images

package
v0.80.0 Latest Latest
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 Go to latest Published: Dec 31, 2020 License: Apache-2.0 Imports: 24 Imported by: 5

Documentation

Overview

Package images provides template functions for manipulating images.

Index

Constants

This section is empty.

Variables

This section is empty.

Functions

func AddColorToPalette added in v0.59.0 

func AddColorToPalette(c color.Color, p color.Palette) color.Palette

AddColorToPalette adds c as the first color in p if not already there. Note that it does no additional checks, so callers must make sure that the palette is valid for the relevant format.

func IsOpaque added in v0.59.0 

func IsOpaque(img image.Image) bool

IsOpaque returns false if the image has alpha channel and there is at least 1 pixel that is not (fully) opaque.

func ReplaceColorInPalette added in v0.59.0 

func ReplaceColorInPalette(c color.Color, p color.Palette)

ReplaceColorInPalette will replace the color in palette p closest to c in Euclidean R,G,B,A space with c.

func ToFilters 

func ToFilters(in interface{}) []gift.Filter

Types

type ExifConfig 

type ExifConfig struct {

	// Regexp matching the Exif fields you want from the (massive) set of Exif info
	// available. As we cache this info to disk, this is for performance and
	// disk space reasons more than anything.
	// If you want it all, put ".*" in this config setting.
	// Note that if neither this or ExcludeFields is set, Hugo will return a small
	// default set.
	IncludeFields string

	// Regexp matching the Exif fields you want to exclude. This may be easier to use
	// than IncludeFields above, depending on what you want.
	ExcludeFields string

	// Hugo extracts the "photo taken" date/time into .Date by default.
	// Set this to true to turn it off.
	DisableDate bool

	// Hugo extracts the "photo taken where" (GPS latitude and longitude) into
	// .Long and .Lat. Set this to true to turn it off.
	DisableLatLong bool
}

type Filters 

type Filters struct {
}

func (*Filters) Brightness 

func (*Filters) Brightness(percentage interface{}) gift.Filter

Brightness creates a filter that changes the brightness of an image. The percentage parameter must be in range (-100, 100).

func (*Filters) ColorBalance 

func (*Filters) ColorBalance(percentageRed, percentageGreen, percentageBlue interface{}) gift.Filter

ColorBalance creates a filter that changes the color balance of an image. The percentage parameters for each color channel (red, green, blue) must be in range (-100, 500).

func (*Filters) Colorize 

func (*Filters) Colorize(hue, saturation, percentage interface{}) gift.Filter

Colorize creates a filter that produces a colorized version of an image. The hue parameter is the angle on the color wheel, typically in range (0, 360). The saturation parameter must be in range (0, 100). The percentage parameter specifies the strength of the effect, it must be in range (0, 100).

func (*Filters) Contrast 

func (*Filters) Contrast(percentage interface{}) gift.Filter

Contrast creates a filter that changes the contrast of an image. The percentage parameter must be in range (-100, 100).

func (*Filters) Gamma 

func (*Filters) Gamma(gamma interface{}) gift.Filter

Gamma creates a filter that performs a gamma correction on an image. The gamma parameter must be positive. Gamma = 1 gives the original image. Gamma less than 1 darkens the image and gamma greater than 1 lightens it.

func (*Filters) GaussianBlur 

func (*Filters) GaussianBlur(sigma interface{}) gift.Filter

GaussianBlur creates a filter that applies a gaussian blur to an image.

func (*Filters) Grayscale 

func (*Filters) Grayscale() gift.Filter

Grayscale creates a filter that produces a grayscale version of an image.

func (*Filters) Hue 

func (*Filters) Hue(shift interface{}) gift.Filter

Hue creates a filter that rotates the hue of an image. The hue angle shift is typically in range -180 to 180.

func (*Filters) Invert 

func (*Filters) Invert() gift.Filter

Invert creates a filter that negates the colors of an image.

func (*Filters) Overlay added in v0.80.0 

func (*Filters) Overlay(src ImageSource, x, y interface{}) gift.Filter

Overlay creates a filter that overlays src at position x y.

func (*Filters) Pixelate 

func (*Filters) Pixelate(size interface{}) gift.Filter

Pixelate creates a filter that applies a pixelation effect to an image.

func (*Filters) Saturation 

func (*Filters) Saturation(percentage interface{}) gift.Filter

Saturation creates a filter that changes the saturation of an image.

func (*Filters) Sepia 

func (*Filters) Sepia(percentage interface{}) gift.Filter

Sepia creates a filter that produces a sepia-toned version of an image.

func (*Filters) Sigmoid 

func (*Filters) Sigmoid(midpoint, factor interface{}) gift.Filter

Sigmoid creates a filter that changes the contrast of an image using a sigmoidal function and returns the adjusted image. It's a non-linear contrast change useful for photo adjustments as it preserves highlight and shadow detail.

func (*Filters) UnsharpMask 

func (*Filters) UnsharpMask(sigma, amount, threshold interface{}) gift.Filter

UnsharpMask creates a filter that sharpens an image. The sigma parameter is used in a gaussian function and affects the radius of effect. Sigma must be positive. Sharpen radius roughly equals 3 * sigma. The amount parameter controls how much darker and how much lighter the edge borders become. Typically between 0.5 and 1.5. The threshold parameter controls the minimum brightness change that will be sharpened. Typically between 0 and 0.05.

type Format 

type Format int

Format is an image file format. 

const (
	JPEG Format = iota + 1
	PNG
	GIF
	TIFF
	BMP
)

func ImageFormatFromExt 

func ImageFormatFromExt(ext string) (Format, bool)

func (Format) DefaultExtension added in v0.59.0 

func (f Format) DefaultExtension() string

DefaultExtension returns the default file extension of this format, starting with a dot. For example: .jpg for JPEG

func (Format) MediaType added in v0.59.0 

func (f Format) MediaType() media.Type

MediaType returns the media type of this image, e.g. image/jpeg for JPEG

func (Format) RequiresDefaultQuality added in v0.59.0 

func (f Format) RequiresDefaultQuality() bool

RequiresDefaultQuality returns if the default quality needs to be applied to images of this format

func (Format) SupportsTransparency added in v0.59.0 

func (f Format) SupportsTransparency() bool

SupportsTransparency reports whether it supports transparency in any form.

type Image 

type Image struct {
	Format Format
	Proc   *ImageProcessor
	Spec   Spec
	// contains filtered or unexported fields
}

func NewImage 

func NewImage(f Format, proc *ImageProcessor, img image.Image, s Spec) *Image

func (*Image) EncodeTo 

func (i *Image) EncodeTo(conf ImageConfig, img image.Image, w io.Writer) error

func (*Image) Height 

func (i *Image) Height() int

Height returns i's height.

func (*Image) InitConfig added in v0.60.0 

func (i *Image) InitConfig(r io.Reader) error

InitConfig reads the image config from the given reader.

func (*Image) Width 

func (i *Image) Width() int

Width returns i's width.

func (Image) WithImage 

func (i Image) WithImage(img image.Image) *Image

func (Image) WithSpec 

func (i Image) WithSpec(s Spec) *Image

type ImageConfig 

type ImageConfig struct {
	// This defines the output format of the output image. It defaults to the source format
	TargetFormat Format

	Action string

	// If set, this will be used as the key in filenames etc.
	Key string

	// Quality ranges from 1 to 100 inclusive, higher is better.
	// This is only relevant for JPEG images.
	// Default is 75.
	Quality int

	// Rotate rotates an image by the given angle counter-clockwise.
	// The rotation will be performed first.
	Rotate int

	// Used to fill any transparency.
	// When set in site config, it's used when converting to a format that does
	// not support transparency.
	// When set per image operation, it's used even for formats that does support
	// transparency.
	BgColor    color.Color
	BgColorStr string

	Width  int
	Height int

	Filter    gift.Resampling
	FilterStr string

	Anchor    gift.Anchor
	AnchorStr string
}

ImageConfig holds configuration to create a new image from an existing one, resize etc.

func DecodeImageConfig 

func DecodeImageConfig(action, config string, defaults Imaging) (ImageConfig, error)

func (ImageConfig) GetKey 

func (i ImageConfig) GetKey(format Format) string

type ImageProcessor 

type ImageProcessor struct {
	Cfg ImagingConfig
	// contains filtered or unexported fields
}

func NewImageProcessor 

func NewImageProcessor(cfg ImagingConfig) (*ImageProcessor, error)

func (*ImageProcessor) ApplyFiltersFromConfig 

func (p *ImageProcessor) ApplyFiltersFromConfig(src image.Image, conf ImageConfig) (image.Image, error)

func (*ImageProcessor) DecodeExif 

func (p *ImageProcessor) DecodeExif(r io.Reader) (*exif.Exif, error)

func (*ImageProcessor) Filter 

func (p *ImageProcessor) Filter(src image.Image, filters ...gift.Filter) (image.Image, error)

func (*ImageProcessor) GetDefaultImageConfig 

func (p *ImageProcessor) GetDefaultImageConfig(action string) ImageConfig

type ImageSource added in v0.80.0 

type ImageSource interface {
	DecodeImage() (image.Image, error)
	Key() string
}

ImageSource identifies and decodes an image.

type Imaging 

type Imaging struct {
	// Default image quality setting (1-100). Only used for JPEG images.
	Quality int

	// Resample filter to use in resize operations..
	ResampleFilter string

	// The anchor to use in Fill. Default is "smart", i.e. Smart Crop.
	Anchor string

	// Default color used in fill operations (e.g. "fff" for white).
	BgColor string

	Exif ExifConfig
}

Imaging contains default image processing configuration. This will be fetched from site (or language) config.

type ImagingConfig added in v0.59.0 

type ImagingConfig struct {
	BgColor color.Color

	// Config as provided by the user.
	Cfg Imaging
}

func DecodeConfig 

func DecodeConfig(m map[string]interface{}) (ImagingConfig, error)

type Spec 

type Spec interface {
	// Loads the image source.
	ReadSeekCloser() (hugio.ReadSeekCloser, error)
}

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