C#winform自定义控件模拟设计时界面鼠标移动和调节大小、选中效果

要想玩转Winform自定义控件需要对GDI+非常熟悉，对常用的控件有一些了解，好选择合适的基类控件来简化。

要点说明及代码

1)定义接口：

using System;
using System.Windows.Forms;

namespace GDIPrinterDriver
{
    /// <summary>
    /// 模板元素接口
    /// </summary>
    public interface ILabelDesignElement
    {
        /// <summary>
        /// PrintData/codeContext里的字段，{} [] 
        /// </summary>
        string 动态内容 { get; set; }
        /// <summary>
        /// 是否被选中
        /// </summary>
        bool DesignSelected { get; set; }
        /// <summary>
        /// 选择状态发生改变
        /// </summary>
        event Action<object, bool> SelectedStatusChange;
        /// <summary>
        /// 本控件被选中时键盘方向键被按下
        /// </summary>
        /// <param name="keyData"></param>
        void KeysChangedLocation(Keys keyData);
    }
}

2)控件基类实现：

using GDIPrinterDriver;
using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.Windows.Forms;

namespace GDILabelDesigner
{
    /// <summary>
    /// 设计时控件基类
    /// </summary>
    public abstract class DesignCellControl : PictureBox, ILabelDesignElement
    {
        #region 鼠标移动和缩放
        private enum EnumMousePointPosition
        {
            MouseSizeNone = 0, //'无    
            MouseSizeRight = 1, //'拉伸右边框    
            MouseSizeLeft = 2, //'拉伸左边框    
            MouseSizeBottom = 3, //'拉伸下边框    
            MouseSizeTop = 4, //'拉伸上边框    
            MouseSizeTopLeft = 5, //'拉伸左上角    
            MouseSizeTopRight = 6, //'拉伸右上角    
            MouseSizeBottomLeft = 7, //'拉伸左下角    
            MouseSizeBottomRight = 8, //'拉伸右下角    
            MouseDrag = 9   // '鼠标拖动    
        }
        const int Band = 5;
        const int MinWidth = 10;
        const int MinHeight = 10;
        private EnumMousePointPosition m_MousePointPosition;
        private Point p, p1;
        private EnumMousePointPosition MousePointPosition(Size size, System.Windows.Forms.MouseEventArgs e)
        {

            if ((e.X >= -1 * Band) | (e.X <= size.Width) | (e.Y >= -1 * Band) | (e.Y <= size.Height))
            {
                if (e.X < Band)
                {
                    if (e.Y < Band) { return EnumMousePointPosition.MouseSizeTopLeft; }
                    else
                    {
                        if (e.Y > -1 * Band + size.Height)
                        { return EnumMousePointPosition.MouseSizeBottomLeft; }
                        else
                        { return EnumMousePointPosition.MouseSizeLeft; }
                    }
                }
                else
                {
                    if (e.X > -1 * Band + size.Width)
                    {
                        if (e.Y < Band)
                        { return EnumMousePointPosition.MouseSizeTopRight; }
                        else
                        {
                            if (e.Y > -1 * Band + size.Height)
                            { return EnumMousePointPosition.MouseSizeBottomRight; }
                            else
                            { return EnumMousePointPosition.MouseSizeRight; }
                        }
                    }
                    else
                    {
                        if (e.Y < Band)
                        { return EnumMousePointPosition.MouseSizeTop; }
                        else
                        {
                            if (e.Y > -1 * Band + size.Height)
                            { return EnumMousePointPosition.MouseSizeBottom; }
                            else
                            { return EnumMousePointPosition.MouseDrag; }
                        }
                    }
                }
            }
            else
            { return EnumMousePointPosition.MouseSizeNone; }
        }
        #endregion
        public bool DesignSelected
        {
            get
            {
                return designSelected;
            }
            set
            {
                designSelected = value;
                Invalidate();
            }
        }
        private bool designSelected = false;
        public DynamicMapProperty DynamicMapProperty { get; set; }
        public StaticMapProperty StaticMapProperty { get; set; }
        public string 动态内容 { get; set; }
        public RoteDescription RoteDescription { get; set; }
        /// <summary>
        /// 被选中，获取到焦点的事件
        /// </summary>
        public event Action<object, bool> SelectedStatusChange;
        protected override void OnClick(EventArgs e)
        {
            DesignSelected = true;
            SelectedStatusChange?.Invoke(this, DesignSelected);
        }
        protected override void OnMouseWheel(MouseEventArgs e)
        {
            base.OnMouseWheel(e);
            double d = 1.068D;
            if (e.Delta > 0 && DesignSelected)
            {
                this.Size = new Size((int)(this.Size.Width * d), (int)(this.Size.Height * d));
            }
            else
            {
                this.Size = new Size((int)(this.Size.Width / d), (int)(this.Size.Height / d));
            }
        }
        protected override void OnMouseDown(MouseEventArgs e)
        {
            p.X = e.X;
            p.Y = e.Y;
            p1.X = e.X;
            p1.Y = e.Y;
        }
        protected override void OnMouseUp(MouseEventArgs e)
        {
            m_MousePointPosition = EnumMousePointPosition.MouseSizeNone;
            this.Cursor = Cursors.Arrow;
        }
        protected override void OnMouseMove(MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                switch (m_MousePointPosition)
                {
                    #region 位置计算
                    case EnumMousePointPosition.MouseDrag:
                        Left = Left + e.X - p.X;
                        Top = Top + e.Y - p.Y;
                        break;
                    case EnumMousePointPosition.MouseSizeBottom:
                        Height = Height + e.Y - p1.Y;
                        p1.X = e.X;
                        p1.Y = e.Y; //'记录光标拖动的当前点    
                        break;
                    case EnumMousePointPosition.MouseSizeBottomRight:
                        Width = Width + e.X - p1.X;
                        Height = Height + e.Y - p1.Y;
                        p1.X = e.X;
                        p1.Y = e.Y; //'记录光标拖动的当前点    
                        break;
                    case EnumMousePointPosition.MouseSizeRight:
                        Width = Width + e.X - p1.X;
                        Height = Height + e.Y - p1.Y;
                        p1.X = e.X;
                        p1.Y = e.Y; //'记录光标拖动的当前点    
                        break;
                    case EnumMousePointPosition.MouseSizeTop:
                        Top = Top + (e.Y - p.Y);
                        Height = Height - (e.Y - p.Y);
                        break;
                    case EnumMousePointPosition.MouseSizeLeft:
                        Left = Left + e.X - p.X;
                        Width = Width - (e.X - p.X);
                        break;
                    case EnumMousePointPosition.MouseSizeBottomLeft:
                        Left = Left + e.X - p.X;
                        Width = Width - (e.X - p.X);
                        Height = Height + e.Y - p1.Y;
                        p1.X = e.X;
                        p1.Y = e.Y; //'记录光标拖动的当前点    
                        break;
                    case EnumMousePointPosition.MouseSizeTopRight:
                        Top = Top + (e.Y - p.Y);
                        Width = Width + (e.X - p1.X);
                        Height = Height - (e.Y - p.Y);
                        p1.X = e.X;
                        p1.Y = e.Y; //'记录光标拖动的当前点    
                        break;
                    case EnumMousePointPosition.MouseSizeTopLeft:
                        Left = Left + e.X - p.X;
                        Top = Top + (e.Y - p.Y);
                        Width = Width - (e.X - p.X);
                        Height = Height - (e.Y - p.Y);
                        break;
                    default:
                        break;
                        #endregion
                }
                if (Width < MinWidth) Width = MinWidth;
                if (Height < MinHeight) Height = MinHeight;
                if (Tag != null)
                {                   
                    if (Tag is ImageElementNode)
                    {
                        var tag = Tag as ImageElementNode;
                        tag.Location = Location;
                    }
                    else if (Tag is BarcodeElementNode)
                    {
                        var tag = Tag as BarcodeElementNode;
                        tag.Location = Location;
                    }
                    else if (Tag is TextBoxElementNode)
                    {
                        var tag = Tag as TextBoxElementNode;
                        tag.Location = Location;
                    }
                }
            }
            else
            {
                m_MousePointPosition = MousePointPosition(Size, e);
                switch (m_MousePointPosition)
                {
                    #region 改变光标
                    case EnumMousePointPosition.MouseSizeNone:
                        this.Cursor = Cursors.Arrow;        //'箭头    
                        break;
                    case EnumMousePointPosition.MouseDrag:
                        this.Cursor = Cursors.SizeAll;      //'四方向    
                        break;
                    case EnumMousePointPosition.MouseSizeBottom:
                        this.Cursor = Cursors.SizeNS;       //'南北    
                        break;
                    case EnumMousePointPosition.MouseSizeTop:
                        this.Cursor = Cursors.SizeNS;       //'南北    
                        break;
                    case EnumMousePointPosition.MouseSizeLeft:
                        this.Cursor = Cursors.SizeWE;       //'东西    
                        break;
                    case EnumMousePointPosition.MouseSizeRight:
                        this.Cursor = Cursors.SizeWE;       //'东西    
                        break;
                    case EnumMousePointPosition.MouseSizeBottomLeft:
                        this.Cursor = Cursors.SizeNESW;     //'东北到南西    
                        break;
                    case EnumMousePointPosition.MouseSizeBottomRight:
                        this.Cursor = Cursors.SizeNWSE;     //'东南到西北    
                        break;
                    case EnumMousePointPosition.MouseSizeTopLeft:
                        this.Cursor = Cursors.SizeNWSE;     //'东南到西北    
                        break;
                    case EnumMousePointPosition.MouseSizeTopRight:
                        this.Cursor = Cursors.SizeNESW;     //'东北到南西    
                        break;
                    default:
                        break;
                        #endregion
                }
            }
        }

        /// <summary>
        /// 绘制方框
        /// </summary>
        /// <param name="g"></param>
        protected void DrawSelectedStatus(Graphics g)
        {
            Rectangle rect = ClientRectangle;
            rect.Inflate(-6, -6);
            using (Pen p = new Pen(Brushes.Black, 1))
            {
                p.DashStyle = DashStyle.Dot;
                p.DashStyle = DashStyle.Solid;
                //8个方块
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left - 4, rect.Top - 4, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left + rect.Width / 2 - 3, rect.Top - 4, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left + rect.Width, rect.Top - 4, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left - 4, rect.Top + rect.Height / 2 - 3, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left - 4, rect.Top + rect.Height, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left + rect.Width, rect.Top + rect.Height / 2 - 3, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left + rect.Width / 2 - 3, rect.Top + rect.Height, 4, 4));
                g.FillRectangle(Brushes.White, new Rectangle(rect.Left + rect.Width, rect.Top + rect.Height, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left - 4, rect.Top - 4, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left + rect.Width / 2 - 3, rect.Top - 4, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left + rect.Width, rect.Top - 4, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left - 4, rect.Top + rect.Height / 2 - 3, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left - 4, rect.Top + rect.Height, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left + rect.Width, rect.Top + rect.Height / 2 - 3, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left + rect.Width / 2 - 3, rect.Top + rect.Height, 4, 4));
                g.DrawRectangle(p, new Rectangle(rect.Left + rect.Width, rect.Top + rect.Height, 4, 4));
            }
        }
        /// <summary>
        /// 旋转图片
        /// </summary>
        /// <param name="bmp">源图</param>
        /// <param name="angle">角度</param>
        /// <param name="bkColor">背景色</param>
        /// <returns></returns>
        protected Bitmap ImageRotate(Bitmap bmp, float angle, Color bkColor)
        {
            int w = bmp.Width + 2;
            int h = bmp.Height + 2;
            PixelFormat pf;
            if (bkColor == Color.Transparent)
            {
                pf = PixelFormat.Format32bppArgb;
            }
            else
            {
                pf = bmp.PixelFormat;
            }
            Bitmap tmp = new Bitmap(w, h, pf);
            Graphics g = Graphics.FromImage(tmp);
            g.Clear(bkColor);
            g.DrawImageUnscaled(bmp, 1, 1);
            g.Dispose();
            GraphicsPath path = new GraphicsPath();
            path.AddRectangle(new RectangleF(0f, 0f, w, h));
            Matrix mtrx = new Matrix();
            mtrx.Rotate(angle);
            RectangleF rct = path.GetBounds(mtrx);
            Bitmap dst = new Bitmap((int)rct.Width, (int)rct.Height, pf);
            g = Graphics.FromImage(dst);
            g.Clear(bkColor);
            g.TranslateTransform(-rct.X, -rct.Y);
            g.RotateTransform(angle);
            g.InterpolationMode = InterpolationMode.HighQualityBilinear;
            g.DrawImageUnscaled(tmp, 0, 0);
            g.Dispose();
            tmp.Dispose();
            return dst;
        }
        /// <summary>
        /// 响应键盘光标键
        /// </summary>
        /// <param name="keyData"></param>
        public virtual void KeysChangedLocation(Keys keyData)
        {
            if (keyData == Keys.Up)
            {
                Top -= 1;
            }
            if (keyData == Keys.Down)
            {
                Top += 1;
            }
            if (keyData == Keys.Left)
            {
                Left -= 1;
            }
            if (keyData == Keys.Right)
            {
                Left += 1;
            }
            if (Tag != null)
            {
                if (Tag is ImageElementNode)
                {
                    var tag = Tag as ImageElementNode;
                    tag.Location = Location;
                }
                else if (Tag is BarcodeElementNode)
                {
                    var tag = Tag as BarcodeElementNode;
                    tag.Location = Location;
                }
                else if (Tag is TextBoxElementNode)
                {
                    var tag = Tag as TextBoxElementNode;
                    tag.Location = Location;
                }
            }
        }
    }
}