/*

   This Source Code Form is subject to the terms of the Mozilla Public

   License, v. 2.0. If a copy of the MPL was not distributed with this

   file, You can obtain one at http://mozilla.org/MPL/2.0/.

   Copyright (C) 2010-2011 Michael Möller <mmoeller@openhardwaremonitor.org>

 	Copyright (C) 2010 Paul Werelds <paul@werelds.net>

 */

 using System;

 using System.Drawing;

 using System.Drawing.Drawing2D;

 using System.Drawing.Text;

 using System.Reflection;

 using System.Runtime.InteropServices;

 using System.Windows.Forms;

 namespace OpenHardwareMonitor.GUI {

   public class GadgetWindow : NativeWindow, IDisposable {

     private bool visible = false;

     private bool lockPositionAndSize = false;

     private bool alwaysOnTop = false;

     private byte opacity = 255;

     private Point location = new Point(100, 100);

     private Size size = new Size(130, 84);

     private ContextMenu contextMenu = null;

     private MethodInfo commandDispatch;

     private IntPtr handleBitmapDC;

     private Size bufferSize;

     private Graphics graphics;

     public GadgetWindow() {

       Type commandType = 

         typeof(Form).Assembly.GetType("System.Windows.Forms.Command");

       commandDispatch = commandType.GetMethod("DispatchID", 

         BindingFlags.Static | BindingFlags.NonPublic | BindingFlags.Public, 

         null, new Type[]{ typeof(int) }, null);

       this.CreateHandle(CreateParams);

       // move window to the bottom

       MoveToBottom(Handle);

       // prevent window from fading to a glass sheet when peek is invoked

       try {

         bool value = true;

         NativeMethods.DwmSetWindowAttribute(Handle,

           WindowAttribute.DWMWA_EXCLUDED_FROM_PEEK, ref value,

           Marshal.SizeOf(value));

       } catch (DllNotFoundException) { } catch (EntryPointNotFoundException) { }

       CreateBuffer();

     }

     private void ShowDesktopChanged(bool showDesktop) {

       if (showDesktop) {

         MoveToTopMost(Handle);

       } else {

         MoveToBottom(Handle);

       }

     }

     private void MoveToBottom(IntPtr handle) {

       NativeMethods.SetWindowPos(handle, HWND_BOTTOM, 0, 0, 0, 0,

         SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE | SWP_NOSENDCHANGING);

     }

     private void MoveToTopMost(IntPtr handle) {

       NativeMethods.SetWindowPos(handle, HWND_TOPMOST, 0, 0, 0, 0,

         SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE | SWP_NOSENDCHANGING);

     }

     private void ShowContextMenu(Point position) {

       NativeMethods.TrackPopupMenuEx(contextMenu.Handle, 

         TPM_RIGHTBUTTON | TPM_VERTICAL, position.X,

         position.Y, Handle, IntPtr.Zero);

     }

     protected virtual CreateParams CreateParams {

       get {

         CreateParams cp = new CreateParams();        

         cp.Width = 4096;

         cp.Height = 4096;

         cp.X = location.X;

         cp.Y = location.Y;

         cp.ExStyle = WS_EX_LAYERED | WS_EX_TOOLWINDOW;

         return cp;

       }

     }

     protected override void WndProc(ref Message message) {

       switch (message.Msg) {

         case WM_COMMAND: {

             // need to dispatch the message for the context menu

             if (message.LParam == IntPtr.Zero)

               commandDispatch.Invoke(null, new object[] { 

               message.WParam.ToInt32() & 0xFFFF });

           } break;

         case WM_NCHITTEST: {

             message.Result = (IntPtr)HitResult.Caption;

             if (HitTest != null) {

               Point p = new Point(

                 Macros.GET_X_LPARAM(message.LParam) - location.X,

                 Macros.GET_Y_LPARAM(message.LParam) - location.Y

               );

               HitTestEventArgs e = new HitTestEventArgs(p, HitResult.Caption);

               HitTest(this, e);

               message.Result = (IntPtr)e.HitResult;

             }

           } break;

         case WM_NCLBUTTONDBLCLK: {

             if (MouseDoubleClick != null) {

               MouseDoubleClick(this, new MouseEventArgs(MouseButtons.Left, 2,

                 Macros.GET_X_LPARAM(message.LParam) - location.X,

                 Macros.GET_Y_LPARAM(message.LParam) - location.Y, 0));

             }

             message.Result = IntPtr.Zero;

           } break;

         case WM_NCRBUTTONDOWN: {

             message.Result = IntPtr.Zero;

           } break;

         case WM_NCRBUTTONUP: {

             if (contextMenu != null)

               ShowContextMenu(new Point(

                 Macros.GET_X_LPARAM(message.LParam),

                 Macros.GET_Y_LPARAM(message.LParam)

               ));

             message.Result = IntPtr.Zero;

           } break;

         case WM_WINDOWPOSCHANGING: {

             WindowPos wp = (WindowPos)Marshal.PtrToStructure(

               message.LParam, typeof(WindowPos));

             if (!lockPositionAndSize) {

               // prevent the window from leaving the screen

               if ((wp.flags & SWP_NOMOVE) == 0) {

                 Rectangle rect = Screen.GetWorkingArea(

                   new Rectangle(wp.x, wp.y, wp.cx, wp.cy));

                 const int margin = 16;

                 wp.x = Math.Max(wp.x, rect.Left - wp.cx + margin);

                 wp.x = Math.Min(wp.x, rect.Right - margin);

                 wp.y = Math.Max(wp.y, rect.Top - wp.cy + margin);

                 wp.y = Math.Min(wp.y, rect.Bottom - margin);

               }

               // update location and fire event

               if ((wp.flags & SWP_NOMOVE) == 0) {

                 if (location.X != wp.x || location.Y != wp.y) {

                   location = new Point(wp.x, wp.y);

                   if (LocationChanged != null)

                     LocationChanged(this, EventArgs.Empty);

                 }

               }

               // update size and fire event

               if ((wp.flags & SWP_NOSIZE) == 0) {

                 if (size.Width != wp.cx || size.Height != wp.cy) {

                   size = new Size(wp.cx, wp.cy);

                   if (SizeChanged != null)

                     SizeChanged(this, EventArgs.Empty);

                 }

               } 

               // update the size of the layered window

               if ((wp.flags & SWP_NOSIZE) == 0) {

                 NativeMethods.UpdateLayeredWindow(Handle, IntPtr.Zero,

                   IntPtr.Zero, ref size, IntPtr.Zero, IntPtr.Zero, 0,

                   IntPtr.Zero, 0);                

               }

               // update the position of the layered window

               if ((wp.flags & SWP_NOMOVE) == 0) {

                 NativeMethods.SetWindowPos(Handle, IntPtr.Zero, 

                   location.X, location.Y, 0, 0, SWP_NOSIZE | SWP_NOACTIVATE | 

                   SWP_NOZORDER | SWP_NOSENDCHANGING);

               }

             }

             // do not forward any move or size messages

             wp.flags |= SWP_NOSIZE | SWP_NOMOVE;

             // suppress any frame changed events

             wp.flags &= ~SWP_FRAMECHANGED;

             Marshal.StructureToPtr(wp, message.LParam, false);                      

             message.Result = IntPtr.Zero;

           } break;

         default: {

             base.WndProc(ref message);

           } break;

       }      

     }

     private BlendFunction CreateBlendFunction() {

       BlendFunction blend = new BlendFunction();

       blend.BlendOp = AC_SRC_OVER;

       blend.BlendFlags = 0;

       blend.SourceConstantAlpha = opacity;

       blend.AlphaFormat = AC_SRC_ALPHA;

       return blend;

     }

     private void CreateBuffer() {      

       IntPtr handleScreenDC = NativeMethods.GetDC(IntPtr.Zero);

       handleBitmapDC = NativeMethods.CreateCompatibleDC(handleScreenDC);

       NativeMethods.ReleaseDC(IntPtr.Zero, handleScreenDC);

       bufferSize = size;

       BitmapInfo info = new BitmapInfo();

       info.Size = Marshal.SizeOf(info);

       info.Width = size.Width;

       info.Height = -size.Height;

       info.BitCount = 32;

       info.Planes = 1;

       IntPtr ptr;

       IntPtr hBmp = NativeMethods.CreateDIBSection(handleBitmapDC, ref info, 0, 

         out ptr, IntPtr.Zero, 0);

       IntPtr hBmpOld = NativeMethods.SelectObject(handleBitmapDC, hBmp);

       NativeMethods.DeleteObject(hBmpOld);

       graphics = Graphics.FromHdc(handleBitmapDC);

       if (Environment.OSVersion.Version.Major > 5) {

         this.graphics.TextRenderingHint = TextRenderingHint.SystemDefault;

         this.graphics.SmoothingMode = SmoothingMode.HighQuality;

       } 

     }

     private void DisposeBuffer() {

       graphics.Dispose();

       NativeMethods.DeleteDC(handleBitmapDC);

     }

     public virtual void Dispose() {

       DisposeBuffer();

     } 

     public PaintEventHandler Paint; 

     public void Redraw() {

       if (!visible || Paint == null)

         return;

       if (size != bufferSize) {

         DisposeBuffer();

         CreateBuffer();

       }

       Paint(this, 

         new PaintEventArgs(graphics, new Rectangle(Point.Empty, size))); 

         Point pointSource = Point.Empty;

         BlendFunction blend = CreateBlendFunction();

         NativeMethods.UpdateLayeredWindow(Handle, IntPtr.Zero, IntPtr.Zero,

           ref size, handleBitmapDC, ref pointSource, 0, ref blend, ULW_ALPHA);

         // make sure the window is at the right location

         NativeMethods.SetWindowPos(Handle, IntPtr.Zero,

           location.X, location.Y, 0, 0, SWP_NOSIZE | SWP_NOACTIVATE |

           SWP_NOZORDER | SWP_NOSENDCHANGING);

     }

     public byte Opacity {

       get {

         return opacity;

       }

       set {

         if (opacity != value) {

           opacity = value;

           BlendFunction blend = CreateBlendFunction();

           NativeMethods.UpdateLayeredWindow(Handle, IntPtr.Zero, IntPtr.Zero,

             IntPtr.Zero, IntPtr.Zero, IntPtr.Zero, 0, ref blend, ULW_ALPHA);

         }

       }

     }

     public bool Visible {

       get {

         return visible;

       }

       set {

         if (visible != value) {

           visible = value;

           NativeMethods.SetWindowPos(Handle, IntPtr.Zero, 0, 0, 0, 0,

             SWP_NOMOVE | SWP_NOSIZE | SWP_NOACTIVATE | SWP_NOZORDER |

             (value ? SWP_SHOWWINDOW : SWP_HIDEWINDOW));

           if (value) {

             if (!alwaysOnTop)

               ShowDesktop.Instance.ShowDesktopChanged += ShowDesktopChanged;

           } else {

             if (!alwaysOnTop)

               ShowDesktop.Instance.ShowDesktopChanged -= ShowDesktopChanged;

           }

         }

       }

     }

     // if locked, the window can not be moved or resized

     public bool LockPositionAndSize {

       get {

         return lockPositionAndSize;

       }

       set {

         lockPositionAndSize = value;

       }

     }

     public bool AlwaysOnTop {

       get {

         return alwaysOnTop;

       }

       set {

         if (value != alwaysOnTop) {

           alwaysOnTop = value;

           if (alwaysOnTop) {

             if (visible)

               ShowDesktop.Instance.ShowDesktopChanged -= ShowDesktopChanged;

             MoveToTopMost(Handle);            

           } else {

             MoveToBottom(Handle);

             if (visible)

               ShowDesktop.Instance.ShowDesktopChanged += ShowDesktopChanged;

           }

         }

       }

     }

     public Size Size {

       get {

         return size; 

       }

       set {

         if (size != value) {

           size = value;

           NativeMethods.UpdateLayeredWindow(Handle, IntPtr.Zero, IntPtr.Zero,

             ref size, IntPtr.Zero, IntPtr.Zero, 0, IntPtr.Zero, 0);                    

           if (SizeChanged != null)

             SizeChanged(this, EventArgs.Empty);

         }

       }

     }

     public event EventHandler SizeChanged;

     public Point Location {

       get {

         return location;

       }

       set {

         if (location != value) {

           location = value;

           NativeMethods.SetWindowPos(Handle, IntPtr.Zero, 

             location.X, location.Y, 0, 0, 

             SWP_NOSIZE | SWP_NOACTIVATE | SWP_NOZORDER | SWP_NOSENDCHANGING);          

           if (LocationChanged != null)

             LocationChanged(this, EventArgs.Empty);

         }

       }

     }

     public event EventHandler LocationChanged;

     public ContextMenu ContextMenu {

       get {

         return contextMenu;

       }

       set {

         this.contextMenu = value;

       }

     }

     public event HitTestEventHandler HitTest;

     public event MouseEventHandler MouseDoubleClick;

     [StructLayout(LayoutKind.Sequential, Pack = 1)]

     private struct BlendFunction {

       public byte BlendOp;

       public byte BlendFlags;

       public byte SourceConstantAlpha;

       public byte AlphaFormat;

     }

     [StructLayout(LayoutKind.Sequential, Pack = 1)]

     private struct WindowPos {

       public IntPtr hwnd;

       public IntPtr hwndInsertAfter;

       public int x;

       public int y;

       public int cx;

       public int cy;

       public uint flags;

     }

     [StructLayout(LayoutKind.Sequential)]

     public struct BitmapInfo {

       public Int32 Size;

       public Int32 Width;

       public Int32 Height;

       public Int16 Planes;

       public Int16 BitCount;

       public Int32 Compression;

       public Int32 SizeImage;

       public Int32 XPelsPerMeter;

       public Int32 YPelsPerMeter;

       public Int32 ClrUsed;

       public Int32 ClrImportant;

       public Int32 Colors;

     }

     public static readonly IntPtr HWND_BOTTOM = (IntPtr)1;

     public static readonly IntPtr HWND_TOPMOST = (IntPtr)(-1);

     public const int WS_EX_LAYERED = 0x00080000;

     public const int WS_EX_TOOLWINDOW = 0x00000080;

     public const uint SWP_NOSIZE = 0x0001;

     public const uint SWP_NOMOVE = 0x0002;

     public const uint SWP_NOACTIVATE = 0x0010;

     public const uint SWP_FRAMECHANGED = 0x0020;

     public const uint SWP_HIDEWINDOW = 0x0080;

     public const uint SWP_SHOWWINDOW = 0x0040;

     public const uint SWP_NOZORDER = 0x0004;

     public const uint SWP_NOSENDCHANGING = 0x0400;

     public const int ULW_COLORKEY = 0x00000001;

     public const int ULW_ALPHA = 0x00000002;

     public const int ULW_OPAQUE = 0x00000004;

     public const byte AC_SRC_OVER = 0x00;

     public const byte AC_SRC_ALPHA = 0x01;

     public const int WM_NCHITTEST = 0x0084;

     public const int WM_NCLBUTTONDBLCLK = 0x00A3;

     public const int WM_NCLBUTTONDOWN = 0x00A1;

     public const int WM_NCLBUTTONUP = 0x00A2;

     public const int WM_NCRBUTTONDOWN = 0x00A4;

     public const int WM_NCRBUTTONUP = 0x00A5;

     public const int WM_WINDOWPOSCHANGING = 0x0046;

     public const int WM_COMMAND = 0x0111;

     public const int TPM_RIGHTBUTTON = 0x0002;

     public const int TPM_VERTICAL = 0x0040;

     private enum WindowAttribute : int {

       DWMWA_NCRENDERING_ENABLED = 1,

       DWMWA_NCRENDERING_POLICY,

       DWMWA_TRANSITIONS_FORCEDISABLED,

       DWMWA_ALLOW_NCPAINT,

       DWMWA_CAPTION_BUTTON_BOUNDS,

       DWMWA_NONCLIENT_RTL_LAYOUT,

       DWMWA_FORCE_ICONIC_REPRESENTATION,

       DWMWA_FLIP3D_POLICY,

       DWMWA_EXTENDED_FRAME_BOUNDS,

       DWMWA_HAS_ICONIC_BITMAP,

       DWMWA_DISALLOW_PEEK,

       DWMWA_EXCLUDED_FROM_PEEK,

       DWMWA_LAST

     }

     /// <summary>

     /// Some macros imported and converted from the Windows SDK

     /// </summary>

     private static class Macros {

       public static ushort LOWORD(IntPtr l) {

         return (ushort) ((ulong)l & 0xFFFF);

       }

       public static UInt16 HIWORD(IntPtr l) {

         return (ushort) (((ulong)l >> 16) & 0xFFFF);

       }

       public static int GET_X_LPARAM(IntPtr lp) {

         return (short) LOWORD(lp);

       }

       public static int GET_Y_LPARAM(IntPtr lp) {

         return (short) HIWORD(lp);

       }

     }

     /// <summary>

     /// Imported native methods

     /// </summary>

     private static class NativeMethods {

       private const string USER = "user32.dll";

       private const string GDI = "gdi32.dll";

       public const string DWMAPI = "dwmapi.dll";

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       [return: MarshalAs(UnmanagedType.Bool)]

       public static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst,

         IntPtr pptDst, ref Size psize, IntPtr hdcSrc, IntPtr pprSrc,

         int crKey, IntPtr pblend, int dwFlags);

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       [return: MarshalAs(UnmanagedType.Bool)]

       public static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst, 

         IntPtr pptDst, ref Size psize, IntPtr hdcSrc, ref Point pprSrc, 

         int crKey, ref BlendFunction pblend, int dwFlags);

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       [return: MarshalAs(UnmanagedType.Bool)]

       public static extern bool UpdateLayeredWindow(IntPtr hwnd, IntPtr hdcDst,

         IntPtr pptDst, IntPtr psize, IntPtr hdcSrc, IntPtr pprSrc,

         int crKey, ref BlendFunction pblend, int dwFlags);  

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       public static extern IntPtr GetDC(IntPtr hWnd);

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       public static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       public static extern bool SetWindowPos(IntPtr hWnd,

         IntPtr hWndInsertAfter, int X, int Y, int cx, int cy, uint uFlags);

       [DllImport(USER, CallingConvention = CallingConvention.Winapi)]

       public static extern bool TrackPopupMenuEx(IntPtr hMenu, uint uFlags, 

         int x, int y, IntPtr hWnd, IntPtr tpmParams);

       [DllImport(GDI, CallingConvention = CallingConvention.Winapi)]

       public static extern IntPtr CreateCompatibleDC(IntPtr hDC);

       [DllImport(GDI, CallingConvention = CallingConvention.Winapi)]

       public static extern IntPtr CreateDIBSection(IntPtr hdc, 

         [In] ref BitmapInfo pbmi, uint pila, out IntPtr ppvBits, 

         IntPtr hSection, uint dwOffset);

       [DllImport(GDI, CallingConvention = CallingConvention.Winapi)]

       [return: MarshalAs(UnmanagedType.Bool)]

       public static extern bool DeleteDC(IntPtr hdc);

       [DllImport(GDI, CallingConvention = CallingConvention.Winapi)]

       public static extern IntPtr SelectObject(IntPtr hDC, IntPtr hObject);

       [DllImport(GDI, CallingConvention = CallingConvention.Winapi)]

       [return: MarshalAs(UnmanagedType.Bool)]

       public static extern bool DeleteObject(IntPtr hObject);

       [DllImport(DWMAPI, CallingConvention = CallingConvention.Winapi)]

       public static extern int DwmSetWindowAttribute(IntPtr hwnd,

         WindowAttribute dwAttribute, ref bool pvAttribute, int cbAttribute);

     }    

   }

   public enum HitResult {

     Transparent = -1,

     Nowhere = 0,

     Client = 1,

     Caption = 2,

     Left = 10,

     Right = 11,

     Top = 12,

     TopLeft = 13,

     TopRight = 14,

     Bottom = 15,

     BottomLeft = 16,

     BottomRight = 17,

     Border = 18

   }

   public delegate void HitTestEventHandler(object sender, HitTestEventArgs e);

   public class HitTestEventArgs : EventArgs {

     public HitTestEventArgs(Point location, HitResult hitResult) {

       Location = location;

       HitResult = hitResult;

     }

     public Point Location { get; private set; }

     public HitResult HitResult { get; set; }

   }

 }