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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

           # Put a black frame around the picture

           # Draw a blue oval

           # And fill it with 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:

            An image class, which holds the image data and accepts graphic
            primitive method calls.

            A font class, which holds static font information and used for
            text rendering.

            A simple polygon object, used for storing lists of vertices prior
            to rendering a polygon into an image.

            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:


               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

               # Put a black frame around the picture

               # Draw a blue oval

               # And fill it with 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;


       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.

Object Constructors: Creating Images
       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

           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


           somewhere before creating new images.  To switch back to palette
           based by default, use:


       $image = GD::Image->newPalette([$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

           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.


             open (PNG,"barnswallow.png") || die;
             $myImage = newFromPng GD::Image(\*PNG) || die;
             close PNG;

             $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)
       $image = GD::Image->newFromGifData($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)
           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.

       $image = GD::Image->newFromGd($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

                   $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

           NOTE: The libgd library is unable to read certain XPM files,
           returning an all-black image instead.

GD::Image Methods
       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

   Image Data Output Methods
       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

       $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

       $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.

   Color Control
       These methods allow you to control and manipulate the GD::Image color

       $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

           If no colors are allocated, then this function returns -1.


                   $white = $myImage->colorAllocate(0,0,0); #background color
                   $black = $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

           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.


                   $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.


                   $apricot = $myImage->colorClosest(255,200,180);

       $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.


                   $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->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;

       $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.


                   $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.


                   @RGB = $myImage->rgb($peachy);

           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.


                   $im = newFromPng GD::Image(PNG);
                   $white = $im->colorClosest(255,255,255); # find 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

           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.


                   # 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);
                   $diagonal_brush->line(0,4,4,0,$black); # NE diagonal

                   # Set the brush

                   # Draw a circle using the brush

           Lines drawn with line(), rectangle(), arc(), and so forth are 1
           pixel thick by default.  Call setThickness() to change the line
           drawing width.

           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.


                   # Set a style consisting of 4 pixels of yellow,
                   # 4 pixels of blue, and a 2 pixel gap

           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.

           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.

           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.

           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().

           "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.

           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:


   Drawing Commands
       These methods allow you to draw lines, rectangles, and ellipses, as
       well as to perform various special operations like flood-fill.

           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.


                   # This assumes $peach already allocated

           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.


                   # Draw a diagonal line using the currently defined
                   # paintbrush pattern.

           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.



           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.



           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.


                   # read in a fill pattern and set it
                   $tile = newFromPng GD::Image('happyface.png');

                   # draw the rectangle, filling it with the pattern

           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.


                   $poly = new GD::Polygon;

           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

           You need libgd 2.0.33 or higher to use this feature.


                   $poly = new GD::Polygon;

           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.


                   # make a polygon
                   $poly = new GD::Polygon;

                   # draw the polygon, filling it with a 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.

           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

           You can specify a normal color or one of the special colors
           gdBrushed, gdStyled, or gdStyledBrushed.


                   # draw a semicircle centered at 100,100

           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."



           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.


                   # Draw a rectangle, and then make its interior blue

           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.


                   # This has the same effect as the previous example

   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.


           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.


                   $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

           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.


                   $myImage = new GD::Image(100,100);
                   ... various drawing stuff ...
                   $copy = $myImage->clone;


           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.


                   $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%


           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.


           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.


                   $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


           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.


           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 Transformation Commands
       Gd also provides some common image transformations:

       $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.

           These methods are similar to the copy* versions, but instead modify
           the image in place.

   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 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 scaleable fonts, GD offers the stringFT()
       method, which allows you to load and render any TrueType font on your

           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.


                   $myImage->string(gdSmallFont,2,10,"Peachy Keen",$peach);

           Just like the previous call, but draws the text rotated
           counterclockwise 90 degrees.

           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 =
       @bounds =
       @bounds =
           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 string may contain UTF-8 sequences like: "&#192;"

           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

           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.


                         "hi there\r\nbye now",
                          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.


           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.

       $result =
           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.

   Alpha channels
       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:

       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.

           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.

           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.

   Miscellaneous Image Methods
       These are various utility methods that are useful in some

           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 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
             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!";

       ($x1,$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.

   Grouping Methods
       GD does not support grouping of objects, but GD::SVG does. In that
       subclass, the following methods declare new groups of graphical

       $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;

          Add point (x,y) to the polygon.


       ($x,$y) = $poly->getPt($index)
          Retrieve the point at the specified vertex.

                  ($x,$y) = $poly->getPt(2);

          Change the value of an already existing vertex.  It is an error to
          set a vertex that isn't already defined.


       ($x,$y) = $poly->deletePt($index)
          Delete the specified vertex, returning its value.

                  ($x,$y) = $poly->deletePt(1);

          Delete all vertices, restoring the polygon to its initial empty

          Draw from current vertex to a new vertex, using relative (dx,dy)
          coordinates.  If this is the first point, act like addPt().


       $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;

          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.


          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

          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.

          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

       Please see GD::Polyline for information on creating open polygons and

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 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

       Each of these fonts is available both as an imported global (e.g.
       gdSmallFont) and as a package method (e.g. GD::Font->Small).

            This is the basic small font, "borrowed" from a well known public
            domain 6x12 font.

            This is the basic large font, "borrowed" from a well known public
            domain 8x16 font.

            This is a bold font intermediate in size between the small and
            large fonts, borrowed from a public domain 7x13 font;

            This is a tiny, almost unreadable font, 5x8 pixels wide.

            This is a 9x15 bold font converted by Jan Pazdziora from a sans
            serif X11 font.

            This returns the number of characters in the font.

                    print "The large font contains ",gdLargeFont->nchars," characters\n";

            This returns the ASCII value of the first character in the font

       $width = $font->width
       $height = $font->height
            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.

       The GD.pm interface is copyright 1995-2007, Lincoln D. Stein.  It is
       distributed under GPL and the Artistic License 2.0.

       The latest versions of GD.pm are available at


       GD::Polyline, GD::SVG, GD::Simple, Image::Magick

       Hey! The above document had some coding errors, which are explained

       Around line 463:
           You forgot a '=back' before '=head1'

       Around line 475:
           '=item' outside of any '=over'

perl v5.12.1                      2010-07-05                             GD(3)

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