Option Explicit
Dim a, b As Single

Private Sub Command1_Click()
CommonDialog1.DialogTitle = "打开文件"
CommonDialog1.Action = 1
CommonDialog1.Filter = " All File (*.*) | *.*| JPG文件（.jpg)|*.jpg "
CommonDialog1.FilterIndex = 2
Image1.Stretch = True
Image1.Picture = LoadPicture(CommonDialog1.FileName)
End Sub

Private Sub Command2_Click()
Unload Me
End Sub

Private Sub Form_Load()
'Image1.Stretch = True
'Image1.Picture = LoadPicture("d:\6.jpg")
a = Image1.Width / Form1.ScaleWidth
b = Image1.Height / Form1.ScaleHeight
End Sub

Private Sub Form_Resize()
Image1.Width = a * Form1.ScaleWidth
Image1.Height = b * Form1.ScaleHeight
End Sub

程序运行后，在第一次打开一个图片后，接着再一次打开时，却无法显示jpg的图片，这是怎么回事？？？？

[ 本帖最后由 zhnzz4229 于 2013-9-2 20:12 编辑 ]

需改command1_click里的代码如下：
Private Sub Command1_Click()
CommonDialog1.DialogTitle = "打开文件"
CommonDialog1.Filter = "All File (*.*)|*.*|JPG文件(*.jpg)|*.jpg"
CommonDialog1.FilterIndex = 2
CommonDialog1.ShowOpen
Image1.Stretch = True
Image1.Picture = LoadPicture(CommonDialog1.FileName)
End Sub

你这个代码跟我的一样。
我已经解决了，说起来郁闷。代码没错，只需要在打开文件窗口把文件类型选为所有文件，*.jpg类型图片就出来了。

CommonDialog1.DialogTitle = "打开文件"
CommonDialog1.Action = 1
CommonDialog1.Filter = " All File (*.*) | *.*| JPG文件（.jpg)|*.jpg|PNG文件（.png)|*.png "
CommonDialog1.FilterIndex = 1
Image1.Stretch = True
Image1.Picture = LoadPicture(CommonDialog1.FileName)

代码是这样改的：
把默认文件类型选为“所有文件”。