干货！ 用StretchBlt处理图片，保存后的图片有黑边？

用 StretchBlt 处理图像有后黑边，
原图如下：

处理后保存的图片如下（处理后的图片超过2M 论坛上传不了，故对图片进行了QQ截图，展示效果如下）：




代码如下：
思路：以制作宽长比为： 102/152 的 的图像尺寸， picture2控件加载原始图片，获取原始图片长宽像素值， 对此原始像素值按照102/152的比例进行计算，计算出长度或者宽度上需要增补的尺寸，以达到102/152这一比例。然后将picture1控件的长宽尺寸设置为 通过计算后的目标尺寸，然后用StretchBlt 函数将picture2控件的图像 加载打 picture1控件，然后再保存picture1控件上的目标图片，即为保存到C盘的123.jpg 如源码。 奇怪的是 保存后的图片，下面有黑边，实在是不知道怎么处理了，求教各位高手！

'Form1上添加1个图片框picture1

Private Declare Function GetPixel Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long) As Long

Private Declare Function SetPixelV Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long, ByVal crColor As Long) As Long

Private Declare Function StretchBlt Lib "gdi32" (ByVal hDC As Long, ByVal X As Long, ByVal Y As Long, ByVal nWidth As Long, ByVal nHeight As Long, ByVal hSrcDC As Long, ByVal xSrc As Long, ByVal ySrc As Long, ByVal nSrcWidth As Long, ByVal nSrcHeight As Long, ByVal dwRop As Long) As Long

Private Declare Function SetStretchBltMode Lib "gdi32" (ByVal hDC As Long, ByVal nStretchMode As Long) As Long

Private Declare Function GetDC Lib "user32 " (ByVal hWND As Long) As Long

Private Const HALFTONE = 4

Private Const SRCCOPY = &HCC0020



 Dim fs

 Dim wScreen As Long

 Dim hScreen As Long

 Dim w As Long

 Dim h As Long

 Dim cw As Long

 Dim ch As Long

 Dim Dw As Long

 Dim Dh As Long

 Dim DifferenceH As Long

 Dim DifferenceW As Long

 Dim PIC As PictureBox

 Dim rtn As Boolean

 Dim rtm As Long

 Dim Hdc1 As Long, Hdc2 As Long



Private Sub Form_Load()

Picture2.Picture = LoadPicture("C:\1.jpg")

    Printer.ScaleMode = 3

    Printer.ScaleWidth = 1181

    Printer.ScaleHeight = 1772

    Printer.ScaleLeft = 0

    Printer.ScaleTop = 0

AllPrint





End Sub

Sub AllPrint() '此函数用来对图片进行裁切打印



        w = Picture2.Width

        h = Picture2.Height

        

If w <= h Then '此判断用来打印宽带小于等等高度的图片

        Printer.Orientation = 1 '打印机纵向

        ch = w * 152 \ 102

        cw = 102 * h \ 152

        DifferenceW = w - cw

        DifferenceH = h - ch

        Debug.Print DifferenceW

        Debug.Print DifferenceH

        If DifferenceW >= 0 And DifferenceH <= 0 Then

            Picture1.Width = w

            Picture1.Height = ch

            Call SetStretchBltMode(Picture1.hDC, HALFTONE)

            rtm = StretchBlt(Picture1.hDC, 0, Abs(DifferenceH / 2), w, ch, Picture2.hDC, 0, 0, w, ch, vbSrcCopy)

            Picture1.Refresh

            SavePicture Picture1.Image, "c:\123.jpg "

        End If

End If

 End Sub