grokify/mogo

package imageutil

import (
    "image"
    "image/color"
    "os"

    "github.com/grokify/mogo/image/colors"
)

func ImageAspect(img image.Image) float64 {
    return Aspect(img.Bounds().Dx(), img.Bounds().Dy())
}

func Aspect(width, height int) float64 {
    return float64(width) / float64(height)
}

func NegativeOffset(width, height, offset uint) image.Point {
    return image.Pt(int(width-offset), int(height-offset))
}

func IsNilOrEmpty(img image.Image) bool {
    if img == nil || img.Bounds().Dx() == 0 || img.Bounds().Dy() == 0 {
        return true
    }
    return false
}

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

func NewImageMeta(img image.Image) ImageMeta {
    return ImageMeta{Image: img}
}

func (meta *ImageMeta) ColorAverage() color.Color {
    return colors.ColorAverageImage(meta.Image)
}

func RectanglePixelCount(r image.Rectangle) int {
    w := r.Dx()
    h := r.Dy()
    if w <= 0 || h <= 0 {
        return 0
    }
    return w * h
}

// ImageColors returns colors for an image covering the pixels
// described in `image.Rectangle`: https://pkg.go.dev/image#Rectangle
func ImageColors(img image.Image) [][]color.Color {
    rows := [][]color.Color{}
    minPt := img.Bounds().Min
    maxPt := img.Bounds().Max
    if minPt.X == maxPt.X || minPt.Y == maxPt.Y {
        return rows
    }
    for y := minPt.Y; y < maxPt.Y; y++ {
        row := []color.Color{}
        for x := minPt.X; x < maxPt.X; x++ {
            row = append(row, img.At(x, y))
        }
        rows = append(rows, row)
    }
    return rows
}

type ImageMetadata struct {
    Width  uint
    Height uint
}

func NewImageMetadata(img image.Image) ImageMetadata {
    return ImageMetadata{
        Width:  uint(img.Bounds().Dx()),
        Height: uint(img.Bounds().Dy())}
}