determining size of image

[Anonymous Monk]

I know how to get the size of an image via Image::Info, but I want to add a little snippet that does a little more.

I have a picture posting site where users can upload images to and some are too large and ends up making horizontal scrollbards on the browser (not acceptable!). I can now detect which images are larger than 800x600, which is what I want to test against, but how can I dynamically resize the HTML renderation of the image?

I'm NOT trying to resize the image itself, just the HTML code of the image. Ie. <code> I'm just using HTML to make it appear smaller on screen so the user can click the image to make it appear full in a new window.

So let's say the image was 1100x900, I want to use the HTML image size to show the image at the first size in which both dimensions are smaller than my required size (800x600). In short, I want the resize to be proportioned to the size of the image itself. I COULD just resize everything that's too large to 800x600 but that'd cause a lot of crappy images, I want to keep the same proportions.

Can anyone help me with this?

[ikegami]

my ($width,        $height       ) = ...;
my ($max_width,    $max_height   ) = (800, 600);
my ($width_factor, $height_factor) = ($max_width/$width, $max_height/$
+height);

if ($width_factor < 1 || $height_factor < 1) {
   my $factor = ($width_factor < $height_factor
      ? $width_factor
      : $height_factor
   );

   $width  = int($width  * $factor + 0.5);
   $height = int($height * $factor + 0.5);
}

The above was extracted from a script I use to resize images.

Read more... (940 Bytes)

[zentara]

Just as an aside, the ImageMagick ping method is the most efficient way to get size.

#!/usr/bin/perl -w
use Image::Magick;

my $x = $ARGV[0];
my $image = Image::Magick->new;
#$image->Read($x);
#my ($w,$h)= $image->Get('columns','height');
#print $x,' is ',$w.'x'.$h,"\n";
#this is very inneficient memory wise, use Ping

($width, $height, $size, $format) = $image->Ping($x); 
print $width,"\n", $height,"\n" ,$size,"\n", $format,"\n";

and here is a script I had in my library to do an actual distortion free resize.

#!/usr/bin/perl

# I need to adjust an image to a minimum size, but without distoring i
+t, 
# so I basically want to add space evenly around the existing image. 
# Using Resize is out since that will distort the image, so I gave 
# "Composite" a shot,

use Image::Magick;
use strict;
use warnings;

my $im = Image::Magick->new();
my $bg = Image::Magick->new(size => "200x400");

my $rc = $bg->Read("xc:white");

$rc = $im->Read($ARGV[0]);
die $rc if $rc;

$rc = $im->Resize("200x400");
warn $rc if $rc;

$rc = $bg->Composite(gravity => "Center", image => $im);
warn $rc if $rc;

$rc = $bg->Write("$ARGV[0]-resized.png");
die $rc if $rc;

[dorward]

I'm NOT trying to resize the image itself, just the HTML code of the image.

I suggest not doing that. Browsers suck at scaling images, and transfering all those bytes across a network just to have detail thrown away is a waste of bandwidth.

[kwaping]

Of course, there's always Image::Size. :)

[mreece]

i typically use something like the following (using Image::Size)

use Image::Size;

my ($w, $h) = imgsize("blort.jpg");
if ($w > 800) { my $f = $w / 800; $w = int($w/$f); $h = int($h/$f) };
if ($h > 600) { my $f = $h / 600; $w = int($w/$f); $h = int($h/$f) };