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using System;
using System.ComponentModel;
using System.Windows.Forms;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Runtime.InteropServices;
namespace Eugenis
{
[ToolboxBitmap(typeof(System.Windows.Forms.ComboBox))]
class CustomComboBox : ComboBox
{
#region Internal Classes
#region internal class ComboInfoHelper
internal class ComboInfoHelper
{
[DllImport("user32")]
private static extern bool GetComboBoxInfo(IntPtr hwndCombo, ref ComboBoxInfo info);
#region private struct RECT
[StructLayout(LayoutKind.Sequential)]
private struct RECT
{
public int Left;
public int Top;
public int Right;
public int Bottom;
}
#endregion
#region private struct ComboBoxInfo
[StructLayout(LayoutKind.Sequential)]
private struct ComboBoxInfo
{
public int cbSize;
public RECT rcItem;
public RECT rcButton;
public IntPtr stateButton;
public IntPtr hwndCombo;
public IntPtr hwndEdit;
public IntPtr hwndList;
}
#endregion
#region public static int GetDropDownWidth()
public static int GetDropDownWidth()
{
ComboBox cb = new ComboBox();
int width = GetDropDownWidth(cb.Handle);
cb.Dispose();
return width;
}
#endregion
#region public static int GetDropDownWidth(IntPtr handle)
public static int GetDropDownWidth(IntPtr handle)
{
ComboBoxInfo cbi = new ComboBoxInfo();
cbi.cbSize = Marshal.SizeOf(cbi);
GetComboBoxInfo(handle, ref cbi);
int width = cbi.rcButton.Right - cbi.rcButton.Left;
return width;
}
#endregion
}
#endregion
#endregion
#region Private Fields
private const int WM_ERASEBKGND = 0x14;
private const int WM_PAINT = 0xF;
private const int WM_NC_PAINT = 0x85;
private const int WM_PRINTCLIENT = 0x318;
private const int WM_MOUSEHOVER = 0x2A1;
private const int WM_MOUSELEAVE = 0x2A3;
private static int DropDownButtonWidth;
private bool _isLostFocusChangeStyle;
private bool _isGotFocusChangeStyle;
private Color _lostFocusBorderColor;
private Color _gotFocusBorderColor;
private ButtonBorderStyle _lostFocusBorderStyle;
private ButtonBorderStyle _gotFocusBorderStyle;
private EugenisButtonState _lostFocusDropDownButtonState;
private EugenisButtonState _gotFocusDropDownButtonState;
private IntPtr hDC;
private Graphics gdc;
private Rectangle rectBorder;
private Rectangle rectDropDownButton;
#endregion
#region Enumerators
#region public enum EugenisButtonState
public enum EugenisButtonState
{
Original = 1,
Normal = ButtonState.Normal,
Inactive = ButtonState.Inactive,
Pushed = ButtonState.Pushed,
Checked = ButtonState.Checked,
Flat = ButtonState.Flat,
All = ButtonState.All,
}
#endregion
#endregion
#region Properties
#region [Category("Custom")]
#region public bool UseLostFocusStyle
[Category("Custom")]
[Description("Proceed with the user-defined styling change on lost focus.")]
public bool UseLostFocusStyle
{
get
{
return _isLostFocusChangeStyle;
}
set
{
_isLostFocusChangeStyle = value;
Invalidate();
}
}
#endregion
#region public bool UseGotFocusStyle
[Category("Custom")]
[Description("Proceed with the user-defined styling change on got focus.")]
public bool UseGotFocusStyle
{
get
{
return _isGotFocusChangeStyle;
}
set
{
_isGotFocusChangeStyle = value;
Invalidate();
}
}
#endregion
#endregion
#region [Category("Custom-LostFocusStyle")]
#region public Color LostFocusBorderColor
[Category("Custom-LostFocusStyle")]
[Description("User-defined border color on lost focus.")]
public Color LostFocusBorderColor
{
get
{
return _lostFocusBorderColor;
}
set
{
_lostFocusBorderColor = value;
Invalidate();
}
}
#endregion
#region public ButtonBorderStyle LostFocusBorderStyle
[Category("Custom-LostFocusStyle")]
[Description("User-defined border style on lost focus.")]
public ButtonBorderStyle LostFocusBorderStyle
{
get
{
return _lostFocusBorderStyle;
}
set
{
_lostFocusBorderStyle = value;
Invalidate();
}
}
#endregion
#region public EugenisButtonState LostFocusDropDownButtonState
[Category("Custom-LostFocusStyle")]
[Description("User-defined drop down button state on lost focus.")]
public EugenisButtonState LostFocusDropDownButtonState
{
get
{
return _lostFocusDropDownButtonState;
}
set
{
_lostFocusDropDownButtonState = value;
Invalidate();
}
}
#endregion
#endregion
#region [Category("Custom-GotFocusStyle")]
#region public Color GotFocusBorderColor
[Category("Custom-GotFocusStyle")]
[Description("User-defined border color on got focus.")]
public Color GotFocusBorderColor
{
get
{
return _gotFocusBorderColor;
}
set
{
_gotFocusBorderColor = value;
}
}
#endregion
#region public ButtonBorderStyle GotFocusBorderStyle
[Category("Custom-GotFocusStyle")]
[Description("User-defined border style on got focus.")]
public ButtonBorderStyle GotFocusBorderStyle
{
get
{
return _gotFocusBorderStyle;
}
set
{
_gotFocusBorderStyle = value;
}
}
#endregion
#region public EugenisButtonState GotFocusDropDownButtonState
[Category("Custom-GotFocusStyle")]
[Description("User-defined drop down button state on got focus.")]
public EugenisButtonState GotFocusDropDownButtonState
{
get
{
return _gotFocusDropDownButtonState;
}
set
{
_gotFocusDropDownButtonState = value;
Invalidate();
}
}
#endregion
#endregion
#endregion
#region Constructors
#region internal static CustomComboBox()
static CustomComboBox()
{
DropDownButtonWidth = ComboInfoHelper.GetDropDownWidth() + 2;
}
#endregion
#region public CustomComboBox() : base()
public CustomComboBox() : base()
{
_isLostFocusChangeStyle = false;
_isGotFocusChangeStyle = false;
_lostFocusBorderColor = Color.Gray;
_gotFocusBorderColor = Color.Black;
_lostFocusBorderStyle = ButtonBorderStyle.Solid;
_gotFocusBorderStyle = ButtonBorderStyle.Solid;
_lostFocusDropDownButtonState = EugenisButtonState.Flat;
_gotFocusDropDownButtonState = EugenisButtonState.Original;
hDC = GetDC(Handle);
gdc = Graphics.FromHdc(hDC);
rectBorder = new Rectangle(0, 0, Width, Height);
rectDropDownButton = new Rectangle(Width - DropDownButtonWidth, 0, DropDownButtonWidth, Height);
SetStyle(ControlStyles.DoubleBuffer, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, true);
SetStyle(ControlStyles.AllPaintingInWmPaint, true);
SetStyle(ControlStyles.UserPaint, false);
}
#endregion
#endregion
#region Functions
#region Public Functions
#endregion
#region Internal Functions
#endregion
#region Protected Functions
#region protected override void OnGotFocus(System.EventArgs e)
protected override void OnGotFocus(System.EventArgs e)
{
Invalidate();
base.OnGotFocus(e);
}
#endregion
#region protected override void OnLostFocus(System.EventArgs e)
protected override void OnLostFocus(System.EventArgs e)
{
Invalidate();
base.OnLostFocus(e);
}
#endregion
#region protected override void OnResize(EventArgs e)
protected override void OnResize(EventArgs e)
{
Invalidate();
base.OnResize(e);
}
#endregion
#region protected override void OnSelectedValueChanged(EventArgs e)
protected override void OnSelectedValueChanged(EventArgs e)
{
Invalidate();
base.OnSelectedValueChanged(e);
}
#endregion
#region protected override void WndProc(ref Message m)
protected override void WndProc(ref Message m)
{
if (this.DropDownStyle == ComboBoxStyle.Simple)
{
base.WndProc(ref m);
return;
}
switch (m.Msg)
{
case WM_NC_PAINT:
break;
case WM_PAINT:
base.WndProc(ref m);
PaintControlDropDownButton();
PaintControlBorder();
break;
default:
base.WndProc(ref m);
break;
}
}
#endregion
#endregion
#region Private Functions
[DllImport("user32")]
private static extern IntPtr GetWindowDC(IntPtr hWnd);
[DllImport("user32")]
private static extern IntPtr GetDC(IntPtr hWnd);
[DllImport("user32")]
private static extern int ReleaseDC(IntPtr hWnd, IntPtr hDC);
#region private void PaintControlBorder()
private void PaintControlBorder()
{
if (Focused && _isGotFocusChangeStyle)
ControlPaint.DrawBorder(gdc, rectBorder, _gotFocusBorderColor, _gotFocusBorderStyle);
else if (!Focused && _isLostFocusChangeStyle)
ControlPaint.DrawBorder(gdc, rectBorder, _lostFocusBorderColor, _lostFocusBorderStyle);
else { }
}
#endregion
#region private void PaintControlDropDownButton()
private void PaintControlDropDownButton()
{
if (Focused && _isGotFocusChangeStyle && _gotFocusDropDownButtonState != EugenisButtonState.Original)
ControlPaint.DrawComboButton(gdc, rectDropDownButton, (ButtonState)_gotFocusDropDownButtonState);
else if (!Focused && _isLostFocusChangeStyle && _lostFocusDropDownButtonState != EugenisButtonState.Original)
ControlPaint.DrawComboButton(gdc, rectDropDownButton, (ButtonState)_lostFocusDropDownButtonState);
else { }
}
#endregion
#endregion
#endregion
}
}
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Ng Pei Jiun, Eugenis, graduated from National University of Singapore. After worked for one year as VB .NET and C# .NET programmer, I had decided to do freelancing in order to experience more about SDLC and Project Management.
I am currently unemployed and having intermediate skill in C# .NET programming.
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