Draw semi transparent overlay image all over the windows form having some controls such that all its child controls should be visible but you can't click them. It should just like we see some things through some semi transparent black mirror.
I have tried using Transparent control. That is sub-classing Panel control and drawing image over that control, however all the controls are fully visible.
This is going to require another form that you display on top of the existing one. Its Opacity property can create the intended effect. Add a new class to your project and paste the code shown below. Call the Close() method to remove the effect again.
using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;
class Plexiglass : Form {
public Plexiglass(Form tocover) {
this.BackColor = Color.DarkGray;
this.Opacity = 0.30; // Tweak as desired
this.FormBorderStyle = FormBorderStyle.None;
this.ControlBox = false;
this.ShowInTaskbar = false;
this.StartPosition = FormStartPosition.Manual;
this.AutoScaleMode = AutoScaleMode.None;
this.Location = tocover.PointToScreen(Point.Empty);
this.ClientSize = tocover.ClientSize;
tocover.LocationChanged += Cover_LocationChanged;
tocover.ClientSizeChanged += Cover_ClientSizeChanged;
this.Show(tocover);
tocover.Focus();
// Disable Aero transitions, the plexiglass gets too visible
if (Environment.OSVersion.Version.Major >= 6) {
int value = 1;
DwmSetWindowAttribute(tocover.Handle, DWMWA_TRANSITIONS_FORCEDISABLED, ref value, 4);
}
}
private void Cover_LocationChanged(object sender, EventArgs e) {
// Ensure the plexiglass follows the owner
this.Location = this.Owner.PointToScreen(Point.Empty);
}
private void Cover_ClientSizeChanged(object sender, EventArgs e) {
// Ensure the plexiglass keeps the owner covered
this.ClientSize = this.Owner.ClientSize;
}
protected override void OnFormClosing(FormClosingEventArgs e) {
// Restore owner
this.Owner.LocationChanged -= Cover_LocationChanged;
this.Owner.ClientSizeChanged -= Cover_ClientSizeChanged;
if (!this.Owner.IsDisposed && Environment.OSVersion.Version.Major >= 6) {
Create a layered window that is kept on top of your primary form and synced with its location. You can alter the layered window's alpha using a 32-bit RGBA image in order to get your desired effect.
There's a decent codeproject article showing you how to do this here.