/******************************************************/
/*          NULLFX FREE SOFTWARE LICENSE              */
/******************************************************/
/*  ScrollableRichTextBox Library                     */
/*  by: Steve Whitley                                 */
/*  © 2005 NullFX Software                            */
/*                                                    */
/* NULLFX SOFTWARE DISCLAIMS ALL WARRANTIES,          */
/* RESPONSIBILITIES, AND LIABILITIES ASSOCIATED WITH  */
/* USE OF THIS CODE IN ANY WAY, SHAPE, OR FORM        */
/* REGARDLESS HOW IMPLICIT, EXPLICIT, OR OBSCURE IT   */
/* IS. IF THERE IS ANYTHING QUESTIONABLE WITH REGARDS */
/* TO THIS SOFTWARE BREAKING AND YOU GAIN A LOSS OF   */
/* ANY NATURE, WE ARE NOT THE RESPONSIBLE PARTY. USE  */
/* OF THIS SOFTWARE CREATES ACCEPTANCE OF THESE TERMS */
/*                                                    */
/* USE OF THIS CODE MUST RETAIN ALL COPYRIGHT NOTICES */
/* AND LICENSES (MEANING THIS TEXT).                  */
/*                                                    */
/******************************************************/

namespace NullFX.Controls {
    using System;
    using System.Windows.Forms;
    /// <summary>
    /// This components adds a much lacking function
    /// "Scroll to the end" which is missing
    /// from the original rich text box.
    /// </summary>
    public class ScrollableRichTextBox : RichTextBox {
        // constants for the message sending
        const int WM_VSCROLL = 0x0115;
        const int WM_LBUTTONDOWN = 0x0201;
        const int WM_SETFOCUS = 0x0007;
        const int WM_KILLFOCUS = 0x0008;
        readonly IntPtr SB_ENDSCROLL = (IntPtr)8;
        readonly IntPtr SB_BOTTOM = (IntPtr)7;
        // flag we use to determine if we can scroll
        bool _scrollable = true;
        private delegate void AppendTextDelegate(string text, bool scrollToEnd);
        public void AppendText(string text, bool scrollToEnd) {
            if(InvokeRequired) {
                Invoke(new AppendTextDelegate(AppendText), 
                           new object[] {text, scrollToEnd});
            }else {
                decimal length = base.Text.Length + text.Length;
                if(length >= base.MaxLength) base.Clear();
                base.Text += text;
                if(_scrollable && scrollToEnd) {
                    if(IntPtr.Zero != base.Handle) {
                        base.SelectionStart = base.Text.Length;
                        Message m = Message.Create(
                            base.Handle, 
                            WM_VSCROLL, 
                            SB_BOTTOM, IntPtr.Zero);
                        base.WndProc(ref m);
                    }
                }
            }

        }

        protected override void WndProc(ref Message m) {
            // if we're in a scroll set the scrolling flag 
            // to false & skip theauto scroll
            if((m.Msg == WM_LBUTTONDOWN) 
                || m.Msg == WM_VSCROLL 
                && m.WParam != SB_BOTTOM) {
                _scrollable = false;
            }

            // if we are done scrolling, set the falg to true & do the scrolling
            if(m.Msg == WM_VSCROLL && m.WParam == SB_ENDSCROLL) {
                _scrollable = true;
            }
            // HACK: this keeps the user from setting the cursor in the textbox
            //  because that causes problems if they do
            if(m.Msg == WM_SETFOCUS && base.ReadOnly) m.Msg = WM_KILLFOCUS;

            base.WndProc (ref m);
        }
    }
}

/******************************************************/
/*          NULLFX FREE SOFTWARE LICENSE              */
/******************************************************/
/*  ScrollableRichTextBox Library                     */
/*  by: Steve Whitley                                 */
/*  © 2005 NullFX Software                            */
/*                                                    */
/* NULLFX SOFTWARE DISCLAIMS ALL WARRANTIES,          */
/* RESPONSIBILITIES, AND LIABILITIES ASSOCIATED WITH  */
/* USE OF THIS CODE IN ANY WAY, SHAPE, OR FORM        */
/* REGARDLESS HOW IMPLICIT, EXPLICIT, OR OBSCURE IT   */
/* IS. IF THERE IS ANYTHING QUESTIONABLE WITH REGARDS */
/* TO THIS SOFTWARE BREAKING AND YOU GAIN A LOSS OF   */
/* ANY NATURE, WE ARE NOT THE RESPONSIBLE PARTY. USE  */
/* OF THIS SOFTWARE CREATES ACCEPTANCE OF THESE TERMS */
/*                                                    */
/* USE OF THIS CODE MUST RETAIN ALL COPYRIGHT NOTICES */
/* AND LICENSES (MEANING THIS TEXT).                  */
/*                                                    */
/******************************************************/

namespace NullFX.Controls {
    using System;
    using System.Windows.Forms;
    /// <summary>
    /// This components adds a much lacking function
    /// "Scroll to the end" which is missing
    /// from the original rich text box.
    /// </summary>
    public class ScrollableRichTextBox : RichTextBox {
        // constants for the message sending
        const int WM_VSCROLL = 0x0115;
        const int WM_LBUTTONDOWN = 0x0201;
        const int WM_SETFOCUS = 0x0007;
        const int WM_KILLFOCUS = 0x0008;
        readonly IntPtr SB_ENDSCROLL = (IntPtr)8;
        readonly IntPtr SB_BOTTOM = (IntPtr)7;
        // flag we use to determine if we can scroll
        bool _scrollable = true;
        private delegate void AppendTextDelegate(string text, bool scrollToEnd);
        public void AppendText(string text, bool scrollToEnd) {
            if(InvokeRequired) {
                Invoke(new AppendTextDelegate(AppendText), 
                           new object[] {text, scrollToEnd});
            }else {
                decimal length = base.Text.Length + text.Length;
                if(length >= base.MaxLength) base.Clear();
                base.Text += text;
                if(_scrollable && scrollToEnd) {
                    if(IntPtr.Zero != base.Handle) {
                        base.SelectionStart = base.Text.Length;
                        Message m = Message.Create(
                            base.Handle, 
                            WM_VSCROLL, 
                            SB_BOTTOM, IntPtr.Zero);
                        base.WndProc(ref m);
                    }
                }
            }

        }

        protected override void WndProc(ref Message m) {
            // if we're in a scroll set the scrolling flag 
            // to false & skip theauto scroll
            if((m.Msg == WM_LBUTTONDOWN) 
                || m.Msg == WM_VSCROLL 
                && m.WParam != SB_BOTTOM) {
                _scrollable = false;
            }

            // if we are done scrolling, set the falg to true & do the scrolling
            if(m.Msg == WM_VSCROLL && m.WParam == SB_ENDSCROLL) {
                _scrollable = true;
            }
            // HACK: this keeps the user from setting the cursor in the textbox
            //  because that causes problems if they do
            if(m.Msg == WM_SETFOCUS && base.ReadOnly) m.Msg = WM_KILLFOCUS;

            base.WndProc (ref m);
        }
    }
}