adding text decorations to console output

Question

I have a c# .net 3.5 application that writes text to the console using a StreamWriter. Is there a way I can add text decorations like underline and strikethrough to the text that is printed to the console? Possibly using ANSI escape sequences?

TextWriter writer = new StreamWriter(Console.OpenStandardOutput());
writer.WriteLine("some underlined text");

Thanks, PaulH

Answer 1

The Windows console does not support ANSI escape sequences. To my knowledge, the only way to change the attributes of an output character is to call SetConsoleTextAttribute before writing the character. Or, in .NET, modify the Console.ForegroundColor or Console.BackgroundColor attributes.

It might be possible to set those properties to custom values (i.e. values not defined by ConsoleColor) with a type cast. But I don't know what good that would do you.

I don't know that I've ever seen strikethrough text on a Windows console, and it's been years since I saw underline. I suppose it's possible, but I don't know how it's done.

Answer 2

using System;
using System.Runtime.InteropServices;

class Program
{
    const int STD_OUTPUT_HANDLE = -11;
    const uint ENABLE_VIRTUAL_TERMINAL_PROCESSING = 4;

    [DllImport("kernel32.dll", SetLastError = true)]
    static extern IntPtr GetStdHandle(int nStdHandle);

    [DllImport("kernel32.dll")]
    static extern bool GetConsoleMode(IntPtr hConsoleHandle, out uint lpMode);

    [DllImport("kernel32.dll")]
    static extern bool SetConsoleMode(IntPtr hConsoleHandle, uint dwMode);

    static void Main()
    {
        var handle = GetStdHandle(STD_OUTPUT_HANDLE);
        uint mode;
        GetConsoleMode(handle, out mode);
        mode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
        SetConsoleMode(handle, mode);

        const string UNDERLINE = "\x1B[4m";
        const string RESET = "\x1B[0m";
        Console.WriteLine("Some " + UNDERLINE + "underlined" + RESET + " text");
    }
}

Answer 3

Short answer, no; the console doesn't allow the use of underlined characters in output.

Longer answer: The screen buffer used by the console is little more than a byte array. Each cursor position is one byte or one character. To create an underline, you either need two characters overlapping (which isn't possible in the console), or you need access to a codepage that uses the upper 128 character values as underlined or strikethrough versions of the lower 128 (I don't know of one).

You can work around this if you are willing to go "double-spaced" for lines that have underlines. Character code 0x00AF (decimal 175) is a "text art" character representing a border across the top of the character space. If you use those in the line underneath your text, presto, underlines.

Answer 4

It's pretty easy to change the foreground/background color of console : http://www.dotnetperls.com/console-color but AFAIK there is no way to put some bold text, for example. But I didn't really tried to achieve that so i'm not sure.

Answer 5

I use this code. It's a fixed version of Vladimir Reshetnikov's answer, using the correct escape code for the reset.

    private static void WriteUnderline(string s)
    {
        var handle = GetStdHandle(STD_OUTPUT_HANDLE);
        uint mode;
        GetConsoleMode(handle, out mode);
        mode |= ENABLE_VIRTUAL_TERMINAL_PROCESSING;
        SetConsoleMode(handle, mode);
        Console.WriteLine($"\x1B[4m{s}\x1B[24m");
    }

This will do underlined text, and has the benefit of not resetting any colors you have set.