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 = )
         {
             if (_isOnWaiting)
             {
                 return;
             }
             _isOnWaiting = true;
             this.Invoke(new Action(() =>
             {
                 CreateWaitingBox();
                 SetWaitingMessage(message);
                 waitingBox.Visible = true;
                 waitingBox.BringToFront();
             }));
         }

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

                        waitingBoxInnerPanel = new Panel();
                        waitingBoxInnerPanel.Width = ;
                        waitingBoxInnerPanel.Height = ;
                        waitingBoxInnerPanel.BackColor = Color.Gray;
                        waitingBoxInnerPanel.Padding = new Padding(, , , );

                        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(, );
                        pb.Image = Properties.Resources.loading;
                        pb.Margin = new System.Windows.Forms.Padding(, , , );
                        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 >=  ? w : ;
                             w = this.Width -  >= w ? w : this.Width - ;
                             this.waitingBoxInnerPanel.Width = w + ;
                             waitingBoxInnerPanel.Location = new Point(waitingBox.Bounds.X + waitingBox.Width /  - waitingBoxInnerPanel.Width / ,
                                 waitingBox.Bounds.Y + waitingBox.Height /  - 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(, ), 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();
                 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, , , sw, sh, hDC, , , 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

     }

封装代码

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");
       }
 }