winform Loading效果

      做winform项目时，有可能用到异步耗时加载数据啥的，这个时候就需要我们封装一个正在加载的效果。下面是实现思路：

     步骤一：把当前form界面使用句柄的方式截图出一个图片，这个图片会在下面用到，使用句柄获取截图的方式会在最后代码展示里附录上。

     步骤二：定义一个和当前form一样大小的panel,让这个panel带到当前form的Z顺序的最前面，把当前界面覆盖住，这样当前form的控件就不可点击。

     步骤三：把从步骤一获取的图片设置为步骤而定义的panel的背景，这样让这个panel看起来是和界面一样的。

     步骤四：在panel中间定义一个新的panel放置加载Loading图片和文字。

下面是封装的代码：

public partial class customForm : Form
    {
        #region properties

        /// <summary>
        /// 显示的等待框
        /// </summary>
        private System.Windows.Forms.Panel waitingBox;

        Panel waitingBoxInnerPanel;

        Label waitingBoxLab;

        private PictureBox _waitPicBox;

        private bool _IsWaitingBoxCreated = false;

        private bool _isOnWaiting = false;

        #endregion

        public baseLogin()
        {
            InitializeComponent();

            //设置程序图标
            Icon = Icon.FromHandle(Properties.Resources.icon.GetHicon());

            //Task.Delay(1000).ContinueWith((t) => { CreateWaitingBox(); });
        }

        public void ShowProgress(string message = "", int second = 60)
        {
            if (_isOnWaiting)
            {
                return;
            }
            _isOnWaiting = true;
            this.Invoke(new Action(() =>
            {
                CreateWaitingBox();
                SetWaitingMessage(message);
                waitingBox.Visible = true;
                waitingBox.BringToFront();
            }));
        }

        public void ShowMessage(string message = "", int second = 2)
        {
            if (_isOnWaiting)
            {
                return;
            }
            _isOnWaiting = true;
            CreateWaitingBox();
            SetWaitingMessage(message);
            if (IsHandleCreated)
            {
                this.Invoke(new Action(() =>
                {
                    waitingBox.Visible = true;
                    waitingBox.BringToFront();
                }));
                Task.Delay(second * 1000).ContinueWith((t) =>
                {
                    DisMissMessage();
                });
            }
        }

        public void DisMissMessage()
        {
            if (waitingBox == null)
            {
                return;
            }
            if (!waitingBox.Visible)
            {
                return;
            }
            else
            {
                this.Invoke(new Action(() =>
                {
                    waitingBox.Visible = false;
                    this._isOnWaiting = false;
                }));
            }
        }

        #region private

        private void CreateWaitingBox()
        {

            if (this.IsHandleCreated)
            {
                this.Invoke(new Action(() =>
               {
                   //Image backImg = this.CreateBacgroundImage();
                   Control frm = this;
                   Image backImg = CaptureImage(ref frm);
                   if (!_IsWaitingBoxCreated)
                   {
                       waitingBox = new Panel()
                       {
                           Visible = false,
                       };
                       waitingBox.BackColor = Color.FromArgb(234, 244, 252);

                       waitingBoxInnerPanel = new Panel();
                       waitingBoxInnerPanel.Width = 280;
                       waitingBoxInnerPanel.Height = 80;
                       waitingBoxInnerPanel.BackColor = Color.Gray;
                       waitingBoxInnerPanel.Padding = new Padding(8, 5, 5, 5);

                       waitingBoxLab = new Label();
                       waitingBoxLab.TextAlign = ContentAlignment.MiddleLeft;
                       waitingBoxLab.AutoEllipsis = true;
                       waitingBoxLab.Dock = DockStyle.Fill;

                       waitingBoxInnerPanel.Controls.Add(waitingBoxLab);

                       PictureBox pb = new PictureBox();
                       pb.Dock = DockStyle.Left;
                       pb.Size = new System.Drawing.Size(72, 70);
                       pb.Image = Properties.Resources.loading;
                       pb.Margin = new System.Windows.Forms.Padding(3, 3, 20, 3);
                       pb.SizeMode = PictureBoxSizeMode.StretchImage;
                       this._waitPicBox = pb;
                       waitingBoxInnerPanel.Controls.Add(pb);

                       waitingBox.Controls.Add(waitingBoxInnerPanel);
                       //waitingBox.BringToFront();
                       if (!this.Controls.Contains(waitingBox))
                       {
                           this.Controls.Add(waitingBox);
                       }
                       //waitingBox.Show();

                       this._IsWaitingBoxCreated = true;

                   }

                   Rectangle rect = this.ClientRectangle;
                   waitingBox.Width = rect.Width;
                   waitingBox.Height = rect.Height;
                   waitingBox.Location = new Point(rect.X, rect.Y);

                   waitingBox.BackgroundImage = backImg;
                   waitingBox.BackgroundImageLayout = ImageLayout.Stretch;
               }));
            }
        }

        /// <summary>
        /// 设置等待显示的信息
        /// </summary>
        /// <param name="message">The message.</param>
        /// User:Ryan  CreateTime:2012-8-5 16:22.
        private void SetWaitingMessage(string message)
        {
            if (this.IsHandleCreated)
            {
                this.Invoke(new Action(() =>
                {
                    message = " " + message.Trim();
                    if (this.waitingBoxLab != null && this.waitingBoxInnerPanel != null)
                    {
                        using (Graphics g = this.CreateGraphics())
                        {
                            int w = Convert.ToInt32(g.MeasureString(message, this.waitingBoxLab.Font).Width);
                            w = w >= 200 ? w : 200;
                            w = this.Width - 100 >= w ? w : this.Width - 100;
                            this.waitingBoxInnerPanel.Width = w + 60;
                            waitingBoxInnerPanel.Location = new Point(waitingBox.Bounds.X + waitingBox.Width / 2 - waitingBoxInnerPanel.Width / 2,
                                waitingBox.Bounds.Y + waitingBox.Height / 2 - waitingBoxInnerPanel.Height);
                        }

                        this.waitingBoxLab.Text = message;
                    }
                }));
            }
        }

        private Bitmap CreateBacgroundImage()
        {
            Rectangle rect = this.ClientRectangle;
            int w = rect.Width;
            int h = rect.Height;
            try
            {
                Bitmap img = new Bitmap(w, h);
                using (Graphics g = Graphics.FromImage(img))
                {
                    g.CopyFromScreen(new Point(this.Location.X, this.Location.Y), new Point(0, 0), new Size(w, h));
                }
                //img.Save("a.jpg");
                return img;
            }
            catch (Exception ex)
            {
                return null;
            }
        }


        public Bitmap CaptureImage(ref Control c)
        {
            int hDC;
            int sh;
            int sw;
            if (c == null)
            {
                hDC = GetDC(0);
                sw = Screen.PrimaryScreen.Bounds.Width;
                sh = Screen.PrimaryScreen.Bounds.Height;
            }
            else
            {
                hDC = GetDC((int)c.Handle);
                sw = c.Width;
                sh = c.Height;
            }
            int hMDC = CreateCompatibleDC(hDC);
            int hBMP = CreateCompatibleBitmap(hDC, sw, sh);
            int hBMPOld = SelectObject(hMDC, hBMP);
            BitBlt(hMDC, 0, 0, sw, sh, hDC, 0, 0, 0xcc0020);
            hBMP = SelectObject(hMDC, hBMPOld);
            Bitmap result = Image.FromHbitmap(new IntPtr(hBMP));
            DeleteDC(hDC);
            DeleteDC(hMDC);
            DeleteObject(hBMP);
            return result;
        }
        [DllImport("gdi32.dll", EntryPoint = "CreateCompatibleBitmap")]
        public static extern int CreateCompatibleBitmap(int hdc, int nWidth, int nHeight);
        [DllImport("gdi32.dll", EntryPoint = "CreateCompatibleDC")]
        public static extern int CreateCompatibleDC(int hdc);
        [DllImport("user32.dll", EntryPoint = "GetDC")]
        public static extern int GetDC(int hwnd);
        [DllImport("gdi32.dll", EntryPoint = "DeleteDC")]
        public static extern int DeleteDC(int hdc);
        [DllImport("gdi32.dll", EntryPoint = "SelectObject")]
        public static extern int SelectObject(int hdc, int hObject);
        [DllImport("gdi32.dll", EntryPoint = "DeleteObject")]
        public static extern int DeleteObject(int hObject);
        [DllImport("gdi32.dll", EntryPoint = "BitBlt")]
        public static extern int BitBlt(int hDestDC, int x, int y, int nWidth, int nHeight, int hSrcDC, int xSrc, int ySrc, int dwRop);


        #endregion

    }

下面是示例代码：

 public partial class Form1:customForm
{
     private void button1_Click(object sender,EventArgs e)
     {
            ShowMessage("我是消息");
      }
}