Virtual Keyboard Control

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;

    //------------------
    //Creator: aeonhack
    //Converted by: recuperare
    //Site: elitevs.net
    //Created: 03/25/2013
    //Changed: 03/25/2013
    //Version: 1.0.0
    //------------------

    class VirtualKeyboard : Control
    {

        private Bitmap TextBitmap;

        private Graphics TextGraphics;
        const string LowerKeys = "`1234567890-=qwertyuiop[]\\asdfghjkl;'zxcvbnm,./";

        const string UpperKeys = "~!@#$%^&*()_+QWERTYUIOP{}|ASDFGHJKL:\"ZXCVBNM<>?";
        public VirtualKeyboard()
        {
            SetStyle((ControlStyles)139270, true);

            Font = new Font("Verdana", 8.25f);

            TextBitmap = new Bitmap(1, 1);
            TextGraphics = Graphics.FromImage(TextBitmap);

            MinimumSize = new Size(386, 162);
            MaximumSize = new Size(386, 162);

            Randomize();
            PrepareCache();
        }

        private Control Target;
        public void AssignControl(Control c)
        {
            Target = c;
        }


        private bool Shift;
        private int Pressed = -1;

        private Rectangle[] Buttons;
        private char[] Lower;
        private char[] Upper;
        private string[] Other = {
        "Shift",
        "Space",
        "Back"

    };
        private void PrepareCache()
        {
            Buttons = new Rectangle[51];

            int I = 0;

            for (int Y = 0; Y <= 3; Y++)
            {
                for (int X = 0; X <= 11; X++)
                {
                    I = (Y * 12) + X;
                    Buttons[I] = new Rectangle(X * 32, Y * 32, 32, 32);
                }
            }

            Buttons[48] = new Rectangle(0, 4 * 32, 2 * 32, 32);
            Buttons[49] = new Rectangle(Buttons[48].Right, 4 * 32, 8 * 32, 32);
            Buttons[50] = new Rectangle(Buttons[49].Right, 4 * 32, 2 * 32, 32);
        }

        private void Randomize()
        {
            Lower = LowerKeys.ToCharArray();
            Upper = UpperKeys.ToCharArray();

            Random R = new Random();
            int X = 0;
            int Y = 0;
            char C1 = '\0';
            char C2 = '\0';

            for (int I = 1; I <= 12; I++)
            {
                X = R.Next(Lower.Length);
                Y = R.Next(Lower.Length);

                C1 = Lower[X];
                C2 = Upper[X];

                Lower[X] = Lower[Y];
                Upper[X] = Upper[Y];

                Lower[Y] = C1;
                Upper[Y] = C2;
            }
        }

        private Graphics G;
        protected override void OnPaint(System.Windows.Forms.PaintEventArgs e)
        {
            G = e.Graphics;
            G.TextRenderingHint = TextRenderingHint.ClearTypeGridFit;

            G.Clear(SystemColors.Control);

            SizeF S = default(SizeF);
            Rectangle R = default(Rectangle);
            int Offset = 0;

            G.DrawRectangle(SystemPens.ControlDarkDark, 0, 0, (12 * 32) + 1, (5 * 32) + 1);

            for (int I = 0; I <= Buttons.Length - 1; I++)
            {
                R = Buttons[I];

                Offset = 0;
                if (I == Pressed)
                    Offset = 1;

                switch (I)
                {
                    case 48:
                    case 49:
                    case 50:
                        S = G.MeasureString(Other[I - 48], Font);
                        G.DrawString(Other[I - 48], Font, SystemBrushes.ControlText, R.X + (R.Width / 2 - S.Width / 2) + Offset, R.Y + (R.Height / 2 - S.Height / 2) + Offset);
                        break;
                    case 47:
                        DrawArrow(R.X + Offset, R.Y + Offset);
                        break;
                    default:
                        if (Shift)
                        {
                            G.DrawString(Upper[I].ToString(), Font, SystemBrushes.ControlText, R.X + 4 + Offset, R.Y + 3 + Offset);
                        }
                        else
                        {
                            G.DrawString(Lower[I].ToString(), Font, SystemBrushes.ControlText, R.X + 4 + Offset, R.Y + 3 + Offset);
                        }
                        break;
                }

                G.DrawRectangle(SystemPens.ControlLightLight, R.X + 1 + Offset, R.Y + 1 + Offset, R.Width - 2, R.Height - 2);
                G.DrawRectangle(SystemPens.ControlDark, R.X + Offset, R.Y + Offset, R.Width, R.Height);

                if (I == Pressed)
                {
                    G.DrawLine(SystemPens.ControlDarkDark, R.X, R.Y, R.Right, R.Y);
                    G.DrawLine(SystemPens.ControlDarkDark, R.X, R.Y, R.X, R.Bottom);
                }
            }
        }

        private void DrawArrow(int rx, int ry)
        {
            Rectangle R = new Rectangle(rx + 8, ry + 8, 16, 16);
            G.SmoothingMode = SmoothingMode.AntiAlias;

            Pen P = new Pen(SystemColors.ControlText, 1);
            AdjustableArrowCap C = new AdjustableArrowCap(3, 2);
            P.CustomEndCap = C;

            G.DrawArc(P, R, 0f, 290f);

            P.Dispose();
            C.Dispose();
            G.SmoothingMode = SmoothingMode.None;
        }

        protected override void OnMouseDown(MouseEventArgs e)
        {
            int Index = ((e.Y / 32) * 12) + (e.X / 32);

            if (Index > 47)
            {
                for (int I = 48; I <= Buttons.Length - 1; I++)
                {
                    if (Buttons[I].Contains(e.X, e.Y))
                    {
                        Pressed = I;
                        break; // TODO: might not be correct. Was : Exit For
                    }
                }
            }
            else
            {
                Pressed = Index;
            }

            HandleKey();
            Invalidate();
        }

        protected override void OnMouseUp(MouseEventArgs e)
        {
            Pressed = -1;
            Invalidate();
        }

        private void HandleKey()
        {
            if (Target == null)
                return;

            switch (Pressed)
            {
                case 47:
                    Randomize();
                    break;
                case 48:
                    Shift = !Shift;
                    break;
                case 49:
                    Target.Text += " ";
                    break;
                case 50:
                    if (!(Target.Text.Length == 0))
                    {
                        Target.Text = Target.Text.Remove(Target.Text.Length - 1);
                    }
                    break;
                default:
                    if (Shift)
                    {
                        Target.Text += Upper[Pressed];
                    }
                    else
                    {
                        Target.Text += Lower[Pressed];
                    }
                    break;
            }
        }

    }