C# - VS2019通過重寫pictureBox實現簡單的桌面截圖功能

前言

通過創建客制化組件（繼承pictureBox），新增屬性和構造方法，實現屏幕截圖時需要用到的功能點。再通過監控鼠標按下、移動和釋放，來獲取起始點區域。最后通過操作BMP圖像，實現截圖的新增、修改和保存功能。

核心點

• 組件的創建（重寫）
• 鼠標監控事件
• BMP圖像重繪

核心代碼

    /// <summary>
    /// 重寫圖片控件
    /// </summary>
    [Serializable]
    public partial class HexPictureBox : PictureBox
    {
        #region 屬性和構造函數

        public HexPictureBox()
        {
            InitializeComponent();
        }

        private bool startDraw = false;

        public bool StartDraw
        {
            get { return startDraw; }

            set { startDraw = value; }
        }

        private List<HLine> lineHistory = new List<HLine>();

        public List<HLine> LineHistory
        {
            get { return lineHistory; }

            private set { lineHistory = value; }
        }

        private HLine curLine = new HLine() { LineColor = Color.White, LineWidth = 2, PointList = new List<Point>() };

        /// <summary>
        /// 當前繪制線
        /// </summary>
        public HLine CurLine
        {
            get { return curLine; }

            private set { curLine = value; }
        }

        private HRectangle curRect = new HRectangle() { LineColor = Color.White, LineWidth = 2, Start = new Point(0, 0), End = new Point(0, 0) };

        /// <summary>
        /// 當前需要繪制的矩形
        /// </summary>
        public HRectangle CurRect
        {
            get { return curRect; }

            set { curRect = value; }
        }

        private List<HRectangle> rectHistory = new List<HRectangle>();

        public List<HRectangle> RectHistory
        {
            get { return rectHistory; }

            private set { rectHistory = value; }
        }

        private DrawType drawTypes = DrawType.None;

        public DrawType DrawTypes
        {
            get { return drawTypes; }

            set { drawTypes = value; }
        }

        #endregion

        #region 繪制功能

        protected override void OnPaint(PaintEventArgs pe)
        {
            base.OnPaint(pe);
            Graphics g = pe.Graphics;
            DrawHistory(g);
            //繪制當前線
            if (startDraw && this.curLine.PointList != null && this.curLine.PointList.Count > 0)
            {
                DrawLine(g, this.curLine);
            }
            if (startDraw && this.curRect.Start != null && this.curRect.End != null && this.curRect.Start != this.curRect.End)
            {
                DrawRectangle(g, this.curRect);
            }
        }

        public void DrawHistory(Graphics g)
        {
            //繪制線歷史記錄
            if (LineHistory != null)
            {
                foreach (HLine lh in LineHistory)
                {
                    if (lh.PointList.Count > 10)
                    {
                        DrawLine(g, lh);
                    }
                }
            }
            //繪制矩形歷史記錄
            if (RectHistory != null)
            {
                foreach (HRectangle lh in RectHistory)
                {
                    if (lh.Start != null && lh.End != null && lh.Start != lh.End)
                    {
                        DrawRectangle(g, lh);
                    }
                }
            }
        }

        /// <summary>
        /// 繪制線
        /// </summary>
        /// <param name="g"></param>
        /// <param name="line"></param>
        private void DrawLine(Graphics g, HLine line)
        {
            g.SmoothingMode = SmoothingMode.AntiAlias;
            using (Pen p = new Pen(line.LineColor, line.LineWidth))
            {
                //設置起止點線帽  
                p.StartCap = LineCap.Round;
                p.EndCap = LineCap.Round;

                //設置連續兩段的聯接樣式  
                p.LineJoin = LineJoin.Round;
                g.DrawCurve(p, line.PointList.ToArray()); //畫平滑曲線  
            }
        }

        /// <summary>
        /// 繪制矩形
        /// </summary>
        /// <param name="g"></param>
        /// <param name="rect"></param>
        private void DrawRectangle(Graphics g, HRectangle rect)
        {
            g.SmoothingMode = SmoothingMode.AntiAlias;
            using (Pen p = new Pen(rect.LineColor, rect.LineWidth))
            {
                //設置起止點線帽  
                p.StartCap = LineCap.Round;
                p.EndCap = LineCap.Round;

                //設置連續兩段的聯接樣式  
                p.LineJoin = LineJoin.Round;
                g.DrawRectangle(p, rect.Start.X, rect.Start.Y, rect.End.X - rect.Start.X, rect.End.Y - rect.Start.Y); //畫平滑曲線  
            }
        }

        public void Earser(Point p0)
        {
            for (int i = lineHistory.Count - 1; i >= 0; i--)
            {
                HLine line = lineHistory[i];
                bool flag = false;
                foreach (Point p1 in line.PointList)
                {
                    double distance = GetDistance(p0, p1);
                    if (Math.Abs(distance) < 6)
                    {
                        //需要刪除
                        flag = true;
                        break;
                    }

                }
                if (flag)
                {
                    lineHistory.RemoveAt(i);
                }
            }
            //擦除矩形
            for (int i = rectHistory.Count - 1; i >= 0; i--)
            {
                HRectangle rect = rectHistory[i];

                if (p0.X > rect.Start.X && p0.X < rect.End.X && p0.Y > rect.Start.Y && p0.Y < rect.End.Y)
                {

                    rectHistory.RemoveAt(i);
                }
            }
        }

        /// <summary>
        /// 獲取兩點之間的距離
        /// </summary>
        /// <param name="p0"></param>
        /// <param name="p1"></param>
        /// <returns></returns>
        private double GetDistance(Point p0, Point p1)
        {
            return Math.Sqrt(Math.Pow((p0.X - p1.X), 2) + Math.Pow((p0.Y - p1.Y), 2));
        }

        #endregion

        #region 鼠標事件響應

        /// <summary>
        /// 鼠標移動時設置點
        /// </summary>
        /// <param name="p"></param>
        public void SetPointAndRefresh(Point p)
        {
            if (this.drawTypes == DrawType.Line)
            {
                this.curLine.PointList.Add(p);
            }
            if (this.drawTypes == DrawType.Rect)
            {
                this.curRect.End = p;
            }
            this.Refresh();

        }

        public void OnMouseDown(Point p)
        {
            if (this.DrawTypes == DrawType.Line)
            {
                this.CurLine.PointList.Clear();
                this.CurLine.PointList.Add(p);
            }
            if (this.DrawTypes == DrawType.Rect)
            {
                this.CurRect.Start = p;
            }
        }

        public void OnMouseUp(Point p)
        {
            if (this.DrawTypes == DrawType.Line)
            {
                //右鍵起來時，停止繪圖，並寫入歷史記錄
                Point[] pCopy = this.CurLine.PointList.ToArray();
                List<Point> lstPoint = new List<Point>();
                lstPoint.AddRange(pCopy);
                this.LineHistory.Add(new HLine() { LineColor = this.CurLine.LineColor, LineWidth = this.CurLine.LineWidth, PointList = lstPoint });
                this.CurLine.PointList.Clear();
            }
            if (this.DrawTypes == DrawType.Rect)
            {
                this.RectHistory.Add(new HRectangle() { LineColor = this.CurRect.LineColor, LineWidth = this.CurRect.LineWidth, Start = this.CurRect.Start, End = this.CurRect.End });
                this.CurRect.Start = new Point(0, 0);
                this.CurRect.End = new Point(0, 0);
            }
            if (this.DrawTypes == DrawType.Earser)
            {
                //如果是橡皮擦功能
                this.Earser(p);
                this.Refresh();
            }
        }

        #endregion

        #region 初始設置

        public void SetPen(Color c)
        {
            this.DrawTypes = DrawType.Line;
            this.CurLine.LineWidth = 2;
            this.CurLine.LineColor = c;
            //通過圖片的句柄獲取指針
            this.Cursor = new Cursor(global::ScreenShot.Properties.Resources.pen.GetHicon());
            this.StartDraw = true;
        }

        public void SetLightPen()
        {
            this.StartDraw = true;
            this.CurLine.LineWidth = 6;
            this.DrawTypes = DrawType.Line;
            this.Cursor = new Cursor(global::ScreenShot.Properties.Resources.lightpen.GetHicon());
            this.CurLine.LineColor = Color.FromArgb(100, Color.Yellow);
        }

        public void SetRectangle()
        {
            this.StartDraw = true;
            this.CurRect.LineWidth = 3;
            this.DrawTypes = DrawType.Rect;
            this.CurRect.LineColor = Color.Red;
            this.Cursor = Cursors.Cross;
        }

        public void SetEarser()
        {
            this.DrawTypes = DrawType.Earser;//橡皮檫
            this.Cursor = new Cursor(global::ScreenShot.Properties.Resources.easer1.GetHicon());
        }

        public void SetDefault()
        {
            this.Cursor = Cursors.Default;
            this.StartDraw = false;
        }

        #endregion
    }

實現效果

 

  作者：Jeremy.Wu
  出處：https://www.cnblogs.com/jeremywucnblog/
  本文版權歸作者和博客園共有，歡迎轉載，但未經作者同意必須保留此段聲明，且在文章頁面明顯位置給出原文連接，否則保留追究法律責任的權利。