如何设置WPF窗口最小化目标坐标 解决WS_EX_NOACTIVATE导致的位置异常

你可以通过Windows API操作WINDOWPLACEMENT结构体来自定义窗口最小化的目标坐标，完全可以实现两个窗口最小化动画同步的需求，具体实现步骤如下：

步骤1：导入所需Win32 API #

在WPF项目中添加如下API声明：

[StructLayout(LayoutKind.Sequential)]
public struct POINT
{
    public int X;
    public int Y;
}

[StructLayout(LayoutKind.Sequential)]
public struct WINDOWPLACEMENT
{
    public int length;
    public int flags;
    public int showCmd;
    public POINT ptMinPosition;
    public POINT ptMaxPosition;
    public RECT rcNormalPosition;
}

[StructLayout(LayoutKind.Sequential)]
public struct RECT
{
    public int Left, Top, Right, Bottom;
}

[DllImport("user32.dll")]
private static extern bool GetWindowPlacement(IntPtr hWnd, ref WINDOWPLACEMENT lpwndpl);

[DllImport("user32.dll")]
private static extern bool SetWindowPlacement(IntPtr hWnd, [In] ref WINDOWPLACEMENT lpwndpl);

private const int WM_SYSCOMMAND = 0x0112;
private const int SC_MINIMIZE = 0xF020;
private const int SW_MINIMIZE = 6;

步骤2：拦截窗口消息自定义最小化坐标 #

给背景窗口重写消息处理逻辑，在触发最小化之前同步主窗口的最小化坐标：

private IntPtr _bgWindowHandle;
// 背景窗口Loaded事件中初始化句柄和消息钩子
private void Window_Loaded(object sender, RoutedEventArgs e)
{
    _bgWindowHandle = new WindowInteropHelper(this).Handle;
    HwndSource.FromHwnd(_bgWindowHandle).AddHook(WndProc);
}

private IntPtr WndProc(IntPtr hwnd, int msg, IntPtr wParam, IntPtr lParam, ref bool handled)
{
    if (msg == WM_SYSCOMMAND && wParam.ToInt32() == SC_MINIMIZE)
    {
        // 获取主窗口的最小化坐标
        IntPtr mainWindowHandle = new WindowInteropHelper(/* 传入你的主窗口实例 */).Handle;
        WINDOWPLACEMENT mainPlacement = new WINDOWPLACEMENT();
        mainPlacement.length = Marshal.SizeOf(mainPlacement);
        GetWindowPlacement(mainWindowHandle, ref mainPlacement);
        
        // 同步设置背景窗口的最小化坐标
        WINDOWPLACEMENT bgPlacement = new WINDOWPLACEMENT();
        bgPlacement.length = Marshal.SizeOf(bgPlacement);
        GetWindowPlacement(_bgWindowHandle, ref bgPlacement);
        bgPlacement.ptMinPosition = mainPlacement.ptMinPosition;
        bgPlacement.showCmd = SW_MINIMIZE;
        SetWindowPlacement(_bgWindowHandle, ref bgPlacement);
    }
    return IntPtr.Zero;
}

步骤3：最小化完成后隐藏背景窗口 #

监听主窗口的StateChanged事件，当主窗口完全进入最小化状态后，将背景窗口设置为Visibility.Collapsed即可。窗口还原时先恢复背景窗口显示，再同步坐标，不影响原生动画效果。

注意事项 #

• 你当前设置的WS_EX_NOACTIVATE扩展样式可以保留，不影响上述逻辑执行
• 如果需要自定义最小化到任意位置（比如类似Rocket Dock的 dock 栏位置），直接给ptMinPosition赋值目标坐标即可

内容的提问来源于stack exchange，提问作者Selastin