NAME

Imager::Font::BBox - objects representing the bounding box of a string.

SYNOPSIS

  use Imager::Font;
  # get the object
  my $font = Imager::Font->new(...);
  my $bbox = $font->bounding_box(string=>$text, size=>$size);
  # methods
  my $start = $bbox->start_offset;
  my $left_bearing = $bbox->left_bearing;
  my $right_bearing = $bbox->right_bearing;
  my $end = $bbox->end_offset;
  my $gdescent = $box->global_descent;
  my $gascent = $bbox->global_ascent;
  my $ascent = $bbox->ascent;
  my $decent = $bbox->descent;
  my $total_width = $bbox->total_width;
  my $fheight = $bbox->font_height;
  my $theight = $bbox->text_height;
  my $display_width = $bbox->display_width;

DESCRIPTION

Objects of this class are returned by the Imager::Font bounding_box() method when it is called in scalar context.

This will hopefully make the information from this method more accessible.

METHODS

start_offset()

neg_width

left_bearing

Returns the horizontal offset from the selected drawing location to the left edge of the first character drawn. If this is positive, the first glyph is to the right of the drawing location.

The alias neg_width() is present to match the bounding_box() documentation for list context.

The alias left_bearing() is present to match font terminology.

advance_width()

The advance width of the string, if the driver supports that, otherwise the same as end_offset.

right_bearing

The distance from the right of the last glyph to the end of the advance point.

If the glyph overflows the right side of the advance width this value is negative.

display_width

The distance from the left-most pixel of the left-most glyph to the right-most pixel of the right-most glyph.

Equals advance_width - left_bearing - right_bearing (and implemented that way.)

global_descent()

The lowest position relative to the font baseline that any character in the font reaches in the character cell. Normally negative.

At least one font we've seen has reported a positive number for this.

global_ascent()

The highest position relative to the font baseline that any character in the font reaches in the character cell. Normally positive.

descent()

The lowest position relative to the font baseline that any character in the supplied string reaches. Negative when any character's glyph reaches below the baseline.

ascent()

The highest position relative to the font baseline that any character in the supplied string reaches. Positive if any character's glyph reaches above the baseline.

font_height()

The maximum displayed height of any string using this font.

text_height()

The displayed height of the supplied string.

OBSOLETE METHODS

These methods include bugs kept for backwards compatibility and shouldn't be used in new code.

total_width()

The total displayed width of the string.

New code should use display_width().

This depends on end_offset(), and is limited by it's backward compatibility.

end_offset

pos_width

The offset from the selected drawing location to the right edge of the last character drawn. Should always be positive.

You can use the alias pos_width() if you are used to the bounding_box() documentation for list context.

For backwards compatibility this method returns the maximum of the advance width and the offset of the right edge of the last glyph.

INTERNAL FUNCTIONS

new(...): Called by Imager::Font->bounding_box() to create the object.

BUGS

Doesn't reproduce the functionality that you get using the x and y parameters to Imager::Font->bounding_box(). I considered:

  my ($left, $top, $right, $bottom) = $box->offset(x=>$x, y=>$y)

but this is about as clumsy as the original.

AUTHOR

Tony Cook <tony@develop-help.com>