nusdownloader-fork/NUS Downloader/WaterMarkTextBox.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms;
using System.Drawing;

namespace wmgCMS
{
    class WaterMarkTextBox : TextBox
    {
        private Font oldFont = null;
        private Boolean waterMarkTextEnabled = false;

        #region Attributes
        private Color _waterMarkColor = Color.Gray;
        public Color WaterMarkColor
        {
            get { return _waterMarkColor; }
            set { _waterMarkColor = value; Invalidate();/*thanks to Bernhard Elbl for Invalidate()*/ }
        }

        private string _waterMarkText = "Water Mark";
        public string WaterMarkText
        {
            get { return _waterMarkText; }
            set { _waterMarkText = value; Invalidate(); }
        }
        #endregion

        //Default constructor
        public WaterMarkTextBox()
        {
            JoinEvents(true);
        }

        //Override OnCreateControl ... thanks to  "lpgray .. codeproject guy"
        protected override void OnCreateControl()
        {
            base.OnCreateControl();
            //WaterMark_Toggel(null, null);
            EnableWaterMark();
        }

        //Override OnPaint
        protected override void OnPaint(PaintEventArgs args)
        {
            // Use the same font that was defined in base class
            System.Drawing.Font drawFont = new System.Drawing.Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit);
            //Create new brush with gray color or 
            SolidBrush drawBrush = new SolidBrush(WaterMarkColor);//use Water mark color
            //Draw Text or WaterMark
            float xpoint = ((float)args.ClipRectangle.Width / 2.0F) - ((float)TextRenderer.MeasureText(WaterMarkText, Font).Width / 2.0F);
            ;
            PointF centeredtext = new PointF(xpoint, 0.0F);
            args.Graphics.DrawString((waterMarkTextEnabled ? WaterMarkText : Text), drawFont, drawBrush, centeredtext);
            base.OnPaint(args);
        }

        private void JoinEvents(Boolean join)
        {
            if (join)
            {
                this.TextChanged += new System.EventHandler(this.WaterMark_Toggel);
                this.LostFocus += new System.EventHandler(this.WaterMark_Toggel);
                this.GotFocus += new System.EventHandler(this.WaterMark_Toggel);
                this.MouseCaptureChanged += new System.EventHandler(this.WaterMark_Toggel);
                this.FontChanged += new System.EventHandler(this.WaterMark_FontChanged);
                //No one of the above events will start immeddiatlly 
                //TextBox control still in constructing, so,
                //Font object (for example) couldn't be catched from within WaterMark_Toggle
                //So, call WaterMark_Toggel through OnCreateControl after TextBox is totally created
                //No doupt, it will be only one time call

                //Old solution uses Timer.Tick event to check Create property
            }
        }

        private void WaterMark_Toggel(object sender, EventArgs args)
        {
            /*if (this.Text.Length <= 0)
                EnableWaterMark();
            else
                DisbaleWaterMark(); */

            /*if (this.Text.Length > 0)
            {
                System.Diagnostics.Debug.WriteLine(sender.ToString() + " disabled watermark");
                DisbaleWaterMark();
            }*/
            DisbaleWaterMark();
        }

        private void EnableWaterMark()
        {
            //Save current font until returning the UserPaint style to false (NOTE: It is a try and error advice)
            oldFont = new System.Drawing.Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit);
            //Enable OnPaint event handler
            this.SetStyle(ControlStyles.UserPaint, true);
            this.waterMarkTextEnabled = true;
            //Triger OnPaint immediatly
            Refresh();
        }

        private void DisbaleWaterMark()
        {
            //Disbale OnPaint event handler
            this.waterMarkTextEnabled = false;
            this.SetStyle(ControlStyles.UserPaint, false);
            //Return back oldFont if existed
            if (oldFont != null)
                this.Font = new System.Drawing.Font(oldFont.FontFamily, oldFont.Size, oldFont.Style, oldFont.Unit);
        }

        private void WaterMark_FontChanged(object sender, EventArgs args)
        {
            if (waterMarkTextEnabled)
            {
                oldFont = new System.Drawing.Font(Font.FontFamily, Font.Size, Font.Style, Font.Unit);
                Refresh();
            }
        }
    }
}