Blank window before all is loaded

Question

How do I code a blank window, like this, before the whole form is loaded? I've tried dragging a white picturebox over the window at Window_Load and Window_Shown, but that didn't work out. Any ideas?

Answer 1

I have made a custom window so when it shows up it would appear as a message box with custom appearance and when the loading done I close this window like that

CMessageBox cmb = new CMessageBox("Loading...");
cmb.Show(this);

//Do the heavy work here
//after the heavy work finish call cmb.close()

cmb.Close();

of course cmb is the custom window that you have to make your self

actually it is just a form that I have removed its borders and give it 'loading' text in the middle!

OK I will add the code for the custom form

Create a new form and add this code to it

public CMessageBox(string message)
{
    InitializeComponent();
    this.lblMessage.Text = message;
}

private void CMessageBox_Load(object sender, EventArgs e)
{
    this.lblMessage.Top = (this.Height - this.lblMessage.Height) / 2;
    this.lblMessage.Left = (this.Width - this.lblMessage.Width) / 2;
}

private void lblMessage_TextChanged(object sender, EventArgs e)
{
    this.lblMessage.Top = (this.Height - this.lblMessage.Height) / 2;
    this.lblMessage.Left = (this.Width - this.lblMessage.Width) / 2;
    this.Refresh();
}

public string _Caption
{
    get { return this.lblMessage.Text; }
    set { this.lblMessage.Text = value; }
}

After that you call it as I showed you at the beginning

I have set the window so it would have a small width and height just to contain the message, if you would like to change this you can ignore those 2 events

private void CMessageBox_Load(object sender, EventArgs e)
{
    this.lblMessage.Top = (this.Height - this.lblMessage.Height) / 2;
    this.lblMessage.Left = (this.Width - this.lblMessage.Width) / 2;
}

private void lblMessage_TextChanged(object sender, EventArgs e)
{
    this.lblMessage.Top = (this.Height - this.lblMessage.Height) / 2;
    this.lblMessage.Left = (this.Width - this.lblMessage.Width) / 2;
    this.Refresh();
}

You need to add label in the design and give it a name lblMessage also you need to set the BorderStyle to none

Answer 2

Windows uses the painter's algorithm to draw, it goes from the back to the front. So your PictureBox trick cannot work since it is the last one to be drawn. The technical term is that it is highest in the Z-order. Making it the lowest in the Z-order doesn't work either, it no longer covers the slow controls.

Trying to cover the controls isn't in general going to work anyway, removing the cover forces the controls to repaint themselves and you'll see the slow redraw at work again. Technically you can cover it with another borderless form but that doesn't work on older Windows versions or ones that have Aero turned off.

You need another trick, still get the controls to paint but just not making it visible to the user. Easily done with the Opacity property. Like this:

public partial class Form1 : Form {
    public Form1() {
        InitializeComponent();
        this.Opacity = 0;
    }
    protected override void OnShown(EventArgs e) {
        this.Update();
        this.Opacity = 0.99;
        base.OnShown(e);
    }
}

Your window will of course not be any faster to show up, it however now snaps onto the screen, giving the perception of speed. Don't make the mistake of changing the Opacity assignment to 1.0, that makes it slow again because the window needs to be recreated and re-drawn.