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[Bug]: Colors ComboBox problem

See original GitHub issue

I want to create a Custom ComboBox containing a list of colors.

The DrawItemEventHandler event is only raised when the DrawMode property is set to DrawMode.OwnerDrawFixed or DrawMode.OwnerDrawVariable.

I set this.DrawMode = DrawMode.OwnerDrawFixed; but CustomComboBox_DrawItem never executed, is this a bug of KryptonComboBox?

using Krypton.Toolkit;
using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Reflection;
using System.Windows.Forms;

namespace ColorComboBox
{
    public class CustomComboBox : KryptonComboBox
    {
        #region Fields
        private IPalette? _palette;
        private List<Color> _colorList = new List<Color>();
        #endregion

        #region Constructor
        public CustomComboBox()
        {
            SetStyle(ControlStyles.AllPaintingInWmPaint | ControlStyles.OptimizedDoubleBuffer | ControlStyles.ResizeRedraw, true);

            _colorList = GetColorList();
            this.DataSource = _colorList;
            this.DropDownStyle = ComboBoxStyle.DropDownList;
            this.DrawMode = DrawMode.OwnerDrawFixed;
            this.DrawItem += CustomComboBox_DrawItem;
        }
        #endregion

        #region AvoidFlicker
        protected override CreateParams CreateParams
        {
            get
            {
                CreateParams createParams = base.CreateParams;
                createParams.ExStyle |= 0x02000000;  // Turn on WS_EX_COMPOSITED
                return createParams;
            }
        }
        #endregion

        #region Color
        public List<Color> GetColorList()
        {
            List<Color> colorList = new List<Color>();
            foreach (PropertyInfo property in typeof(Color).GetProperties())
            {
                if (property.PropertyType == typeof(Color))
                {
                    object? objColor = property.GetValue(null);
                    if (objColor != null)
                    {
                        colorList.Add((Color)objColor);
                    }
                }
            }
            return colorList;
        }
        #endregion

        #region Render
        private void CustomComboBox_DrawItem(object sender, DrawItemEventArgs e)
        {
            e.DrawBackground();
            if (e.Index >= 0)
            {
                Color color = (Color)_colorList[e.Index];
                Rectangle r1 = new Rectangle(e.Bounds.Left + 1, e.Bounds.Top + 1, 2 * (e.Bounds.Height - 2), e.Bounds.Height - 2);
                Rectangle r2 = Rectangle.FromLTRB(r1.Right + 2, e.Bounds.Top, e.Bounds.Right, e.Bounds.Bottom);
                string txt = this.GetItemText(this.Items[e.Index]);
                using (var b = new SolidBrush(color))
                {
                    e.Graphics.FillRectangle(b, r1);
                    e.Graphics.DrawRectangle(Pens.Black, r1);

                    TextRenderer.DrawText(e.Graphics, txt, this.Font, r2, this.ForeColor, TextFormatFlags.Left | TextFormatFlags.VerticalCenter);
                }
            }
        }
        #endregion
    }
}

Issue Analytics

State:
Created 2 years ago
Comments:7 (4 by maintainers)

Top GitHub Comments

1reaction

mbsysde99commented, Nov 4, 2021

I found a bug in KryptonComboBox.cs.

A. Look OnComboBoxDrawItem method in KryptonComboBox.cs

Add OnDrawItem(e); in last line of OnComboBoxDrawItem

 private void OnComboBoxDrawItem(object sender, DrawItemEventArgs e)
 {
     // others code not displayed for easy reading
     // ...
     OnDrawItem(e); // add this to trigger CustomComboBox_DrawItem (BUG IN HERE, MISSING THIS IN LAST OF CODE )
 }

Add EnableColorComboBox property in KryptonComboBox.cs

public static bool EnableColorComboBox { get; set; } = false;

Add follows code in WndProc method in KryptonComboBox.cs

 protected override void WndProc(ref Message m)
 {
     // others code not displayed for easy reading
     // ...
 	switch (m.Msg)
 	{				
 		case PI.WM_.PAINT:
 		{
 			// Draw using a solid brush
 			Rectangle rectangle = new(rect.left, rect.top, rect.right - rect.left, rect.bottom - rect.top);
 			rectangle = CommonHelper.ApplyPadding(VisualOrientation.Top, rectangle,	states.Content.GetContentPadding(state));

 			try
 			{						
 				if (EnableColorComboBox)
 				{
 					if (SelectedIndex >= 0)
 					{
 						var color = (Color)this.Items[SelectedIndex];
 						var rect1 = new Rectangle((int)(rectangle.Left + 1), (int)(rectangle.Top + 1), (int)(2 * (rectangle.Height - 2)), (int)(rectangle.Height - 3));
 						var rect2 = Rectangle.FromLTRB(rect1.Right + 2, (int)rectangle.Top, (int)rectangle.Right, (int)rectangle.Bottom);
 						var text = this.GetItemText(this.Items[SelectedIndex]);
 						using (var b = new SolidBrush(color))
 						{
 							g.FillRectangle(b, rect1);
 							g.DrawRectangle(Pens.LightSteelBlue, rect1);

 							TextRenderer.DrawText(g, text, this.Font, rect2, this.ForeColor, TextFormatFlags.Left | TextFormatFlags.VerticalCenter);
 						}
 					}
 				}
 			        else {
 					using SolidBrush foreBrush = new(states.Content.GetContentShortTextColor1(state));
 					g.DrawString(Text, states.Content.GetContentShortTextFont(state), foreBrush, rectangle, stringFormat);	
 				}
 			}
 			catch (ArgumentException)
 			{
 				using SolidBrush foreBrush = new(ForeColor);
 				g.DrawString(Text, Font, foreBrush, rectangle, stringFormat);
 			}
 		}

 		// Remove clipping settings
 		PI.SelectClipRgn(hdc, IntPtr.Zero);

 		// Draw the drop down button
 		DrawDropButton(g, dropRect);
 	}
 }

B. Look Constructor of CustomComboBox.cs

Add EnableColorComboBox = true; in CustomComboBox method in CustomComboBox.cs

  #region Constructor
  public CustomComboBox()
  {
 	// others code not displayed for easy reading
 	// ...
 	
 	_colorList = GetColorList();		
 	
 	EnableColorComboBox = true;	 // add this to enable color mode	 	
 	 
 	this.DataSource = _colorList;
 	this.DropDownStyle = ComboBoxStyle.DropDownList;
 	this.DrawMode = DrawMode.OwnerDrawFixed;
 	this.DrawItem += CustomComboBox_DrawItem;
  }
  #endregion

Add EnableColorComboBox = true; in CustomComboBox_DrawItem method in CustomComboBox.cs

 #region Render
 private void CustomComboBox_DrawItem(object sender, DrawItemEventArgs e)
 {
 	if (EnableColorComboBox)
 	{				
 		e.DrawBackground();
 		if (e.Index >= 0)
 		{
 			Color color = (Color)_colorList[e.Index];
 			Rectangle r1 = new Rectangle(e.Bounds.Left + 1, e.Bounds.Top + 1, 2 * (e.Bounds.Height - 2), e.Bounds.Height - 2);
 			Rectangle r2 = Rectangle.FromLTRB(r1.Right + 2, e.Bounds.Top, e.Bounds.Right, e.Bounds.Bottom);
 			string txt = this.GetItemText(this.Items[e.Index]);
 			using (var b = new SolidBrush(color))
 			{
 				e.Graphics.FillRectangle(b, r1);
 				e.Graphics.DrawRectangle(Pens.Black, r1);

 				TextRenderer.DrawText(e.Graphics, txt, this.Font, r2, this.ForeColor, TextFormatFlags.Left | TextFormatFlags.VerticalCenter);
 			}
 		}
 	}
 }
 #endregion

Result is