Trivial-Thumbnail

About Trivial-Thumbnail

A tiny library to create thumbnails with ImageMagick. The binaries convert and mogrify need to be available on your system for this to work.

How To

The main function to use is create.

(thumbnail:create #p"~/input.png" #p"~/input-thumb.png")
=> #p"~/input-thumb.png"

Of course it allows for different kinds of thumbnail generation with the crop argument:

(thumbnail:create #p"~/input.png" #p"~/input-thumb.png" :crop :WIDTH)
(thumbnail:create #p"~/input.png" #p"~/input-thumb.png" :crop :HEIGHT)
(thumbnail:create #p"~/input.png" #p"~/input-thumb.png" :crop T)

Using :WIDTH means that the image is first scaled down preserving the aspect ratio to fit into the given height and then crops the remaining width to fit the given width. :HEIGHT works similarly. T just crops the image without any scaling.

This library uses ImageMagick mostly because it can handle gif animations properly, which a lot of other tools cannot. Processing animation is calculation-intensive though, so if you want to disable that (resulting in a static gif), you can pass :preserve-gif NIL.

Trivial-Thumbnail attempts to locate the necessary binaries automatically, searching the usual paths such as /usr/bin, /usr/local/bin and C:/windows/system32/, C:/Program Files/ImageMagick*/. If it fails to find a suitable binary, it throws a warning at startup. When the binary is somewhere else, but still within your PATH, it should still work properly. Otherwise you will have to set *CONVERT-BIN* and *MOGRIFY-BIN* yourself.

Copyright

trivial-thumbnail is licensed under the Artistic license. © Nicolas Hafner <shinmera@tymoon.eu> . This library can be obtained on https://github.com/Shinmera/trivial-thumbnail.

Package Index

TRIVIAL-THUMBNAIL (ORG.TYMOONNEXT.TRIVIAL-THUMBNAIL THUMBNAIL)

special

`CONVERT-BIN`

String or pathname designating the location of the imagemagick CONVERT binary.

special

`MOGRIFY-BIN`

String or pathname designating the location of the imagemagick MOGRIFY binary.

function (

`CONVERT`

IN OUT &REST ARGS)

Runs imagemagick's CONVERT on IN with the result to OUT using the command-line ARGS.

function (

`CREATE`

IN OUT &KEY (WIDTH 150) (HEIGHT 150) CROP (QUALITY 100) (PRESERVE-GIF T)
 (IF-EXISTS :ERROR)

)

Creates a thumbnail of IN with the result to OUT.

IN           --- A pathname or string to the source image. Strings are parsed using 
                 UIOP:PARSE-NATIVE-NAMESTRING.
OUT          --- A pathname or string to the source image or NIL. If NIL, OUT is the
                 same as IN, with 'thumb-' prefixed to the pathname-name.
WIDTH        --- The width of the thumbnail in pixels.
HEIGHT       --- The height of the thumbnail in pixels.
CROP         --- How to create the thumbnail. Can be one of the following:
                 NIL     Scale the image, preserving the aspect ratio.
                 :WIDTH  Scale the image to HEIGHT and crop the width down to fit WIDTH.
                 :HEIGHT Scale the image to WIDTH and crop the height down to fit HEIGHT.
                 T       Crop the image width and height to fit WIDTH and HEIGHT.
QUALITY      --- Percentage for the quality to use (0-100).
PRESERVE-GIF --- Whether to run imagemagick with -coalesce, which preserves
                 GIF animations, but will take more time to compute.
IF-EXISTS    --- What to do if OUT exists. Can be one of the following:
                 NIL        Don't create a thumbnail and just return NIL.
                 :ERROR     Signal an error.
                 :WARN      Signal a warning.
                 :SUPERSEDE Overwrite the file.

Returns OUT.

function (

`MOGRIFY`

IN &REST ARGS)

Runs imagemagick's MOGRIFY on IN using the command-line ARGS.