How to composite images with transparency using alpha blending in Go?

To composite images with transparency using alpha blending in Go, you can use the draw.Draw function from the image/draw package. Here's an example code:

package main

import (
	"image"
	"image/draw"
	"image/png"
	"log"
	"os"
)

func main() {
	// Load the foreground and background images
	foregroundImageFile, err := os.Open("foreground.png")
	if err != nil {
		log.Fatal(err)
	}
	foregroundImage, _, err := image.Decode(foregroundImageFile)
	if err != nil {
		log.Fatal(err)
	}
	foregroundImageFile.Close()

	backgroundImageFile, err := os.Open("background.png")
	if err != nil {
		log.Fatal(err)
	}
	backgroundImage, _, err := image.Decode(backgroundImageFile)
	if err != nil {
		log.Fatal(err)
	}
	backgroundImageFile.Close()

	// Create a new RGBA image for the final composition
	compositeImage := image.NewRGBA(backgroundImage.Bounds())

	// Copy the background image to the composite image
	draw.Draw(compositeImage, backgroundImage.Bounds(), backgroundImage, image.ZP, draw.Src)

	// Copy the foreground image to the composite image with alpha blending
	draw.DrawMask(compositeImage, foregroundImage.Bounds(), foregroundImage, image.ZP, foregroundImage, image.ZP, draw.Over)

	// Save the composite image to a file
	outputFile, err := os.Create("composite.png")
	if err != nil {
		log.Fatal(err)
	}
	err = png.Encode(outputFile, compositeImage)
	if err != nil {
		log.Fatal(err)
	}
	outputFile.Close()

	log.Println("Image composition complete!")
}

Make sure to replace "foreground.png" and "background.png" with the paths to your actual foreground and background images, respectively.

This code loads the foreground and background images, creates a new RGBA image for the final composition, copies the background image to the composite image, and then copies the foreground image to the composite image using the draw.DrawMask function with the draw.Over operation to perform alpha blending.

Finally, the composite image is saved to "composite.png".