twebp

native module that libwebp for nodejs without memory leaking.

Installation

$3

``
yum install libpng-devel libjpeg-turbo-devel libwebp-devel -y
`

$3


`
brew install webp libpng jpeg
`

API Reference

$3

Get outline from buffer of webp.

* buffer: image buffer of webp.

The method returns an object similar to:

``json
{
"width": 100,
"height": 200,
"has_alpha": 0
}
``

$3

$3

Translate to webp format from Jpeg or Png

* buffer: image buffer of Jpeg or Png.
* options: see blow

$3

$3

Translate to webp format from Jpeg or Png,

This method uses more memory than sync method but doesn't block loop event.

- buffer: image buffer of Jpeg or Png.
- options: see blow




$3

`c++
int lossless; // Lossless encoding (0=lossy(default), 1=lossless).
float quality; // between 0 (smallest file) and 100 (biggest)
// default value is 75.
int method; // quality/speed trade-off (0=fast, 6=slower-better)

// Parameters related to lossy compression only:
int target_size; // if non-zero, set the desired target size in bytes.
// Takes precedence over the 'compression' parameter.
float target_PSNR; // if non-zero, specifies the minimal distortion to
// try to achieve. Takes precedence over target_size.
int segments; // maximum number of segments to use, in [1..4]
int sns_strength; // Spatial Noise Shaping. 0=off, 100=maximum.
int filter_strength; // range: [0 = off .. 100 = strongest]
int filter_sharpness; // range: [0 = off .. 7 = least sharp]
int filter_type; // filtering type: 0 = simple, 1 = strong (only used
// if filter_strength > 0 or autofilter > 0)
int autofilter; // Auto adjust filter's strength [0 = off, 1 = on]
int alpha_compression; // Algorithm for encoding the alpha plane (0 = none,
// 1 = compressed with WebP lossless). Default is 1.
int alpha_filtering; // Predictive filtering method for alpha plane.
// 0: none, 1: fast, 2: best. Default if 1.
int alpha_quality; // Between 0 (smallest size) and 100 (lossless).
// Default is 100.
int pass; // number of entropy-analysis passes (in [1..10]).

int show_compressed; // if true, export the compressed picture back.
// In-loop filtering is not applied.
int preprocessing; // preprocessing filter:
// 0=none, 1=segment-smooth, 2=pseudo-random dithering
int partitions; // log2(number of token partitions) in [0..3]. Default
// is set to 0 for easier progressive decoding.
int partition_limit; // quality degradation allowed to fit the 512k limit
// on prediction modes coding (0: no degradation,
// 100: maximum possible degradation).
int emulate_jpeg_size; // If true, compression parameters will be remapped
// to better match the expected output size from
// JPEG compression. Generally, the output size will
// be similar but the degradation will be lower.
int thread_level; // If non-zero, try and use multi-threaded encoding.
int low_memory; // If set, reduce memory usage (but increase CPU use).

int near_lossless; // Near lossless encoding [0 = max loss .. 100 = off
// (default)].
int exact; // if non-zero, preserve the exact RGB values under
// transparent area. Otherwise, discard this invisible
// RGB information for better compression. The default
// value is 0.

int use_delta_palette; // reserved for future lossless feature
int use_sharp_yuv; // if needed, use sharp (and slow) RGB->YUV conversion
``