yaodurant.drawing.choosecolor.cs

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// YaoDurant.Drawing.ChooseColor.cs - Wrapper for calling Win32
// color picker common dialog box.
//
// Code from _Programming the .NET Compact Framework with C#_
// and _Programming the .NET Compact Framework with VB_
// (c) Copyright 2002-2004 Paul Yao and David Durant. 
// All rights reserved.

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Runtime.InteropServices;

namespace YaoDurant.Drawing
{
   /// <summary>
   /// Summary description for YaoDurant.
   /// </summary>
   public class ChooseColorDlg
   {
      public ChooseColorDlg()
      {
      }

      // Private data -- the Win32 CHOOSECOLOR structure
      private CHOOSECOLOR m_cc;

      // Class initialization function
      public bool Init(Control ctrlParent)
      {
         // Allocate array for initial colors.
         int cbColorData = 16 * 4;
         IntPtr ipColors = LocalAlloc(LMEM_FIXED, cbColorData);
         if (ipColors == IntPtr.Zero)
            return false;

         m_cc = new CHOOSECOLOR();
         m_cc.lStructSize = Marshal.SizeOf(m_cc);
         m_cc.hwndOwner = GetHwndFromControl(ctrlParent);
         m_cc.hInstance = IntPtr.Zero;
         m_cc.rgbResult = 0;
         m_cc.lpCustColors = ipColors;
         m_cc.Flags = CC_RGBINIT;
         m_cc.lCustData = 0;
         m_cc.lpfnHook = IntPtr.Zero;
         m_cc.lpTemplateName = IntPtr.Zero;

         return true;
      }

      public bool ShowDialog(ref Color clrValue)
      {
         int iRet = 0;
         byte Red = clrValue.R;
         byte Green = clrValue.G;
         byte Blue = clrValue.B;

         m_cc.rgbResult = (Blue << 16) + (Green << 8) + Red;

         iRet = ChooseColor(ref m_cc);
         if (iRet != 0)
         {
            Red   = (byte)(m_cc.rgbResult & 0xff);
            Green = (byte)((m_cc.rgbResult & 0xff00) >> 8);
            Blue  = (byte)((m_cc.rgbResult & 0xff0000) >> 16);
            clrValue = Color.FromArgb(Red, Green, Blue);
            return true;
         }
         else
            return false;
      }

      //
      // Memory allocation functions & values.
      //
      public const int LMEM_FIXED = 0x0000;
      [DllImport("coredll.dll")]
      public static extern 
      IntPtr LocalAlloc (int uFlags, int uBytes);
      [DllImport("coredll.dll")]
      public static extern IntPtr LocalFree (IntPtr hMem);

      public static int INVALID_HANDLE_VALUE = -1;

      //
      // Color dialog function & values.
      //
      [DllImport("commdlg.dll")]
      public static extern int ChooseColor (ref CHOOSECOLOR lpcc);
      public struct CHOOSECOLOR
      {
         public int lStructSize;
         public IntPtr hwndOwner;
         public IntPtr hInstance;
         public int rgbResult;
         public IntPtr lpCustColors;
         public int Flags;
         public int lCustData;
         public IntPtr lpfnHook;
         public IntPtr lpTemplateName;
      };
      public const int CC_RGBINIT = 0x00000001;
      public const int CC_FULLOPEN = 0x00000002;
      public const int CC_PREVENTFULLOPEN = 0x00000004;
      public const int CC_ENABLEHOOK = 0x00000010;
      public const int CC_ENABLETEMPLATE = 0x00000020;
      public const int CC_ENABLETEMPLATEHANDLE = 0x00000040;
      public const int CC_SOLIDCOLOR = 0x00000080;
      public const int CC_ANYCOLOR = 0x00000100;

      //
      // Focus functions
      //
      [DllImport("coredll.dll")]
      public static extern IntPtr GetFocus ();
      [DllImport("coredll.dll")]
      public static extern IntPtr SetFocus (IntPtr hWnd);

      public IntPtr GetHwndFromControl(Control ctrl)
      {
         IntPtr hwndControl;

         // Check whether control has focus.
         if (ctrl.Focused)
         {
            hwndControl = GetFocus();
         }
         else
         {
            IntPtr ipFocus = GetFocus();
            ctrl.Focus();
            hwndControl = GetFocus();
            SetFocus(ipFocus);
         }
         
         return hwndControl;
      }

   } // class
} // namespace