在 WinForm 中 如何实现 加载等待功能

1，需要一个动态的londing文件；在项目中我们新建一个文件夹来存放它；

2，在需要出现londing状态的窗体上加上一个Panel；

黄色区域是Panel，灰色的是需要被加载的区域。当需要触发londing，我们就把Panel显示出来，不让用户在这个区域能做任何修改；

下面的两个button事件就是触发londing的；在这里实例化的 OpaqueCommand对象；我们需要创建一个OpaqueCommand类

        OpaqueCommand cmd = new OpaqueCommand();
        /// <summary>
        /// 启动加载功能
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void show_Click(object sender, EventArgs e)
        {
            cmd.ShowOpaqueLayer(panelLonding, 125, true);
        }
        /// <summary>
        /// 关闭加载功能
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void hide_Click(object sender, EventArgs e)
        {
            cmd.HideOpaqueLayer();
        }

3，OpaqueCommand类里面的内容

public class OpaqueCommand
    {
        private OpaqueLayer m_OpaqueLayer = null;

        public void ShowOpaqueLayer(Control control, int alpha, bool isShowLoadingImage)
        {
            try
            {
                if (this.m_OpaqueLayer == null)
                {
                    this.m_OpaqueLayer = new OpaqueLayer(alpha, isShowLoadingImage);
                    control.Controls.Add(this.m_OpaqueLayer);
                    this.m_OpaqueLayer.Dock = DockStyle.Fill;
                    this.m_OpaqueLayer.BringToFront();
                }
                this.m_OpaqueLayer.Enabled = true;
                this.m_OpaqueLayer.Visible = true;
            }
            catch { }
        }

        public void HideOpaqueLayer()
        {
            try
            {
                if (this.m_OpaqueLayer != null)
                {
                    this.m_OpaqueLayer.Visible = false;
                    this.m_OpaqueLayer.Enabled = false;
                }
            }
            catch (Exception ex)
            {
                //MessageBox.Show(ex.Message);
            }
        }
    }

　4，创建　OpaqueLayer 类，这里面是重新绘制了窗体，内容如下

[ToolboxBitmap(typeof(OpaqueLayer))]
    public class OpaqueLayer:Control
    {
        private bool transparentBG = true;//是否使用透明
        private int alpha = 125;//设置透明度
        private Container components = new Container();
        public OpaqueLayer()
            : this(125, true)
        {
        }

        public OpaqueLayer(int Alpha, bool IsShowLoadingImage)
        {
            SetStyle(System.Windows.Forms.ControlStyles.Opaque, true);
            base.CreateControl();

            this.alpha = Alpha;
            if (IsShowLoadingImage)
            {
                PictureBox pictureBox_Loading = new PictureBox();
                pictureBox_Loading.BackColor = System.Drawing.Color.White;
                pictureBox_Loading.Image = WinLonding.Properties.Resources.Loading;
                pictureBox_Loading.Name = "pictureBox_Loading";
                pictureBox_Loading.Size = new System.Drawing.Size(48, 48);
                pictureBox_Loading.SizeMode = System.Windows.Forms.PictureBoxSizeMode.AutoSize;
                Point Location = new Point(this.Location.X + (this.Width - pictureBox_Loading.Width) / 2, this.Location.Y + (this.Height - pictureBox_Loading.Height) / 2);//居中
                pictureBox_Loading.Location = Location;
                pictureBox_Loading.Anchor = AnchorStyles.None;
                this.Controls.Add(pictureBox_Loading);
            }
        }

        protected override void Dispose(bool disposing)
        {
            if (disposing)
            {
                if (!((components == null)))
                {
                    components.Dispose();
                }
            }
            base.Dispose(disposing);
        }

        /// <summary>
        /// 自定义绘制窗体
        /// </summary>
        /// <param name="e"></param>
        protected override void OnPaint(PaintEventArgs e)
        {
            float vlblControlWidth;
            float vlblControlHeight;

            Pen labelBorderPen;
            SolidBrush labelBackColorBrush;

            if (transparentBG)
            {
                Color drawColor = Color.FromArgb(this.alpha, this.BackColor);
                labelBorderPen = new Pen(drawColor, 0);
                labelBackColorBrush = new SolidBrush(drawColor);
            }
            else
            {
                labelBorderPen = new Pen(this.BackColor, 0);
                labelBackColorBrush = new SolidBrush(this.BackColor);
            }
            base.OnPaint(e);
            vlblControlWidth = this.Size.Width;
            vlblControlHeight = this.Size.Height;
            e.Graphics.DrawRectangle(labelBorderPen, 0, 0, vlblControlWidth, vlblControlHeight);
            e.Graphics.FillRectangle(labelBackColorBrush, 0, 0, vlblControlWidth, vlblControlHeight);
        }

        protected override CreateParams CreateParams//v1.10
        {
            get
            {
                CreateParams cp = base.CreateParams;
                cp.ExStyle |= 0x00000020; //0x20;  // 开启 WS_EX_TRANSPARENT,使控件支持透明
                return cp;
            }
        }

        [Category("OpaqueLayer"), Description("Whether to use transparent, the default is true")]
        public bool TransparentBG
        {
            get
            {
                return transparentBG;
            }
            set
            {
                transparentBG = value;
                this.Invalidate();
            }
        }

        [Category("OpaqueLayer"), Description("Set the transparency")]
        public int Alpha
        {
            get
            {
                return alpha;
            }
            set
            {
                alpha = value;
                this.Invalidate();
            }
        }
    }

这时候再点击show button 就能看到效果啦！