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输入

clone¶

Take a "snapshot" of the Sharp instance, returning a new instance. Cloned instances inherit the input of their parent instance. This allows multiple output Streams and therefore multiple processing pipelines to share a single input Stream.

示例

const pipeline = sharp().rotate();
pipeline.clone().resize(800, 600).pipe(firstWritableStream);
pipeline.clone().extract({ left: 20, top: 20, width: 100, height: 100 }).pipe(secondWritableStream);
readableStream.pipe(pipeline);
// firstWritableStream receives auto-rotated, resized readableStream
// secondWritableStream receives auto-rotated, extracted region of readableStream

返回 Sharp

metadata¶

Fast access to (uncached) image metadata without decoding any compressed image data. A Promises/A+ promise is returned when callback is not provided.

format: Name of decoder used to decompress image data e.g. jpeg, png, webp, gif, svg
width: Number of pixels wide
height: Number of pixels high
space: Name of colour space interpretation e.g. srgb, rgb, cmyk, lab, b-w ...
channels: Number of bands e.g. 3 for sRGB, 4 for CMYK
depth: Name of pixel depth format e.g. uchar, char, ushort, float ...
density: Number of pixels per inch (DPI), if present
hasProfile: Boolean indicating the presence of an embedded ICC profile
hasAlpha: Boolean indicating the presence of an alpha transparency channel
orientation: Number value of the EXIF Orientation header, if present
exif: Buffer containing raw EXIF data, if present
icc: Buffer containing raw ICC profile data, if present

参数

callback Function? called with the arguments (err, metadata)

示例

const image = sharp(inputJpg);
image
  .metadata()
  .then(function(metadata) {
    return image
      .resize(Math.round(metadata.width / 2))
      .webp()
      .toBuffer();
  })
  .then(function(data) {
    // data contains a WebP image half the width and height of the original JPEG
  });

返回 (Promise<Object> | Sharp)

stats¶

Access to pixel-derived image statistics for every channel in the image. A Promise is returned when callback is not provided.

channels: Array of channel statistics for each channel in the image. Each channel statistic contains
- min (minimum value in the channel)
- max (maximum value in the channel)
- sum (sum of all values in a channel)
- squaresSum (sum of squared values in a channel)
- mean (mean of the values in a channel)
- stdev (standard deviation for the values in a channel)
- minX (x-coordinate of one of the pixel where the minimum lies)
- minY (y-coordinate of one of the pixel where the minimum lies)
- maxX (x-coordinate of one of the pixel where the maximum lies)
- maxY (y-coordinate of one of the pixel where the maximum lies)
isOpaque: Value to identify if the image is opaque or transparent, based on the presence and use of alpha channel

参数

callback Function? called with the arguments (err, stats)

示例

const image = sharp(inputJpg);
image
  .stats()
  .then(function(stats) {
     // stats contains the channel-wise statistics array and the isOpaque value
  });

返回 Promise<Object>

limitInputPixels¶

Do not process input images where the number of pixels (width _ height) exceeds this limit. Assumes image dimensions contained in the input metadata can be trusted. The default limit is 268402689 (0x3FFF _ 0x3FFF) pixels.

参数

limit (Number | Boolean) an integral Number of pixels, zero or false to remove limit, true to use default limit.
Throws Error Invalid limit

返回 Sharp

sequentialRead¶

An advanced setting that switches the libvips access method to VIPS_ACCESS_SEQUENTIAL. This will reduce memory usage and can improve performance on some systems.

The default behaviour before function call is false, meaning the libvips access method is not sequential.

参数

sequentialRead Boolean (optional, default true)

返回 Sharp