that require extra arguments,
"_file" attempts to use sane
defaults:
C<gdImageGd2> chunk size = 0, compression is enabled.
C<gdImageJpeg> quality = -1 (i.e. the reasonable default)
C<gdImageWBMP> foreground is the darkest available color
Everything else is called with the two-argument function and
so will use the default values.
"_file" and the underlying
libgd "gdImageFile" has some
rudimentary error detection and will return FALSE (0) if a detectable
error occurred. However, the image loaders do not normally return their
error status so a result of TRUE (1) does **not** mean the file was
saved successfully.
These methods allow you to control and manipulate the GD::Image color table for
palette, non-truecolor images.
- $index =
$image->colorAllocate(red,green,blue)
- 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:
$black = $myImage->colorAllocate(0,0,0); #background color
$white = $myImage->colorAllocate(255,255,255);
$peachpuff = $myImage->colorAllocate(255,218,185);
- $index =
$image->colorAllocateAlpha(reg,green,blue,alpha)
- This allocates a color with the specified red, green, and blue components,
plus the specified alpha channel. The alpha value may range from 0
(opaque) to 127 (transparent). The
"alphaBlending" function changes the way
this alpha channel affects the resulting image.
- $image->colorDeallocate(colorIndex)
- 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);
- $index =
$image->colorClosest(red,green,blue)
- 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);
- $index =
$image->colorClosestAlpha(red,green,blue,alpha)
- This returns the index of the color closest in the color table to the red
green blue and alpha components specified. If no colors have yet been
allocated, then this call returns -1.
Example:
$apricot = $myImage->colorClosestAlpha(255,200,180,0);
- $index =
$image->colorClosestHWB(red,green,blue)
- This also attempts to return the color closest in the color table to the
red green and blue components specified. It uses a Hue/White/Black color
representation to make the selected color more likely to match human
perceptions of similar colors.
If no colors have yet been allocated, then this call returns
-1.
Example:
$mostred = $myImage->colorClosestHWB(255,0,0);
- $index =
$image->colorExact(red,green,blue)
- 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;
- $index =
$image->colorExactAlpha(red,green,blue,alpha)
- This returns the index of a color that exactly matches the specified red
green blue and alpha components. If such a color is not in the color
table, this call returns -1.
$rosey = $myImage->colorExactAlpha(255,100,80,0);
warn "Everything's coming up roses.\n" if $rosey >= 0;
- $index =
$image->colorResolve(red,green,blue)
- 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;
- $index =
$image->colorResolveAlpha(red,green,blue,alpha)
- This returns the index of a color that exactly matches the specified red
green blue and alpha 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->colorResolveAlpha(255,100,80,0);
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;
In the case of a TrueColor image, this call will return
undef.
- $index = $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);
- ($red,$green,$blue) = $image->rgb($index)
- This returns a list containing the red, green and blue components of the
specified color index.
Example:
@RGB = $myImage->rgb($peachy);
- ($alpha) = $image->alpha($index)
- This returns an item containing the alpha component of the specified color
index.
Example:
@RGB = $myImage->rgb($peachy);
- $image->transparent($colorIndex)
- 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;
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.
- $image->setBrush($image)
- You can draw lines and shapes using a brush pattern. Brushes are just
palette, not TrueColor, 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->colorAllocate(255,255,255);
$black = $diagonal_brush->colorAllocate(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);
- $image->setThickness($thickness)
- Lines drawn with line(), rectangle(), arc(), and so
forth are 1 pixel thick by default. Call setThickness() to change
the line drawing width.
- $image->setStyle(@colors)
- 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.
- gdAntiAliased
- The "gdAntiAliased" color is used for
drawing lines with antialiasing turned on. Antialiasing will blend the
jagged edges of lines with the background, creating a smoother look. The
actual color drawn is set with setAntiAliased().
- $image->setAntiAliased($color)
- "Antialiasing" is a process by which jagged edges associated
with line drawing can be reduced by blending the foreground color with an
appropriate percentage of the background, depending on how much of the
pixel in question is actually within the boundaries of the line being
drawn. All line-drawing methods, such as line() and polygon, will
draw antialiased lines if the special "color"
gdAntiAliased is used when calling them.
setAntiAliased() is used to specify the actual
foreground color to be used when drawing antialiased lines. You may set
any color to be the foreground, however as of libgd version 2.0.12 an
alpha channel component is not supported.
Antialiased lines can be drawn on both truecolor and
palette-based images. However, attempts to draw antialiased lines on
highly complex palette-based backgrounds may not give satisfactory
results, due to the limited number of colors available in the palette.
Antialiased line-drawing on simple backgrounds should work well with
palette-based images; otherwise create or fetch a truecolor image
instead. When using palette-based images, be sure to allocate a broad
spectrum of colors in order to have sufficient colors for the
antialiasing to use.
- $image->setAntiAliasedDontBlend($color,[$flag])
- Normally, when drawing lines with the special gdAntiAliased
"color," blending with the background to reduce jagged edges is
the desired behavior. However, when it is desired that lines not be
blended with one particular color when it is encountered in the
background, the setAntiAliasedDontBlend() method can be used to
indicate the special color that the foreground should stand out more
clearly against.
Once turned on, you can turn this feature off by calling
setAntiAliasedDontBlend() with a second argument of 0:
$image->setAntiAliasedDontBlend($color,0);
These methods allow you to draw lines, rectangles, and ellipses, as well as to
perform various special operations like flood-fill.
- $image->setPixel($x,$y,$color)
- 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);
- $image->line($x1,$y1,$x2,$y2,$color)
- 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 defined
# paintbrush pattern.
$myImage->line(0,0,150,150,gdBrushed);
- $image->dashedLine($x1,$y1,$x2,$y2,$color)
- DEPRECATED: The libgd library provides this method solely for backward
compatibility with libgd version 1.0, and there have been reports that it
no longer works as expected. Please use the setStyle() and gdStyled
methods as described below.
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);
- $image->rectangle($x1,$y1,$x2,$y2,$color)
- 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);
- $image->filledRectangle($x1,$y1,$x2,$y2,$color)
=item $image->setTile($otherimage)
- This draws a rectangle 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:
# read in a fill pattern and set it
$tile = newFromPng GD::Image('happyface.png');
$myImage->setTile($tile);
# draw the rectangle, filling it with the pattern
$myImage->filledRectangle(10,10,150,200,gdTiled);
- $image->openPolygon($polygon,$color)
- 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);
$myImage->openPolygon($poly,$blue);
- $image->unclosedPolygon($polygon,$color)
- This draws a sequence of connected lines with the specified color, without
connecting the first and last point to a closed polygon. The polygon must
be created first (see below). The polygon must have at least three
vertices. Both real color indexes and the special colors gdBrushed,
gdStyled and gdStyledBrushed can be specified.
You need libgd 2.0.33 or higher to use this feature.
Example:
$poly = new GD::Polygon;
$poly->addPt(50,0);
$poly->addPt(99,99);
$poly->addPt(0,99);
$myImage->unclosedPolygon($poly,$blue);
- $image->filledPolygon($poly,$color)
- 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);
- $image->ellipse($cx,$cy,$width,$height,$color)
- $image->filledEllipse($cx,$cy,$width,$height,$color)
- These methods() draw ellipses. ($cx,$cy) is the center of the arc,
and ($width,$height) specify the ellipse width and height, respectively.
filledEllipse() is like Ellipse() except that the former
produces filled versions of the ellipse.
- $image->arc($cx,$cy,$width,$height,$start,$end,$color)
- 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 right end 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);
- $image->filledArc($cx,$cy,$width,$height,$start,$end,$color
[,$arc_style])
- This method is like arc() except that it colors in the pie wedge
with the selected color. $arc_style is optional.
If present it is a bitwise OR of the following constants:
gdArc connect start & end points of arc with a rounded edge
gdChord connect start & end points of arc with a straight line
gdPie synonym for gdChord
gdNoFill outline the arc or chord
gdEdged connect beginning and ending of the arc to the center
gdArc and gdChord are mutually exclusive. gdChord just
connects the starting and ending angles with a straight line, while
gdArc produces a rounded edge. gdPie is a synonym for gdArc. gdNoFill
indicates that the arc or chord should be outlined, not filled. gdEdged,
used together with gdNoFill, indicates that the beginning and ending
angles should be connected to the center; this is a good way to outline
(rather than fill) a "pie slice."
Example:
$image->filledArc(100,100,50,50,0,90,$blue,gdEdged|gdNoFill);
- $image->fill($x,$y,$color)
- 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)
- 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);
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.
- $image->copy($sourceImage,$dstX,$dstY,$srcX,$srcY,$width,$height)
- 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);
- $image->clone()
- 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)
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)
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.
- $image->copyResized($sourceImage,$dstX,$dstY,
- $srcX,$srcY,$destW,$destH,$srcW,$srcH)
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);
- $image->copyResampled($sourceImage,$dstX,$dstY,
- $srcX,$srcY,$destW,$destH,$srcW,$srcH)
This method is similar to copyResized() but provides
"smooth" copying from a large image to a smaller one, using a
weighted average of the pixels of the source area rather than selecting
one representative pixel. This method is identical to
copyResized() when the destination image is a palette image.
- $image->copyRotated($sourceImage,$dstX,$dstY,
- $srcX,$srcY,$width,$height,$angle)
Like copyResized() but the
$angle argument specifies an arbitrary amount to
rotate the image clockwise (in degrees). In addition,
$dstX and $dstY species
the center of the destination image, and not the top left
corner.
- $image->trueColorToPalette([$dither],
[$colors])
- This method converts a truecolor image to a palette image. The code for
this function was originally drawn from the Independent JPEG Group library
code, which is excellent. The code has been modified to preserve as much
alpha channel information as possible in the resulting palette, in
addition to preserving colors as well as possible. This does not work as
well as might be hoped. It is usually best to simply produce a truecolor
output image instead, which guarantees the highest output quality. Both
the dithering (0/1, default=0) and maximum number of colors used
(<=256, default = gdMaxColors) can be specified.
- $image =
$sourceImage->createPaletteFromTrueColor([$dither],
[$colors])
- Creates a new palette image from a truecolor image. Same as above, but
returns a new image.
Don't use these function -- write real truecolor PNGs and
JPEGs. The disk space gain of conversion to palette is not great (for
small images it can be negative) and the quality loss is ugly.
- $error =
$image->colorMatch($otherimage)
- Bring the palette colors in $otherimage to be
closer to truecolor $image. A negative return
value is a failure.
-1 image must be True Color
-2 otherimage must be indexed
-3 the images are meant to be the same dimensions
-4 At least 1 color in otherimage must be allocated
This method is only available with libgd >= 2.1.0
- $image =
$sourceImage->neuQuant($maxcolor=256,$samplefactor=5)
- Creates a new palette image from a truecolor image.
- samplefactor The quantization precision between 1 (highest quality) and 10
(fastest).
- maxcolor The number of desired palette entries.
This is the same as createPaletteFromTrueColor with the
quantization method GD_QUANT_NEUQUANT. This does not support dithering. This
method is only available with libgd >= 2.1.0
Gd provides these simple image transformations, non-interpolated.
- $image =
$sourceImage->copyRotate90()
- $image =
$sourceImage->copyRotate180()
- $image =
$sourceImage->copyRotate270()
- $image =
$sourceImage->copyFlipHorizontal()
- $image =
$sourceImage->copyFlipVertical()
- $image =
$sourceImage->copyTranspose()
- $image =
$sourceImage->copyReverseTranspose()
- These methods can be used to rotate, flip, or transpose an image. The
result of the method is a copy of the image.
- $image->rotate180()
- $image->flipHorizontal()
- $image->flipVertical()
- These methods are similar to the copy* versions, but instead modify the
image in place.
Since libgd 2.1.0 there are better transformation methods, with these
interpolation methods:
GD_BELL - Bell
GD_BESSEL - Bessel
GD_BILINEAR_FIXED - fixed point bilinear
GD_BICUBIC - Bicubic
GD_BICUBIC_FIXED - fixed point bicubic integer
GD_BLACKMAN - Blackman
GD_BOX - Box
GD_BSPLINE - BSpline
GD_CATMULLROM - Catmullrom
GD_GAUSSIAN - Gaussian
GD_GENERALIZED_CUBIC - Generalized cubic
GD_HERMITE - Hermite
GD_HAMMING - Hamming
GD_HANNING - Hannig
GD_MITCHELL - Mitchell
GD_NEAREST_NEIGHBOUR - Nearest neighbour interpolation
GD_POWER - Power
GD_QUADRATIC - Quadratic
GD_SINC - Sinc
GD_TRIANGLE - Triangle
GD_WEIGHTED4 - 4 pixels weighted bilinear interpolation
GD_LINEAR - bilinear interpolation
- $image->interpolationMethod( [$method] )
- Gets or sets the interpolation methods for all subsequent interpolations.
See above for the valid values. Only available since libgd 2.2.0
- $image->copyScaleInterpolated( width, height
)
- Returns a copy, using interpolation.
- $image->copyRotateInterpolated( angle, bgcolor
)
- Returns a copy, using interpolation.
Gd also provides some common image filters, they modify the image in place and
return TRUE if modified or FALSE if not. Most of them need libgd >= 2.1.0,
with older versions those functions are undefined.
- $ok = $image->scatter($sub,
$plus )
- if $sub and $plus are 0,
nothing is changed, TRUE is returned. if $sub
>= $plus, nothing is changed, FALSE is
returned. else random pixels are changed.
- $ok = $image->scatterColor($sub,
$plus, @colors)
- Similar to scatter, but using the given array of colors, i.e. palette
indices.
- $ok = $image->pixelate($blocksize,
$mode)
- if $blocksize <= 0, nothing is changed, FALSE
is returned. if $blocksize == 1, nothing is
changed, TRUE is returned. else the following modes are observed:
GD_PIXELATE_UPPERLEFT
GD_PIXELATE_AVERAGE
- $ok =
$image->negate()
- $ok =
$image->grayscale()
- $ok = $image->brightness($add)
- $add: -255..255
- $ok =
$image->contrast($contrast)
- $contrast: a double value. The contrast adjustment
value. Negative values increase, positive values decrease the contrast.
The larger the absolute value, the stronger the effect.
- $ok =
$image->color($red,$green,$blue,$alpha)
- Change channel values of an image.
$red - The value to add to the red channel of all pixels.
$green - The value to add to the green channel of all pixels.
$blue - The value to add to the blue channel of all pixels.
$alpha - The value to add to the alpha channel of all pixels.
- $ok =
$image->selectiveBlur()
- $ok =
$image->edgeDetectQuick()
- $ok =
$image->gaussianBlur()
- $ok =
$image->emboss()
- $ok =
$image->meanRemoval()
- $ok = $image->smooth($weight)
- $image =
$sourceImage->copyGaussianBlurred($radius,
$sigma )
- $radius: int, the blur radius (*not*
diameter--range is 2*radius + 1) a radius, not a diameter so a radius of 2
(for example) will blur across a region 5 pixels across (2 to the center,
1 for the center itself and another 2 to the other edge).
$sigma: the sigma value or a value
<= 0.0 to use the computed default. represents the
"fatness" of the curve (lower == fatter).
The result is always truecolor.
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 monospaced fonts,
available in the global variables gdGiantFont, gdLargeFont,
gdMediumBoldFont, gdSmallFont and gdTinyFont.
In addition, you can use the load() method to load
GD-formatted bitmap font files at runtime. You can create these bitmap files
from X11 BDF-format files using the bdf2gd.pl script, which should have been
installed with GD (see the bdf_scripts directory if it wasn't). The format
happens to be identical to the old-style MSDOS bitmap ".fnt"
files, so you can use one of those directly if you happen to have one.
For writing proportional scalable fonts, GD offers the
stringFT() method, which allows you to load and render any TrueType
font on your system.
- $image->string($font,$x,$y,$string,$color)
- This method draws a string starting 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);
- $image->stringUp($font,$x,$y,$string,$color)
- Just like the previous call, but draws the text rotated counterclockwise
90 degrees.
- $image->char($font,$x,$y,$char,$color)
- $image->charUp($font,$x,$y,$char,$color)
- 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.
- $font = GD::Font->load($fontfilepath)
- This method dynamically loads a font file, returning a font that you can
use in subsequent calls to drawing methods. For example:
my $courier = GD::Font->load('./courierR12.fnt') or die "Can't load font";
$image->string($courier,2,10,"Peachy Keen",$peach);
Font files must be in GD binary format, as described
above.
- @bounds =
$image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
- @bounds =
GD::Image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string)
- @bounds =
$image->stringFT($fgcolor,$fontname,$ptsize,$angle,$x,$y,$string,\%options)
- 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 A path to the TrueType (.ttf) font file or a font pattern.
ptsize The desired point size (may be fractional)
angle The rotation angle, in radians (positive values rotate counter clockwise)
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
FT support not being available), the method returns an empty list and
sets $@ to the error message.
The fontname argument is the name of the font, which
can be a full pathname to a .ttf file, or if not the paths in
$ENV{GDFONTPATH} will be searched or if empty
the libgd compiled DEFAULT_FONTPATH. The TrueType extensions .ttf, .pfa,
.pfb or .dfont can be omitted.
The string may contain UTF-8 sequences like:
"À"
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.
Using a negative color index will disable antialiasing, as
described in the libgd manual page at
<http://www.boutell.com/gd/manual2.0.9.html#gdImageStringFT>.
An optional 8th argument allows you to pass a hashref of
options to stringFT(). Several hashkeys are recognized:
linespacing, charmap, resolution, and
kerning.
The value of linespacing is supposed to be a multiple
of the character height, so setting linespacing to 2.0 will result in
double-spaced lines of text. However the current version of libgd
(2.0.12) does not do this. Instead the linespacing seems to be double
what is provided in this argument. So use a spacing of 0.5 to get
separation of exactly one line of text. In practice, a spacing of 0.6
seems to give nice results. Another thing to watch out for is that
successive lines of text should be separated by the "\r\n"
characters, not just "\n".
The value of charmap is one of "Unicode",
"Shift_JIS" and "Big5". The interaction between
Perl, Unicode and libgd is not clear to me, and you should experiment a
bit if you want to use this feature.
The value of resolution is the vertical and horizontal
resolution, in DPI, in the format "hdpi,vdpi". If present, the
resolution will be passed to the Freetype rendering engine as a hint to
improve the appearance of the rendered font.
The value of kerning is a flag. Set it to false to turn
off the default kerning of text.
Example:
$gd->stringFT($black,'/c/windows/Fonts/pala.ttf',40,0,20,90,
"hi there\r\nbye now",
{linespacing=>0.6,
charmap => 'Unicode',
});
If GD was compiled with fontconfig support, and the fontconfig
library is available on your system, then you can use a font name
pattern instead of a path. Patterns are described in fontconfig and will
look something like this "Times:italic". For backward
compatibility, this feature is disabled by default. You must enable it
by calling useFontConfig(1) prior to the stringFT()
call.
$image->useFontConfig(1);
For backward compatibility with older versions of the FreeType
library, the alias stringTTF() is also recognized.
- $hasfontconfig =
$image->useFontConfig($flag)
- Call useFontConfig() with a value of 1 in order to enable support
for fontconfig font patterns (see stringFT). Regardless of the value of
$flag, this method will return a true value if the
fontconfig library is present, or false otherwise.
This method can also be called as a class method of
GD::Image;
- $result =
$image->stringFTCircle($cx,$cy,$radius,$textRadius,$fillPortion,$font,$points,$top,$bottom,$fgcolor)
- This draws text in a circle. Currently (libgd 2.0.33) this function does
not work for me, but the interface is provided for completeness. The call
signature is somewhat complex. Here is an excerpt from the libgd manual
page:
Draws the text strings specified by top and bottom on the
image, curved along the edge of a circle of radius radius, with its
center at cx and cy. top is written clockwise along the top; bottom is
written counterclockwise along the bottom. textRadius determines the
"height" of each character; if textRadius is 1/2 of radius,
characters extend halfway from the edge to the center. fillPortion
varies from 0 to 1.0, with useful values from about 0.4 to 0.9, and
determines how much of the 180 degrees of arc assigned to each section
of text is actually occupied by text; 0.9 looks better than 1.0 which is
rather crowded. font is a freetype font; see gdImageStringFT. points is
passed to the freetype engine and has an effect on hinting; although the
size of the text is determined by radius, textRadius, and fillPortion,
you should pass a point size that "hints" appropriately -- if
you know the text will be large, pass a large point size such as 24.0 to
get the best results. fgcolor can be any color, and may have an alpha
component, do blending, etc.
Returns a true value on success.
The alpha channel methods allow you to control the way drawings are processed
according to the alpha channel. When true color is turned on, colors are
encoded as four bytes, in which the last three bytes are the RGB color values,
and the first byte is the alpha channel. Therefore the hexadecimal
representation of a non transparent RGB color will be: C=0x00(rr)(bb)(bb)
When alpha blending is turned on, you can use the first byte of
the color to control the transparency, meaning that a rectangle painted with
color 0x00(rr)(bb)(bb) will be opaque, and another one painted with
0x7f(rr)(gg)(bb) will be transparent. The Alpha value must be >= 0 and
<= 0x7f.
- $image->alphaBlending($integer)
- The alphaBlending() method allows for two different modes of
drawing on truecolor images. In blending mode, which is on by default
(libgd 2.0.2 and above), the alpha channel component of the color supplied
to all drawing functions, such as
"setPixel", determines how much of the
underlying color should be allowed to shine through. As a result, GD
automatically blends the existing color at that point with the drawing
color, and stores the result in the image. The resulting pixel is opaque.
In non-blending mode, the drawing color is copied literally with its alpha
channel information, replacing the destination pixel. Blending mode is not
available when drawing on palette images.
Pass a value of 1 for blending mode, and 0 for non-blending
mode.
- $image->saveAlpha($saveAlpha)
- By default, GD (libgd 2.0.2 and above) does not attempt to save full alpha
channel information (as opposed to single-color transparency) when saving
PNG images. (PNG is currently the only output format supported by gd which
can accommodate alpha channel information.) This saves space in the output
file. If you wish to create an image with alpha channel information for
use with tools that support it, call saveAlpha(1)
to turn on saving of such information, and call
alphaBlending(0) to turn off alpha blending within
the library so that alpha channel information is actually stored in the
image rather than being composited immediately at the time that drawing
functions are invoked.
These are various utility methods that are useful in some circumstances.
- $image->interlaced([$flag])
- 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.
- ($width,$height) =
$image->getBounds()
- This method will return a two-member list containing the width and height
of the image. You query but not change the size of the image once it's
created.
- $width = $image->width
- $height = $image->height
- Return the width and height of the image, respectively.
- $is_truecolor =
$image->isTrueColor()
- This method will return a Boolean representing whether the image is true
color or not.
- $flag =
$image1->compare($image2)
- Compare two images and return a bitmap describing the differences found,
if any. The return value must be logically AND'ed 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
GD_CMP_TRUECOLOR The two images are not both true color
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!";
}
- $image->clip($x1,$y1,$x2,$y2)
- ($x1,$y1,$x2,$y2) = $image->clip
- Set or get the clipping rectangle. When the clipping rectangle is set, all
drawing will be clipped to occur within this rectangle. The clipping
rectangle is initially set to be equal to the boundaries of the whole
image. Change it by calling clip() with the coordinates of the new
clipping rectangle. Calling clip() without any arguments will
return the current clipping rectangle.
- $flag =
$image->boundsSafe($x,$y)
- The boundsSafe() method will return true if the point indicated by
($x,$y) is within the clipping rectangle, or false if it is not. If the
clipping rectangle has not been set, then it will return true if the point
lies within the image boundaries.
GD does not support grouping of objects, but GD::SVG does. In that subclass, the
following methods declare new groups of graphical objects:
- $image->startGroup([$id,\%style])
- $image->endGroup()
- $group = $image->newGroup
- See GD::SVG for information.
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). Also see
GD::Polyline.
- $poly = GD::Polygon->new
- Create an empty polygon with no vertices.
$poly = new GD::Polygon;
- $poly->addPt($x,$y)
- Add point (x,y) to the polygon.
$poly->addPt(0,0);
$poly->addPt(0,50);
$poly->addPt(25,25);
$myImage->fillPoly($poly,$blue);
- ($x,$y) = $poly->getPt($index)
- Retrieve the point at the specified vertex.
($x,$y) = $poly->getPt(2);
- $poly->setPt($index,$x,$y)
- Change the value of an already existing vertex. It is an error to set a
vertex that isn't already defined.
$poly->setPt(2,100,100);
- ($x,$y) = $poly->deletePt($index)
- Delete the specified vertex, returning its value.
($x,$y) = $poly->deletePt(1);
- $poly->clear()
- Delete all vertices, restoring the polygon to its initial empty
state.
- $poly->toPt($dx,$dy)
- 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);
- $vertex_count = $poly->length
- Return the number of vertices in the polygon.
$points = $poly->length;
- @vertices = $poly->vertices
- Return a list of all the vertices in the polygon object. Each member of
the list is a reference to an (x,y) array.
@vertices = $poly->vertices;
foreach $v (@vertices)
print join(",",@$v),"\n";
}
- @rect = $poly->bounds
- Return the smallest rectangle that completely encloses the polygon. The
return value is an array containing the (left,top,right,bottom) of the
rectangle.
($left,$top,$right,$bottom) = $poly->bounds;
- $poly->offset($dx,$dy)
- 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);
- $poly->map($srcL,$srcT,$srcR,$srcB,$destL,$dstT,$dstR,$dstB)
- 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);
- $poly->scale($sx,$sy)
- 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.
- $poly->transform($sx,$rx,$sy,$ry,$tx,$ty)
- 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.
Please see GD::Polyline for information on creating open polygons and splines.
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
stringFT() 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.
Each of these fonts is available both as an imported global (e.g.
gdSmallFont) and as a package method (e.g.
GD::Font->Small).
- gdSmallFont
- GD::Font->Small
- This is the basic small font, "borrowed" from a well known
public domain 6x12 font.
- gdLargeFont
- GD::Font->Large
- This is the basic large font, "borrowed" from a well known
public domain 8x16 font.
- gdMediumBoldFont
- GD::Font->MediumBold
- 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
- This is a tiny, almost unreadable font, 5x8 pixels wide.
- gdGiantFont
- GD::Font->Giant
- This is a 9x15 bold font converted by Jan Pazdziora from a sans serif X11
font.
- $font->nchars
- This returns the number of characters in the font.
print "The large font contains ",gdLargeFont->nchars," characters\n";
- $font->offset
- This returns the ASCII value of the first character in the font
- $width = $font->width
- $height = $font->height
- "height"
- These return the width and height of the font.
($w,$h) = (gdLargeFont->width,gdLargeFont->height);
- GD::LIBGD_VERSION
- Returns a number of the libgd VERSION, like 2.0204, 2.0033 or 2.01.
- GD::VERSION_STRING
- Returns the string of the libgd VERSION, like "2.2.4".
- GD::constant
libgd, the C-language version of gd, can be obtained at URL http://libgd.org/
Directions for installing and using it can be found at that site. Please do
not contact me for help with libgd.
The GD.pm interface is copyright 1995-2010, Lincoln D. Stein. This package and
its accompanying libraries is free software; you can redistribute it and/or
modify it under the terms of the GPL (either version 1, or at your option, any
later version) or the Artistic License 2.0. Refer to LICENSE for the full
license text. package for details.
The latest versions of GD.pm are available at
https://github.com/lstein/Perl-GD
GD::Polyline, GD::SVG, GD::Simple, Image::Magick
Visit the GSP FreeBSD Man Page Interface. Output converted with ManDoc. |