如何将多个图像合并为一个图像？

Question

我已使用go-fitz将pdf转换为jpeg，这为我提供了目录中jpeg的列表。我正在从目录中读取图像列表，然后尝试将它们组合成一个图像。该图像为jpeg类型，如果我仅使用第1页和第2页使用索引，则该图像可以部分工作。我想将pdf页面jpeg图像拼接回一个jpeg图像。代码的最终结果将在第一页生成单个图像。

Golang how to concatenate/append images to one another

如果我使用图像索引0和1，则此代码有效。但是不能在我的代码的动态列表中使用。但是，我将获得一个动态图像列表，需要将它们放到一个图像中。我假设它与最终图像画布大小有关，并将其添加到画布中。当我尝试使用流程叠加示例时，代码最终将第一页和最后一页放在宽阔的画布中，而缺少其余页面。

package converter

import (
    "fmt"
    "image"
    "image/draw"
    "image/jpeg"
    "os"
    "path/filepath"
    "strings"

    log "github.com/sirupsen/logrus"
)

func openAndDecode(imgPath string) image.Image {
    img, err := os.Open(imgPath)
    if err != nil {
        log.Fatalf("Failed to open %s", err)
    }

    decoded, _, err := image.Decode(img)
    if err != nil {
        log.Fatalf("Failed to decode %s", err)
    }
    defer img.Close()

    return decoded
}

// StichImages takes a directory of images and combine them into a single image
func StichImages(dirPath string) {
    fileList := []string{}
    decodedImages := []image.Image{}
    err := filepath.Walk(dirPath, func(path string, f os.FileInfo, err error) error {
        fileList = append(fileList, path)
        return nil
    })

    if err != nil {
        log.Fatal(err)
    }

    // If there is only one image in folder no need to stich
    if len(fileList) == 1 {
        return
    }

    for _, filePath := range fileList {
        if strings.Contains(filePath, ".jpg") {
            decodedImage := openAndDecode(filePath)
            decodedImages = append(decodedImages, decodedImage)
        }
    }

    outPutPath := filepath.Join(dirPath, "output.jpg")

    if len(decodedImages) == 0 {
        log.Error(fmt.Sprintf("No images found in: %s", dirPath))
    }

    //starting position of the second image (bottom left)
    startingPoint := image.Point{}
    finalImageCanvas := image.Rectangle{image.Point{0, 0}, decodedImages[0].Bounds().Max}
    rgba := image.NewRGBA(finalImageCanvas)

    for index, newImage := range decodedImages {
        if index == 0 {
            startingPoint = image.Point{newImage.Bounds().Dx(), 0}
            draw.Draw(rgba, newImage.Bounds(), newImage, image.Point{0, 0}, draw.Src)
        } else {
            newImageRect := image.Rectangle{startingPoint, startingPoint.Add(newImage.Bounds().Size())}
            finalImageCanvas = image.Rectangle{image.Point{0, 0}, newImageRect.Max}
            draw.Draw(rgba, newImageRect, newImage, image.Point{0, 0}, draw.Src)
            startingPoint = image.Point{newImageRect.Bounds().Dx(), 0}
        }
    }

    out, err := os.Create(outPutPath)
    if err != nil {
        fmt.Println(err)
    }

    var opt jpeg.Options
    opt.Quality = 80

    jpeg.Encode(out, rgba, &opt)
}