CODEWITHSUNDEEP
c#winforms
Thomas
Thomas

Reputation: 34188

How to draw overlay window winform apps c#

my request is suppose i have two sdi form. one sdi main form has button and when user click on that button then a overlay semi transparent window will appear and cover the main sdi form and as well as another sdi will come on top of the over lay window.

here is my overlay window code

namespace CSRAssistant
{
    public partial class MaskedDialog : Form
    {
        static MaskedDialog mask;
        static Form frmContainer;

        private Form dialog;
        private UserControl ucDialog;

        private MaskedDialog(Form parent, Form dialog)
        {
            this.dialog = dialog;
            this.FormBorderStyle = FormBorderStyle.None;
            this.BackColor = System.Drawing.Color.Black;
            this.Opacity = 0.50;
            this.ShowInTaskbar = false;
            this.StartPosition = FormStartPosition.Manual;
            this.Size = parent.ClientSize;
            this.Location = parent.PointToScreen(System.Drawing.Point.Empty);
            parent.Move += AdjustPosition;
            parent.SizeChanged += AdjustPosition;
        }

        private MaskedDialog(Form parent, UserControl ucDialog)
        {
            this.ucDialog = ucDialog;
            this.FormBorderStyle = FormBorderStyle.None;
            this.BackColor = System.Drawing.Color.Black;
            this.Opacity = 0.50;
            this.ShowInTaskbar = false;
            this.StartPosition = FormStartPosition.Manual;
            this.Size = parent.ClientSize;
            this.Location = parent.PointToScreen(System.Drawing.Point.Empty);
            parent.Move += AdjustPosition;
            parent.SizeChanged += AdjustPosition;
        }

        private void AdjustPosition(object sender, EventArgs e)
        {
            Form parent = sender as Form;
            this.Location = parent.PointToScreen(System.Drawing.Point.Empty);
            this.ClientSize = parent.ClientSize;
        }

        //
        public static DialogResult ShowDialog(Form parent, Form dialog)
        {
            mask = new MaskedDialog(parent, dialog);
            dialog.StartPosition = FormStartPosition.CenterParent;
            mask.MdiParent = parent.MdiParent;
            mask.Show();
            DialogResult result = dialog.ShowDialog(mask);
            mask.Close();
            return result;
        }

        public static DialogResult ShowDialog(Form parent, UserControl dialog)
        {
            mask = new MaskedDialog(parent, dialog);
            frmContainer = new Form();
            frmContainer.ShowInTaskbar = false;
            frmContainer.FormBorderStyle = System.Windows.Forms.FormBorderStyle.None;
            frmContainer.StartPosition = FormStartPosition.CenterParent;
            frmContainer.Height = dialog.Height;
            frmContainer.Width = dialog.Width;

            frmContainer.Controls.Add(dialog);
            mask.MdiParent = parent.MdiParent;
            mask.Show();
            DialogResult result = frmContainer.ShowDialog(mask);
            frmContainer.Close();
            mask.Close();
            return result;
        }

        public static void CloseDialog()
        {
            if (frmContainer != null)
            {
                frmContainer.Close();
            }
        }

        private void InitializeComponent()
        {
            this.SuspendLayout();
            // 
            // MaskedDialog
            // 
            this.ClientSize = new System.Drawing.Size(284, 262);
            this.Name = "MaskedDialog";
            this.FormClosing += new System.Windows.Forms.FormClosingEventHandler(this.MaskedDialog_FormClosing);
            this.Load += new System.EventHandler(this.MaskedDialog_Load);
            this.ResumeLayout(false);

        }

        private void MaskedDialog_Load(object sender, EventArgs e)
        {
        }

        private void MaskedDialog_FormClosing(object sender, FormClosingEventArgs e)
        {
        }
    }
}

this way i am calling my overlay when user click on main sdi button.

Form2 f2 = new Form2();
f2.Show();
MaskedDialog.ShowDialog(this, f2);
f2.Dispose();
f2 = null;

when i am running the code and MaskedDialog.ShowDialog(this, f2); is calling then i am getting a error....the error message is Form that is already visible cannot be displayed as a modal dialog box. Set the form's visible property to false before calling showDialog.

so i am not being able to understand where i am making the mistake. anyone can help me to fix the problem. thanks

Upvotes: 1

Views: 3239

Answers (1)

Luaan
Luaan

Reputation: 63722

You're doing this wrong - call mask.ShowDialog(), not mask.Show() and dialog.ShowDialog(). The error message is pretty clear - you can't ShowDialog a form that's already visible - and that's exactly what you're doing in dialog.ShowDialog(mask);.

Or, in a way that probably more closely shows what you want to do, when calling MaskedDialog.ShowDialog, do this:

Form2 f2 = new Form2();
MaskedDialog.ShowDialog(this, f2);

In other words - don't show the form you're going to ShowDialog. It's going to be made visible by the ShowDialog call.

Upvotes: 1

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