核心思路 #

• 基于96DPI定义A4页面像素尺寸（宽827px、高1169px，可按需调整DPI）
• 划分2列5行网格，扣除边距和间距后计算单个图片单元格的大小
• 按每10张图片为一组分页，逐页绘制内容
• 双面模式下，偶数页反转列顺序，保证翻页后内容阅读逻辑一致

完整实现代码 #

Imports System.Drawing
Imports System.Drawing.Drawing2D
Imports System.Collections.Generic
Imports System.IO

Public Class ImageMerger
    ' A4参数（96DPI），300DPI可改为2480×3508
    Private Const A4Width As Integer = 827
    Private Const A4Height As Integer = 1169
    ' 布局固定参数
    Private Const Columns As Integer = 2
    Private Const Rows As Integer = 5
    Private Const PageImageCount As Integer = Columns * Rows ' 单页10张
    Private Const Margin As Integer = 20 ' 页面边距
    Private Const Spacing As Integer = 10 ' 图片间距

    ''' <summary>
    ''' 生成符合A4布局的页面集合
    ''' </summary>
    ''' <param name="imagePaths">待合并的图片路径列表</param>
    ''' <param name="isDoubleSided">是否启用双面布局</param>
    ''' <returns>页面Bitmap列表</returns>
    Public Function MergeImagesToA4Pages(imagePaths As List(Of String), isDoubleSided As Boolean) As List(Of Bitmap)
        Dim pages As New List(Of Bitmap)
        If imagePaths.Count = 0 Then Return pages

        ' 计算单个图片单元格的尺寸
        Dim cellWidth As Integer = (A4Width - Margin * 2 - Spacing * (Columns - 1)) \ Columns
        Dim cellHeight As Integer = (A4Height - Margin * 2 - Spacing * (Rows - 1)) \ Rows

        ' 按每页10张分组处理
        For pageIndex As Integer = 0 To (imagePaths.Count - 1) \ PageImageCount
            Dim startIdx = pageIndex * PageImageCount
            Dim endIdx = Math.Min(startIdx + PageImageCount - 1, imagePaths.Count - 1)
            Dim currentPageImgs As New List(Of Image)

            ' 加载当前页图片，失败时用空白图兜底
            For i = startIdx To endIdx
                Try
                    currentPageImgs.Add(Image.FromFile(imagePaths(i)))
                Catch
                    currentPageImgs.Add(New Bitmap(cellWidth, cellHeight))
                End Try
            Next

            ' 创建A4页面画布
            Dim pageBmp As New Bitmap(A4Width, A4Height)
            Using g As Graphics = Graphics.FromImage(pageBmp)
                g.Clear(Color.White)
                g.SmoothingMode = SmoothingMode.HighQuality
                g.InterpolationMode = InterpolationMode.HighQualityBicubic

                ' 绘制当前页所有图片
                For imgIdx = 0 To currentPageImgs.Count - 1
                    Dim row = imgIdx \ Columns
                    Dim col = imgIdx Mod Columns

                    ' 双面模式下偶数页反转列顺序
                    If isDoubleSided AndAlso pageIndex Mod 2 = 1 Then
                        col = Columns - 1 - col
                    End If

                    ' 计算图片绘制坐标
                    Dim x = Margin + col * (cellWidth + Spacing)
                    Dim y = Margin + row * (cellHeight + Spacing)

                    ' 按比例缩放图片并居中绘制
                    Dim img = currentPageImgs(imgIdx)
                    Dim scale = Math.Min(cellWidth / img.Width, cellHeight / img.Height)
                    Dim drawWidth = CInt(img.Width * scale)
                    Dim drawHeight = CInt(img.Height * scale)
                    Dim drawX = x + (cellWidth - drawWidth) \ 2
                    Dim drawY = y + (cellHeight - drawHeight) \ 2

                    g.DrawImage(img, drawX, drawY, drawWidth, drawHeight)
                Next
            End Using

            ' 释放当前页图片资源
            For Each img In currentPageImgs
                img.Dispose()
            Next

            pages.Add(pageBmp)
        Next

        Return pages
    End Function

    ''' <summary>
    ''' 保存生成的页面到指定目录
    ''' </summary>
    ''' <param name="pages">页面Bitmap列表</param>
    ''' <param name="outputDir">输出目录路径</param>
    Public Sub SavePages(pages As List(Of Bitmap), outputDir As String)
        If Not Directory.Exists(outputDir) Then
            Directory.CreateDirectory(outputDir)
        End If

        For i = 0 To pages.Count - 1
            pages(i).Save(Path.Combine(outputDir, $"Page_{i + 1}.png"), Imaging.ImageFormat.Png)
            pages(i).Dispose()
        Next
    End Sub
End Class

' 使用示例
' Dim merger As New ImageMerger()
' Dim imgPaths As New List(Of String) From {"img1.jpg", "img2.jpg", "img3.jpg", ...}
' Dim resultPages = merger.MergeImagesToA4Pages(imgPaths, isDoubleSided:=True)
' merger.SavePages(resultPages, "C:\ImageOutput")

关键细节说明 #

• 分辨率调整：如果需要更高打印精度，可替换A4尺寸为300DPI对应的2480×3508像素
• 图片适配：通过计算最小缩放比例保证图片不变形，同时居中对齐单元格
• 双面逻辑：偶数页反转列索引，解决双面打印时背面内容顺序颠倒的问题
• 资源管理：所有Image和Bitmap对象使用后必须调用Dispose，避免内存泄漏

内容的提问来源于stack exchange，提问作者dlaksmi