grokify/mogo

package padding

import (
    "image"
    "image/color"
    "image/draw"

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

type IsPaddingFunc func(c color.Color) bool

func CreateIsPaddingFuncSimple(paddingColor color.Color) func(testColor color.Color) bool {
    return func(testColor color.Color) bool {
        return colors.Equal(paddingColor, testColor)
    }
}

func AddPaddingUniform(im image.Image, paddingWidth uint, paddingColor color.Color) image.Image {
    out := image.NewRGBA(image.Rect(0, 0, im.Bounds().Dx()+int(2*paddingWidth), im.Bounds().Dy()+int(2*paddingWidth)))
    draw.Draw(out, out.Bounds(), &image.Uniform{paddingColor}, image.Point{}, draw.Src)
    draw.Draw(out, image.Rect(
        int(paddingWidth),
        int(paddingWidth),
        out.Bounds().Max.X-1-int(paddingWidth),
        out.Bounds().Max.Y-1-int(paddingWidth)), im, image.Point{}, draw.Over)
    return out
}

func NonPaddingRectangle(im image.Image, isPadding IsPaddingFunc) image.Rectangle {
    topP, rightP, bottomP, leftP := PaddingWidths(im, isPadding)
    return image.Rect(
        int(leftP)+im.Bounds().Min.X,
        int(topP)+im.Bounds().Min.Y,
        int(rightP)*-1+im.Bounds().Max.X,
        int(bottomP)*-1+im.Bounds().Max.Y)
}

func PaddingWidths(im image.Image, isPadding IsPaddingFunc) (top uint, right uint, bottom uint, left uint) {
    top = PaddingWidthTop(im, isPadding)
    right = PaddingWidthRight(im, isPadding)
    bottom = PaddingWidthBottom(im, isPadding)
    left = PaddingWidthLeft(im, isPadding)
    return
}

func PaddingWidthTop(im image.Image, isPadding IsPaddingFunc) uint {
    if im == nil {
        return 0
    }
    for yi := im.Bounds().Min.Y; yi < im.Bounds().Max.Y; yi++ {
        for xi := im.Bounds().Min.X; xi < im.Bounds().Max.X; xi++ {
            if !isPadding(im.At(xi, yi)) {
                return uint(yi - im.Bounds().Min.Y)
            }
        }
    }
    return uint(im.Bounds().Dy())
}

func PaddingWidthBottom(im image.Image, isPadding IsPaddingFunc) uint {
    if im == nil {
        return 0
    }
    for yi := im.Bounds().Max.Y - 1; yi >= im.Bounds().Min.Y; yi-- {
        for xi := im.Bounds().Min.X; xi < im.Bounds().Max.X; xi++ {
            if !isPadding(im.At(xi, yi)) {
                return uint(im.Bounds().Max.Y - 1 - yi)
            }
        }
    }
    return uint(im.Bounds().Dy())
}

func PaddingWidthLeft(im image.Image, isPadding IsPaddingFunc) uint {
    if im == nil {
        return 0
    }
    for xi := im.Bounds().Min.X; xi < im.Bounds().Max.X; xi++ {
        for yi := im.Bounds().Min.Y; yi < im.Bounds().Max.Y; yi++ {
            if !isPadding(im.At(xi, yi)) {
                return uint(xi - im.Bounds().Min.X)
            }
        }
    }
    return uint(im.Bounds().Dx())
}

func PaddingWidthRight(im image.Image, isPadding func(c color.Color) bool) uint {
    if im == nil {
        return 0
    }
    for xi := im.Bounds().Max.X - 1; xi >= im.Bounds().Min.X; xi-- {
        for yi := im.Bounds().Min.Y; yi < im.Bounds().Max.Y; yi++ {
            if !isPadding(im.At(xi, yi)) {
                return uint(im.Bounds().Max.X - 1 - xi)
            }
        }
    }
    return uint(im.Bounds().Dx())
}