Compute number of lines typed in a rich text box control

Question

Compute number of lines typed in a rich text box control

John 511

I would like to know more about computing the number of lines in a rich text box control.

From there, I would also like to include it in a for loop structure.

Also, what is the length property of the lines object of the rich text box control do?

John 511 Reputation points

2023-09-20T12:12:29.71+00:00
I have this code snippet below:

for (int Line_Number=0; Line_Number < this.rtSpace.Lines.LongLength; Line_Number++) { }
Minxin Yu 13,506 Reputation points Microsoft External Staff

2023-09-25T08:19:49.8066667+00:00

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John 511 Reputation points

2023-09-20T12:12:29.71+00:00

I have this code snippet below:

for (int Line_Number=0; Line_Number < this.rtSpace.Lines.LongLength; Line_Number++) { }
Minxin Yu 13,506 Reputation points Microsoft External Staff

2023-09-25T08:19:49.8066667+00:00

Did the answers below solve your problem?

Answer 1

KOZ6.0 6,735

To find out the number of lines displayed in the RichTextBox, run the GetLineFromCharIndex method.

private void Form1_Load(object sender, EventArgs e) {
    richTextBox1.Text = "Hello, World! \r\n Hello, World!Hello, World!Hello, World!Hello, World!";
}

private void RichTextBox1_TextChanged(object sender, EventArgs e) {
    RichTextBox rbox = (RichTextBox)sender;
    int len = rbox.TextLength;
    int lines;
    if (len > 0) {
        lines = rbox.GetLineFromCharIndex(len - 1) + 1;
    } else {
        lines = 0;
    }
    label1.Text = $"lines:{lines}";
}

enter image description here

see also:

GetCharIndexFromPosition
GetPositionFromCharIndex

There are many messages to provide layout information.

「Edit Control Messages」

https://learn.microsoft.com/en-us/windows/win32/controls/bumper-edit-control-reference-messages

EM_GETLINECOUNT, EM_LINEFROMCHAR, ...etc

KOZ6.0 6,735

These messages are also valid for Multiline TextBox.

I think you will be happy if you create meny extension method for TextBoxBase.

using System;
using System.Runtime.InteropServices;
using System.Windows.Forms;

internal static class TextBoxBaseHelper
{
    private static class ExternDll
    {
        public const string User32 = "user32.dll";
    }

    [DllImport(ExternDll.User32, CharSet = CharSet.Auto)]
    private static extern IntPtr SendMessage(
            IntPtr hWnd, int Msg, IntPtr wParam, IntPtr lParam);

    private const int EM_GETLINECOUNT = 0x00BA;
    
    public static int GetLineCount(this TextBoxBase target) {
        if (target.TextLength > 0) {
            return (int)SendMessage(
                target.Handle, EM_GETLINECOUNT,
                IntPtr.Zero, IntPtr.Zero);
        } else {
            return 0;
        }
    }
}

Answer 2

Minxin Yu 13,506 Microsoft External Staff

Hi, @John

Lines is Array type string[]. And Length properties: Gets the total number of elements in all the dimensions of the Array. Length represents the number of lines (end with \r\n is one line).

Eg.
richTextBox1.Text = "Hello, World! \r\n Hello, World!Hello, World!Hello, World!Hello, World!";

Enabled word wrap, but the length is 2.

User's image

Best regards,

Minxin Yu

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John 511 Reputation points

2023-09-21T01:12:13.6966667+00:00

What could I do with a string[] data type with rich text box control?

I'm not sure if your answer is correct.

Could I perform anything with array string data types while using that control?

If so, then can anyone provide me some examples?
Minxin Yu 13,506 Reputation points Microsoft External Staff

2023-09-21T06:11:53.63+00:00
This is the definition of Lines: public string[] Lines { get; set; } Gets or sets the lines of text in a text box control.
And the example: print the text of richtextbox1

string[] tempArray = richTextBox1.Lines; // Loop through the array and send the contents of the array to debug window. for (int counter = 0; counter < tempArray.Length; counter++) { System.Diagnostics.Debug.WriteLine(tempArray[counter]); }

And please read the document: TextBoxBase.Lines Property

If the Multiline property of the text box control is set to true and a newline character appears in the text, the text following the newline character is added to a new element in the array and displayed on a separate line.

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Compute number of lines typed in a rich text box control

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