使用过ACDSEE的朋友一定对它的JPG图片旋转功能记忆犹新，其实我们利用VB6的先进功能，可以对任意格式的图片文件（包括JPG、GIF、BMP、ICO等）进行45度、180度旋转，确实可以和ACDSEE一较高下。
启动vb6建立一个标准exe工程，首先添加两个图片框（picture1和picture2），添加三个命令按钮command1（caption=“正常显示”）、command2（caption=“180度倒立”）、command3（caption=“45度旋转”），双击窗体，写入以下代码：
PrivateConstSRCCOPY=&HCC0020
PrivateConstPi=3.14
PrivateDeclareFunctionSetPixelLib"gdi32"(ByValhdcAsLong, ByValxAsLong,ByValyAsLong,ByValcrColorAsLong)AsLong
PrivateDeclareFunctionGetPixelLib"gdi32"(ByValhdcAsLong, ByValxAsLong,ByValyAsLong)AsLong
PrivateDeclareFunctionStretchBltLib"gdi32"(ByValhdcAsLong, ByValxAsLong,ByValyAsLong,ByValnWidthAsLong,ByValnHeightAsLong, ByValhSrcDCAsLong,ByValxSrcAsLong,ByValySrcAsLong,ByValnSrcWidth AsLong,ByValnSrcHeightAsLong,ByValdwRopAsLong)AsLong
privateSubbmp_rotate(pic1AsPictureBox,pic2AsPictureBox,ByValtheta)‘45度旋转
Dimc1xAsInteger,c1yAsInteger
Dimc2xAsInteger,c2yAsInteger
DimaAsSingle
Dimp1xAsInteger,p1yAsInteger
Dimp2xAsInteger,p2yAsInteger
DimnAsInteger,rAsInteger
c1x=pic1.ScaleWidth\2
c1y=pic1.ScaleHeight\2
c2x=pic2.ScaleWidth\2
c2y=pic2.ScaleHeight\2
Ifc2x
pic1hDC=pic1.hdc
pic2hDC=pic2.hdc
Forp2x=0Ton
Forp2y=0Ton
Ifp2x=0Thena=Pi/2Elsea=Atn(p2y/p2x)
r=Sqr(1&*p2x*p2x+1&*p2y*p2y)
p1x=r*Cos(a+theta)
p1y=r*Sin(a+theta)
c0&=GetPixel(pic1hDC,c1x+p1x,c1y+p1y)
c1&=GetPixel(pic1hDC,c1x-p1x,c1y-p1y)
c2&=GetPixel(pic1hDC,c1x+p1y,c1y-p1x)
c3&=GetPixel(pic1hDC,c1x-p1y,c1y+p1x)
Ifc0&<>-1ThenSetPixelpic2hDC,c2x+p2x,c2y+p2y,c0
Ifc1&<>-1ThenSetPixelpic2hDC,c2x-p2x,c2y-p2y,c1
Ifc2&<>-1ThenSetPixelpic2hDC,c2x+p2y,c2y-p2x,c2
Ifc3&<>-1ThenSetPixelpic2hDC,c2x-p2y,c2y+p2x,c3
Next
Next
EndSub
PrivateSubCommand1_Click()‘正常复制
Picture2.Cls
px=Picture1.ScaleWidth
py=Picture1.ScaleHeight
StretchBltPicture2.hdc,px,0,-px,py,Picture1.hdc,0,0,px,py,SRCCOPY
EndSub
PrivateSubCommand2_Click()‘180度倒立
Picture2.Cls
px=Picture1.ScaleWidth
py=Picture1.ScaleHeight
StretchBltPicture2.hdc,0,py,px,-py,Picture1.hdc,0,0,px,py,SRCCOPY
EndSub
PrivateSubCommand3_Click()‘45旋转
Picture2.Cls
Callbmp_rotate(Picture1,Picture2,3.14/4)
EndSub
PrivateSubForm_Load()
onErrorResumeNext
Me.Caption=App.Title"添加应用程序标题
Me.Left=(Screen.Width-Me.Width)/2
Me.Top=(Screen.Height-Me.Height)/2"窗体具中
Picture1.ScaleMode=3
Picture2.ScaleMode=3
EndSub
