using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Text;
using System.Windows.Forms;
namespace Client
{
    public partial class Catch : Form
    {
        public Catch()
        {
            InitializeComponent();
        }
        用戶變量#region 用戶變量
        private Point DownPoint = Point.Empty;//記錄鼠標按下坐標，用來確定繪圖起點
        private bool CatchFinished = false;//用來表示是否截圖完成
        private bool CatchStart = false;//表示截圖開始
        private Bitmap originBmp;//用來保存原始圖像
        private Rectangle CatchRect;//用來保存截圖的矩形
        #endregion
        //窗體初始化操作
        private void Catch_Load(object sender, EventArgs e)
        {
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
            this.UpdateStyles();
            //以上兩句是為了設置控件樣式為雙緩沖，這可以有效減少圖片閃爍的問題，關于這個大家可以自己去搜索下
            originBmp = new Bitmap(this.BackgroundImage);//BackgroundImage為全屏圖片，我們另用變量來保存全屏圖片
        }
        //鼠標右鍵點擊結束截圖
        private void Catch_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                this.DialogResult = DialogResult.OK;
                this.Close();
            }
        }
        //鼠標左鍵按下時動作
        private void Catch_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                if (!CatchStart)
                {//如果捕捉?jīng)]有開始
                    CatchStart = true;
                    DownPoint = new Point(e.X, e.Y);//保存鼠標按下坐標
                }
            }
        }
        private void Catch_MouseMove(object sender, MouseEventArgs e)
        {
            if (CatchStart)
            {//如果捕捉開始
                Bitmap destBmp = (Bitmap)originBmp.Clone();//新建一個圖片對象，并讓它與原始圖片相同
                Point newPoint = new Point(DownPoint.X, DownPoint.Y);//獲取鼠標的坐標
                Graphics g = Graphics.FromImage(destBmp);//在剛才新建的圖片上新建一個畫板
                Pen p = new Pen(Color.Blue,1);
                int width = Math.Abs(e.X - DownPoint.X), height = Math.Abs(e.Y - DownPoint.Y);//獲取矩形的長和寬
                if (e.X < DownPoint.X)
                {
                    newPoint.X = e.X;
                }
                if (e.Y < DownPoint.Y)
                {
                    newPoint.Y = e.Y;
                }
                CatchRect = new Rectangle(newPoint,new Size(width,height));//保存矩形
                g.DrawRectangle(p,CatchRect);//將矩形畫在這個畫板上
                g.Dispose();//釋放目前的這個畫板
                p.Dispose();
                Graphics g1 = this.CreateGraphics();//重新新建一個Graphics類
                //如果之前那個畫板不釋放，而直接g=this.CreateGraphics()這樣的話無法釋放掉第一次創(chuàng)建的g,因為只是把地址轉到新的g了．如同string一樣
                g1 = this.CreateGraphics();//在整個全屏窗體上新建畫板
                g1.DrawImage(destBmp,new Point(0,0));//將剛才所畫的圖片畫到這個窗體上
                //這個也可以屬于二次緩沖技術，如果直接將矩形畫在窗體上，會造成圖片抖動并且會有無數(shù)個矩形．
                g1.Dispose();
                destBmp.Dispose();//要及時釋放，不然內(nèi)存將會被大量消耗

            }
        }
        private void Catch_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                if (CatchStart)
                {
                    CatchStart = false;
                    CatchFinished = true;

                }
            }
        }
        //鼠標雙擊事件，如果鼠標位于矩形內(nèi)，則將矩形內(nèi)的圖片保存到剪貼板中
        private void Catch_MouseDoubleClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left&&CatchFinished)
            {
                if (CatchRect.Contains(new Point(e.X, e.Y)))
                {
                    Bitmap CatchedBmp = new Bitmap(CatchRect.Width, CatchRect.Height);//新建一個于矩形等大的空白圖片
                    Graphics g = Graphics.FromImage(CatchedBmp);
                    g.DrawImage(originBmp, new Rectangle(0, 0, CatchRect.Width, CatchRect.Height), CatchRect, GraphicsUnit.Pixel);
                    //把orginBmp中的指定部分按照指定大小畫在畫板上
                    Clipboard.SetImage(CatchedBmp);//將圖片保存到剪貼板
                    g.Dispose();
                    CatchFinished = false;
                    this.BackgroundImage = originBmp;
                    CatchedBmp.Dispose();
                    this.DialogResult = DialogResult.OK;
                    this.Close();
                }
            }
        }
    }
}

 private void bCatch_Click(object sender, EventArgs e)
        {
            if (bCatch_HideCurrent.Checked)
            {
                this.Hide();//隱藏當前窗體
                Thread.Sleep(50);//讓線程睡眠一段時間，窗體消失需要一點時間
                Catch CatchForm = new Catch();
                Bitmap CatchBmp = new Bitmap(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height);//新建一個和屏幕大小相同的圖片        
                Graphics g = Graphics.FromImage(CatchBmp);
                g.CopyFromScreen(new Point(0, 0), new Point(0, 0), new Size(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height));//保存全屏圖片
                CatchForm.BackgroundImage = CatchBmp;//將Catch窗體的背景設為全屏時的圖片
                if (CatchForm.ShowDialog() == DialogResult.OK)
                {//如果Catch窗體結束,就將剪貼板中的圖片放到信息發(fā)送框中
                    IDataObject iData = Clipboard.GetDataObject();
                    DataFormats.Format myFormat = DataFormats.GetFormat(DataFormats.Bitmap);
                    if (iData.GetDataPresent(DataFormats.Bitmap))
                    {
                        richtextbox1.Paste(myFormat);
                        Clipboard.Clear();//清除剪貼板中的對象
                    }
                    this.Show();//重新顯示窗體
                }
            }
        }