imageutil

Documentation

Index

• Constants
• func AddBackgroundColor(imgSrc image.Image, clr color.Color) image.Image
• func AddBackgroundWhite(imgSrc image.Image) image.Image
• func Aspect(width, height int) float64
• func ImageAnyToRGBA(src image.Image) *image.RGBA
• func ImageAspect(img image.Image) float64
• func ImageToRGBA(img image.Image) *image.RGBA
• func ImageWithSetToRGBA(src ImageWithSet) *image.RGBA
• func IsImageExt(imagePath string) bool
• func MergeHorizontalRGBA(ims ImageMetaSet) image.Image
• func NRGBAtoRGBA(imgNRGBA *image.NRGBA) *image.RGBA
• func NegativeOffset(width, height, offset uint) image.Point
• func OverlayCenterYLeftAlign(imgBg, imgOver image.Image) image.Image
• func PaintBorderRGBA(img *image.RGBA, clr color.RGBA, width uint)
• func PaintColorRGBA(img *image.RGBA, clr color.RGBA)
• func PaintColorRGBARectangle(img *image.RGBA, clr color.RGBA, rectNew image.Rectangle)
• func ParseScaler(rawInterpolation string) (draw.Scaler, error)
• func ReadImageAny(s string) (image.Image, string, error)
• func ReadImageDimensions(imagePath string) (int, int, error)
• func ReadImageFile(filename string) (image.Image, string, error)
• func ReadImageHttp(imageUrl string) (image.Image, string, error)
• func RectangleBorderXMax(rect image.Rectangle, pixels uint) image.Rectangle
• func RectangleBorderXMin(rect image.Rectangle, pixels uint) image.Rectangle
• func RectangleBorderYMax(rect image.Rectangle, pixels uint) image.Rectangle
• func RectangleBorderYMin(rect image.Rectangle, pixels uint) image.Rectangle
• func Resize(width, height uint, src image.Image, scale draw.Scaler) image.Image
• func ResizeMaxDimension(maxSide uint, src image.Image, scale draw.Scaler) image.Image
• func Scale(src image.Image, rect image.Rectangle, scale draw.Scaler) image.Image
• func ScalerBest() draw.Scaler
• func ScalerDefault() draw.Scaler
• func Square(src image.Image) image.Image
• func WriteFileJPEG(filename string, img image.Image, quality int) error
• func WriteFilePNG(filename string, img image.Image) error
• func YCbCrToRGBA(src *image.YCbCr) *image.RGBA
• type ImageMeta
• type ImageMetaSet
  • func NewImageSetFiles(filenames []string) (ImageMetaSet, error)
  • func (ims *ImageMetaSet) CloseFilesAll() error
  • func (ims *ImageMetaSet) MaxX() int
  • func (ims *ImageMetaSet) MaxY() int
  • func (ims *ImageMetaSet) Stats() ImageStatsMulti
  • func (ims *ImageMetaSet) SumX(maxIndexInclusive int) int
  • func (ims *ImageMetaSet) SumY(maxIndexInclusive int) int
• type ImageStatsMulti
• type ImageWithSet

Constants

const (
	JPEGQualityDefault int = 80
	JPEGQualityMax     int = 100
)

Functions

func AddBackgroundColor

func AddBackgroundColor(imgSrc image.Image, clr color.Color) image.Image

AddBackgroundColor adds a background of `color.Color` to an image. It is is useful when the image has a transparent background.

func AddBackgroundWhite

func AddBackgroundWhite(imgSrc image.Image) image.Image

AddBackgroundWhite adds a white background which is usable when the image has a transparent background.

func Aspect

func Aspect(width, height int) float64

func ImageAnyToRGBA

func ImageAnyToRGBA(src image.Image) *image.RGBA

func ImageAspect

func ImageAspect(img image.Image) float64

func ImageToRGBA

func ImageToRGBA(img image.Image) *image.RGBA

func ImageWithSetToRGBA

func ImageWithSetToRGBA(src ImageWithSet) *image.RGBA

func IsImageExt

func IsImageExt(imagePath string) bool

func MergeHorizontalRGBA

func MergeHorizontalRGBA(ims ImageMetaSet) image.Image

MergeHorizontalRGBA returns an image that is composed of non-overlapping imagers in ImageMetaSet. The code here is adapted from https://stackoverflow.com/a/35965499/1908967

func NRGBAtoRGBA

func NRGBAtoRGBA(imgNRGBA *image.NRGBA) *image.RGBA

func NegativeOffset

func NegativeOffset(width, height, offset uint) image.Point

func OverlayCenterYLeftAlign

func OverlayCenterYLeftAlign(imgBg, imgOver image.Image) image.Image

func PaintBorderRGBA

func PaintBorderRGBA(img *image.RGBA, clr color.RGBA, width uint)

func PaintColorRGBA

func PaintColorRGBA(img *image.RGBA, clr color.RGBA)

func PaintColorRGBARectangle

func PaintColorRGBARectangle(img *image.RGBA, clr color.RGBA, rectNew image.Rectangle)

func ParseScaler

func ParseScaler(rawInterpolation string) (draw.Scaler, error)

func ReadImageAny

func ReadImageAny(s string) (image.Image, string, error)

func ReadImageDimensions

func ReadImageDimensions(imagePath string) (int, int, error)

func ReadImageFile

func ReadImageFile(filename string) (image.Image, string, error)

func ReadImageHttp

func ReadImageHttp(imageUrl string) (image.Image, string, error)

func RectangleBorderXMax

func RectangleBorderXMax(rect image.Rectangle, pixels uint) image.Rectangle

func RectangleBorderXMin

func RectangleBorderXMin(rect image.Rectangle, pixels uint) image.Rectangle

func RectangleBorderYMax

func RectangleBorderYMax(rect image.Rectangle, pixels uint) image.Rectangle

func RectangleBorderYMin

func RectangleBorderYMin(rect image.Rectangle, pixels uint) image.Rectangle

func Resize

func Resize(width, height uint, src image.Image, scale draw.Scaler) image.Image

Resize scales an image to the provided size units. Use a 0 to scale the aspect ratio. See gitub.com/nfnt/resize for Lanczos3, etc. https://github.com/nfnt/resize .

func ResizeMaxDimension

func ResizeMaxDimension(maxSide uint, src image.Image, scale draw.Scaler) image.Image

func Scale

func Scale(src image.Image, rect image.Rectangle, scale draw.Scaler) image.Image

Scale will resize the image to the provided rectangle using the provided interpolation function.

func ScalerBest

func ScalerBest() draw.Scaler

func ScalerDefault

func ScalerDefault() draw.Scaler

ScalerDefault returns a general best results interpolation algorithm. See more here https://blog.codinghorror.com/better-image-resizing/ , https://support.esri.com/en/technical-article/000005606 , https://stackoverflow.com/questions/384991/what-is-the-best-image-downscaling-algorithm-quality-wise/6171860 .

func Square

func Square(src image.Image) image.Image

func WriteFileJPEG

func WriteFileJPEG(filename string, img image.Image, quality int) error

func WriteFilePNG

func WriteFilePNG(filename string, img image.Image) error

func YCbCrToRGBA

func YCbCrToRGBA(src *image.YCbCr) *image.RGBA

Types

type ImageMeta

type ImageMeta struct {
	File       *os.File
	FormatName string
	Image      image.Image
}

type ImageMetaSet

type ImageMetaSet struct {
	ImageMetas []ImageMeta
}

func NewImageSetFiles

func NewImageSetFiles(filenames []string) (ImageMetaSet, error)

func (*ImageMetaSet) CloseFilesAll

func (ims *ImageMetaSet) CloseFilesAll() error

func (*ImageMetaSet) MaxX

func (ims *ImageMetaSet) MaxX() int

func (*ImageMetaSet) MaxY

func (ims *ImageMetaSet) MaxY() int

func (*ImageMetaSet) Stats

func (ims *ImageMetaSet) Stats() ImageStatsMulti

func (*ImageMetaSet) SumX

func (ims *ImageMetaSet) SumX(maxIndexInclusive int) int

func (*ImageMetaSet) SumY

func (ims *ImageMetaSet) SumY(maxIndexInclusive int) int

type ImageStatsMulti

type ImageStatsMulti struct {
	MaxX int
	SumX int
	MaxY int
	SumY int
}

type ImageWithSet

type ImageWithSet interface {
	// ColorModel returns the Image's color model.
	ColorModel() color.Model
	// Bounds returns the domain for which At can return non-zero color.
	// The bounds do not necessarily contain the point (0, 0).
	Bounds() image.Rectangle
	// At returns the color of the pixel at (x, y).
	// At(Bounds().Min.X, Bounds().Min.Y) returns the upper-left pixel of the grid.
	// At(Bounds().Max.X-1, Bounds().Max.Y-1) returns the lower-right one.
	At(x, y int) color.Color
	Set(x, y int, c color.Color)
}