Question

I use the following to read a PDF file and get text strings of a page:

my $pdf = CAM::PDF->new($pdf_file); my $pagetree = $pdf->getPageContentTree($page_no);  # Get all text strings of the page # MyRenderer is a separate package which implements getTextBlocks and # renderText methods  my @text = $pagetree->traverse('MyRenderer')->getTextBlocks; 

Now, @text has all the text strings and start x,y of each text string.

How can I get the width (and possibly the height) of each string?

MyRenderer package is as follows:

package MyRenderer; use base 'CAM::PDF::GS'; sub new {     my ($pkg, @args) = @_;     my $self = $pkg->SUPER::new(@args);     $self->{refs}->{text} = [];     return $self; }  sub getTextBlocks {     my ($self) = @_;     return @{$self->{refs}->{text}}; }  sub renderText {     my ($self, $string, $width) = @_;     my ($x, $y) = $self->textToDevice(0,0);     push @{$self->{refs}->{text}}, {                                     str => $string,                                     left => $x,                                     bottom => $y,                                     right =>$x + $width,                                    };     return; } 

Update 1: There’s a function getStringWidth($fontmetrics, $string) in CAM::PDF. Altough there’s a parameter $fontmetrics in that function, irespective of what I pass to that parameter, the function returns the same value for a given string.

Also, I am not sure of the unit of measure the returned value uses.

Update 2: I changed the renderText function to following:

sub renderText {     my ($self, $string, $width) = @_;     my ($x, $y) = $self->textToDevice(0,0);     push @{$self->{refs}->{text}}, {                                 str => $string,                                 left => $x,                                 bottom => $y,                                 right =>$x + ($width * $self->{Tfs}),                                 font => $self->{Tf},                                 font_size => $self->{Tfs},                                };     return; } 

Note that in addition to getting font and font_size, I multiplied $width with font size to get the real width of the string.

Now, only thing missing is the height.

Answer 1

getStringWidth() depends heavily on the font metrics you provide. If it can’t find the character widths in that data structure, then it falls back to the following code:

   if ($width == 0)    {       # HACK!!!                                                                          #warn 'Using klugy width!\n';                                                      $width = 0.2 * length $string;    } 

which may be what you’re seeing. When I wrote that, I thought it was better than returning 0. If your font metrics seem good and you think there’s a bug in CAM::PDF, feel free to post more details and I’ll take a look.