You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: utils.go
    path of file: ./repos/mattermost/server/channels/app/imaging
    
    the code of the file until where you have to start completion: // Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
// See LICENSE.txt for license information.

package imaging

import (
	"image"
	"image/color"

	"github.com/disintegration/imaging"
)

type rawImg interface {
	Set(x, y int, c color.Color)
	Opaque() bool
}

func isFullyTransparent(c color.Color) bool {
	// TODO: This can be optimized by checking the color type and
	// only extract the needed alpha value.
	_, _, _, a := c.RGBA()
	return a == 0
}

// FillImageTransparency fills in-place all the fully transparent pixels of the
// input image with the given color.
func FillImageTransparency(img image.Image, c color.Color) {
	var i rawImg

	bounds := img.Bounds()

	fillFunc := func() {
		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
			for x := bounds.Min.X; x < bounds.Max.X; x++ {
				if isFullyTransparent(img.At(x, y)) {
					i.Set(x, y, c)
				}
			}
		}
	}

	switch raw := img.(type) {
	case *image.Alpha:
		i = raw
	case *image.Alpha16:
		i = raw
	case *image.Gray:
		i = raw
	case *image.Gray16:
		i = raw
	case *image.NRGBA:
		i = raw
		col := color.NRGBAModel.Convert(c).(color.NRGBA)
		fillFunc = func() {
			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
				fo
    
func FillImageTransparency(img image.Image, c color.Color) {
	var i rawImg

	bounds := img.Bounds()

	fillFunc := func() {
		for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
			for x := bounds.Min.X; x < bounds.Max.X; x++ {
				if isFullyTransparent(img.At(x, y)) {
					i.Set(x, y, c)
				}
			}
		}
	}

	switch raw := img.(type) {
	case *image.Alpha:
		i = raw
	case *image.Alpha16:
		i = raw
	case *image.Gray:
		i = raw
	case *image.Gray16:
		i = raw
	case *image.NRGBA:
		i = raw
		col := color.NRGBAModel.Convert(c).(color.NRGBA)
		fillFunc = func() {
			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
				for x := bounds.Min.X; x < bounds.Max.X; x++ {
					i := raw.PixOffset(x, y)
					if raw.Pix[i+3] == 0x00 {
						raw.Pix[i] = col.R
						raw.Pix[i+1] = col.G
						raw.Pix[i+2] = col.B
						raw.Pix[i+3] = col.A
					}
				}
			}
		}
	case *image.NRGBA64:
		i = raw
		col := color.NRGBA64Model.Convert(c).(color.NRGBA64)
		fillFunc = func() {
			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
				for x := bounds.Min.X; x < bounds.Max.X; x++ {
					i := raw.PixOffset(x, y)
					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
					if a == 0 {
						raw.Pix[i] = uint8(col.R >> 8)
						raw.Pix[i+1] = uint8(col.R)
						raw.Pix[i+2] = uint8(col.G >> 8)
						raw.Pix[i+3] = uint8(col.G)
						raw.Pix[i+4] = uint8(col.B >> 8)
						raw.Pix[i+5] = uint8(col.B)
						raw.Pix[i+6] = uint8(col.A >> 8)
						raw.Pix[i+7] = uint8(col.A)
					}
				}
			}
		}
	case *image.Paletted:
		i = raw
		fillFunc = func() {
			for i := range raw.Palette {
				if isFullyTransparent(raw.Palette[i]) {
					raw.Palette[i] = c
				}
			}
		}
	case *image.RGBA:
		i = raw
		col := color.RGBAModel.Convert(c).(color.RGBA)
		fillFunc = func() {
			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
				for x := bounds.Min.X; x < bounds.Max.X; x++ {
					i := raw.PixOffset(x, y)
					if raw.Pix[i+3] == 0x00 {
						raw.Pix[i] = col.R
						raw.Pix[i+1] = col.G
						raw.Pix[i+2] = col.B
						raw.Pix[i+3] = col.A
					}
				}
			}
		}
	case *image.RGBA64:
		i = raw
		col := color.RGBA64Model.Convert(c).(color.RGBA64)
		fillFunc = func() {
			for y := bounds.Min.Y; y < bounds.Max.Y; y++ {
				for x := bounds.Min.X; x < bounds.Max.X; x++ {
					i := raw.PixOffset(x, y)
					a := uint16(raw.Pix[i+6])<<8 | uint16(raw.Pix[i+7])
					if a == 0 {
						raw.Pix[i] = uint8(col.R >> 8)
						raw.Pix[i+1] = uint8(col.R)
						raw.Pix[i+2] = uint8(col.G >> 8)
						raw.Pix[i+3] = uint8(col.G)
						raw.Pix[i+4] = uint8(col.B >> 8)
						raw.Pix[i+5] = uint8(col.B)
						raw.Pix[i+6] = uint8(col.A >> 8)
						raw.Pix[i+7] = uint8(col.A)
					}
				}
			}
		}
	default:
		return
	}

	if !i.Opaque() {
		fillFunc()
	}
}