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package Image::PNG::FileConvert; |
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require Exporter; |
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@ISA = qw(Exporter); |
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@EXPORT_OK = qw/file2png png2file/; |
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use warnings; |
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use strict; |
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our $VERSION = 0.08; |
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use Carp; |
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use Image::PNG::Libpng ':all'; |
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use Image::PNG::Const ':all'; |
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use constant { |
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default_row_length => 0x800, |
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default_max_rows => 0x800, |
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}; |
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sub file2png |
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{ |
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my ($file, $png_file, $options) = @_; |
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if (! -f $file) { |
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carp "I can't find '$file'"; |
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return; |
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} |
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if (! $png_file) { |
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carp "I need a name for the PNG output"; |
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return; |
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} |
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if (-f $png_file) { |
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carp "Output PNG file '$png_file' already exists"; |
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return; |
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} |
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if (! $options) { |
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$options = {}; |
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} |
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if (! $options->{row_length}) { |
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$options->{row_length} = default_row_length; |
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} |
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if (! $options->{max_rows}) { |
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$options->{max_rows} = default_max_rows; |
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} |
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my @rows; |
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my $bytes = -s $file; |
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open my $input, "<:raw", $file; |
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my $i = 0; |
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my $total_red = 0; |
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while (! eof ($input)) { |
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my $red = read ($input, $rows[$i], $options->{row_length}); |
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if ($red != $options->{row_length}) { |
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if ($total_red + $red != $bytes) { |
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warn "Short read of $red bytes at row $i.\n" |
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} |
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} |
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$total_red += $red; |
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$i++; |
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} |
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close $input; |
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if ($options->{verbose}) { |
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printf "Read 0x%X rows.\n", $i; |
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} |
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# Fill the final row up with useless bytes so that we are not |
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# reading from unallocated memory. |
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# The number of bytes in the last row. |
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my $end_bytes = $bytes % $options->{row_length}; |
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if ($end_bytes > 0) { |
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$rows[-1] .= "X" x ($options->{row_length} - $end_bytes); |
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} |
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# Create the PNG data in a Perl structure. |
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my $png = create_write_struct (); |
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my %IHDR = ( |
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width => $options->{row_length}, |
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height => scalar @rows, |
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color_type => PNG_COLOR_TYPE_GRAY, |
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bit_depth => 8, |
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); |
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set_IHDR ($png, \%IHDR); |
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set_rows ($png, \@rows); |
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# Write the PNG data to a file. |
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open my $output, ">:raw", "$png_file"; |
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init_io ($png, $output); |
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# Set the timestamp of the PNG file to the current time. |
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set_tIME ($png); |
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my $name; |
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if ($options->{name}) { |
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$name = $options->{name}; |
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} |
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else { |
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$name = $file; |
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} |
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# Put the name and size of the file into the file as text |
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# segments. |
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set_text ($png, [{key => 'bytes', |
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text => $bytes, |
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compression => PNG_TEXT_COMPRESSION_NONE}, |
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{key => 'name', |
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text => $name, |
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compression => PNG_TEXT_COMPRESSION_NONE}, |
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]); |
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write_png ($png); |
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close $output; |
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} |
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110
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sub png2file |
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{ |
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my ($png_file, $options) = @_; |
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my $me = __PACKAGE__ . "::png2file"; |
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if (! $png_file) { |
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croak "$me: please specify a file"; |
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} |
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if (! -f $png_file) { |
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croak "$me: can't find the PNG file '$png_file'"; |
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} |
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if (! defined $options) { |
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$options = {}; |
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} |
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open my $input, "<:raw", $png_file; |
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my $png = create_read_struct (); |
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init_io ($png, $input); |
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if ($options->{verbose}) { |
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print "Reading file\n"; |
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} |
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read_png ($png); |
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my $IHDR = get_IHDR ($png); |
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if ($options->{verbose}) { |
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print "Getting rows\n"; |
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} |
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my $rows = get_rows ($png); |
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if ($options->{verbose}) { |
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print "Finished reading file\n"; |
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} |
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close $input; |
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my $text_segments = get_text ($png); |
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if (! defined $text_segments) { |
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croak "$me: the PNG file '$png_file' does not have any text segments, so either it was not created by " . __PACKAGE__ . "::file2png, or it has had its text segments removed"; |
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return; |
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} |
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my $name; |
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my $bytes; |
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for my $text_segment (@$text_segments) { |
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if ($text_segment->{key} eq 'name') { |
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$name = $text_segment->{text}; |
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} |
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elsif ($text_segment->{key} eq 'bytes') { |
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$bytes = $text_segment->{text}; |
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} |
153
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else { |
154
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carp "Unknown text segment with key '$text_segment->{key}' in '$png_file'"; |
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} |
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} |
157
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if (! $name || ! $bytes) { |
158
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croak "$me: the PNG file '$png_file' does not have information about the file name or the number of bytes of data, so either it was not created by " . __PACKAGE__ . "::file2png, or it has had its text segments removed"; |
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} |
160
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if ($bytes <= 0) { |
161
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croak "$me: the byte file size $bytes in '$png_file' is impossible"; |
162
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} |
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my $row_bytes = get_rowbytes ($png); |
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if (-f $name) { |
165
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croak "$me: a file with the name '$name' already exists"; |
166
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} |
167
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open my $output, ">:raw", $name; |
168
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for my $i (0..$#$rows - 1) { |
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print $output $rows->[$i]; |
170
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} |
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my $final_row = substr ($rows->[-1], 0, $bytes % $row_bytes); |
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print $output $final_row; |
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close $output; |
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return; |
175
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} |
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177
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1; |
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179
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=head1 NAME |
180
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181
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Image::PNG::FileConvert - convert a file to or from a PNG image |
182
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183
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=head1 SYNOPSIS |
184
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185
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use Image::PNG::FileConvert qw/file2png png2file/; |
186
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# Convert a data file into a PNG image |
187
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file2png ('myfile.txt', 'myfile.png'); |
188
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# Extract a data file from a PNG image |
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png2file ('myfile.png'); |
190
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191
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=head1 FUNCTIONS |
192
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193
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=head2 file2png |
194
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195
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file2png ('myfile.txt', 'myfile.png'); |
196
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197
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Convert C into a PNG graphic. The function uses the data |
198
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from myfile.txt to write a greyscale (black and white) image. The |
199
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bytes of the file correspond to the pixels of the image. |
200
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201
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When this PNG is unwrapped using L, it will be called |
202
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C again. If you want to specify a different name, |
203
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204
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file2png ('myfile.txt', 'myfile.png', |
205
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{ name => 'not-the-same-name.txt' }); |
206
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207
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and the file will be unwrapped into C. |
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209
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If you want your PNG to have a different width than the default, there |
210
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is another option, C, specified in the same way: |
211
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212
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file2png ('myfile.txt', 'myfile.png', { row_length => 0x100 }); |
213
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214
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The number you specify for C will be the width of the |
215
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image in pixels. |
216
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217
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=head2 png2file |
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219
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png2file ('myfile.png'); |
220
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221
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Convert C into a data file. C must be a PNG |
222
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created using L. The file is stored in whatever the name of |
223
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the file given to L was. |
224
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225
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Please note that this only converts PNG files output by L, |
226
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not general PNG files. |
227
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228
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=head1 BUGS |
229
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230
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=over |
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=item Holds file in memory |
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Both the routines here hold the entire file in memory, limiting the |
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data size which can be converted to or from a PNG. |
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=item There should be a way to specify the output name in png2file |
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There should be some option to specify the name of the output file in |
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L. |
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=back |
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=head1 AUTHOR |
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Ben Bullock, |
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=head1 LICENCE |
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You can use, modify and distribute this software under the Perl |
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Artistic Licence or the GNU General Public Licence. |
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=head1 SEE ALSO |
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=over |
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=item Acme::Steganography::Image::Png |
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L I'm not sure what this does, but |
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maybe it does something similar to Image::PNG::FileConvert. |
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=back |
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=head1 UTILITIES |
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266
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The distribution also includes two utility scripts, file2png and |
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png2file, which convert a file to a PNG image and back again. |
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269
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=cut |
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