Develop Reference

C# - How to display a checkbox when the user has scrolled to the bottom of a rich text box [duplicate]

I have searched the internet far and wide and seen many questions like this, but I have not seen an actual answer.
I have a rich text box control with lots of text in it. It has some legal information in this control. By default the "Accept" button is disabled. I want to detect on the scroll event if the position of the v-scroll bar is at the bottom. If it is at the bottom, enable the button.
How would I detect the current v-scroll bar position?
Thank You!
EDIT
I am using WinForms (.Net 4.0)

This should get you close to what you are looking for. This class inherits from the RichTextBox and uses some pinvoking to determine the scroll position. It adds an event ScrolledToBottom which gets fired if the user scrolls using the scrollbar or uses the keyboard.
public class RTFScrolledBottom : RichTextBox {
public event EventHandler ScrolledToBottom;
private const int WM_VSCROLL = 0x115;
private const int WM_MOUSEWHEEL = 0x20A;
private const int WM_USER = 0x400;
private const int SB_VERT = 1;
private const int EM_SETSCROLLPOS = WM_USER + 222;
private const int EM_GETSCROLLPOS = WM_USER + 221;
[DllImport("user32.dll")]
private static extern bool GetScrollRange(IntPtr hWnd, int nBar, out int lpMinPos, out int lpMaxPos);
[DllImport("user32.dll")]
private static extern IntPtr SendMessage(IntPtr hWnd, Int32 wMsg, Int32 wParam, ref Point lParam);
public bool IsAtMaxScroll() {
int minScroll;
int maxScroll;
GetScrollRange(this.Handle, SB_VERT, out minScroll, out maxScroll);
Point rtfPoint = Point.Empty;
SendMessage(this.Handle, EM_GETSCROLLPOS, 0, ref rtfPoint);
return (rtfPoint.Y + this.ClientSize.Height >= maxScroll);
}
protected virtual void OnScrolledToBottom(EventArgs e) {
if (ScrolledToBottom != null)
ScrolledToBottom(this, e);
}
protected override void OnKeyUp(KeyEventArgs e) {
if (IsAtMaxScroll())
OnScrolledToBottom(EventArgs.Empty);
base.OnKeyUp(e);
}
protected override void WndProc(ref Message m) {
if (m.Msg == WM_VSCROLL || m.Msg == WM_MOUSEWHEEL) {
if (IsAtMaxScroll())
OnScrolledToBottom(EventArgs.Empty);
}
base.WndProc(ref m);
}
}
This is then how it can get used:
public Form1() {
InitializeComponent();
rtfScrolledBottom1.ScrolledToBottom += rtfScrolledBottom1_ScrolledToBottom;
}
private void rtfScrolledBottom1_ScrolledToBottom(object sender, EventArgs e) {
acceptButton.Enabled = true;
}
Tweak as necessary.

The following works very well in one of my solutions:
Point P = new Point(rtbDocument.Width, rtbDocument.Height);
int CharIndex = rtbDocument.GetCharIndexFromPosition(P);
if (rtbDocument.TextLength - 1 == CharIndex)
{
btnAccept.Enabled = true;
}

The question How to get scroll position for RichTextBox? could be helpful, Check out this function
richTextBox1.GetPositionFromCharIndex(0);

Making a text editor with multiple pages using richtextboxes

i am trying to give my text editor multiple pages mode the problem is when the richtextbox reaches the last line it resizes and add a scroll bar which is not what i want, i made a code to transfer the last line of the richtextbox to the one that follows but it's moving the whole text instead and it's kind of sluggish, any help would be appreciated
public partial class Form1 : Form
{
protected static bool GetVisibleScrollbars(Control ctl)
{
int wndStyle = Win32.GetWindowLong(ctl.Handle, Win32.GWL_STYLE);
bool vsVisible = (wndStyle & Win32.WS_VSCROLL) != 0;
return vsVisible;
}
public Form1()
{
InitializeComponent();
}
List<RichTextBox> pages=new List<RichTextBox>();
int currentdocindex = 0;
public void AddPage()
{
RichTextBox B = new RichTextBox();
B.Size = richTextBox1.Size;
panel1.Controls.Add(B);
B.Location = new Point(pages[pages.Count - 1].Location.X, pages[pages.Count - 1].Location.Y + richTextBox1.Height + 20);
pages.Add(B);
B.SelectionIndent = 20;
B.SelectionRightIndent = 20;
B.Enter += new EventHandler(richTextBox_Enter);
}
private void richTextBox_Enter(object sender, EventArgs e)
{
int i = 0;
foreach (RichTextBox box in pages)
{
if (box == (RichTextBox)sender)
{
currentdocindex=i;
break;
}
i++;
}
label1.Text = (currentdocindex + 1).ToString();
}
private void Form1_Load(object sender, EventArgs e)
{
pages.Add(richTextBox1);
richTextBox1.SelectionIndent = 20;
richTextBox1.SelectionRightIndent = 20;
}
private void richTextBox1_Enter(object sender, EventArgs e)
{
int i = 0;
foreach (RichTextBox box in pages)
{
if(box==(RichTextBox)sender)
{
currentdocindex=i;
break;
}
i++;
}
}
bool added = false;
private void timer1_Tick(object sender, EventArgs e)
{
int correntPageIndex = currentdocindex;
if (GetVisibleScrollbars(pages[currentdocindex]))
{
if (!added)
{
AddPage();
added = true;
}
}
else
{
added = false;
}
}
if(GetVisibleScrollbars(pages[correntPageIndex]))
{
string LastLineText = pages[correntPageIndex].Lines[pages[correntPageIndex].Lines.Count() - 1];
int LastLineStartIndex = pages[correntPageIndex].Text.LastIndexOf(LastLineText);
pages[correntPageIndex].SelectionStart = LastLineStartIndex;
pages[correntPageIndex].SelectionLength = pages[correntPageIndex].Text.Length - 1;
LastLineText = pages[correntPageIndex].SelectedRtf;
pages[correntPageIndex].Text = pages[correntPageIndex].Text.Remove(LastLineStartIndex);
pages[correntPageIndex + 1].SelectionStart = 0;
pages[correntPageIndex+1].SelectedRtf = LastLineText;
}
}
}
public class Win32
{
// offset of window style value
public const int GWL_STYLE = -16;
// window style constants for scrollbars
public const int WS_VSCROLL = 0x00200000;
public const int WS_HSCROLL = 0x00100000;
[DllImport("user32.dll", SetLastError = true)]
public static extern int GetWindowLong(IntPtr hWnd, int nIndex);
}

RichTextBox is a pain for this sort of thing, because to mutate a small portion of text you have to actually select the text first (which it appears you're attempting to do) and ensure the change only affects that text. It's a little nasty on the memory usage, but you might be better served by determining how many characters you want per page and subscribing to the KeyDown Event to determine when you move to a new page. Try to adapt something like this and see if it works better.
public void MyKeyDownHandler(object sender, System.Windows.Forms.KeyEventArgs e)
{
if(this.CurrentPageControl.RTB.Text.Length >= MY_LIMITING_CONSTANT_I_SET)
{
MyPageUserControl mpuc = new MyPageUserControl();
mpuc.RTB.Text = this.CurrentPageControl.RTB.Text.Split(' ').Last();
thePageCollectionIPresumeYouHave.Add(mpuc);
this.CurrentPageControl = thePageCollectionIPresumeYouHave.Last();
mpuc.RTB.Focus();
}
}
Caveat: I did that entirely from memory and without a chance to read all of your code ( I had to skim) because I'm at work.
Another Caveat: I assumed you put your RichTextBoxes in a custom "page" control. If you didn't, I hope my code shows you why you might want to.

Get the value of a scrollbar's scroll for a Winforms Text Box (C#)

I am creating a Windows Form Application using C#
I require a checkbox to be greyed out until the user scrolls to the bottom of a text box.
How can I get the value of the textbox's scrollbar position?

This should be a RichTextBox so you can use its SelectionProtected property to ensure that the user cannot change the text. It does not have a Scroll event but that can be added by overriding WndProc() and detecting the WM_VSCROLL message. Checking if the last line is visible like #TaW does is not reliable unless the WordWrap property is set to False. Easier to just check the state of the scrollbar.
Add a new class to your project and paste the code shown below. Compile. Drop the new control from the top of the toolbox onto your form. Subscribe the LicenseViewed event and set the checkbox' Enabled property to true. I would be remiss if I did not point out that only lawyers ever think this is a good idea, users find these kind of text boxes universally annoying and hate them with a passion. You only have one chance to create a good first impression.
using System;
using System.Windows.Forms;
using System.Runtime.InteropServices;
class LicenseBox : RichTextBox {
public event EventHandler LicenseViewed;
public override string Text {
get { return base.Text; }
set { base.Text = value; textChanged(); }
}
public new string Rtf {
get { return base.Rtf; }
set { base.Rtf = value; textChanged(); }
}
private bool eventFired;
private void textChanged() {
this.SelectAll();
this.SelectionProtected = true;
this.SelectionStart = this.SelectionLength = 0;
eventFired = false;
checkScrollbar();
}
private void checkScrollbar() {
if (eventFired || !this.IsHandleCreated) return;
var pos = new ScrollInfo();
pos.cbSize = Marshal.SizeOf(pos);
pos.fMask = 7;
if (!GetScrollInfo(this.Handle, SB_VERT, ref pos)) return;
if (pos.nPos >= pos.nMax - pos.nPage) {
if (LicenseViewed != null) LicenseViewed(this, EventArgs.Empty);
eventFired = true;
}
}
protected override void WndProc(ref Message m) {
base.WndProc(ref m);
if (m.Msg == WM_VSCROLL || m.Msg == WM_MOUSEWHEEL) checkScrollbar();
}
// Pinvoke
private const int WM_VSCROLL = 0x115;
private const int WM_MOUSEWHEEL = 0x20A;
private const int SB_VERT = 1;
private struct ScrollInfo {
public int cbSize, fMask, nMin, nMax, nPage, nPos, nTrackPos;
}
[DllImport("user32.dll", SetLastError = true)]
private static extern bool GetScrollInfo(IntPtr hwnd, int bar, ref ScrollInfo pos);
}

Here is a function that tells you if the last line is visible:
bool LastLineVisible(TextBox textbox)
{
Point lowPoint = new Point(3, textbox.ClientSize.Height - 3);
int lastline = textbox.Lines.Count() - 1;
int charOnLastvisibleLine = textbox.GetCharIndexFromPosition(lowPoint);
int lastVisibleLine = textbox.GetLineFromCharIndex(charOnLastvisibleLine);
return lastVisibleLine >= lastline;
}
You will still need to detect the scrolling event itself. See here on how to detect the scrolling.

Mouse wheel scrolling Toolstrip menu items

I have some menus that contain many menuitems. Mouse wheel doesn't scroll them. I have to use the keyboard arrows or click the arrows at top and bottom.
Is it possible to use the mouse wheel to scroll toolstrip menu items?
Thanks

You can enable it application wide with this class:
public class DropDownMenuScrollWheelHandler : System.Windows.Forms.IMessageFilter
{
private static DropDownMenuScrollWheelHandler Instance;
public static void Enable(bool enabled)
{
if (enabled)
{
if (Instance == null)
{
Instance = new DropDownMenuScrollWheelHandler();
Application.AddMessageFilter(Instance);
}
}
else
{
if (Instance != null)
{
Application.RemoveMessageFilter(Instance);
Instance = null;
}
}
}
private IntPtr activeHwnd;
private ToolStripDropDown activeMenu;
public bool PreFilterMessage(ref Message m)
{
if (m.Msg == 0x200 && activeHwnd != m.HWnd) // WM_MOUSEMOVE
{
activeHwnd = m.HWnd;
this.activeMenu = Control.FromHandle(m.HWnd) as ToolStripDropDown;
}
else if (m.Msg == 0x20A && this.activeMenu != null) // WM_MOUSEWHEEL
{
int delta = (short)(ushort)(((uint)(ulong)m.WParam) >> 16);
handleDelta(this.activeMenu, delta);
return true;
}
return false;
}
private static readonly Action<ToolStrip, int> ScrollInternal
= (Action<ToolStrip, int>)Delegate.CreateDelegate(typeof(Action<ToolStrip, int>),
typeof(ToolStrip).GetMethod("ScrollInternal",
System.Reflection.BindingFlags.NonPublic
| System.Reflection.BindingFlags.Instance));
private void handleDelta(ToolStripDropDown ts, int delta)
{
if (ts.Items.Count == 0)
return;
var firstItem = ts.Items[0];
var lastItem = ts.Items[ts.Items.Count - 1];
if (lastItem.Bounds.Bottom < ts.Height && firstItem.Bounds.Top > 0)
return;
delta = delta / -4;
if (delta < 0 && firstItem.Bounds.Top - delta > 9)
{
delta = firstItem.Bounds.Top - 9;
}
else if (delta > 0 && delta > lastItem.Bounds.Bottom - ts.Height + 9)
{
delta = lastItem.Bounds.Bottom - owner.Height + 9;
}
if (delta != 0)
ScrollInternal(ts, delta);
}
}

A working solution:
Register for MouseWheel event of your form and DropDownClosed event of your root MenuStripItem (here, rootItem) in the Load event of the form
this.MouseWheel += Form3_MouseWheel;
rootItem.DropDownOpened += rootItem_DropDownOpened;
rootItem.DropDownClosed += rootItem_DropDownClosed;
Add the code for Keyboard class which simulate key presses
public static class Keyboard
{
[DllImport("user32.dll")]
static extern uint keybd_event(byte bVk, byte bScan, int dwFlags, int dwExtraInfo);
const byte VK_UP = 0x26; // Arrow Up key
const byte VK_DOWN = 0x28; // Arrow Down key
const int KEYEVENTF_EXTENDEDKEY = 0x0001; //Key down flag, the key is going to be pressed
const int KEYEVENTF_KEYUP = 0x0002; //Key up flag, the key is going to be released
public static void KeyDown()
{
keybd_event(VK_DOWN, 0, KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_DOWN, 0, KEYEVENTF_KEYUP, 0);
}
public static void KeyUp()
{
keybd_event(VK_UP, 0, KEYEVENTF_EXTENDEDKEY, 0);
keybd_event(VK_UP, 0, KEYEVENTF_KEYUP, 0);
}
}
Add the code for DropDownOpened, DropDownClosed, MouseWheel events:
bool IsMenuStripOpen = false;
void rootItem_DropDownOpened(object sender, EventArgs e)
{
IsMenuStripOpen = true;
}
void rootItem_DropDownClosed(object sender, EventArgs e)
{
IsMenuStripOpen = false;
}
void Form3_MouseWheel(object sender, MouseEventArgs e)
{
if (IsMenuStripOpen)
{
if (e.Delta > 0)
{
Keyboard.KeyUp();
}
else
{
Keyboard.KeyDown();
}
}
}

This is very simply using a submenu (ToolStripMenuItem) of the context menu :
Assuming using a form1 (or UserControl) and a contextMenuStrip1 :
private void form1_Load( object sender , EventArgs e )
{
//this.MouseWheel -= When_MouseWheel;
this.MouseWheel += When_MouseWheel;
}
void When_MouseWheel( object sender , MouseEventArgs e )
{
if ( this.contextMenuStrip1.IsDropDown ) {
//this.Focus();
if ( e.Delta > 0 ) SendKeys.SendWait( "{UP}" );
else SendKeys.SendWait( "{DOWN}" );
}
}

I modified Mohsen Afshin's answer to click the up/down arrows instead of sending up/down key presses. My application had a ContextMenuStrip called menu. Here's the code.
In the initialization:
menu.VisibleChanged += (s, e) =>
{
if (menu.Visible)
{
MouseWheel += ScrollMenu;
menu.MouseWheel += ScrollMenu;
}
else
{
MouseWheel -= ScrollMenu;
menu.MouseWheel -= ScrollMenu;
}
};
The ScrollMenu function:
[System.Runtime.InteropServices.DllImport("user32.dll")]
private static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint cButtons, uint dwExtraInfo);
private void ScrollMenu(object sender, MouseEventArgs e)
{
Point origin = Cursor.Position;
int clicks;
if (e.Delta < 0)
{
Cursor.Position = menu.PointToScreen(new Point(menu.DisplayRectangle.Left + 5, menu.DisplayRectangle.Bottom + 5));
clicks = e.Delta / -40;
}
else
{
Cursor.Position = menu.PointToScreen(new Point(menu.DisplayRectangle.Left + 5, menu.DisplayRectangle.Top - 5));
clicks = e.Delta / 40;
}
for (int i = 0; i < clicks; i++)
mouse_event(0x0006, 0, 0, 0, 0);//Left mouse button up and down on cursor position
Cursor.Position = origin;
}
I was having trouble getting the mouse_event function to click a specific location, so I moved the cursor, clicked, and then moved the cursor back. It doesn't seem the cleanest, but it works.

Size RichTextBox according to contents

This code automatically sizes a RichTextBox according to it's contents. I'm having issues, especially with tables. \t may be ignored. I tried a managed solution, now I'm trying platform invoke. Current Output:
[DllImport("gdi32.dll")]
static extern bool GetTextExtentPoint32(IntPtr hdc, string lpString, int cbString, out SIZE lpSize);
[DllImport("user32.dll", SetLastError = true)]
static extern IntPtr GetDC(IntPtr hWnd);
[StructLayout(System.Runtime.InteropServices.LayoutKind.Sequential)]
public struct SIZE
{
public int cx;
public int cy;
public SIZE(int cx, int cy)
{
this.cx = cx;
this.cy = cy;
}
}
public static void Main()
{
Form form = new Form();
RichTextBox rtfBox = new RichTextBox();
rtfBox.Rtf = #"{\rtf1\ansi\deff0{\fonttbl{\f0\fnil Arial;}}\viewkind4\uc1\trowd\trgaph100\cellx1000\cellx2000\pard\intbl\lang1033\f0\fs20 hi\cell bye\cell\row\intbl one\cell two\cell\row\pard\par}";
rtfBox.ScrollBars = RichTextBoxScrollBars.None;
string sInput = "hi\t bye\t\n";// one\t two\t\n";
SIZE CharSize;
form.Controls.Add(rtfBox);
IntPtr hdc = GetDC(IntPtr.Zero);//Context for entire screen
GetTextExtentPoint32(hdc, sInput, sInput.Length, out CharSize);
rtfBox.Width = CharSize.cx;
rtfBox.Height = CharSize.cy;
form.Visible = false;
form.ShowDialog();
}
(Note, for simplicity this is a console application with a reference to System.Windows.Forms.dll)

Have you looked at the ContentsResized event? Add the following method to be called when the event fires:
private void richTextBox_ContentsResized(object sender, ContentsResizedEventArgs e)
{
var richTextBox = (RichTextBox) sender;
richTextBox.Width = e.NewRectangle.Width;
richTextBox.Height = e.NewRectangle.Height;
}
When the RTF content is changed (using Rtf), the RichTextBox should be resized to match its contents. Make sure you also set the WordWrap property to false.
I've tried it with your table example and it does appear to work (albeit with a little offset, which you could possibly solve by adding a few pixels of width to the adjusted size - not sure why that happens):
P.Brian.Mackey EDIT
This answer worked for me. To clarify, here's the final code including border fix:
public static void Main()
{
string sInput = "hi\t bye\t\n";// one\t two\t\n";
SIZE CharSize;
Form form = new Form();
RichTextBox rtfBox = new RichTextBox();
rtfBox.ContentsResized += (object sender, ContentsResizedEventArgs e) =>
{
var richTextBox = (RichTextBox)sender;
richTextBox.Width = e.NewRectangle.Width;
richTextBox.Height = e.NewRectangle.Height;
rtfBox.Width += rtfBox.Margin.Horizontal + SystemInformation.HorizontalResizeBorderThickness;
};
rtfBox.WordWrap = false;
rtfBox.ScrollBars = RichTextBoxScrollBars.None;
rtfBox.Rtf = #"{\rtf1\ansi\deff0{\fonttbl{\f0\fnil Arial;}}\viewkind4\uc1\trowd\trgaph100\cellx1000\cellx2000\pard\intbl\lang1033\f0\fs20 hi\cell bye\cell\row\intbl one\cell two\cell\row\pard\par}";
form.Controls.Add(rtfBox);
form.ShowDialog();
}

It's much easier to use GetPreferredSize, as described in this answer. Then you don't need to wait for a ContentsResized event,

What about the Height ?
I added
richTextBox.Height += richTextBox.Margin.Vertical +
SystemInformation.VerticalResizeBorderThickness;
at the end.
It also looks like a good candidate for an extension method :
static public class RichTextBoxResizer {
static public void ResizeToContents(this RichTextBox richTextBox, ContentsResizedEventArgs e) {
richTextBox.Width = e.NewRectangle.Width;
richTextBox.Height = e.NewRectangle.Height;
richTextBox.Width += richTextBox.Margin.Horizontal +
SystemInformation.HorizontalResizeBorderThickness +
SystemInformation.HorizontalScrollBarThumbWidth;
richTextBox.Height += richTextBox.Margin.Vertical +
SystemInformation.VerticalResizeBorderThickness;
}
static public void ResizeToContentsHorizontally(this RichTextBox richTextBox, ContentsResizedEventArgs e) {
richTextBox.Width = e.NewRectangle.Width;
richTextBox.Width += richTextBox.Margin.Horizontal +
SystemInformation.HorizontalResizeBorderThickness +
SystemInformation.HorizontalScrollBarThumbWidth;
}
static public void ResizeToContentsVertically(this RichTextBox richTextBox, ContentsResizedEventArgs e) {
richTextBox.Height = e.NewRectangle.Height;
richTextBox.Height += richTextBox.Margin.Vertical +
SystemInformation.VerticalResizeBorderThickness;
}
}
So the event sink looks like :
private void rtfBox_ContentsResized(object sender, ContentsResizedEventArgs e) {
RichTextBox rtb = (RichTextBox)sender;
rtb.ResizeToContents(e);
}