C# 屏幕取词 取密码 例程 源码

基本原理

GetCursorPos 用来取得鼠标的坐标
WindowFromPoint 用来取得相应坐标上的对象的句柄
GetWindowText 取得相应对象上的文字

以上函数在C#中的定义方法例程

GetCursorPos定义与用法

using System.Runtime.InteropServices;

[DllImport("user32.dll")]

static extern bool GetCursorPos(ref Point lpPoint);

[DllImport("user32.dll")]
[return: MarshalAs(UnmanagedType.Bool)]
static extern bool GetCursorPos(out Point lpPoint);

例程：
Point p;
if (GetCursorPos(out p))
{
label1.Text = Convert.ToString(p.X) + ";" + Convert.ToString(p.Y);
}

WindowFromPoint定义与用法

[DllImport("user32.dll")]
static extern IntPtr WindowFromPoint(POINT Point);

例程：

[DllImport("user32.dll")]
static extern IntPtr WindowFromPoint(POINT Point);

[DllImport("user32.dll")]
static extern bool GetCursorPos(out Point lpPoint);

[DllImport("user32.dll")]
static extern bool SetWindowText(IntPtr hWnd, string lpString);

Point p;
if (GetCursorPos(out p))
{
IntPtr hWnd = WindowFromPoint(p);
SetWindowText(hWnd, "Window Found");
}

GetWindowText/GetWindowTextLength定义与用法例程

//[DllImport("user32.dll", SetLastError=true, CharSet=CharSet.Auto)]
//static extern int GetWindowText(IntPtr hWnd, [Out] StringBuilder lpString, int nMaxCount);

[DllImport("user32.dll", CharSet = CharSet.Auto, SetLastError = true)]
static extern int GetWindowText(IntPtr hWnd, StringBuilder lpString, int nMaxCount);
[DllImport("user32.dll", SetLastError=true, CharSet=CharSet.Auto)]
static extern int GetWindowTextLength(IntPtr hWnd);

例程：

public string GetText(IntPtr hWnd)
{
// Allocate correct string length first
int length = GetWindowTextLength(hWnd);
StringBuilder sb = new StringBuilder(length + 1);
GetWindowText(hWnd, sb, sb.Capacity);
return sb.ToString();
}

用VB编写屏幕取看密码工具

　　看到诸如Suit Boy、GetCaption之类的看密码（星星）的软件后，我总想自己编一个。经过一番努力，终于实现了这一愿望。不敢独享，现介绍如下：
　　一、用GetCursorPos和WindowFormPoint 两个 API 函数获得鼠标所指的对象的句柄。

　　二、获取文本。这个用GetWindowText是得不到的，但用SendMessage发一条WM_GETTEXT消息，它就会老老实实地把密码传回来了。
　　程序如下：
　　新建一标准的EXE工程，在窗体中添加一文本框（Name = Txt Text = ″″）、一定时器（Name = Tim Interval= 100 Enabled = False）、两个按钮（Name = CmdStart Caption=″Start″、Name = CmdStop Caption=″Stop″）。安排好界面后输入以下代码：
　　′申明部分
　　Private Type POINTAPI
　　 x As Long
　　 y As Long
　　End Type
　　Dim Pos As POINTAPI
　　Dim hResult As Long
　　Dim hNow As Long
　　Dim hLength As Long
　　Dim bArr() As Byte, bArr2() As Byte
　　Private Const WM_GETTEXT = ＆HD
　　Private Const WM_GETTEXTLENGTH = ＆HE
　　Private Declare Sub RtlMoveMemory Lib ″KERNEL32″ (lpvDest As Any, lpvSource As Any, ByVal cbCopy As Long)
　　Private Declare Function SendMessage Lib ″user32″ Alias ″SendMessageA″ (ByVal hWnd As Long, ByVal wMsg As Long, ByVal wParam As Long, lParam As Any) As LongPrivate Declare Function WindowFromPoint Lib ″user32″ (ByVal xPoint As Long, ByVal yPoint As Long) As Long
　　Private Declare Function GetCursorPos Lib ″user32″ (lpPoint As POINTAPI) As Long′获取文本的函数
　　Function GetText(ByVal hWndNow As Long) As String
　　′获取文本长度
　　hLength = SendMessage(hWndNow, WM_GETTEXTLENGTH, 0, 0)
　　If hLength > 0 Then
　　′设置缓冲区
　　 ReDim bArr(hLength ＋ 1) As Byte, bArr2(hLength － 1) As Byte
　　 Call RtlMoveMemory(bArr(0), hLength, 2)
　　′发送 WM_GETTEXT 消息
　　 Call SendMessage(hWndNow, WM_GETTEXT, hLength ＋ 1, bArr(0))
　　 Call RtlMoveMemory(bArr2(0), bArr(0), hLength)
　　′得到文本
　　 GetText = StrConv(bArr2, vbUnicode)
　　Else
　　 GetText = ″″
　　End If
　　End Function
　　′开始获取文本
　　Private Sub CmdStart_Click()
　　Tim.Enabled = True
　　End Sub
　　′停止获取文本
　　Private Sub CmdStop_Click()
　　Tim.Enabled = False
　　End Sub
　　′Timer控件调用获取文本函数
　　Private Sub Tim_Timer()
　　hResult = GetCursorPos(Pos)
　　hNow = WindowFromPoint(Pos.x, Pos.y)
　　′防止获取自身文本
　　If hNow <> Txt.hWnd Then
　　 Txt.Text = GetText(hNow)
　　End If
　　DoEvents
　　End Sub
　　运行程序，按 Start按钮后，鼠标所指的密码就看到了