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@ -7,155 +7,35 @@ Rust, with a C interface.
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> starting from v0.6.0 the library is written in Rust and no longer in C. There's a C interface, but it's not backward
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> compatible with the <0.6.0.
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## Usage in Rust
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## Usage example
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Libcaesium exposes two functions, auto-detecting the input file type
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### Based on quality values
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```Rust
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pub fn compress(
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input_path: String,
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output_path: String,
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parameters: &CSParameters
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) -> Result<(), Box<dyn Error>>
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use caesium::parameters::CSParameters;
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use caesium::compress;
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let mut parameters = CSParameters::new();
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parameters.keep_metadata = true;
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parameters.jpeg.quality = 60;
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let success = compress(input, output, ¶meters).is_ok();
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```
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#### Parameters
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## Compilation
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- `input_path` - input file path (full filename)
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- `output_path` - output file path (full filename)
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- `parameters` - options struct, containing compression parameters (see below)
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Compilation is available for all supported platforms: Windows, macOS and Linux.
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### Based on output size
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> [!NOTE]
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> if you don't use the `--release` flag, the PNG optimizations can take a very long time to complete, especially
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> using the zopfli algorithm.
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>
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```Rust
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pub fn compress_to_size(
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input_path: String,
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output_path: String,
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parameters: &CSParameters,
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max_output_size: usize,
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) -> Result<(), Box<dyn Error>>
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```bash
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cargo build --release
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```
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#### Parameters
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- `input_path` - input file path (full filename)
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- `output_path` - output file path (full filename)
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- `parameters` - options struct, containing compression parameters (see below)
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- `max_output_size` - the maximum output size, in bytes
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This function will attempt to compress the given file *below* the desired size. It will never exceed it. The function
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will start looping until the best size under the desired is achieved. The function has a 2% tolerance for the output
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size.
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All quality value set to the parameters will be ignored and overwritten during the compression.
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NOTE: The output folder where the file is compressed **must** exist.
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### Compression options
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Libcaesium supports a few compression parameters for each file it supports.
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They are defined into a top level struct containing each supported file parameters, as follows:
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```Rust
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pub struct CSParameters {
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pub jpeg: jpeg::Parameters,
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pub png: png::Parameters,
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pub gif: gif::Parameters,
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pub webp: webp::Parameters,
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pub tiff: tiff::Parameters,
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pub keep_metadata: bool,
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pub optimize: bool,
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pub width: u32,
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pub height: u32,
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}
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```
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Each file type has its own options, but the last two are generic:
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- `keep_metadata`: will keep metadata information for any supported type. JPEG and PNG supported. Default `false`.
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- `optimize`: forces optimization, when available. With this option enabled the compression will be lossless. JPEG, PNG
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and WebP supported. Default `false`.
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- `width`: Resizes the image to the given width. If this value is `0` and the height value is also `0`, no resizing will
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be done. If this is `0` and height is `> 0`, the image will be scaled based on height keeping the aspect ratio.
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Default `0`.
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- `height`: Resizes the image to the given height. If this value is `0` and the width value is also `0`, no resizing
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will be done. If this is `0` and width is `> 0`, the image will be scaled based on width keeping the aspect ratio.
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Default `0`.
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#### jpeg
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```Rust
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pub struct Parameters {
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pub quality: u32,
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pub chroma_subsampling: jpeg::ChromaSubsampling,
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pub progressive: bool
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}
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```
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- `quality`: in a range from 0 to 100, the quality of the resulting image. Default `80`.
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- `chroma_subsampling`: [chroma subsampling](https://en.wikipedia.org/wiki/Chroma_subsampling) to apply during
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compression. Default `Auto`.
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- `progressive`: outputs a progressive image (recommended). Set to `false` for baseline. Default `true`.
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#### png
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```Rust
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pub struct Parameters {
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pub quality: u32,
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pub force_zopfli: bool,
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pub optimization_level: u32
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}
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```
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- `quality`: in a range from 0 to 100, the quality of the resulting image. Default `80`.
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- `force_zopfli`: if `optimization` is `true` and this option is also `true`, will use zopfli algorithm for compression,
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resulting in a smaller image, but it may take minutes to finish the process. Default `false`.
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- `optimization_level`: if `optimization` is `true` will set the level of oxipng optimization, from 0 to 6. Default `3`.
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#### gif
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GIF support is experimental, has many know issues and does not support optimization. Expect bugs (especially on
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Windows).
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```Rust
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pub struct Parameters {
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pub quality: u32,
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}
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```
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- `quality`: in a range from 0 to 100, the quality of the resulting image. If the optimization flag is `true`, the level
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is set to `100`. Default: `80`.
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#### webp
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WebP's compression is tricky. The format is already well optimized and using the `optimize` flag will probably result in
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a bigger image.
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```Rust
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pub struct Parameters {
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pub quality: u32,
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}
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```
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- `quality`: in a range from 0 to 100, the quality of the resulting image. If the optimization flag is `true`, this
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option will be ignored. Default: `60`.
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#### tiff
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Supported TIFF compression is only lossless. The supported algorithms are: Lzw, Deflate, Packbits, Uncompressed.
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```Rust
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pub struct Parameters {
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pub algorithm: TiffCompression,
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pub deflate_level: TiffDeflateLevel,
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}
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```
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- `algorithm`: supported algorithms are: Lzw, Deflate, Packbits, Uncompressed.
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- `deflate_level`: can be one of `Fast`, `Balanced`, `Best`.
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_________________
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The result will be a dynamic library usable by external applications through its C interface.
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## Usage in C
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@ -248,39 +128,20 @@ pub struct CCSParameters {
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}
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```
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The option description is the same as the Rust counterpart.
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Valid values for `jpeg_chroma_subsampling` are [444, 422, 420, 411]. Any other value will be ignored and will be used
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the default option.
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Valid values for `tiff_compression` are [0 (Uncompressed), 1 (Lzw), 2 (Deflate), 3 (Packbits)]. Any other value will be
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ignored and `0` will be used.
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Valid values for `tiff_deflate_level` are [1 (Fast), 6 (Balanced), 9 (Best)]. Any other value will be ignored and `Best`
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The option description is the same as the Rust counterpart.
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Valid values for `jpeg_chroma_subsampling` are `[444, 422, 420, 411]`. Any other value will be ignored and will be used
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the default option.
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Valid values for `tiff_compression` are `[0 (Uncompressed), 1 (Lzw), 2 (Deflate), 3 (Packbits)]`. Any other value will be
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ignored and `0` will be used.
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Valid values for `tiff_deflate_level` are `[1 (Fast), 6 (Balanced), 9 (Best)]`. Any other value will be ignored and `Best`
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will be used.
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## Download
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Binaries not available. Please refer to the compilation section below.
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## Compilation and Installation
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Compilation is available for all supported platforms: Windows, macOS and Linux.
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```
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cargo build --release
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```
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Note: if you don't use the `--release` flag, the PNG optimizations can take a very long time to complete, especially
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using the zopfli algorithm.
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The result will be a dynamic library usable by external applications through its C interface.
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## Compression vs Optimization
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JPEG is a lossy format: that means you will always lose some information after each compression. So, compressing a file
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with
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100 quality for 10 times will result in an always different image, even though you can't really see the difference.
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with 100 quality for 10 times will result in an always different image, even though you can't really see the difference.
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Libcaesium also supports optimization, by setting the _quality_ to 0. This performs a lossless process, resulting in the
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same image,
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but with a smaller size (10-12% usually).
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same image, but with a smaller size (10-12% usually).
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GIF optimization is possible, but currently not supported.
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WebP's optimization is also possible, but it will probably result in a bigger output file as it's well suited to
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losslessly convert from PNG or JPEG.
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