filled rubber band in Winforms Application

Question

how can i draw a zero opacity rubber band over a windows form with 0.3 opacity? (The rubber band is made after a Microsoft example

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Update:

I need that rubber band to work something like a mask. If you use Jing or any other screen shot tool, you will see EXACTLY what I need to do when do you try to make a screenshot: the screen goes semi-opaque and when you make the selection, you will see the 0 opacity selection

Answer 1

Is this the droid you were looking for?

    public Form1()
    {
        InitializeComponent();
        DoubleBuffered = true;
    }

    bool mouseDown = false;
    Point mouseDownPoint = Point.Empty;
    Point mousePoint = Point.Empty;

    protected override void OnMouseDown(MouseEventArgs e)
    {
        base.OnMouseDown(e);
        mouseDown = true;
        mousePoint = mouseDownPoint = e.Location;
    }

    protected override void OnMouseUp(MouseEventArgs e)
    {
        base.OnMouseUp(e);
        mouseDown = false;
    }

    protected override void OnMouseMove(MouseEventArgs e)
    {
        base.OnMouseMove(e);
        mousePoint = e.Location;
        Invalidate();
    }

    protected override void OnPaint(PaintEventArgs e)
    {
        base.OnPaint(e);

        if (mouseDown)
        {
            Region r = new Region(this.ClientRectangle);
            Rectangle window = new Rectangle(
                Math.Min(mouseDownPoint.X, mousePoint.X),
                Math.Min(mouseDownPoint.Y, mousePoint.Y),
                Math.Abs(mouseDownPoint.X - mousePoint.X),
                Math.Abs(mouseDownPoint.Y - mousePoint.Y));
            r.Xor(window);
            e.Graphics.FillRegion(Brushes.Red, r);
            Console.WriteLine("Painted: " + window);
        }
    }

Answer 2

You need to use a partially opaque color when drawing:

Updated line from linked article, in the MyDrawReversibleRectangle method:

ControlPaint.DrawReversibleFrame( rc, Color.FromArgb(80, 120, 120, 120), FrameStyle.Dashed );

Answer 3

I used the code that @Dearmash supplied in the screen capture utility that comes with my open source app BugTracker.NET. The app isn't very big, so if you are doing screen capture stuff, it might be a good starting point. More info here:

http://ifdefined.com/blog/post/Screen-capture-utility-in-C-NET.aspx