C#截取屏幕中選定區域的圖像

C#截取屏幕中選定區域的圖像

原理:主窗體首先截取整個屏幕圖像作為主窗體的背景圖,並且最大化,然後再做一個可調整大小的半透明窗體,將該窗體顯示在主窗體上,那麼該窗體所在的方框就是所要截取的方框.調整該窗体也就可以調整截取的范圍.

1.主窗體的設計
相關屬性:
            this.TopMost = true;
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;

--1.截取整個屏幕圖像

        private Bitmap GetScreenImage()
        {
            Bitmap bmp = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
                                    Screen.PrimaryScreen.Bounds.Height);
            Graphics g = Graphics.FromImage(bmp);
            g.CopyFromScreen(0, 0, 0, 0, Screen.PrimaryScreen.Bounds.Size);
            g.Dispose();

            return bmp;
        }

--2.畫方框 

private void FormBack_MouseMove(object sender, MouseEventArgs e)
        {
            if (!this.catcher.Visible)
            {
                this.label_CatcherLoc.Text = "位置 X: " + e.X + ", Y: " + e.Y;
            }
            if (this.isMouseLeftDown)
            {
                Rectangle rect = new Rectangle();
                rect.X = e.X > this.catcherLoc.X ? this.catcherLoc.X : e.X;
                rect.Y = e.Y > this.catcherLoc.Y ? this.catcherLoc.Y : e.Y;
                rect.Width = Math.Abs(e.X - this.catcherLoc.X);
                rect.Height = Math.Abs(e.Y - this.catcherLoc.Y);

                this.catcher.Bounds = rect;
                if (!this.catcher.Visible)
                {
                    this.catcher.Show(this);
                }

            }
        }

--3.取消繪製或退出:

        private void FormBack_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                if (!this.catcher.Visible)
                {
                    Application.Exit();
                }
                else
                {
                    this.catcher.Visible = false;
                    this.catcherLoc = Point.Empty;
                    this.isMouseLeftDown = false;
                }
            }
            else if (e.Button == MouseButtons.Left)
            {
                if (!this.catcher.Visible)
                {
                    this.catcherLoc = e.Location;
                    this.isMouseLeftDown = true;
                }
            }
        }

--4.調整顯示面板
如果改成(左上-->右上-->右下-->左下),代碼也不難,效果應該更好.

  private void panel_Info_MouseEnter(object sender, EventArgs e)
        {
            Panel pl = (Panel)sender;
            if (pl.Right < this.Width / 2)//在左邊
            {
                pl.Location = new Point(this.Width - pl.Width - 20, pl.Location.Y);
            }
            else
            {
                pl.Location = new Point(10, 10);
            }
        }

--5.複製:
還可以繼續添加一個右鍵菜單,擴展成更多的保存方式.

        void catcher_DoubleClick(object sender, EventArgs e)
        {
            Bitmap bmpCatched = new Bitmap(this.catcher.Width, this.catcher.Height);
            Graphics g = Graphics.FromImage(bmpCatched);
            g.CopyFromScreen(this.catcher.Location, new Point(0, 0), this.catcher.ClientRectangle.Size);
            Clipboard.SetImage(bmpCatched);

            if (MessageBox.Show("已經復制導剪切板") == DialogResult.OK)
            {
                Application.Exit();
            }
        }

2.製作一個可調整大小的半透明的無標題欄窗體.
在該窗體中應盡量實現應有的功能.

設置相關屬性:
            this.Cursor = System.Windows.Forms.Cursors.SizeAll;
            this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            this.ShowInTaskbar = false;

--1.繪製邊線及小方塊     

   //繪制矩形邊框與8個小方塊
        private void FormCatcher_Paint(object sender, PaintEventArgs e)
        {
            using (Graphics g = e.Graphics)
            {
                Rectangle rect = new Rectangle(2, 2, this.ClientRectangle.Width-4, this.ClientRectangle.Height-4);
                g.DrawRectangle(Pens.Red, rect);

                //繪制小方塊,只要有邊線,不畫方塊,也可以調整大小
                for (int i = 0; i <= 7; i++)
                {
                    g.FillRectangle(Brushes.Red, this.GetBoundsOfSmallBlock(i));
                }
            }
        }

--2.調整窗體大小及移動窗体

         //注意:調得太快時,鼠標好像跑得太快,有點不同步的感覺.
        private void FormCatcher_MouseMove(object sender, MouseEventArgs e)
        {

            int d = 10;
            if (e.X < d)//左邊緣
            {
                if (e.Y < d)//左上
                {
                    this.Cursor = Cursors.SizeNWSE;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X, Cursor.Position.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);
                    }

                }
                else if (Math.Abs(e.Y - this.Height) < d)//左下
                {
                    this.Cursor = Cursors.SizeNESW;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X,this.Location.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.Location.Y);
                    }
                }
                else//左
                {
                    this.Cursor = Cursors.SizeWE;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X, this.Location.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                    }


                }
            }
            else if (Math.Abs(e.X - this.Width) < d)//右邊緣
            {

                if (e.Y < d)//右上
                {
                    this.Cursor = Cursors.SizeNESW;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(this.Location.X, Cursor.Position.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.Location.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);

                    }
                }
                else if (Math.Abs(e.Y - this.Height) < d)//右下
                {
                    this.Cursor = Cursors.SizeNWSE;
                    if (this.isMouseLeftDown)
                    {
                        this.Height = Cursor.Position.Y - this.Location.Y;
                        this.Width = Cursor.Position.X - this.Location.X;
                    }
                }
                else//右
                {
                    this.Cursor = Cursors.SizeWE;
                    if (this.isMouseLeftDown)
                    {
                        this.Width = Cursor.Position.X - this.Location.X;
                    }
                }
            }
            else
            {
                if (e.Y < d)//上邊緣
                {
                    this.Cursor = Cursors.SizeNS;//中上
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(this.Location.X,Cursor.Position.Y);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);
                    }
                }
                else if (Math.Abs(e.Y - this.Height) < d)//下邊緣
                {
                    this.Cursor = Cursors.SizeNS;//中下
                    if (this.isMouseLeftDown)
                    {
                        this.Height = Cursor.Position.Y - this.Location.Y;
                    }
                }
                else//非邊緣區域
                {
                    this.Cursor = Cursors.SizeAll;

                    if (this.isMouseLeftDown)
                    {//按下鼠標左鍵並拖動窗口,改變窗口位置
                        this.Location = new Point(Cursor.Position.X - this.dxCursorToWindow,
                                                  Cursor.Position.Y - this.dyCursorToWindow);
                    }
                }
            }

        }

3.附源碼
源碼1:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;

namespace QQCatchScreen
{
    public partial class FormCatcher : Form
    {
        public FormCatcher()
        {
            InitializeComponent();
            this.Paint += new System.Windows.Forms.PaintEventHandler(this.FormCatcher_Paint);
            this.Resize += new EventHandler(FormCatcher_Resize);
            this.MouseUp += new System.Windows.Forms.MouseEventHandler(this.FormCatcher_MouseUp);
            this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.FormCatcher_MouseDown);
            this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.FormCatcher_MouseMove);

        }

        private bool isMouseLeftDown = false;
        /// <summary>
        /// 鼠標按下時鼠標與窗體位置橫坐標差
        /// </summary>
        private int dxCursorToWindow = 0;
        /// <summary>
        /// 鼠標按下時鼠標與窗體位置縱坐標差
        /// </summary>
        private int dyCursorToWindow = 0;
        /// <summary>
        /// 窗體右下角的座標
        /// </summary>
        private Point bottomLoc = Point.Empty;

        void FormCatcher_Resize(object sender, EventArgs e)
        {
            this.Refresh();
        }

        //繪制矩形邊框與8個小方塊
        private void FormCatcher_Paint(object sender, PaintEventArgs e)
        {
            using (Graphics g = e.Graphics)
            {
                Rectangle rect = new Rectangle(2, 2, this.ClientRectangle.Width-4, this.ClientRectangle.Height-4);
                g.DrawRectangle(Pens.Red, rect);

                //繪制小方塊,只要有邊線,不畫方塊,也可以調整大小
                for (int i = 0; i <= 7; i++)
                {
                    g.FillRectangle(Brushes.Red, this.GetBoundsOfSmallBlock(i));
                }
            }
        }

        /// <summary>
        /// 獲取指定序號的小方塊的位置
        /// </summary>
        /// <param name="index"></param>
        /// <returns></returns>
        private Rectangle GetBoundsOfSmallBlock(int index)
        {
            int x = 0;
            int y = 0;
            int w = 4;
            int h = 4;

            switch (index)
            {
                case 0:
                case 3:
                case 5:
                    x = 0;
                    break;
                case 1:
                case 6:
                    x = this.ClientRectangle.Width / 2 -3;//
                    break;
                case 2:
                case 4:
                case 7:
                    x = this.ClientRectangle.Width-4;//
                    break;
                default:
                    throw new IndexOutOfRangeException("小方塊序號錯誤，應該在?0，?");
            }

            switch (index)
            {
                case 0:
                case 1:
                case 2:
                    y = 0;
                    break;
                case 3:
                case 4:
                    y = this.ClientRectangle.Height / 2 -3;//
                    break;
                case 5:
                case 6:
                case 7:
                    y = this.ClientRectangle.Height-4;//
                    break;
                default:
                    throw new IndexOutOfRangeException("小方塊序號錯誤，應該在?0，?");
            }

            return new Rectangle(x, y, w, h);
        }

        private void FormCatcher_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.isMouseLeftDown = true;
                this.dxCursorToWindow = Cursor.Position.X - this.Location.X;
                this.dyCursorToWindow = Cursor.Position.Y - this.Location.Y;
                this.bottomLoc = new Point(this.Location.X + this.Width, this.Location.Y + this.Height);
            }
        }

        private void FormCatcher_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.isMouseLeftDown = false;
                this.dxCursorToWindow = this.dyCursorToWindow = 0;
                this.bottomLoc = new Point(this.Location.X + this.Width, this.Location.Y + this.Height);
            }
        }

        //調整大小就在這裡實現
        //Bug:調得太快時,效果不好.
        private void FormCatcher_MouseMove(object sender, MouseEventArgs e)
        {

            int d = 10;
            if (e.X < d)//左邊緣
            {
                if (e.Y < d)//左上
                {
                    this.Cursor = Cursors.SizeNWSE;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X, Cursor.Position.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);
                    }

                }
                else if (Math.Abs(e.Y - this.Height) < d)//左下
                {
                    this.Cursor = Cursors.SizeNESW;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X,this.Location.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.Location.Y);
                    }
                }
                else//左
                {
                    this.Cursor = Cursors.SizeWE;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(Cursor.Position.X, this.Location.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.bottomLoc.X);
                    }


                }
            }
            else if (Math.Abs(e.X - this.Width) < d)//右邊緣
            {

                if (e.Y < d)//右上
                {
                    this.Cursor = Cursors.SizeNESW;
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(this.Location.X, Cursor.Position.Y);
                        this.Width = Math.Abs(Cursor.Position.X - this.Location.X);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);

                    }
                }
                else if (Math.Abs(e.Y - this.Height) < d)//右下
                {
                    this.Cursor = Cursors.SizeNWSE;
                    if (this.isMouseLeftDown)
                    {
                        this.Height = Cursor.Position.Y - this.Location.Y;
                        this.Width = Cursor.Position.X - this.Location.X;
                    }
                }
                else//右
                {
                    this.Cursor = Cursors.SizeWE;
                    if (this.isMouseLeftDown)
                    {
                        this.Width = Cursor.Position.X - this.Location.X;
                    }
                }
            }
            else
            {
                if (e.Y < d)//上邊緣
                {
                    this.Cursor = Cursors.SizeNS;//中上
                    if (this.isMouseLeftDown)
                    {
                        this.Location = new Point(this.Location.X,Cursor.Position.Y);
                        this.Height = Math.Abs(Cursor.Position.Y - this.bottomLoc.Y);
                    }
                }
                else if (Math.Abs(e.Y - this.Height) < d)//下邊緣
                {
                    this.Cursor = Cursors.SizeNS;//中下
                    if (this.isMouseLeftDown)
                    {
                        this.Height = Cursor.Position.Y - this.Location.Y;
                    }
                }
                else//非邊緣區域
                {
                    this.Cursor = Cursors.SizeAll;

                    if (this.isMouseLeftDown)
                    {//按下鼠標左鍵並拖動窗口,改變窗口位置
                        this.Location = new Point(Cursor.Position.X - this.dxCursorToWindow,
                                                  Cursor.Position.Y - this.dyCursorToWindow);
                    }
                }
            }

        }

    }
}

源碼2:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Text;
using System.Windows.Forms;

namespace QQCatchScreen
{
    public partial class FormBack : Form
    {
        /// <summary>
        /// 保存整個屏幕的圖像
        /// </summary>
        private Bitmap screenImage = null;

        /// <summary>
        /// 用於確定最終捕獲圖像的窗口
        /// </summary>
        private FormCatcher catcher = new FormCatcher();

        /// <summary>
        /// 用於記錄catcher的位置
        /// </summary>
        private Point catcherLoc = Point.Empty;

        /// <summary>
        /// 標記鼠標左鍵是否按下
        /// </summary>
        private bool isMouseLeftDown = false;


        public FormBack()
        {
            InitializeComponent();
            this.MouseUp += new System.Windows.Forms.MouseEventHandler(this.FormBack_MouseUp);
            this.MouseMove += new System.Windows.Forms.MouseEventHandler(this.FormBack_MouseMove);
            this.MouseDown += new System.Windows.Forms.MouseEventHandler(this.FormBack_MouseDown);
            this.Load += new System.EventHandler(this.FormBack_Load);
        }

        private void FormBack_Load(object sender, EventArgs e)
        {
            this.Cursor = new Cursor("cur.cur");
            //設置位置和背景
            this.Bounds = Screen.PrimaryScreen.Bounds;
            this.screenImage = this.GetScreenImage();
            this.BackgroundImage = this.screenImage;

            //加載捕獲窗口
            this.catcher.Opacity = 0.4;
            this.catcher.Visible = false;
            this.catcher.MouseDown += new MouseEventHandler(catcher_MouseDown);
            this.catcher.DoubleClick += new EventHandler(catcher_DoubleClick);
            this.catcher.SizeChanged += new EventHandler(catcher_SizeChanged);
            this.catcher.VisibleChanged += new EventHandler(catcher_VisibleChanged);
            this.catcher.LocationChanged += new EventHandler(catcher_LocationChanged);

        }

        void catcher_VisibleChanged(object sender, EventArgs e)
        {
            if (!this.catcher.Visible)
            {
                this.label_CatcherWidth.Text = "寬度   ?0";
                this.label_CatcherHeight.Text = "高度   ?0 ";
            }
        }


        void catcher_LocationChanged(object sender, EventArgs e)
        {
            this.label_CatcherLoc.Text = "位置 X: " + this.catcher.Location.X + ", Y: " + this.catcher.Location.Y;
        }

        void catcher_SizeChanged(object sender, EventArgs e)
        {
            this.label_CatcherWidth.Text = "寬度    " + this.catcher.Width;
            this.label_CatcherHeight.Text = "高度    " + this.catcher.Height;
        }

        void catcher_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                this.catcherLoc = Point.Empty;
                this.isMouseLeftDown = false;
                this.catcher.Visible = false;
            }

        }

        void catcher_DoubleClick(object sender, EventArgs e)
        {
            Bitmap bmpCatched = new Bitmap(this.catcher.Width, this.catcher.Height);
            Graphics g = Graphics.FromImage(bmpCatched);
            g.CopyFromScreen(this.catcher.Location, new Point(0, 0), this.catcher.ClientRectangle.Size);
            Clipboard.SetImage(bmpCatched);

            if (MessageBox.Show("已經復制導剪切板") == DialogResult.OK)
            {
                Application.Exit();
            }
        }


        /// <summary>
        /// 獲取屏幕圖像
        /// </summary>
        private Bitmap GetScreenImage()
        {
            Bitmap bmp = new Bitmap(Screen.PrimaryScreen.Bounds.Width,
                                    Screen.PrimaryScreen.Bounds.Height);
            Graphics g = Graphics.FromImage(bmp);
            g.CopyFromScreen(0, 0, 0, 0, Screen.PrimaryScreen.Bounds.Size);
            g.Dispose();

            return bmp;
        }
        private void FormBack_MouseUp(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Left)
            {
                this.catcherLoc = Point.Empty;
                this.isMouseLeftDown = false;
            }
        }

        private void FormBack_MouseDown(object sender, MouseEventArgs e)
        {
            if (e.Button == MouseButtons.Right)
            {
                if (!this.catcher.Visible)
                {
                    Application.Exit();
                }
                else
                {
                    this.catcher.Visible = false;
                    this.catcherLoc = Point.Empty;
                    this.isMouseLeftDown = false;
                }
            }
            else if (e.Button == MouseButtons.Left)
            {
                if (!this.catcher.Visible)
                {
                    this.catcherLoc = e.Location;
                    this.isMouseLeftDown = true;
                }
            }
        }

        private void FormBack_MouseMove(object sender, MouseEventArgs e)
        {
            if (!this.catcher.Visible)
            {
                this.label_CatcherLoc.Text = "位置 X: " + e.X + ", Y: " + e.Y;
            }
            if (this.isMouseLeftDown)
            {
                Rectangle rect = new Rectangle();
                rect.X = e.X > this.catcherLoc.X ? this.catcherLoc.X : e.X;
                rect.Y = e.Y > this.catcherLoc.Y ? this.catcherLoc.Y : e.Y;
                rect.Width = Math.Abs(e.X - this.catcherLoc.X);
                rect.Height = Math.Abs(e.Y - this.catcherLoc.Y);

                this.catcher.Bounds = rect;
                if (!this.catcher.Visible)
                {
                    this.catcher.Show(this);
                }

            }
        }

        private void panel_Info_MouseEnter(object sender, EventArgs e)
        {
            Panel pl = (Panel)sender;
            if (pl.Right < this.Width / 2)//在左邊
            {
                pl.Location = new Point(this.Width - pl.Width - 20, pl.Location.Y);
            }
            else
            {
                pl.Location = new Point(10, 10);
            }
        }


    }


}