如何在窗体加载其控件（或更新它们）时在窗体上显示“加载”叠加？

Question

I'm looking for an effective way to notify the user that a given form is currently loading (or updating) it's UI and it will take few seconds.

This may occurs at initial load or at update. Since it's very intensive and modifying ui controls, this has to be done on the ui thread, and therefore blocking the user.

Changing the cursor is not enought, I want to get a similar effect than on ajax pages, with the whole area that is overlayed by a semi transparent panel with an animated gear on the center.

Have you done something like that already? Or do you know interesting websites I should consult?

Thanks a lot

Answer 1

Take a look at this post with a great answer that mimics the Ajax style on WinForms

Javascript Like Modal Window for WinForms.
Javascript Like Modal Window for WinForms

Here is a custom Form that'll do what you want... alter to your taste:

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
}

Answer 2

You can create a transparent panel by subclassing SWFPanel and overriding the CreateParams property:

protected override CreateParams CreateParams
{
    get
    {
        CreateParams createParams = base.CreateParams;
        createParams.ExStyle |= 0x00000020; // WS_EX_TRANSPARENT
        return createParams;
    }
}

Override the OnPaint to add a semi transparent overlay:

protected override void OnPaint(PaintEventArgs e)
{
    e.Graphics.FillRectangle(new SolidBrush(Color.FromArgb(128, 0,0,0)), this.ClientRectangle);
}

Set this panel on Dock.Fill on your form over the other controls. Hide it when loading ends.

Answer 3

Note that Winforms does not allow child controls to actually be transparent. As others have posted a separate transparent window is possible - but messy to manage.

Cheap way

• drag all controls into one panel and make it the size of the window (easy change)
• When operating: Hide that panel. Use the panels .DrawToBitmap method to set form background image.
• show progress bar, do work with 'doevents,' hide it.
• clear background image, re-show panel.

A Better way:

Progress Class - Consumer

I will give you a Usercontrol I wrote and have used in many different programs that does exactly what you want. Here is a trivial consumer example, you can paste into a form's code (yes, it just makes a bunch of new buttons for no reason):

Public Class Form1

    Private Sub Form1_FormClosed(ByVal sender As Object, ByVal e As System.Windows.Forms.FormClosedEventArgs) Handles Me.FormClosed
        End ''// use a flag if you would like a more graceful way to handle this. 
    End Sub

    WithEvents ucProgress As New Progress   ''// just doing it this way so I don''//t have to paste designer code.

    Private Sub Form1_Shown(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Shown
        Controls.Clear()
        Controls.Add(ucProgress)
        Me.ucProgress.pb.Visible = False
        ucProgress.StartProgress()
        Try
            ucProgress.Message = "Starting up..."
            Application.DoEvents()
            Me.ucProgress.pb.Visible = True
            Me.ucProgress.pb.Maximum = 21
            Me.ucProgress.pb.Value = 0

            For i As Integer = 0 To 20
                Dim btn As New Button

                btn.Top = +i * 3
                btn.Left = i * 8
                btn.Text = CStr(i)
                btn.Enabled = False ''// ONLY HAVE TO DO FOR CTLS RIGHT ON MAIN FORM
                ucProgress.EnabledStates.Add(btn, True)  ''// ONLY HAVE TO DO FOR CTLS RIGHT ON MAIN FORM
                Controls.Add(btn)
                btn.BringToFront()

                System.Threading.Thread.Sleep(200)
                Application.DoEvents()

                ucProgress.pb.Value += 1
                ucProgress.Message = "Processing item# " & i.ToString
                If Me.ucProgress.Cancel Then
                    MsgBox("Cancelled - not all loaded.")
                    Me.ucProgress.Cancel = False
                    Exit For
                End If
            Next


        Catch ex As Exception
            MsgBox(ex.ToString, , "Error loading something")
        Finally
            ucProgress.EndProgress()
        End Try
    End Sub
End Class

Progress Class - Definition

And here is the class. The 'designer' code is pasted inline, you can leave it there. The class disables controls when running so all you can do is cancel. It runs on the GUI thread. You can disable the cancel option. In the consumer is an example of dealing with newly added controls so they don't show up enabled, but get enabled when the progress is over.

Option Explicit On
Option Strict On

Public Class Progress
    Inherits System.Windows.Forms.UserControl

#Region "Code for the Designer.vb class"

    Sub New()
        InitializeComponent()
    End Sub
    ''//Form overrides dispose to clean up the component list.
    <System.Diagnostics.DebuggerNonUserCode()> _
    Protected Overrides Sub Dispose(ByVal disposing As Boolean)
        If disposing AndAlso components IsNot Nothing Then
            components.Dispose()
        End If
        MyBase.Dispose(disposing)
    End Sub

    ''//Required by the Windows Form Designer
    Private components As System.ComponentModel.IContainer

    ''//NOTE: The following procedure is required by the Windows Form Designer
    ''//It can be modified using the Windows Form Designer.  
    ''//Do not modify it using the code editor.
    <System.Diagnostics.DebuggerStepThrough()> _
    Private Sub InitializeComponent()
        Me.components = New System.ComponentModel.Container
        Me.btnCancel = New System.Windows.Forms.Button
        Me.lblPlaceholder = New System.Windows.Forms.Label
        Me.pb = New System.Windows.Forms.ProgressBar
        Me.SuspendLayout()
        ''//
        ''//btnCancel
        ''//
        Me.btnCancel.Anchor = System.Windows.Forms.AnchorStyles.Top
        Me.btnCancel.Location = New System.Drawing.Point(73, 33)
        Me.btnCancel.Name = "btnCancel"
        Me.btnCancel.Size = New System.Drawing.Size(91, 21)
        Me.btnCancel.TabIndex = 0
        Me.btnCancel.Text = "Cancel"
        Me.btnCancel.UseVisualStyleBackColor = True
        ''//
        ''//
        ''//lblPlaceholder
        ''//
        Me.lblPlaceholder.Anchor = CType(((System.Windows.Forms.AnchorStyles.Top Or System.Windows.Forms.AnchorStyles.Left) _
                    Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)
        Me.lblPlaceholder.BackColor = System.Drawing.Color.Transparent
        Me.lblPlaceholder.Font = New System.Drawing.Font("Arial Narrow", 8.25!, System.Drawing.FontStyle.Bold, System.Drawing.GraphicsUnit.Point, CType(0, Byte))
        Me.lblPlaceholder.Location = New System.Drawing.Point(12, 3)
        Me.lblPlaceholder.Name = "lblPlaceholder"
        Me.lblPlaceholder.Size = New System.Drawing.Size(221, 29)
        Me.lblPlaceholder.TabIndex = 1
        Me.lblPlaceholder.Text = "Placeholder label for text drawing"
        Me.lblPlaceholder.Visible = False
        ''//
        ''//pb
        ''//
        Me.pb.Anchor = CType(((System.Windows.Forms.AnchorStyles.Bottom Or System.Windows.Forms.AnchorStyles.Left) _
                    Or System.Windows.Forms.AnchorStyles.Right), System.Windows.Forms.AnchorStyles)
        Me.pb.Location = New System.Drawing.Point(6, 60)
        Me.pb.Name = "pb"
        Me.pb.Size = New System.Drawing.Size(225, 10)
        Me.pb.Style = System.Windows.Forms.ProgressBarStyle.Continuous
        Me.pb.TabIndex = 2
        ''//
        ''//ucProgress
        ''//
        Me.AutoScaleDimensions = New System.Drawing.SizeF(6.0!, 13.0!)
        Me.AutoScaleMode = System.Windows.Forms.AutoScaleMode.Font
        Me.BackColor = System.Drawing.Color.LightSteelBlue
        Me.BorderStyle = System.Windows.Forms.BorderStyle.FixedSingle
        Me.Controls.Add(Me.pb)
        Me.Controls.Add(Me.lblPlaceholder)
        Me.Controls.Add(Me.btnCancel)
        Me.Name = "ucProgress"
        Me.Size = New System.Drawing.Size(236, 77)
        Me.ResumeLayout(False)

    End Sub
    Friend WithEvents btnCancel As System.Windows.Forms.Button

    Friend WithEvents lblPlaceholder As System.Windows.Forms.Label
    Public WithEvents pb As System.Windows.Forms.ProgressBar

#End Region

    Dim _mymessage As String
    Public Event WorkerPart()
    Public Cancel As Boolean

    Public EnabledStates As New Dictionary(Of Control, Boolean)
    Dim oldfocus As Control
    Dim OldMinBox As Boolean

    Public Sub StartProgress()
        Cancel = False
        Me.Parent = Me.ParentForm
        oldfocus = Me.ParentForm.ActiveControl
        Parent_SizeChanged(Nothing, Nothing)
        AddHandler Me.ParentForm.SizeChanged, AddressOf Parent_SizeChanged
        Me.Visible = True
        Me.Enabled = True
        Me.btnCancel.Focus()
        EnabledStates.Clear()
        For Each ctl As Control In Me.Parent.Controls
            If ctl IsNot Me Then
                EnabledStates.Add(ctl, ctl.Enabled)
                ctl.Enabled = False
            End If
        Next
        Me.BringToFront()
        Me.pb.Value = 0
        OldMinBox = Me.ParentForm.MinimizeBox
        Me.ParentForm.MinimizeBox = True
    End Sub

    Public Sub EndProgress()
        RemoveHandler Me.ParentForm.SizeChanged, AddressOf Parent_SizeChanged
        For Each ctl As Control In Me.Parent.Controls
            If ctl IsNot Me And EnabledStates.ContainsKey(ctl) Then
                ctl.Enabled = EnabledStates(ctl)
            End If
        Next
        If oldfocus IsNot Nothing Then
            oldfocus.Focus()
        End If
        Me.ParentForm.MinimizeBox = OldMinBox
        Me.Visible = False
    End Sub

    Public Property Message() As String
        Get
            Return _mymessage
        End Get
        Set(ByVal value As String)
            _mymessage = value
            Dim g As Graphics = Me.CreateGraphics()
            DrawString(g)
            g.Dispose()
            ''//lblMessage.Text = value
            Application.DoEvents()
        End Set
    End Property

    Private Sub DrawString(ByVal g As Graphics)
        ''//g.TextRenderingHint = Drawing.Text.TextRenderingHint.SingleBitPerPixel
        Dim rct As New Rectangle(Me.lblPlaceholder.Left, Me.lblPlaceholder.Top, _
           Me.lblPlaceholder.Width, Me.lblPlaceholder.Height)
        g.SetClip(rct)
        Dim b As New SolidBrush(Me.BackColor)
        If Me.BackgroundImage Is Nothing Then
            g.FillRectangle(b, rct)
        Else
            g.DrawImage(Me.BackgroundImage, 0, 0)
        End If
        ''//
        With lblPlaceholder
            g.DrawString(_mymessage, .Font, Brushes.DarkBlue, .Left, _
             .Top + CInt(IIf(InStr(_mymessage, vbCrLf) <> 0, 0, .Height \ 4)))
        End With
    End Sub

    Private Sub frmProgress_Paint(ByVal sender As Object, ByVal e As System.Windows.Forms.PaintEventArgs) Handles Me.Paint
        DrawString(e.Graphics)
    End Sub

    Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
        Cancel = True
    End Sub

    Private Sub Parent_SizeChanged(ByVal sender As Object, ByVal e As System.EventArgs)
        Me.Left = (Me.Parent.Width - Me.Width) \ 2
        Me.Top = (Me.Parent.Height - Me.Height) \ 2
    End Sub
End Class

Good luck!

Answer 4

You can disable all controls on the form by setting the Enabled property to False and then changing it back to True after the process is done.

In addition you can have a hidden label that says "Loading" that you display before disabling the form and hide when re-enabling it.

Finally, I would suggest that you split the process in two parts. One part that does the work without modifying controls that you can run on a worker thread and the part that changes the gui that does it work on the gui thread after the worker thread is done. This way you won't block the entire application, making changes to the Gui easier to do.

Answer 5

My recommended solution is to set the forms opacity to near invisible say 0.01 before initializing the components. Then create a form with the same size and position and place either a progress bar, or marquee on this form.. After the initialization of the main form, set it's opacity to full and dispose of the marquee form.

Answer 6

Use a ProgressBar with marquee or blocks style.

http://msdn.microsoft.com/en-us/library/system.windows.forms.progressbar.aspx