image-processing.go

package main

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

	"github.com/nfnt/resize"
)

func resizeImage(img image.Image, width, height int) (image.Image, error) {
	outputRatio := float64(width) / float64(height)
	inputWidth := img.Bounds().Max.X - img.Bounds().Min.X
	inputHeight := img.Bounds().Max.Y - img.Bounds().Min.Y
	inputRatio := float64(inputWidth) / float64(inputHeight)

	var resizeWidth, resizeHeight uint
	if outputRatio > inputRatio {
		resizeWidth = uint(float64(height) * inputRatio)
		resizeHeight = uint(height)
	} else {
		resizeWidth = uint(width)
		resizeHeight = uint(float64(width) / inputRatio)
	}

	resizedImg := resize.Resize(resizeWidth, resizeHeight, img, resize.NearestNeighbor)
	return resizedImg, nil
}

func createImage(width, height int, bgColor color.RGBA) *image.RGBA {
	outputImg := image.NewRGBA(image.Rect(0, 0, width, height))
	draw.Draw(outputImg, outputImg.Bounds(), &image.Uniform{C: bgColor}, image.Point{}, draw.Src)
	return outputImg
}

func copyImage(srcImg image.Image, destImg draw.Image) {
	resizeWidth := srcImg.Bounds().Max.X - srcImg.Bounds().Min.X
	resizeHeight := srcImg.Bounds().Max.Y - srcImg.Bounds().Min.Y
	offsetX := (destImg.Bounds().Max.X - resizeWidth) / 2
	offsetY := (destImg.Bounds().Max.Y - resizeHeight) / 2

	// Convert the source image to a draw.Image object
	srcDrawImg := drawImageFromImage(srcImg)

	draw.Draw(destImg, image.Rect(offsetX, offsetY, offsetX+resizeWidth, offsetY+resizeHeight), srcDrawImg, srcDrawImg.Bounds().Min, draw.Src)
}

func drawImageFromImage(img image.Image) draw.Image {
	bounds := img.Bounds()
	dest := image.NewRGBA(bounds)
	draw.Draw(dest, bounds, img, bounds.Min, draw.Src)
	return dest
}