带无边框样式的可调整大小的表单和带停靠栏填充的子项

问题描述

我的目标是创建像普通 Win10 窗口一样可调整大小但没有标题栏的窗口（使用 WindowsForms），因此我可以自己绘制它（如 UWP 应用程序）。

解决方法

通过修改这段代码，我终于找到了一个非常好的工作anwser： https://stackoverflow.com/a/29788300/15213858

我现在拥有的：

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

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

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

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

    //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;
            default: base.WndProc(ref m); break;
        }
    }

    //WM_NCCALCSIZE
    private void WmNCCalcSize(ref Message m)
    {

        //Check WPARAM
        if (m.WParam != IntPtr.Zero)    //TRUE
        {
            //When TRUE,LPARAM Points to a NCCALCSIZE_PARAMS structure
            var nccsp = (NCCALCSIZE_PARAMS)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 += 0;      //30-pixel top border
            nccsp.rgrc0.bottom -= 8;    //4-pixel bottom (resize) border
            nccsp.rgrc0.left += 8;      //4-pixel left (resize) border
            nccsp.rgrc0.right -= 8;     //4-pixel right (resize) border

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

            //Like before,we're adjusting the rectangle...
            //Adding to the Top,and Right will size the client area.
            clnRect.top += 0;      //30-pixel top border
            clnRect.bottom -= 8;    //4-pixel bottom (resize) border
            clnRect.left += 8;      //4-pixel left (resize) border
            clnRect.right -= 8;     //4-pixel right (resize) border

            //Set the structure back into memory
            Marshal.StructureToPtr(clnRect,true);
        }

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