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Re: PDF API2 - landscape and rotating text and image

by kcott (Archbishop)
on Jul 24, 2020 at 22:16 UTC ( #11119779=note: print w/replies, xml ) Need Help??

in reply to PDF API2 - landscape and rotating text and image

"# does not rotate correctly because I don't quite understand the translate part"

When you rotate the page ($page->rotate(90)) to change from portrait to landscape, the X-Y axes change from horizontal-vertical to vertical-horizontal. The -translate values reference the axes; you need to adjust them for the page rotation change. I suspect this is maybe causing you problems understanding what's going on here: it's neither immediately obvious nor intuitive, so your confusion is unsurprising. I suggest you spend some time playing around with the values to get a feel for this.

The following code generates a landscape-oriented page which roughly looks like this:

| Left text    Right text |
|                         |
| +------+     +------+   |
| |  ^^  |     |  ^^  |   |
| |  ||  |     |  ||  |   |
| | img1 |     | img2 |   |
| +------+     +------+   |

I used different text and images purely for testing purposes; obviously, you can use the same text and images on both sides. The images were 64x64 pixel PNGs which had a clear UP direction (to check the rotation).

You'll no doubt need to change certain values to suit your layout requirements; however, I hope this gives you a solid starting point.

#!/usr/bin/env perl use strict; use warnings; use autodie; use PDF::API2; my $pdf_file = 'test.pdf'; my $left_text = 'This text on the left.'; my $right_text = 'This text on the right.'; my ($left_img, $right_img) = qw{left.png right.png}; my $pdf = PDF::API2::->new(-file => $pdf_file); my $page = $pdf->page(); $page->mediabox('A4'); $page->rotate(90); my $font = $pdf->corefont('Helvetica'); my @text_cfg = ( { text => $left_text, pos => [50, 40] }, { text => $right_text, pos => [50, 450] }, ); for my $cfg (@text_cfg) { my $text = $page->text(); $text->font($font, 12); $text->transform( -translate => $cfg->{pos}, -rotate => 90, ); $text->text($cfg->{text}); } my @gfx_cfg = ( { img => $pdf->image_png($left_img), pos => [150, 40] }, { img => $pdf->image_png($right_img), pos => [150, 450] }, ); my $gfx = $page->gfx; for my $cfg (@gfx_cfg) { $gfx->save(); $gfx->transform( -translate => $cfg->{pos}, -rotate => 90, ); $gfx->image($cfg->{img}, 0, 0); $gfx->restore(); } $pdf->save();

— Ken

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Re^2: PDF API2 - landscape and rotating text and image
by Anonymous Monk on Jul 25, 2020 at 01:25 UTC

    Hi Ken,

    Thank you so much for your explanation and great working code! Wouldn't have thought of a For loop to do the left and right tasks.

    I have one question for the line below:

    $gfx->image($cfg->{img}, 0, 0);

    The values of 0,0 - that outputs the image in its original size (am I right?). I tried with values like 200, 200 to get bigger images but the images don't appear. How do I output the images to bigger sizes?

    Thanks you for your great help once again :))

      You should look in PDF::API2::Content for information on image(), transform(), and related methods. In particular, look at the "External Objects" and "Coordinate Transformations" sections.

      The '0, 0' to which you referred are co-ordinates, not sizes. As the code already sets the co-ordinates via the '-translate' option of transform(), further modification of the co-ordinates by image() is not wanted.

      The image() method has a number of forms allowing you to change width, height, and scale. There's also a '-scale' option for transform(). Note that if you change the size, you'll also need to adjust the co-ordinates accordingly.

      — Ken

        Ok, thanks!

        The transform() method is new to me. Took a quick look and saw you can do scaling and skewing with it.

        Great learning from your earlier code, many thanks :))

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