c# - 如何在窗体加载其控件(或更新它们)时在Windows窗体上显示 “loading”覆盖？

我正在寻找一种通知用户当前表单正在加载(或更新)其UI的有效方法，这将需要几秒钟。

这可能在初始加载或更新时发生。由于它非常密集且需要修改ui控件，因此必须在ui线程上完成，因此会阻塞用户。

更改光标还不够，我想获得与ajax页面类似的效果，整个区域被半透明面板覆盖，中间带有动画齿轮。

你已经做了类似的事情吗？还是您知道我应该咨询的有趣网站？

非常感谢

最佳答案

看看这篇帖子，这个答案很好，它模仿了WinForms上的Ajax样式

类似于WinForms的Java模态窗口。
Javascript Like Modal Window for WinForms

这是一个自定义表单，可根据您的喜好进行更改...

public partial class ModalLoadingUI : Form
{
    #region Constants
    private readonly Color BackgroundFadeColor = Color.FromArgb(50, Color.Black);
    #endregion

    #region Constructors
    public ModalLoadingUI()
    {
        InitializeComponent();
    }
    #endregion

    #region Properties
    /// <summary>
    /// Gets or Sets the main form that will be used as a background canvas for the loading form.
    /// </summary>
    public Form BackgroundForm { get; set; }

    /// <summary>
    /// Gets or Sets the text to displayed as the progress text.
    /// </summary>
    public string Title
    {
        get
        {
            return label1.Text;
        }

        set
        {
            label1.Text = value;
        }
    }

    /// <summary>
    /// Gets or Sets the value of the progress bar.
    /// </summary>
    public int? Progress
    {
        get
        {
            if (progressBar1.Style == ProgressBarStyle.Marquee)
            {
                return null;
            }
            else
            {
                return progressBar1.Value;
            }
        }

        set
        {
            if (value == null)
            {
                progressBar1.Style = ProgressBarStyle.Marquee;
                progressBar1.Value = 100;

                label2.Visible = false;
            }
            else
            {
                progressBar1.Style = ProgressBarStyle.Continuous;
                progressBar1.Value = value.Value;

                label2.Text = string.Format("{0}%", value);
                label2.Visible = true;
            }
        }
    }

    /// <summary>
    /// Gets or Sets a value to indicate if the background form should be faded out.
    /// </summary>
    public bool UseFadedBackground { get; set; }

    /// <summary>
    /// Gets or Sets a value to indicate if the splash box is to be displayed.
    /// </summary>
    public bool UseSplashBox
    {
        get
        {
            return picShadow.Visible;
        }

        set
        {
            if (value == true)
            {
                picShadow.Visible = true;
                panel1.Visible = true;
            }
            else
            {
                picShadow.Visible = false;
                panel1.Visible = false;
            }
        }
    }
    #endregion

    #region Base Events
    private void ModalLoadingUI_Load(object sender, EventArgs e)
    {
        if (this.BackgroundForm != null)
        {
            this.Location = this.BackgroundForm.Location;
        }
    }

    private void ModalLoadingUI_VisibleChanged(object sender, EventArgs e)
    {
        if (this.Visible == true)
        {
            if (this.BackgroundForm != null)
            {
                this.Location = this.BackgroundForm.Location;
            }
        }

        if (System.Diagnostics.Debugger.IsAttached == true)
        {
            this.TopMost = false;
        }
        else
        {
            this.TopMost = true;
        }
    }

    private void ModalLoadingUI_Shown(object sender, EventArgs e)
    {
    }
    #endregion

    #region Public Methods
    /// <summary>
    /// Paints the background form as the background of this form, if one is defined.
    /// </summary>
    public void CaptureBackgroundForm()
    {
        if (this.InvokeRequired)
        {
            this.BeginInvoke(new MethodInvoker(CaptureBackgroundForm));
            return;
        }

        if (this.BackgroundForm == null)
        {
            return;
        }


        var bmpScreenshot = new Bitmap(Screen.PrimaryScreen.Bounds.Width, Screen.PrimaryScreen.Bounds.Height, PixelFormat.Format32bppArgb);
        Graphics g = Graphics.FromImage(bmpScreenshot);

        try
        {
            // COPY BACKGROUND
            int x = this.BackgroundForm.Left;
            int y = this.BackgroundForm.Top;
            var size = this.BackgroundForm.Size;

            g.CopyFromScreen(x, y, 0, 0, size, CopyPixelOperation.SourceCopy);

            // FADE IF DESIRED
            if (this.UseFadedBackground == true)
            {
                var rect = new Rectangle(0, 0, size.Width, size.Height);

                g.FillRectangle(new SolidBrush(BackgroundFadeColor), rect);
            }

            // PAINT SPLASH BOX SHADOW IF DESIRED
            if(this.UseSplashBox == true)
            {
                PaintPanelShadow(g);
            }
        }
        catch (Exception e)
        {
            g.Clear(Color.White);
        }

        this.BackgroundImage = bmpScreenshot;
    }

    /// <summary>
    /// Paints a shadow around the panel, if one is defined.
    /// </summary>
    /// <param name="g">The graphics object to paint into</param>
    private void PaintPanelShadow(Graphics g)
    {
        var shadowImage = picShadow.Image;

        var x = panel1.Left + (panel1.Width / 2) - (shadowImage.Width / 2);
        var y = panel1.Top + (panel1.Height / 2) - (shadowImage.Height / 2);

        g.DrawImage(shadowImage, x, y, shadowImage.Width, shadowImage.Height);
    }
    #endregion
}