ContextMenuManager/ContextMenuManager/BluePointLilac.Controls/ResizbleForm.cs

using System;
using System.Windows.Forms;

namespace BluePointLilac.Controls
{
    /// <summary>限制水平、竖直方向调整大小的窗体</summary>
    public class ResizbleForm : Form
    {
        /// <summary>水平方向可调整大小</summary>
        public bool HorizontalResizable { get; set; } = true;

        /// <summary>竖直方向可调整大小</summary>
        public bool VerticalResizable { get; set; } = true;

        protected override void WndProc(ref Message m)
        {
            base.WndProc(ref m);
            if(m.Msg == WM_NCHITTEST && this.WindowState == FormWindowState.Normal)
            {
                IntPtr hNowhere = new IntPtr((int)HitTest.Nowhere);
                HitTest value = (HitTest)m.Result;
                switch(value)
                {
                    case HitTest.Top:
                    case HitTest.Bottom:
                        if(!VerticalResizable) m.Result = hNowhere;
                        break;
                    case HitTest.Left:
                    case HitTest.Right:
                        if(!HorizontalResizable) m.Result = hNowhere;
                        break;
                    case HitTest.TopLeft:
                    case HitTest.TopRight:
                    case HitTest.BottomLeft:
                    case HitTest.BottomRight:
                        if(!VerticalResizable || !HorizontalResizable) m.Result = hNowhere;
                        break;
                }
            }
        }

        const int WM_NCHITTEST = 0x84;//光标移动或鼠标按下、释放时的消息
        /// <summary>鼠标击中位置</summary>
        public enum HitTest : int
        {
            Error = -2,
            Transparent = -1,
            Nowhere = 0,
            Client = 1,
            TitleBar = 2,
            SysMenu = 3,
            Size = 4,
            GrowBox = 5,
            Hscroll = 6,
            Vscroll = 7,
            MinButton = 8,
            MaxButton = 9,
            Left = 10,
            Right = 11,
            Top = 12,
            TopLeft = 13,
            TopRight = 14,
            Bottom = 15,
            BottomLeft = 16,
            BottomRight = 17,
            Border = 18,
            Close = 20,
            Help = 21
        }
    }
}