clj-pnm

A Clojure(Script) library for reading and writing Netpbm format. Supports plain-test formats: p1 (.pbm), p2 (.pgm) and p3 (.ppm).

Notes on the state of the library:

• Plain-text Netpbm is supported and implementation is stable.
• The Netpbm format completely ignores whitespace, however clj-pnm requires that characters are separated by whitespace.
• Binary formats (p4, p5 and p6) are not supported.
• pam format is not supported.
• Writing in-line comments to a file (for example in the header part) is not supported.

Good explanation of the format and the resources that are used as guides for this library can be found here and here.

Usage

The library is available on Clojars. Add it to your project as a dependency.

deps.edn:

org.theparanoidtimes/clj-pnm {:mvn/version "0.2.0"}

project.clj:

[org.theparanoidtimes/clj-pnm "0.2.0"]

require the library:

(require '[clj-pnm.core :as pnm])
=> nil

Read the pbm format:

(def pbm
"P1
 2
 2
 1 1
 1 1")
=> #'user/pbm

(pnm/read-pnm pbm)
=> {:type :p1, :width 2, :height 2, :map [[1 1] [1 1]]}

Read the pgm format:

(def pgm
"P2
 3
 2
 4
 # pgm-comment
 1 2 3
 4 3 2")
=> #'user/pgm

(pnm/read-pnm pgm)
=> {:type :p2, :width 3, :height 2, :max-value 4, :map [[1 2 3] [4 3 2]] :comments ("pgm-comment")}

Read the ppm format:

(def ppm
"P3
 2
 2
 255
 # ppm-comment
 255 0 255 128 52 123
 0 0 0 45 45 45")
=> #'user/ppm

(pnm/read-pnm ppm)
=> {:type :p3
    :width 2
    :height 2
    :max-value 255
    :map [[(255 0 255) (128 52 123)]
          [(0 0 0) (45 45 45)]]
    :comments ("ppm-comment")} ; prettified

You can extract comments separately if necessary:

(def pbm-with-comments
"P1
 1
 1
 # A comment
 # Another comment
 1")
=> #'user/pbm-with-comments

(pnm/get-comments (pnm/read-lines pbm-with-comments))
=> ("A comment" "Another comment")

Some files have in-line comments in the header part. They are handled in the same way:

(def pbm-with-in-line-comments
"P1
 1 # this is the width
 1
 # A comment
 # Another comment
 1")
=> #'user/pbm-with-in-line-comments

(pnm/read-pnm pbm-with-in-line-comments)
=> {:type :p1, :width 1, :height 1, :map [[1]] :comments ("1  this is the width" "A comment" "Another comment")}

(def pbm-with-in-line-comments
"P1
 1
 1 # this is the height
 # A comment
 # Another comment
 1")
=> #'user/pbm-with-in-line-comments

(pnm/get-comments (pnm/read-lines pbm-with-in-line-comments))
=> ("1  this is the width" "A comment" "Another comment")

Clojure version of clj-pnm can work with files. To read a pnm file pass it to the read-pnm function:

(require '[clojure.java.io :as io])
=> nil

(slurp (io/file "test.pgm"))
=> P2
 3
 2
 4
 1 2 3
 4 5 6 ; prettified

(pnm/read-pnm (io/file "test.pgm"))
=> {:type :p2, :width 3, :height 2, :max-value 4, :map [[1 2 3] [4 5 6]]}

Writing a file is just a matter of passing a map like the ones explained above. It can include comments which are always written after the header part.

(pnm/write-pnm {:type :p1 :width 1 :height 1 :map [[1]]} "out.pbm")
=> ...out.pbm file...

(slurp *1)
=> "P1
 1
 1
 1" ;prettified

(pnm/write-pnm
{:type :p3 :width 1 :height 1 :max-value 255 :map [[1]] :comments '("A comment" "Another comment")}
"out.ppm")
=> ...out.ppm file...

(slurp *1)
=> "P3
 1
 1
 255
 # A comment
 # Another comment
 255 255 255" ; prettified

License

Copyright 2018-2023, Dejan Josifović, The Paranoid Times

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.