要让vb.net相应外部托拽来的文件，需处理wm_dropfiles消息。
private declare sub dragacceptfiles lib "shell32.dll" (byval hwnd as int32, byval faccept as int32)
private declare sub dragfinish lib "shell32.dll" (byval hdrop as int32)
private declare function dragqueryfile lib "shell32.dll" alias "dragqueryfilea" (byval hdrop as int32, byval uint as int32, byval lpstr as
string, byval ch as int32) as int32
private const wm_dropfiles = &h233
private const max_length = 255
protected overrides sub wndproc(byref m as system.windows.forms.message)
if m.msg = wm_dropfiles then
dragfiles(m.wparam.toint32)
exit sub
end if
mybase.wndproc(m)
end sub
private sub dragfiles(byval hdrop as int32)
dim ireturn as int32
dim sfile as string
sfile = space(max_length)
ireturn = dragqueryfile(hdrop, 0, sfile, max_length)
if ireturn then
textbox3.text = sfile
picturebox1.image = image.fromfile(trim(textbox3.text))
dragfinish(hdrop)
end if
end sub
我的代码只是适用于.net的picturebox能用的图像文件噢！
