Darken a .Net Form

Question

I have a 1080p touchscreen application. When a modal pops up, i want to emphasize that by darkening the main form.

Right now i use a second form, the size of the main form, that is black and has 50% opacity. Whenever a modal needs to appear, i open the opaque form, and then open the desired modal.

I feel this is a bit devious for my purpose. Its also not asshole-proof that when the user alt tabs, the forms will glitch out of sequence.

Is there a better way to achieve the darkening effect. Perhaps by darkening the main form from within itself?

Answer 1

Here is some code, very similar to the method in Thomas's answer. Note to use the Darkness property in a Try...Finally block, to make sure you never leave the form in the dark state.

Public Class Form1


Private _PB As PictureBox

Public WriteOnly Property Darkness
    Set(value)
        If value Then
            Dim Bmp = New Bitmap(Bounds.Size.Width, Bounds.Size.Height)
            Me.DrawToBitmap(Bmp, New Rectangle(Point.Empty, Bounds.Size))
            Using g = Graphics.FromImage(Bmp)
                Dim Brush As New SolidBrush(Color.FromArgb(125, Color.Black))
                g.FillRectangle(Brush, New Rectangle(Point.Empty, Bmp.Size))
            End Using
            _PB = New PictureBox
            Me.Controls.Add(_PB)
            _PB.Size = Bounds.Size
            _PB.Location = Bounds.Location - PointToScreen(Point.Empty)
            _PB.Image = Bmp
            _PB.BringToFront()
        Else
            If _PB IsNot Nothing Then
                Me.Controls.Remove(_PB)
                _PB.Dispose()
            End If
        End If
    End Set
End Property

Private Sub btnDialog_Click(sender As Object, e As EventArgs) Handles btnDialog.Click
    Try
        Darkness = True

        MsgBox("Modal dialog")

    Finally
        Darkness = False
    End Try
End Sub
End Class