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Articles / Desktop Programming / Windows Forms
 

Creating a Custom DropDown Control

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4.93/5 (72 votes)
20 Jul 2010CPOL7 min read 209.9K   9.2K   228  
Explains how to effectively create virtually any type of dropdown control
 
using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Drawing;
using System.Data;
using System.Text;
using System.Windows.Forms;

namespace Unity3.Controls
{
    public partial class CustomColorPicker : UserControl,  IColorPicker
    {
        #region Class Variables

        private ColorManager.HSL m_hsl;
        private Color m_rgb;
        private ColorManager.CMYK m_cmyk;

        public enum eDrawStyle
        {
            Hue,
            Saturation,
            Brightness,
            Red,
            Green,
            Blue
        }


        #endregion

        public Color Color
        {
            get {return Color.FromArgb(255 - tbAlpha.Value, m_rgb);}
            set 
            {
                m_rgb = value;
                tbAlpha.Value = 255 - m_rgb.A;
                UpdateUI(value);
            }
        }

        public CustomColorPicker(Color color)
        {
            InitializeComponent();
            lblOriginalColor.BackColor = color;
            rbHue.Checked = true;
            tbAlpha.Value = 255 - color.A;
            UpdateUI(color);
        }

        private bool isUpdating;
        private void UpdateUI(Color color)
        {
            isUpdating = true;
            m_rgb = color;
            m_hsl = ColorManager.RGB_to_HSL(m_rgb);
            m_cmyk = ColorManager.RGB_to_CMYK(m_rgb);

            txtHue.Text = Round(m_hsl.H * 360).ToString();
            txtSat.Text = Round(m_hsl.S * 100).ToString();
            txtBrightness.Text = Round(m_hsl.L * 100).ToString();
            txtRed.Text = m_rgb.R.ToString();
            txtGreen.Text = m_rgb.G.ToString();
            txtBlue.Text = m_rgb.B.ToString();

            colorBox.HSL = m_hsl;
            colorSlider.HSL = m_hsl;

            colorPanelPending.Color = Color.FromArgb(255 - tbAlpha.Value, m_rgb);

            this.WriteHexData(m_rgb);
            isUpdating = false;
        }


        #region Events

        private void colorBox_Scroll(object sender, System.EventArgs e)
        {
            if (!isUpdating)
                UpdateUI(colorBox.RGB);
        }

        private void colorSlider_Scroll(object sender, System.EventArgs e)
        {
            if (!isUpdating)
                UpdateUI(colorSlider.RGB);
        }

        #region Hex Box (m_txt_Hex)

        private void txtHex_Leave(object sender, System.EventArgs e)
        {
            string text = "";//m_txt_Hex.Text.ToUpper();
            bool has_illegal_chars = false;

            if (text.Length <= 0)
                has_illegal_chars = true;
            foreach (char letter in text)
            {
                if (!char.IsNumber(letter))
                {
                    if (letter >= 'A' && letter <= 'F')
                        continue;
                    has_illegal_chars = true;
                    break;
                }
            }

            if (has_illegal_chars)
            {
                MessageBox.Show("Hex must be a hex value between 0x000000 and 0xFFFFFF");
                WriteHexData(m_rgb);
                return;
            }

            UpdateUI(ParseHexData(text));
        }


        #endregion

        #region Color Boxes

        private void lblOriginalColor_Click(object sender, System.EventArgs e)
        {
        }


        private void m_lbl_Secondary_Color_Click(object sender, System.EventArgs e)
        {
        }


        #endregion

        #region Radio Buttons

        private void rbHue_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbHue.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Hue;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Hue;
            }
        }


        private void rbSat_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbSat.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Saturation;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Saturation;
            }
        }


        private void rbBrightness_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbBrightness.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Brightness;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Brightness;
            }
        }


        private void rbRed_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbRed.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Red;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Red;
            }
        }


        private void rbGreen_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbGreen.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Green;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Green;
            }
        }


        private void rbBlue_CheckedChanged(object sender, System.EventArgs e)
        {
            if (rbBlue.Checked)
            {
                colorSlider.DrawStyle = VerticalColorSlider.eDrawStyle.Blue;
                colorBox.DrawStyle = ColorBox.eDrawStyle.Blue;
            }
        }


        #endregion

        #region Text Boxes

        private void txtHue_Leave(object sender, System.EventArgs e)
        {
            string text = txtHue.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Hue must be a number value between 0 and 360");
                txtHue.Text = Round(m_hsl.H * 360).ToString(); 
                return;
            }

            int hue = int.Parse(text);

            if (hue < 0 || hue > 360)
            {
                MessageBox.Show("An integer between 0 and 360 is required.\nClosest value inserted.");
                hue = hue < 0 ? 0 : 360;               
            }

            m_hsl.H = (double)hue / 360;

            UpdateUI(ColorManager.HSL_to_RGB(m_hsl));
        }


        private void txtSat_Leave(object sender, System.EventArgs e)
        {
            string text = txtSat.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Saturation must be a number value between 0 and 100");
                txtSat.Text = Round(m_hsl.S * 100).ToString();
                return;
            }

            int sat = int.Parse(text);

            if (sat < 0 || sat > 100)
            {
                MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
                sat = sat < 0 ? 0 : 100;
            }

            m_hsl.S = (double)sat / 100;
            UpdateUI(ColorManager.HSL_to_RGB(m_hsl));
        }


        private void txtBrightness_Leave(object sender, System.EventArgs e)
        {
            string text = txtBrightness.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Black must be a number value between 0 and 360");
                txtBrightness.Text = Round(m_hsl.L * 100).ToString();
                return;
            }

            int lum = int.Parse(text);

            if (lum < 0 || lum > 360)
            {
                MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
                lum = lum < 0 ? 0 : 360;
            }

            m_hsl.L = (double)lum / 100;

            UpdateUI(ColorManager.HSL_to_RGB(m_hsl));
        }


        private void txtRed_Leave(object sender, System.EventArgs e)
        {
            string text = txtRed.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Red must be a number value between 0 and 255");
                txtRed.Text = m_rgb.R.ToString();
                return;
            }

            int red = int.Parse(text);

            if (red < 0 || red > 255)
            {
                MessageBox.Show("An integer between 0 and 255 is required.\nClosest value inserted.");
                red = red < 0 ? 0 : 255;
            }
               
            m_rgb = Color.FromArgb(red, m_rgb.G, m_rgb.B);
            UpdateUI(m_rgb);
        }


        private void txtGreen_Leave(object sender, System.EventArgs e)
        {
            string text = txtGreen.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Green must be a number value between 0 and 255");
                txtGreen.Text = m_rgb.G.ToString();
                return;
            }

            int green = int.Parse(text);

            if (green < 0 || green > 255)
            {
                MessageBox.Show("An integer between 0 and 255 is required.\nClosest value inserted.");
                green = green < 0 ? 0 : 255;
            }

            m_rgb = Color.FromArgb(m_rgb.R, green, m_rgb.B);
            UpdateUI(m_rgb);
        }


        private void txtBlue_Leave(object sender, System.EventArgs e)
        {
            string text = txtBlue.Text;
            bool has_illegal_chars = false;

            if (text.Length < 1 || text.Length > 3)
                has_illegal_chars = true;
            else
                foreach (char letter in text)
                {
                    if (!char.IsNumber(letter))
                    {
                        has_illegal_chars = true;
                        break;
                    }
                }

            if (has_illegal_chars)
            {
                MessageBox.Show("Blue must be a number value between 0 and 255");
                txtBlue.Text = m_rgb.B.ToString();
                return;
            }

            int blue = int.Parse(text);

            if (blue < 0 || blue > 255)
            {
                MessageBox.Show("An integer between 0 and 255 is required.\nClosest value inserted.");
                blue = blue < 0 ? 0 : 255;
            }

            m_rgb = Color.FromArgb(m_rgb.R, m_rgb.G, blue);
            UpdateUI(m_rgb);
        }


        //private void m_txt_Cyan_Leave(object sender, System.EventArgs e)
        //{
        //    string text = "";// m_txt_Cyan.Text;
        //    bool has_illegal_chars = false;

        //    if (text.Length <= 0)
        //        has_illegal_chars = true;
        //    else
        //        foreach (char letter in text)
        //        {
        //            if (!char.IsNumber(letter))
        //            {
        //                has_illegal_chars = true;
        //                break;
        //            }
        //        }

        //    if (has_illegal_chars)
        //    {
        //        MessageBox.Show("Cyan must be a number value between 0 and 100");
        //        UpdateTextBoxes();
        //        return;
        //    }

        //    int cyan = int.Parse(text);

        //    if (cyan < 0)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_cmyk.C = 0.0;
        //    }
        //    else if (cyan > 100)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_cmyk.C = 1.0;
        //    }
        //    else
        //    {
        //        m_cmyk.C = (double)cyan / 100;
        //    }

        //    m_rgb = ColorManager.CMYK_to_RGB(m_cmyk);
        //    m_hsl = ColorManager.RGB_to_HSL(m_rgb);
        //    colorBox.HSL = m_hsl;
        //    colorSlider.HSL = m_hsl;
        //    m_lbl_Primary_Color.BackColor = m_rgb;

        //    UpdateTextBoxes();
        //}
        //private void m_txt_Magenta_Leave(object sender, System.EventArgs e)
        //{
        //    string text = "";// m_txt_Magenta.Text;
        //    bool has_illegal_chars = false;

        //    if (text.Length <= 0)
        //        has_illegal_chars = true;
        //    else
        //        foreach (char letter in text)
        //        {
        //            if (!char.IsNumber(letter))
        //            {
        //                has_illegal_chars = true;
        //                break;
        //            }
        //        }

        //    if (has_illegal_chars)
        //    {
        //        MessageBox.Show("Magenta must be a number value between 0 and 100");
        //        UpdateTextBoxes();
        //        return;
        //    }

        //    int magenta = int.Parse(text);

        //    if (magenta < 0)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_Magenta.Text = "0";
        //        m_cmyk.M = 0.0;
        //    }
        //    else if (magenta > 100)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_Magenta.Text = "100";
        //        m_cmyk.M = 1.0;
        //    }
        //    else
        //    {
        //        m_cmyk.M = (double)magenta / 100;
        //    }

        //    m_rgb = ColorManager.CMYK_to_RGB(m_cmyk);
        //    m_hsl = ColorManager.RGB_to_HSL(m_rgb);
        //    colorBox.HSL = m_hsl;
        //    colorSlider.HSL = m_hsl;
        //    m_lbl_Primary_Color.BackColor = m_rgb;

        //    UpdateTextBoxes();
        //}
        //private void m_txt_Yellow_Leave(object sender, System.EventArgs e)
        //{
        //    string text = m_txt_Yellow.Text;
        //    bool has_illegal_chars = false;

        //    if (text.Length <= 0)
        //        has_illegal_chars = true;
        //    else
        //        foreach (char letter in text)
        //        {
        //            if (!char.IsNumber(letter))
        //            {
        //                has_illegal_chars = true;
        //                break;
        //            }
        //        }

        //    if (has_illegal_chars)
        //    {
        //        MessageBox.Show("Yellow must be a number value between 0 and 100");
        //        UpdateTextBoxes();
        //        return;
        //    }

        //    int yellow = int.Parse(text);

        //    if (yellow < 0)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_Yellow.Text = "0";
        //        m_cmyk.Y = 0.0;
        //    }
        //    else if (yellow > 100)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_Yellow.Text = "100";
        //        m_cmyk.Y = 1.0;
        //    }
        //    else
        //    {
        //        m_cmyk.Y = (double)yellow / 100;
        //    }

        //    m_rgb = ColorManager.CMYK_to_RGB(m_cmyk);
        //    m_hsl = ColorManager.RGB_to_HSL(m_rgb);
        //    colorBox.HSL = m_hsl;
        //    colorSlider.HSL = m_hsl;
        //    m_lbl_Primary_Color.BackColor = m_rgb;

        //    UpdateTextBoxes();
        //}
        //private void m_txt_K_Leave(object sender, System.EventArgs e)
        //{
        //    string text = m_txt_K.Text;
        //    bool has_illegal_chars = false;

        //    if (text.Length <= 0)
        //        has_illegal_chars = true;
        //    else
        //        foreach (char letter in text)
        //        {
        //            if (!char.IsNumber(letter))
        //            {
        //                has_illegal_chars = true;
        //                break;
        //            }
        //        }

        //    if (has_illegal_chars)
        //    {
        //        MessageBox.Show("Key must be a number value between 0 and 100");
        //        UpdateTextBoxes();
        //        return;
        //    }

        //    int key = int.Parse(text);

        //    if (key < 0)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_K.Text = "0";
        //        m_cmyk.K = 0.0;
        //    }
        //    else if (key > 100)
        //    {
        //        MessageBox.Show("An integer between 0 and 100 is required.\nClosest value inserted.");
        //        m_txt_K.Text = "100";
        //        m_cmyk.K = 1.0;
        //    }
        //    else
        //    {
        //        m_cmyk.K = (double)key / 100;
        //    }

        //    m_rgb = ColorManager.CMYK_to_RGB(m_cmyk);
        //    m_hsl = ColorManager.RGB_to_HSL(m_rgb);
        //    colorBox.HSL = m_hsl;
        //    colorSlider.HSL = m_hsl;
        //    m_lbl_Primary_Color.BackColor = m_rgb;

        //    UpdateTextBoxes();
        //}


        #endregion

        #endregion

        #region Private Functions

        private int Round(double val)
        {
            int ret_val = (int)val;

            int temp = (int)(val * 100);

            if ((temp % 100) >= 50)
                ret_val += 1;

            return ret_val;
        }


        private void WriteHexData(Color rgb)
        {
            //string red = Convert.ToString(rgb.R, 16);
            //if (red.Length < 2) red = "0" + red;
            //string green = Convert.ToString(rgb.G, 16);
            //if (green.Length < 2) green = "0" + green;
            //string blue = Convert.ToString(rgb.B, 16);
            //if (blue.Length < 2) blue = "0" + blue;

            //m_txt_Hex.Text = red.ToUpper() + green.ToUpper() + blue.ToUpper();
            //m_txt_Hex.Update();
        }


        private Color ParseHexData(string hex_data)
        {
            if (hex_data.Length != 6)
                return Color.Black;

            string r_text, g_text, b_text;
            int r, g, b;

            r_text = hex_data.Substring(0, 2);
            g_text = hex_data.Substring(2, 2);
            b_text = hex_data.Substring(4, 2);

            r = int.Parse(r_text, System.Globalization.NumberStyles.HexNumber);
            g = int.Parse(g_text, System.Globalization.NumberStyles.HexNumber);
            b = int.Parse(b_text, System.Globalization.NumberStyles.HexNumber);

            return Color.FromArgb(r, g, b);
        }


        //private void UpdateTextBoxes()
        //{
        //    txtHue.Text = Round(m_hsl.H * 360).ToString();
        //    txtSat.Text = Round(m_hsl.S * 100).ToString();
        //    txtBrightness.Text = Round(m_hsl.L * 100).ToString();
        //    //m_txt_Cyan.Text = Round(m_cmyk.C * 100).ToString();
        //    //m_txt_Magenta.Text = Round(m_cmyk.M * 100).ToString();
        //    //m_txt_Yellow.Text = Round(m_cmyk.Y * 100).ToString();
        //    //m_txt_K.Text = Round(m_cmyk.K * 100).ToString();
        //    txtRed.Text = m_rgb.R.ToString();
        //    txtGreen.Text = m_rgb.G.ToString();
        //    txtBlue.Text = m_rgb.B.ToString();

        //    //m_txt_Red.Update();
        //    //m_txt_Green.Update();
        //    //m_txt_Blue.Update();
        //    //m_txt_Hue.Update();
        //    //m_txt_Sat.Update();
        //    //m_txt_Brightness.Update();
        //    //m_txt_Cyan.Update();
        //    //m_txt_Magenta.Update();
        //    //m_txt_Yellow.Update();
        //    //m_txt_K.Update();

        //    WriteHexData(m_rgb);
        //}


        #endregion

        #region Public Methods

        public Color PrimaryColor
        {
            get
            {
                return m_rgb;
            }
            set
            {
                UpdateUI(value);
            }
        }


        public eDrawStyle DrawStyle
        {
            get
            {
                if (rbHue.Checked)
                    return eDrawStyle.Hue;
                else if (rbSat.Checked)
                    return eDrawStyle.Saturation;
                else if (rbBrightness.Checked)
                    return eDrawStyle.Brightness;
                else if (rbRed.Checked)
                    return eDrawStyle.Red;
                else if (rbGreen.Checked)
                    return eDrawStyle.Green;
                else if (rbBlue.Checked)
                    return eDrawStyle.Blue;
                else
                    return eDrawStyle.Hue;
            }
            set
            {
                switch (value)
                {
                    case eDrawStyle.Hue:
                        rbHue.Checked = true;
                        break;
                    case eDrawStyle.Saturation:
                        rbSat.Checked = true;
                        break;
                    case eDrawStyle.Brightness:
                        rbBrightness.Checked = true;
                        break;
                    case eDrawStyle.Red:
                        rbRed.Checked = true;
                        break;
                    case eDrawStyle.Green:
                        rbGreen.Checked = true;
                        break;
                    case eDrawStyle.Blue:
                        rbBlue.Checked = true;
                        break;
                    default:
                        rbHue.Checked = true;
                        break;
                }
            }
        }


        #endregion

        private void tbAlpha_ValueChanged(object sender, EventArgs e)
        {
            colorPanelPending.Color = Color.FromArgb(255 - tbAlpha.Value, m_rgb);
        }
    }
}

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Written By
Richard Blythe
Software Developer Unity3 Software
United States United States
Richard Blythe is founder and CEO of Unity3 Software.
In his spare time he enjoys flying Cessna 172s, reading, playing his Taylor acoustic guitar and recording music. He's latest non-computer endeavor is to learn violin. (Ouch)

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Layout: fixed | fluid

Posted 7 Apr 2009

Article Copyright 2009 by Richard Blythe
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