如何实现[VB]图片等比例缩小的技巧？

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摘要：[VB] 图像缩小方法包括：缩小示例、将示例缩小、设置图片长宽+Public Sub setImageWH() Try 设置图片位置 Dim FilePath As String=~\Images\Img.png 获取图片真实路径 Dim realPath As String=Http

摘要:[VB] 图片等比例缩小方法

将图片等比例缩小的方法

‘设定图片长宽 Public Sub setImageWH() Try ‘图片位置 Dim FilePath As String = "~/Images/Img.png" ‘取得图片真实路径 Dim realPath As String = HttpContext.Current.Request.MapPath(FilePath) ‘ Dim ImgDw As System.Drawing.Image = System.Drawing.Image.FromFile(realPath) ‘取得缩图后的长宽 Dim imgSize() As Integer = getThumbnailImageScale(120, 100, ImgDw.Width, ImgDw.Height) ImgDw.Dispose() ‘设定图片长宽 imgTest.Width = imgSize(0) imgTest.Height = imgSize(1) Catch ex As Exception End Try End Sub ‘保存时使用 Private Sub imgresize(ByVal width As Integer, ByVal height As Integer, ByVal saveurl As String, ByVal filebytes As Byte(), ByVal filelength As Integer) Dim ms As MemoryStream = New MemoryStream ms.Write(filebytes, 0, filelength) ms.Flush() Dim img1 As System.Drawing.Image = System.Drawing.Image.FromStream(ms) If img1.Height > height Or img1.Width > width Then ‘是否有超高or宽 Dim newimg As System.Drawing.Image Dim thumbnailScale As Integer() = getThumbnailImageScale(width, height, img1.Width, img1.Height) ‘算出原图长宽比 newimg = img1.GetThumbnailImage(thumbnailScale(0), thumbnailScale(1), Nothing, IntPtr.Zero) ‘释放资源 newimg.Save(saveurl) newimg.Dispose() img1.Dispose() ms.Close() End If End Sub ‘带入限制范围长宽跟原图片长宽 Private Function getThumbnailImageScale(ByVal maxWidth As Integer, ByVal maxHeight As Integer, ByVal oldWidth As Integer, ByVal oldHeight As Integer) As Integer() Dim result() As Integer = New Integer() {0, 0} Dim widthDividend As Single, heightDividend As Single, commonDividend As Single widthDividend = oldWidth / maxWidth heightDividend = oldHeight / maxHeight If (heightDividend > widthDividend) Then commonDividend = heightDividend Else commonDividend = widthDividend End If result(0) = CType((oldWidth / commonDividend), Integer) result(1) = CType((oldHeight / commonDividend), Integer) Return result End Function

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原文:大专栏 [VB] 图片等比例缩小方法