Dear Monks,

I was wondering everyone's opinions on the best way of importing bitmaps into a PDL array (this is called a piddle, right?) on Win32 systems.

A little background:
I have a script that uses Win32::API to make various API calls to avicap32.dll, gdi32.dll, and others in order to capture still images from a webcam. I then use another API call to copy it to the clipboard, where I use Win32::Clipboard to get the image. I would like to use PDL to perform some image manipulation on the image, but unfortunately this image is in bitmap (bmp) format. Looking through prior nodes, I checked for bitmap support using the PDL::IO::Pic module as suggested in the node PDL examples?. I use:

use PDL::IO::Pic;
print join ', ', PDL->wpiccan();

And get the output:
PNM

This indicates that bitmaps are not on the list of supported types (along with GIFs, JPEGs, TIFs, etc, making me suspect my PDL module installed via PPM). I also looked for a bitmap module on CPAN, but didn't see any that would help import bitmap contents, even after a good amount of searching.

Are there any monks familiar with this problem, or who have solutions? Perhaps a neat unpack trick after stripping headers? Any help is appreciated.

Also, this is my first post here on Perl Monks, but I've been an anonymous reader for the last two years. I would appreciate it if any monks would tell me of any improper formatting or conventions of my post.

Code Enclosed for any who might find it useful:

#!/usr/bin/perl

use strict;
use Win32::API;
use Win32::Clipboard;

#############################################
## MAIN BLOCK                              ##
#############################################
print "Using device: " . getDeviceList() . "...\n";

captureImage(0);

print "DONE!\n";
#############################################
## SUBROUTINES                             ##
#############################################
sub getDeviceList {
  my $device = '';
  my $strName = " " x 100; #necessary for the API call
  my $strVer = " " x 100;
  my $i = 0;
  
  my $driverGet = new Win32::API('avicap32.dll', 'capGetDriverDescript
+ionA', 'IPIPI', 'I');
  if($driverGet->Call($i, $strName, 100, $strVer, 100)) { #make API ca
+ll to find devices
    $strName = unpack('A*', $strName); #trim trailing nulls
    $device = $strName;
  }
  
  return ($device ? $device : "Error - No device found"); #if theres a
+ device, show it
}

sub captureImage {
  my $iDevice = shift;
  
  my $getD = new Win32::API('user32.dll', 'GetDesktopWindow', '', 'N')
+;
  my $desktopHwnd = $getD->Call(); #need the desktop handle

  my $cCreate = new Win32::API('avicap32.dll', 'capCreateCaptureWindow
+A', 'PIIIIIII', 'I');
  my $sMsg = new Win32::API('user32.dll', 'SendMessageA', 'IIIP', 'I')
+;
  my $wDestroy = new Win32::API('user32.dll', 'DestroyWindow', 'I', 'I
+');
  my $wDC = new Win32::API('gdi32.dll', 'CreateCompatibleDC', 'N', 'N'
+); #create memory DC as a temporary workspace
  my $memHwnd = $wDC->Call($desktopHwnd);
  
  my $handle = $cCreate->Call($iDevice, 0, 0, 0, 640, 480, $memHwnd, 0
+); #Invisible
  if ($sMsg->Call($handle, 1034, $iDevice, 0)) { #if DRIVER_CONNECT
    $sMsg->Call($handle, 1077, 1 , 0); print "Scale Set...\n";
    $sMsg->Call($handle, 1074, 1, 0); print "Previewing...\n";
    $sMsg->Call($handle, 1076, 1, 0); print "Preview Rate...\n";
    $sMsg->Call($handle, 1054, 0, 0); print "Copying...\n";#copy to cl
+ipboard
    sleep 1;
    $wDestroy->Call($handle);
  } else {
    print "Device invalid or in use.\n";
    $wDestroy->Call($handle);
  }
  
  #save the clipboard to file
  my $image = Win32::Clipboard::GetBitmap();
  open (BITMAP, ">current_image.bmp");
  binmode (BITMAP);
  print BITMAP $image;
  close (BITMAP);
}

[download]

Thank you.

In reply to Importing Bitmaps into PDL by rkosai

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