magick-rust/README.md

# magick-rust

A somewhat safe Rust interface to the [ImageMagick](http://www.imagemagick.org/) system, in particular, the MagickWand library. Many of the functions in the MagickWand API are still missing, but over time more will be added. Pull requests are welcome.

## Dependencies

* Rust stable
* ImageMagick (version 7.0.x)
    - Does _not_ work with ImageMagick 6.x due to backward incompatible changes.
    - [FreeBSD](https://www.freebsd.org): `sudo pkg install ImageMagick7`
    - [Homebrew](http://brew.sh): `brew install imagemagick`
    - Linux may require building ImageMagick from source, see the `Dockerfile` for an example
    - Windows: download `*-dll` [installer](https://www.imagemagick.org/script/download.php#windows). Only MSVC version available. When installing, check the checkbox "Install development headers and libraries for C and C++".
* [Clang](https://clang.llvm.org) (version 3.5 or higher)
    - Or whatever version is dictated by [rust-bindgen](https://github.com/rust-lang/rust-bindgen)
* Windows requires MSVC toolchain
* Optionally `pkg-config`, to facilitate linking with ImageMagick. Or you can set linker parameters via environment variables.

## Build and Test

Pretty simple for now.

```shell
$ cargo build
$ cargo test
```

Optionally you can set some environment variables before building:
* `IMAGE_MAGICK_DIR` - installation directory of ImageMagick
* `IMAGE_MAGICK_LIB_DIRS` - list of lib directories split by `:`
* `IMAGE_MAGICK_INCLUDE_DIRS` - list of include directories split by `:`
* `IMAGE_MAGICK_LIBS` - list of the libs to link to

### Build on Windows

On Windows you will need to launch build in Visual Studio Native Tools Command Prompt.
It can be found in *Start menu -> Visual Studio < VERSION > -> Visual Studio Tools -> Windows Desktop Command Prompts*.
Choose the architecture corresponding to architecture of your rust compiler.
This is required for the proper functioning of `rust-bindgen`.

```shell
> set IMAGE_MAGICK_DIR=<path to ImageMagick installation directory>
> cargo build
> cargo test
```

## Example Usage

MagickWand has some global state that needs to be initialized prior to using the library, but fortunately Rust makes handling this pretty easy. In the example below, we read in an image from a file and resize it to fit a square of 240 by 240 pixels, then convert the image to JPEG.

```rust
use magick_rust::{MagickWand, magick_wand_genesis};
use std::sync::Once;

// Used to make sure MagickWand is initialized exactly once. Note that we
// do not bother shutting down, we simply exit when we're done.
static START: Once = Once::new();

fn resize() -> Result<Vec<u8>, &'static str> {
    START.call_once(|| {
        magick_wand_genesis();
    });
    let wand = MagickWand::new();
    try!(wand.read_image("kittens.jpg"));
    wand.fit(240, 240);
    wand.write_image_blob("jpeg")
}
```

Writing the image to a file rather than an in-memory blob is done by replacing the call to `write_image_blob()` with `write_image()`, which takes a string for the path to the file.

## Frequent API Changes

Because rust-bindgen changes from time to time, and is very difficult to use for a library as large as ImageMagick, the API of this crate may experience dramatic mood swings. Typically this pain manifests itself in the way the enums are represented. I am deeply sorry for this pain. Hopefully someone smarter than me can fix it some day. Pull requests are welcome.

## Contributing

There are still many missing functions, so if you find there is something you would like to see added to this library, feel free to file an issue. Even better, fork the repo, and write the thin wrapper necessary to expose the MagickWand function. For getters and setters this is often very easy, just add a row to the table in `wand/magick.rs`, and it will work with no additional coding. Tests are optional, as this crate is basically a thin wrapper around code that is assumed to be thoroughly tested already. If you make a change that you want to contribute, please feel free to submit a pull request.

## Docker

[Docker](https://www.docker.com) can be used to build and test the code without affecting your development environment, which may have a different version of ImageMagick installed. The use of `docker-compose`, as shown in the example below, is optional, but it makes the process very simple.

```shell
$ cd docker
$ docker-compose build
$ docker-compose run magick-rust
$ cargo clean
$ cargo build
$ cargo test
```