Display BMP on console V2 C# Exercise - C# Programming Course

// Importing the System namespace to use its classes
using System; 

using System.IO; // Importing the IO namespace to handle file operations

class BmpViewer
{
    // The main method, where the program execution begins
    static void Main(string[] args)
    {
        // Check if a BMP file has been provided as a command-line argument
        if (args.Length < 1)
        {
            // Display an error message if no file name is provided
            Console.WriteLine("You must provide a BMP file as an argument.");
            return; // Exit the program if no file is provided
        }

        // Retrieve the file name from the command-line arguments
        string fileName = args[0];

        try
        {
            // Read the entire BMP file into a byte array
            byte[] bmpData = File.ReadAllBytes(fileName);

            // Check if the file starts with the "BM" signature, indicating a valid BMP file
            if (bmpData[0] != 'B' || bmpData[1] != 'M')
            {
                // Display an error message if the file is not a BMP file
                Console.WriteLine("The file is not a valid BMP file.");
                return; // Exit the program if the format is incorrect
            }

            // The starting position of the image data is located at byte 10 (4-byte offset)
            int startOfImageData = BitConverter.ToInt32(bmpData, 10);

            // Set the width and height of the BMP image
            int width = 72; // Fixed width as per the exercise requirement
            int height = 24; // Fixed height as per the exercise requirement

            // Iterate through each pixel in the BMP file
            for (int y = 0; y < height; y++)
            {
                // For each row, we need to read 72 pixels (3 bytes per pixel: Blue, Green, Red)
                for (int x = 0; x < width; x++)
                {
                    // Calculate the byte index for the current pixel
                    int pixelIndex = startOfImageData + (y * width + x) * 3;

                    // Extract the RGB values of the pixel (Blue, Green, Red)
                    byte blue = bmpData[pixelIndex];
                    byte green = bmpData[pixelIndex + 1];
                    byte red = bmpData[pixelIndex + 2];

                    // If the pixel color is white (255, 255, 255), display an "X"
                    if (red == 255 && green == 255 && blue == 255)
                    {
                        Console.Write("X");
                    }
                    else
                    {
                        // Otherwise, display a blank space
                        Console.Write(" ");
                    }
                }

                // After printing a row of pixels, move to the next line
                Console.WriteLine();
            }
        }
        catch (Exception ex)
        {
            // Display an error message if an exception occurs during file processing
            Console.WriteLine($"Error processing the file: {ex.Message}");
        }
    }
}