C# 仿QQ截圖程式 winform

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();
        }

        使用者變數#region 使用者變數
        private Point DownPoint = Point.Empty;//記錄滑鼠按下座標，用來確定繪圖起點
        private bool CatchFinished = false;//用來表示是否完成
        private bool CatchStart = false;//表示開始
        private Bitmap originBmp;//用來儲存原始映像
        private Rectangle CatchRect;//用來儲存的矩形
        #endregion

        //表單初始化操作
        private void Catch_Load(object sender, EventArgs e)
        {
            this.SetStyle(ControlStyles.OptimizedDoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.UserPaint, true);
            this.UpdateStyles();
            //以上兩句是為了設定控制項樣式為雙緩衝，這可以有效減少圖片閃爍的問題，關於這個大家可以自己去搜尋下
            originBmp = new Bitmap(this.BackgroundImage);//BackgroundImage為全屏圖片，我們另用變數來儲存全屏圖片
        }

        //滑鼠右鍵點擊結束
        private void Catch_MouseClick(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                this.DialogResult = DialogResult.OK;
                this.Close();
            }
        }

        //滑鼠左鍵按下時動作
        private void Catch_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                if (!CatchStart)
                {//如果捕捉沒有開始
                    CatchStart = true;
                    DownPoint = new Point(e.X, e.Y);//儲存滑鼠按下座標
                }
            }
        }

        private void Catch_MouseMove(object sender, MouseEventArgs e)
        {
            if (CatchStart)
            {//如果捕捉開始
                Bitmap destBmp = (Bitmap)originBmp.Clone();//建立一個圖片對象，並讓它與原始圖片相同
                Point newPoint = new Point(DownPoint.X, DownPoint.Y);//擷取滑鼠的座標
                Graphics g = Graphics.FromImage(destBmp);//在剛才建立的圖片上建立一個畫板
                Pen p = new Pen(Color.Blue,1);
                int width = Math.Abs(e.X - DownPoint.X), height = Math.Abs(e.Y - DownPoint.Y);//擷取矩形的長和寬
                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));//儲存矩形
                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();//重新建立一個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建立的g,因為只是把地址轉到新的g了．如同string一樣
                g1 = this.CreateGraphics();//在整個全屏表單上建立畫板
                g1.DrawImage(destBmp,new Point(0,0));//將剛才所畫的圖片畫到這個表單上
                //這個也可以屬於二次緩衝技術，如果直接將矩形畫在表單上，會造成圖片抖動並且會有無數個矩形．
                g1.Dispose();
                destBmp.Dispose();//要及時釋放，不然記憶體將會被大量消耗
               
            }
        }

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

        //滑鼠雙擊事件，如果滑鼠位於矩形內，則將矩形內的圖片儲存到剪貼簿中
        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);//建立一個於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);//將圖片儲存到剪貼簿
                    g.Dispose();
                    CatchFinished = false;
                    this.BackgroundImage = originBmp;
                    CatchedBmp.Dispose();
                    this.DialogResult = DialogResult.OK;
                    this.Close();
                }
            }
        }
    }
}
　　C.建立了Catch表單後，我們在按鈕(位於聊天表單上)上加入以下事件：
        private void bCatch_Click(object sender, EventArgs e)
        {

            if (bCatch_HideCurrent.Checked)
            {
                this.Hide();//隱藏當前表單
                Thread.Sleep(50);//讓線程睡眠一段時間，表單消失需要一點時間
                Catch CatchForm = new Catch();
                Bitmap CatchBmp = new Bitmap(Screen.AllScreens[0].Bounds.Width, Screen.AllScreens[0].Bounds.Height);//建立一個和螢幕大小相同的圖片        
                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));//儲存全屏圖片
                CatchForm.BackgroundImage = CatchBmp;//將Catch表單的背景設為全屏時的圖片
                if (CatchForm.ShowDialog() == DialogResult.OK)
                {//如果Catch表單結束,就將剪貼簿中的圖片放到資訊發送框中
                    IDataObject iData = Clipboard.GetDataObject();
                    DataFormats.Format myFormat = DataFormats.GetFormat(DataFormats.Bitmap);
                    if (iData.GetDataPresent(DataFormats.Bitmap))
                    {
                        richtextbox1.Paste(myFormat);
                        Clipboard.Clear();//清除剪貼簿中的對象
                    }
                    this.Show();//重新顯示表單
                }
            }

        }

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