vb将图片生成缩略图 示例源码

【实例截图】

【核心代码】

Imports System.Drawing.Imaging

Public Class Form1

	''' <summary>
	''' 获取文件列表
	''' </summary>
	''' <param name="sender"></param>
	''' <param name="e"></param>
	Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
		FolderBrowserDialog1.RootFolder = Environment.SpecialFolder.Desktop
		FolderBrowserDialog1.Description = "请选择图片文件夹"
		FolderBrowserDialog1.ShowNewFolderButton = True
		If FolderBrowserDialog1.ShowDialog = DialogResult.OK Then
			ListBox1.DataSource = IO.Directory.GetFiles(FolderBrowserDialog1.SelectedPath)
		End If
	End Sub

	''' <summary>
	''' 缩略图转换
	''' </summary>
	''' <param name="sender"></param>
	''' <param name="e"></param>
	Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
		For Each c In ListBox1.Items
			If c <> "" Then GET_SC_IMG(c, 3)
		Next
		MessageBox.Show("缩略图转换完成!", "完成转换")
	End Sub

	''' <summary>
	''' 获取图片缩略图
	''' </summary>
	''' <param name="old_path">原图文件路径</param>
	''' <param name="sc">缩放比例</param>
	''' <returns></returns>
	Function GET_SC_IMG(ByVal old_path As String, ByVal sc As Integer) As Boolean
		Try
			''------------------------------------
			''文件不存在返回false
			If IO.File.Exists(old_path) = False Then Return False
			''------------------------------------
			''保存缩略图文件路径
			Dim f_name As String = Split(old_path, "\")(UBound(Split(old_path, "\"))) ''获取原文件名
			Dim fld_path As String = $"{ old_path.Replace(f_name, "")}图片缩略图\" ''拼接缩略图文件夹路径
			If IO.Directory.Exists(fld_path) = False Then IO.Directory.CreateDirectory(fld_path)  ''创建缩略图文件夹
			Dim new_path As String = $"{fld_path}sc_{f_name}"  ''拼接缩略图文件路径
			'-------------------------------------
			''格式选择及判断
			Dim img_form As ImageFormat = Nothing
			Select Case True
				Case old_path.ToUpper.Contains(".JPG")
					img_form = ImageFormat.Jpeg
				Case old_path.ToUpper.Contains(".BMP")
					img_form = ImageFormat.Bmp
				Case old_path.ToUpper.Contains(".PNG")
					img_form = ImageFormat.Png
				Case old_path.ToUpper.Contains(".ICO")
					img_form = ImageFormat.Icon
				Case old_path.ToUpper.Contains(".GIF")
					img_form = ImageFormat.Gif
				Case old_path.ToUpper.Contains(".TIFF")
					img_form = ImageFormat.Tiff
				Case old_path.ToUpper.Contains(".WMF")
					img_form = ImageFormat.Wmf
				Case old_path.ToUpper.Contains(".EXIF")
					img_form = ImageFormat.Exif
				Case old_path.ToUpper.Contains(".EMF")
					img_form = ImageFormat.Emf
				Case Else
					Return False ''不是以上格式表示为非图片
			End Select
			''--------------------------------------------
			''图片缩放
			Using img As New Bitmap(old_path)
				Dim sc_w As Integer = img.Width / sc
				Dim sc_h As Integer = img.Height / sc
				Using n_img As New Bitmap(sc_w, sc_h)
					Dim grh As Graphics = Graphics.FromImage(n_img)
					grh.DrawImage(img, 0, 0, sc_w, sc_h)
					grh.Dispose()
					''------------------------------------
					''保存图片
					n_img.Save(new_path, img_form)
					Return True
				End Using
			End Using
		Catch ex As Exception
			Return False
		End Try
	End Function


End Class