Go Imagick

Go Imagick is a Go bind to ImageMagick's MagickWand C API.

We support two compatibility branches:

im-7   (tag v3.x.x): 7.x     <= ImageMagick <= 7.x
master (tag v2.x.x): 6.9.1-7 <= ImageMagick <= 6.9.9-35
legacy (tag v1.x.x): 6.7.x   <= ImageMagick <= 6.8.9-10

They map, respectively, through gopkg.in:

gopkg.in/gographics/imagick.v3/imagick
gopkg.in/gographics/imagick.v2/imagick
gopkg.in/gographics/imagick.v1/imagick

Install

Docker

See examples/docker

Mac OS X

brew install imagemagick

Ubuntu / Debian

sudo apt-get install libmagickwand-dev

Windows

Thanks @vprus

Install msys2-x86_64
In msys shell, do:

pacman -Syuu
pacman -S mingw-w64-x86_64-gcc
pacman -S mingw-w64-x86_64-pkg-config
pacman -S mingw-w64-x86_64-zlib
pacman -S mingw-w64-x86_64-imagemagick

Switch to cmd.exe shell, and do:

set PATH=<msys64>\mingw64\bin;%PATH%
set PKG_CONFIG_PATH=<msys64>\mingw64\lib\pkgconfig
set MAGICK_CODER_MODULE_PATH=<msys64>\mingw64\lib\ImageMagick-7.0.6\modules-Q16HDRI\coders
go build gopkg.in/gographics/imagick.v3/imagick

The default installation path of msys2 is C:\msys64 and you must change <msys64> to your installation path of msys2.

The MAGICK_CODER_MODULE_PATH environment variable tells ImageMagick where to find the decoders. If you still get the NoDecodeDelegateForThisImageFormat error, then make sure the version number and folders are correct.

Common

Check if pkg-config is able to find the right ImageMagick include and libs:

pkg-config --cflags --libs MagickWand

Then go get it:

go get gopkg.in/gographics/imagick.v2/imagick

Per the security update https://groups.google.com/forum/#!topic/golang-announce/X7N1mvntnoU you may need whitelist the -Xpreprocessor flag in your environment.

export CGO_CFLAGS_ALLOW='-Xpreprocessor'

Build tags

If you want to specify CGO_CFLAGS/CGO_LDFLAGS manually at build time, such as for building statically or without pkg-config, you can use the "no_pkgconfig" build tag:

go build -tags no_pkgconfig gopkg.in/gographics/imagick.v2/imagick

Examples

The examples folder is full with usage examples ported from C ones found in here: http://www.imagemagick.org/MagickWand/

Quick and partial example

package main

import "gopkg.in/gographics/imagick.v2/imagick"

func main() {
    imagick.Initialize()
    defer imagick.Terminate()

    mw := imagick.NewMagickWand()

    ...
}

`Initialize()` and `Terminate`

As per the ImageMagick C API, Initialize() should be called only once to set up the resources for using ImageMagick. This is typically done in your main() or init() for the entire application or library. Applications can defer a call to Terminate() to tear down the ImageMagick resources.

It is an error to Initialize and Terminate multiple times in specific functions and leads to common problems such as crashes or missing delegates. Do not use Terminate anywhere other than the absolute end of your need for ImageMagick within the program.

Managing memory

Since this is a CGO binding, and the Go GC does not manage memory allocated by the C API, it is then necessary to use the Terminate() and Destroy() methods.

Types which are created via New* constructors (MagickWand, DrawingWand, PixelIterator, PixelWand,...), or created and returned by methods like Clone() are managed by Go GC through the use of finalizers. They are not guaranteed to be cleaned up immediately after the object is not longer in use, but rather at some point later when GC actually executes its finalizers.

If you use struct literals, you should free resources manually:

package main

import "github.com/gographics/imagick/imagick"

func main() {
    imagick.Initialize()
    defer imagick.Terminate()

    mw := imagick.MagickWand{...}
    defer mw.Destroy()

    ...
}

Both methods are compatible if constructor methods used:

package main

import "github.com/gographics/imagick/imagick"

func main() {
    imagick.Initialize()
    defer imagick.Terminate()

    mw := imagick.NewMagickWand()
    defer mw.Destroy()

    ...
}

But you should NOT mix two ways of object creation:

package main

import "github.com/gographics/imagick/imagick"

func main() {
    imagick.Initialize()
    defer imagick.Terminate()

    mw1 := imagick.MagickWand{...}
    defer mw1.Destroy()

    mw2 := imagick.NewMagickWand()

    ...
}

Calling Destroy() on types that are either created via New* or returned from other functions calls forces the cleanup of the item immediately as opposed to later after garbage collection triggers the finalizer for the object. It would be good practice to explicitly call Destroy() to ensure C memory is freed sooner rather than later, depending on how often the GC is triggered.

License

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.
Neither the name of the organization nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL HERBERT G. FISCHER BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

gographics/imagick