I have several png files that represent trends (up, down and no
change). They are 16px x 16px, Can they be centered using formats?
Currently they are flush left. Do I need to create the graphic as wide
as the column? Thge column width is 10 row height is 22.

Images (and other objects) are layered on top of a worksheet so they
aren't in general controlled by formatting.

In the case of images you will need to specify your own offsets to
centre the image using the optional $x, $y parameters in insert_image
().

http://search.cpan.org/~jmcnamara/Spreadsheet-WriteExcel/lib/Spreadsh...)

The default cell width is 64 pixels and the default height is 17
pixels. So to centre a 16x16 image you will need the following
offsets:

    x = int( ( 64 - 16) / 2 ) = 24
    y = int ( ( 17 - 16) /2 ) = 0

Here is an example:

    #!/usr/bin/perl

    use strict;
    use warnings;
    use Spreadsheet::WriteExcel;

    my $workbook  = Spreadsheet::WriteExcel->new('test.xls');
    my $worksheet = $workbook->add_worksheet();

    # Left top align.
    $worksheet->insert_image('B3', '16x16.png');

    # Centred. x = int( ( 64 - 16) / 2 ), y = int ( ( 17 - 16) /2 ).
    $worksheet->insert_image('B5', '16x16.png', 24, 0);

    # Right bottom align. x = ( 64 - 16), y = ( 17 - 16).
    $worksheet->insert_image('B7', '16x16.png', 48, 1);

    __END__

John.
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