Vb图片的显示问题

因为图片大小不定，用Image显示后不理想，小图自动调整大了还可以，但大尺寸图变小了看不清。想要实现图像显示时为自动大小，又可以自己调整大小来看，就想WIN自带的图片查看器一样，可以放大缩小，和抓手的功能。
谁能帮忙写一下代码啊，分不多了，先给50

换成 PictureBox
用两个PictureBox：
PictureBox1 装入图片，AutoSize = true, AutoRedraw = true,
PictureBox2 显示图片，AutoSize = false, AutoRedraw = true,

为自动大小时 PictureBox2 大小 = PictureBox1 大小

使用API 函数 StretchBlt

Declare Function StretchBlt Lib "gdi32" Alias "StretchBlt" (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

将一幅位图从一个设备场景复制到另一个。源和目标DC相互间必须兼容。这个函数会在设备场景中定义一个目标矩形，并在位图中定义一个源图象。源矩形会根据需要进行伸缩，以便与目标矩形的大小相符

参数 类型及说明
hdc Long，目标设备场景
x,y Long，目标矩形左上角的x,y坐标，以逻辑坐标表示
nWidth,nHeight Long，目标矩形的宽度和高度，以逻辑坐标表示
hSrcDC Long，源设备场景。如光栅运算未指定一个源，则这个参数应为零
xSrc,ySrc Long，用源DC的逻辑坐标表示的源矩形左上角位置
nSrcWidth,nSrcHeight Long，分别指定用逻辑单位（以源DC为基础）传输的一幅图象的宽度和高度。如其中有一个参数的符号（指正负号）与对应的目标参数不符，位图就会在对应的轴上作镜像转换处理
dwRop Long，传输过程中进行的光栅运算。如刷子属于光栅运算的一部分，就使用选入目标DC的刷子

Private Const NOTSRCERASE = &H1100A6
Private Const NOTSRCCOPY = &H330008
Private Const SRCERASE = &H440328
Private Const SRCINVERT = &H660046
Private Const SRCAND = &H8800C6
Private Const MERGEPAINT = &HBB0226
Private Const MERGECOPY = &HC000CA
Private Const SRCCOPY = &HCC0020
Private Const SRCPAINT = &HEE0086
Private Const PATPAINT = &HFB0A09

Private Const BLACKNESS = &H42
Private Const DSTINVERT = &H550009
Private Const PATINVERT = &H5A0049
Private Const PATCOPY = &HF00021
Private Const WHITENESS = &HFF0062

Private Declare Function StretchBlt Lib "gdi32" Alias "StretchBlt" (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

调用 StretchBlt

StretchBlt PictureBox2.hdc, 0, 0, PictureBox2.ScaleWidth, PictureBox2.ScaleHeight, PictureBox1.hdc, 0, 0, PictureBox1.ScaleWidth, PictureBox1.ScaleHeight, SRCCOPY

把image图像框的stretch属性改为true就好了！