调用API 实现 窗体 拖动

自定义 做一个窗体 实现 鼠标拖动

private const int WM_SYSCOMMAND = 0x112;

private System.Windows.Interop.HwndSource _HwndSource;

public static IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
switch (msg)
{
case 0x0024:/* WM_GETMINMAXINFO 这个是Windows消息代码，是指窗口大小或位置的改变，每个不同的消息都会有对应的编码 */
//然后对应的操作，在wpf中你得借助HwndSource类来捕获消息，winform中你只要重载该函数就可以
WmGetMinMaxInfo(hwnd, lParam);
handled = true;
break;
default: break;
}
return (System.IntPtr)0;
}

private static void WmGetMinMaxInfo(System.IntPtr hwnd, System.IntPtr lParam)
{

MinMaxInfo mmi = (MinMaxInfo)Marshal.PtrToStructure(lParam, typeof(MinMaxInfo));

// 最大化的大小和位置调整，以适应在正确的显示器的工作区中
int MONITOR_DEFAULTTONEAREST = 0x00000002;
System.IntPtr monitor = MonitorFromWindow(hwnd, MONITOR_DEFAULTTONEAREST);

if (monitor != System.IntPtr.Zero)
{

MONITORINFO monitorInfo = new MONITORINFO();
GetMonitorInfo(monitor, monitorInfo);
RECT rcWorkArea = monitorInfo.rcWork;
RECT rcMonitorArea = monitorInfo.rcMonitor;
mmi.ptMaxPosition.x = Math.Abs(rcWorkArea.left - rcMonitorArea.left);
mmi.ptMaxPosition.y = Math.Abs(rcWorkArea.top - rcMonitorArea.top);
mmi.ptMaxSize.x = Math.Abs(rcWorkArea.right - rcWorkArea.left);
mmi.ptMaxSize.y = Math.Abs(rcWorkArea.bottom - rcWorkArea.top);
mmi.ptMinTrackSize.x = 400;//宽度
mmi.ptMinTrackSize.y = 300;//高度
}

Marshal.StructureToPtr(mmi, lParam, true);
}

/// <summary>
/// POINTAPI：POINT 这是告诉编译器这个结构使用顺序布局，在内存里先后排序
/// 定义点的x、y轴点，作为MinMaxInfo的属性类型
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public struct POINT
{
/// <summary>
/// x坐标点
/// </summary>
public int x;
/// <summary>
/// y坐标点
/// </summary>
public int y;

/// <summary>
/// 由x、y构造的点
/// </summary>
public POINT(int x, int y)
{
this.x = x;
this.y = y;
}
}

/// <summary>
/// 最大化的默认位置和尺寸，以及默认的最小和最大跟踪尺寸的一个MINMAXINFO结构的指针
/// </summary>
[StructLayout(LayoutKind.Sequential)]
public struct MinMaxInfo
{
public POINT ptReserved;
/// <summary>
/// 主显示器的最大高（宽）度
/// </summary>
public POINT ptMaxSize;
/// <summary>
/// 显示的最大高宽度
/// </summary>
public POINT ptMaxPosition;
/// <summary>
/// 最小的高宽度，可用于限定的最小区域
/// </summary>
public POINT ptMinTrackSize;
/// <summary>
/// 最大的高宽度
/// </summary>
public POINT ptMaxTrackSize;
};

[StructLayout(LayoutKind.Sequential, Pack = 0)]
public struct RECT
{
public int left;
public int top;
public int right;
public int bottom;
public static readonly RECT Empty = new RECT();

/// <summary> Win32窗口宽度 </summary>
public int Width
{
get { return Math.Abs(right - left); } // Abs needed for BIDI OS
}
/// <summary> Win32窗口高度 </summary>
public int Height
{
get { return bottom - top; }
}
/// <summary> Win32窗口 </summary>
public RECT(int left, int top, int right, int bottom)
{
this.left = left;
this.top = top;
this.right = right;
this.bottom = bottom;
}
/// <summary> Win32窗口 </summary>
public RECT(RECT rcSrc)
{
this.left = rcSrc.left;
this.top = rcSrc.top;
this.right = rcSrc.right;
this.bottom = rcSrc.bottom;
}
}

/// <summary>
/// 包含显示器信息的类型
/// </summary>
[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Auto)]
public class MONITORINFO
{
/// <summary>
/// 必须指定MONITORINFO结构中的cbSize,大小为 sizeof(MONITORINFO) 或者sizeof(MONITORINFOEX)
/// </summary>
public int cbSize = Marshal.SizeOf(typeof(MONITORINFO));

public RECT rcMonitor = new RECT();//主显示屏

public RECT rcWork = new RECT();//工作显示区

public int dwFlags = 0;
}

/// <summary>
/// GetMonitorInfo函数返回一个显示器的信息
/// </summary>
/// <param name="hMonitor">显示器的句柄</param>
/// <param name="lpmi">显示器信息(输出参数)</param>
/// <returns></returns>
[DllImport("user32")]
internal static extern bool GetMonitorInfo(IntPtr hMonitor, MONITORINFO lpmi);

/// <summary>
/// 获取到屏幕上具有最大交集区域的边界矩形的一个指定的窗口句柄。（能处理多显示器的问题）
/// </summary>
/// <param name="handle">窗口句柄</param>
/// <param name="flags">可能为null、最接近的窗口、主显示屏</param>
/// <returns></returns>
[DllImport("User32")]
internal static extern IntPtr MonitorFromWindow(IntPtr handle, int flags);

 

这样，只要在你要处理的窗口调用WndProc函数就可以了

this.SourceInitialized += delegate(object sender, EventArgs e)
{
this._HwndSource = PresentationSource.FromVisual((Visual)sender) as HwndSource;
this._HwndSource.AddHook(Win32.WndProc);
};
另外，如果只是在主显示器最大化处理有一句更简洁的代码实现：

this.MaximumSize = new Size(Screen.PrimaryScreen.WorkingArea.Width, Screen.PrimaryScreen.WorkingArea.Height);