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使用 VB.net 重新调整图像大小后的白色背景，如下所示。我试图更改一些值但失败了。

Dim FileToResize As String = Server.MapPath("~/images/" & filename & FileUpload1.FileName)
Using originalBitmap As Bitmap = Bitmap.FromFile(FileToResize, True), newbmp As Bitmap = New Bitmap(200, 200)
    Dim WidthVsHeightRatio = CDec(originalBitmap.Width) / CDec(originalBitmap.Height)

    Using newg As Graphics = Graphics.FromImage(newbmp)
        newg.SmoothingMode = Drawing2D.SmoothingMode.HighQuality
        newg.Clear(Color.White)

        If WidthVsHeightRatio = 1D Then
            newg.DrawImage(originalBitmap, 0, 0, 200, 200)
            newg.Save()


        ElseIf WidthVsHeightRatio < 1D Then 'Image is taller than wider

            newg.DrawImage(originalBitmap, New RectangleF(New PointF((100 - (200 * WidthVsHeightRatio) / 2), 0), New SizeF(200 * WidthVsHeightRatio, 200.0F)))
            newg.Save()

        Else 'Image is wider than taller

            Dim inverse As Double = Math.Pow(WidthVsHeightRatio, -1)
            newg.DrawImage(originalBitmap, New RectangleF(New PointF(0, 100 - ((200 * inverse) / 2)), New SizeF(200.0F, 200 * inverse)))
            newg.Save()
        End If
    End Using

    newbmp.Save(Server.MapPath("~/images/" & "_th_" & filename & FileUpload1.FileName), System.Drawing.Imaging.ImageFormat.Jpeg)
    NewsItem.ImageLink = filename & FileUpload1.FileName
    NewsItem.smallimage = "_th_" & filename & FileUpload1.FileName
End Using
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1 回答 1

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我最近做了一些研究，以便为电子商务网站即时生成图像缩略图。我开始自己生成位图，然后调整大小等。在光盘上的图像大小和质量出现问题后，我查看了http://imageresizing.net/，从那以后我就再也没有回头。它可以通过一行代码非常快速地从 byte()、流和物理文件生成图像：

ImageBuilder.Current.Build(New MemoryStream(bImage), sImageLocation + sFullFileName, New      ResizeSettings("maxwidth=214&maxheight=238"))

我肯定会推荐这个组件，而不是试图重新发明轮子......

于 2013-01-15T13:39:10.690 回答