using System;

using System.Drawing;

using System.Windows.Forms;

namespace WFA画图

{

    public partial class Form1 : Form

    {

        #region 成员变量

        Point m_p1, m_p2;

        bool m_flgKeuDowm = false;

        Bitmap m_mapStart;

        Bitmap m_mapEnd;

        Bitmap m_mapInit;

        Graphics m_graphics;

        #endregion

        public Form1()

        {

            InitializeComponent();

            m_graphics = pictureBox1.CreateGraphics();

            // 最初的背景图存起来，清除绘制图形时用

            m_mapInit = (Bitmap)pictureBox1.BackgroundImage;

        }

        #region 鼠标事件

        /// <summary>

        /// 鼠标按下

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void pictureBox1_MouseDown(object sender, MouseEventArgs e)

        {

            m_flgKeuDowm = true;

            _initPoint(e);

        }

        /// <summary>

        /// 鼠标移动

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void pictureBox1_MouseMove(object sender, MouseEventArgs e)

        {

            if (!m_flgKeuDowm)

            {

                return;

            }

            else

            {

                m_p2 = new Point(e.X, e.Y);

            }

            int width = Math.Abs(e.X - m_p1.X);

            int height = Math.Abs(e.Y - m_p1.Y);

            _draw();

        }

        /// <summary>

        /// 鼠标抬起

        /// </summary>

        /// <param name="sender"></param>

        /// <param name="e"></param>

        private void pictureBox1_MouseUp(object sender, MouseEventArgs e)

        {

            m_flgKeuDowm = false;

            // 最终的图片设为背景图

            pictureBox1.BackgroundImage = m_mapEnd;

            // 起止点初始化

            _initPoint(e);

        }

        #endregion

        private void _draw(){

            // 每次的【终止图】都是取自【起始图】

            m_mapEnd = (Bitmap)m_mapStart.Clone();

            Graphics g = Graphics.FromImage(m_mapEnd);

            Pen pen = new Pen(Color.Red,);

            if (rdoRect.Checked)

            {

                Point p1,p2;

                _swapPoint(out p1,out p2 );

                int width = Math.Abs(p2.X - p1.X);

                int height = Math.Abs(p2.Y - p1.Y);

                g.DrawRectangle(pen, p1.X, p1.Y, width, height);

            }else if(rdoLine.Checked){

                // 画直线不用转换点坐标，直接用成员变量的Point

                g.DrawLine(pen, m_p1, m_p2);

            }

            m_graphics.DrawImage(m_mapEnd, new Point(, ));

        }

        private void _initPoint(MouseEventArgs e)

        {

            m_p1 = new Point(e.X, e.Y);

            m_p2 = m_p1;

            if (pictureBox1.BackgroundImage != null)

            {

                m_mapStart = (Bitmap)pictureBox1.BackgroundImage;

            }

        }

        private void _printPoint(Point p)

        {

            Console.WriteLine(p.X+","+p.Y);

        }

        private void _swapPoint(out Point _p1, out Point _p2)

        {

            //实现画框随意翻转

            _p1 = m_p1;

            _p2 = m_p2;

            if (m_p1.X > m_p2.X)

            {

                int tmp = _p1.X;

                _p1.X = _p2.X;

                _p2.X = tmp;

            }

            if (m_p1.Y > m_p2.Y)

            {

                int tmp = _p1.Y;

                _p1.Y = _p2.Y;

                _p2.Y = tmp;

            }

        }

        #region 按钮

        private void btnClear_Click(object sender, EventArgs e)

        {

            pictureBox1.BackgroundImage = m_mapInit;

        }

        private void btnSave_Click(object sender, EventArgs e)

        {

            // 保存

            SaveFileDialog dlg = new SaveFileDialog();

            dlg.DefaultExt = "png";

            dlg.Filter = "Png Files|*.png";

            dlg.FileName = "截图";

            DialogResult dlgRet = dlg.ShowDialog();

            if (dlgRet == DialogResult.OK)

            {

                pictureBox1.BackgroundImage.Save(dlg.FileName, System.Drawing.Imaging.ImageFormat.Png);

            }

        }

        #endregion

    }

}