C# 如何以无边界形式设置客户端区域（ClientRectangle）？

我想知道是否可以设置无边界表单的客户端区域。例如，我定义了这样一个表单：

代码

public class MyForm : Form
{
    public MyForm()
    {
        this.FormBorderStyle = FormBorderStyle.None;
    }
}

结果

我要做的是指定客户机区域，以便表单有一个框架（类似于标准windows框架，但自定义绘制）

结果

基本上，蓝色区域将成为非客户区域，灰色区域将保留为客户区域

我试图设置客户端区域，但这似乎只是调整了整个表单的大小，因此，没有留下“非客户端”区域

---

这是可能的吗？

这是可能的，但是我不知道这在WindowsStyle设置为无边框的Windows窗体中效果如何。使用PInvoke（平台调用）函数，您可以删除窗口主题，这将为您提供一个外观非常基本的Windows窗体。然后可以使用各种PInvoke函数来操作windows窗体的非客户端区域

我建议您通读这些主题。它们是用C++来设计的Win32应用程序，但是PInvoke是使用托管代码（C**）

调用这些本地API的过程。 WM_NCCALCSIZE：

WM_NCPAINT：

GetDCEx：

GetWindowDC：

设置窗口主题：

这个例子非常粗糙，但它提供了基本的功能。我不知道SetWindowTheme在Windows8或8.1上是如何工作的，但在Windows7中，它为Windows提供了“经典”主题

你想剥掉它的皮吗？。。。

public partial class MyForm : Form
{
    //Window Messages
    public const uint WM_NCPAINT = 0x85;
    public const uint WM_NCCALCSIZE = 0x83;
    public const uint WM_NCHITTEST = 0x84;

    //GetDCEx Flags
    public const int DCX_WINDOW = 0x00000001;
    public const int DCX_CACHE = 0x00000002;
    public const int DCX_PARENTCLIP = 0x00000020;
    public const int DCX_CLIPSIBLINGS = 0x00000010;
    public const int DCX_CLIPCHILDREN = 0x00000008;
    public const int DCX_NORESETATTRS = 0x00000004;
    public const int DCX_LOCKWINDOWUPDATE = 0x00000400;
    public const int DCX_EXCLUDERGN = 0x00000040;
    public const int DCX_INTERSECTRGN = 0x00000080;
    public const int DCX_INTERSECTUPDATE = 0x00000200;
    public const int DCX_VALIDATE = 0x00200000;

    //RECT Structure
    [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
    public struct RECT
    {
        public int left, top, right, bottom;
    }

    //WINDOWPOS Structure
    [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
    public struct WINDOWPOS
    {
        public IntPtr hwnd;
        public IntPtr hwndinsertafter;
        public int x, y, cx, cy;
        public int flags;
    }

    //NCCALCSIZE_PARAMS Structure
    [System.Runtime.InteropServices.StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
    public struct NCCALCSIZE_PARAMS
    {
        public RECT rgrc0, rgrc1, rgrc2;
        public WINDOWPOS lppos;
    }

    //SetWindowTheme UXtheme Function
    [System.Runtime.InteropServices.DllImport("uxtheme.dll", ExactSpelling = true, CharSet = System.Runtime.InteropServices.CharSet.Unicode)]
    public static extern int SetWindowTheme(
        IntPtr hWnd,
        String pszSubAppName,
        String pszSubIdList);

    //GetWindowRect User32 Function
    [System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
    [return: System.Runtime.InteropServices.MarshalAs(System.Runtime.InteropServices.UnmanagedType.Bool)]
    public static extern bool GetWindowRect(
        IntPtr hwnd,
        out  RECT lpRect
        );

    //GetWindowDC User32 Function
    [System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
    public static extern IntPtr GetWindowDC(
        IntPtr hWnd
        );

    //GetDCEx User32 Function
    [System.Runtime.InteropServices.DllImport("user32.dll", ExactSpelling = true)]
    public static extern IntPtr GetDCEx(
        IntPtr hWnd,
        IntPtr hrgnClip,
        int flags
        );

    //Window Procedure Hook
    protected override void WndProc(ref Message m)
    {
        //Don't style window in designer...
        if (DesignMode)
            base.WndProc(ref m);

        //Handle Message
        switch ((uint)m.Msg)
        {
            case WM_NCCALCSIZE: WmNCCalcSize(ref m); break;
            case WM_NCPAINT: WmNCPaint(ref m); break;
            default: base.WndProc(ref m); break;
        }
    }

    //Handle Creation
    protected override void OnHandleCreated(EventArgs e)
    {
        //Base Procedure...
        base.OnHandleCreated(e);

        //Remove Theme
        SetWindowTheme(this.Handle, string.Empty, string.Empty);
    }

    //WM_NCCALCSIZE
    private void WmNCCalcSize(ref Message m)
    {
        //Get Window Rect
        RECT formRect = new RECT();
        GetWindowRect(m.HWnd, out formRect);

        //Check WPARAM
        if (m.WParam != IntPtr.Zero)    //TRUE
        {
            //When TRUE, LPARAM Points to a NCCALCSIZE_PARAMS structure
            var nccsp = (NCCALCSIZE_PARAMS)System.Runtime.InteropServices.Marshal.PtrToStructure(m.LParam, typeof(NCCALCSIZE_PARAMS));

            //We're adjusting the size of the client area here. Right now, the client area is the whole form.
            //Adding to the Top, Bottom, Left, and Right will size the client area.
            nccsp.rgrc0.top += 30;      //30-pixel top border
            nccsp.rgrc0.bottom -= 4;    //4-pixel bottom (resize) border
            nccsp.rgrc0.left += 4;      //4-pixel left (resize) border
            nccsp.rgrc0.right -= 4;     //4-pixel right (resize) border

            //Set the structure back into memory
            System.Runtime.InteropServices.Marshal.StructureToPtr(nccsp, m.LParam, true);
        }
        else    //FALSE
        {
            //When FALSE, LPARAM Points to a RECT structure
            var clnRect = (RECT)System.Runtime.InteropServices.Marshal.PtrToStructure(m.LParam, typeof(RECT));

            //Like before, we're adjusting the rectangle...
            //Adding to the Top, Bottom, Left, and Right will size the client area.
            clnRect.top += 30;      //30-pixel top border
            clnRect.bottom -= 4;    //4-pixel bottom (resize) border
            clnRect.left += 4;      //4-pixel left (resize) border
            clnRect.right -= 4;     //4-pixel right (resize) border

            //Set the structure back into memory
            System.Runtime.InteropServices.Marshal.StructureToPtr(clnRect, m.LParam, true);
        }

        //Return Zero
        m.Result = IntPtr.Zero;
    }

    //WM_NCPAINT
    private void WmNCPaint(ref Message m)
    {
        //Store HDC
        IntPtr HDC = IntPtr.Zero;
        Graphics gfx = null;

        //Check the WPARAM
        if(m.WParam == (IntPtr)1)
        {
            //For reasons unknown to me, the update region doesn't contain valid data and calling GetDCEx will do nothing.
            //So I call GetWindowDC and exclude the area using System.Drawing.Graphics instead.

            //Graphics Object from HDC
            HDC = GetWindowDC(m.HWnd);
            gfx = Graphics.FromHdc(HDC);

            //Exclude Client Area
            gfx.ExcludeClip(new Rectangle(4, 30, Width - 8, 34));  //Exclude Client Area (GetWindowDC grabs the WHOLE window's graphics handle)
        }
        else
        {
            //Graphics Object from HDC
            HDC = GetDCEx(m.HWnd, m.WParam, DCX_WINDOW | DCX_INTERSECTRGN);
            gfx = Graphics.FromHdc(HDC);
        }

        //Call Paint
        using (PaintEventArgs ncPaintArgs = new PaintEventArgs(gfx, new Rectangle(0, 0, Width, Height)))
            MyForm_NCPaint(this, ncPaintArgs);

        //Return Zero
        m.Result = IntPtr.Zero;
    }

    public MyForm()
    {
        InitializeComponent();
    }

    private void MyForm_NCPaint(object sender, PaintEventArgs e)
    {
        //Clear
        e.Graphics.Clear(Color.Green);
    }
}