README
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go-blurhash 
A pure Go implementation of Blurhash. The API is stable, however the hashing function in either direction may not be.
Blurhash is an algorithm written by Dag Ågren for Wolt (woltapp/blurhash) that encodes an image into a short (~20-30 byte) ASCII string. When you decode the string back into an image, you get a gradient of colors that represent the original image. This can be useful for scenarios where you want an image placeholder before loading, or even to censor the contents of an image a la Mastodon.
Notable features
- Pure Go with no dependencies
- High performance (as of v1.2)
- Reusable
Encoder/DecoderAPIs for zero-allocation batch processing
Contributing
Issues, feature requests or improvements welcome!
Licence
This project is licensed under the MIT License.
Documentation
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Overview ¶
Package blurhash provides encoding and decoding of Blurhash image placeholders.
Blurhash is an algorithm that encodes an image into a short ASCII string representing a gradient of colors. When decoded, this string produces a blurred placeholder that approximates the original image's colors and structure.
For simple one-off operations, use the package-level Encode and Decode functions. For batch processing with reduced allocations, use the reusable Encoder and Decoder types.
Index ¶
- Variables
- func Components(hash string) (x, y int, err error)
- func Decode(hash string, width, height int, punch int) (image.Image, error)
- func DecodeDraw(dst draw.Image, hash string, punch float64) error
- func Encode(xComponents, yComponents int, img image.Image) (string, error)
- type Decoder
- type Encoder
Constants ¶
This section is empty.
Variables ¶
var ( // ErrInvalidComponents is returned when components passed to Encode are invalid. ErrInvalidComponents = errors.New("blurhash: must have between 1 and 9 components") // ErrInvalidHash is returned when the library encounters a hash it can't recognise. ErrInvalidHash = errors.New("blurhash: invalid hash") // ErrInvalidDimensions is returned when width or height is invalid. ErrInvalidDimensions = errors.New("blurhash: width and height must be positive") )
Functions ¶
func Components ¶
Components returns the X and Y components of a blurhash.
func DecodeDraw ¶
DecodeDraw decodes the given hash into the given image.
Types ¶
type Decoder ¶ added in v1.2.0
type Decoder struct {
// contains filtered or unexported fields
}
Decoder is a reusable blurhash decoder that minimizes allocations by reusing internal buffers across decode operations.
A Decoder is safe for sequential use but not for concurrent use. For concurrent workloads, use a sync.Pool of Decoders.
The zero value is ready to use.
func NewDecoder ¶ added in v1.2.0
func NewDecoder() *Decoder
NewDecoder creates a new reusable Decoder. Buffers are allocated lazily on first use and grown as needed.
type Encoder ¶ added in v1.2.0
type Encoder struct {
// contains filtered or unexported fields
}
Encoder is a reusable blurhash encoder that minimizes allocations by reusing internal buffers across encode operations.
An Encoder is safe for sequential use but not for concurrent use. For concurrent workloads, use a sync.Pool of Encoders.
The zero value is ready to use.
func NewEncoder ¶ added in v1.2.0
func NewEncoder() *Encoder
NewEncoder creates a new reusable Encoder. Buffers are allocated lazily on first use and grown as needed.
Source Files
Directories