GD::Text::Align - Draw aligned strings


GD::Text::Align - Draw aligned strings


  use GD;
  use GD::Text::Align;
  my $gd = GD::Image->new(800,600);
  # allocate colours, do other things.
  my $align = GD::Text::Align->new($gd
    valign => 'top',
    halign => 'right',
  $align->set_font('arial', 12);
  $align->set_text('some string');
  @bb = $align->bounding_box(200, 400, PI/3);
  # you can do things based on the bounding box here
  $align->draw(200, 400, PI/3);


GD::Text::Align provides an object that draws a string aligned to a coordinate at an angle.

For builtin fonts only two angles are valid: 0 and PI/2. All other angles will be converted to one of these two.


This class inherits everything from GD::Text. I will only discuss the methods and attributes here that are not discussed there, or that have a different interface or behaviour. Methods directly inherited include set_text and set_font.

GD::Text::Align->new($gd_object, attrib => value, ...)

Create a new object. The first argument to new has to be a valid GD::Image object. The other arguments will be passed on to the set method.

$align->set(attrib => value, ...)

Set an attribute. Valid attributes are the ones discussed in the GD::Text manpage and:

valign, halign
Vertical and horizontal alignment of the string. See also set_valign and set_halign.

colour, color
Synonyms. The colour to use to draw the string. This should be the index of the colour in the GD::Image object's palette. The default value is the last colour in the GD object's palette at the time of the creation of $align.


Get the value of an attribute. Valid attributes are all the attributes mentioned in the GD::Text manpage, the attributes mentioned under the set method and

x, y and angle
The x and y coordinate and the angle to be used. You can only do this after a call to the draw or bounding_box methods. Note that these coordinates are not necessarily the same ones that were passed in. Instead, they are the coordinates from where the GD methods will start drawing. I doubt that this is very useful to anyone.

Note that while you can set the colour with both 'color' and 'colour', you can only get it as 'colour'. Sorry, but such is life in Australia.


Set the vertical alignment of the string to one of 'top', 'center', 'base' or 'bottom'. For builtin fonts the last two are the same. The value 'base' denotes the baseline of a TrueType font. Returns true on success, false on failure.


Set the horizontal alignment of the string to one of 'left', 'center', or 'right'. Returns true on success, false on failure.

$align->set_align(valign, halign)

Set the vertical and horizontal alignment. Just here for convenience. See also set_valign and set_halign. Returns true on success, false on failure.

$align->draw(x, y, angle)

Draw the string at coordinates x, y at an angle angle in radians. The x and y coordinate become the pivot around which the string rotates.

Note that for the builtin GD fonts the only two valid angles are 0 and PI/2.

Returns the bounding box of the drawn string (see bounding_box()).

$align->bounding_box(x, y, angle)

Return the bounding box of the string to draw. This returns an eight-element list (exactly like the GD::Image->stringTTF method):

  (x1,y1) lower left corner
  (x2,y2) lower right corner
  (x3,y3) upper right corner
  (x4,y4) upper left corner

Note that upper, lower, left and right are relative to the string, not to the canvas.

The bounding box can be used to make decisions about whether to move the string or change the font size prior to actually drawing the string.


As with all Modules for Perl: Please stick to using the interface. If you try to fiddle too much with knowledge of the internals of this module, you may get burned. I may change them at any time.

You can only use TrueType fonts with version of GD > 1.20, and then only if compiled with support for this. If you attempt to do it anyway, you will get errors.

In the following, terms like 'top', 'upper', 'left' and the like are all relative to the string to be drawn, not to the canvas.


Any bugs inherited from GD::Text.


copyright 1999 Martien Verbruggen (


the GD manpage, the GD::Text manpage, the GD::Text::Wrap manpage

 GD::Text::Align - Draw aligned strings