ImageMagick: composite 4 edges from one image into another, side-by-side - perl

Question

I'm using Perl 5.16 with ImageMagick 6.8 (probably old by now, but it works :). I'm trying to extract all 4 edge regions from one image and composite them into another image, side-by-side, oriented vertically.
I can extract edges and rotate them, but I can't get the offset in the target image right. The edges end up on top of each other. I tried x=>$marg, translate=>"$marg,0", geometry with an offset: no dice. Variables: $marg = the edge width, $im = source, $im2 = target, $ext = extracted region
# left edge
$ext=sprintf("%dx%d+%d+%d",$marg,$h,0,0);
$res=$im2->Composite(image=>$im,compose=>Over,extract=>$ext);
# top edge
$ext=sprintf("%dx%d+%d+%d",$w,$marg,0,0);
$geo=sprintf("%dx%d+%d+%d",$marg,$h,0,0);
$res=$im2->Composite(image=>$im,compose=>Over,extract=>$ext,rotate=>90,translate=>"$marg,0");

Answer 1

I haven't used the PerlMagick bindings for years, but I imagine you would want to create each of your 4 edge strips and then use +append to lay them out horizontally, side-by-side. Here's a crude example, just in Terminal:
magick -size 20x50 xc:red xc:lime xc:blue +append result.png
More specifically addressing your question, and starting with this image:
that would look like this:
#!/bin/bash
magick ~/sample/images/blocks-RGB.png -resize 100x100 +repage -write MPR:orig +delete \
\( MPR:orig -gravity northwest -crop 30x+0+0 \) \
\( MPR:orig -gravity northwest -crop x30+0+0 -rotate 90 \) \
\( MPR:orig -gravity southwest -crop x30+0+0 -rotate 90 \) \
\( MPR:orig -gravity northeast -crop 30x+0+0 \) \
+append result.png
Hopefully you can see the parallels with PerlMagick. The first line creates a copy of the image to work with, the second line crops the left edge, the third line crops the top edge, the fourth line crops the bottom edge, the fifth line crops the right edge and the last line appends the four cropped pieces side-by-side.