各位精英,小弟最近用API中的getpixel 想获取屏幕上某一点像素,结果是据点有结果全-1,心情十分沉重,万望知道的指点一二,十分感谢,原代码如下:
 Private Declare Function getpixel Lib "gdi32" Alias "GetPixel" (ByVal hdc As Long, ByVal x As Integer, ByVal y As Integer) As Integer
 Public Shared Function gaincolor(ByVal p As Point, ByVal aaa As IntPtr) As Long

        'Dim bbb As Color
        Dim ccc As Long
        Dim ddd As Long
        ddd = GetWindowDC(aaa)
        ccc = getpixel(ddd, p.X, p.Y),此处ccc总是返回-1   
        SetPixel(ddd, p.X, p.Y, 300),此处好像没有执行结果
        Return ccc
    End Function

上述函数返回值总是-1

Public Shared Function gaincolor(ByVal p As Point, ByVal aaa As IntPtr) As Int32
        Dim ccc As IntPtr
        Dim ddd As Int32
        ccc = GetDC(0)
        ddd = getpixel(ccc, 200, 100)
        ReleaseDC(0, ccc)
        Return ddd
    End Function
改进代码,还是不对,每次获得数值不一样

有人能给我一个最简单的例子吗?比如取屏幕上200,200像素处点的颜色
我用的VB2005,谢谢!!!

算了,不用它了,改用截屏取色吧,已经完成,谢谢大家