using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;

namespace Paint
{

    public partial class MainWindow : Window
    {
        bool paint = false;

        bool brushTool = true;

        int prevX = 0;
        int prevY = 0;

        WriteableBitmap wBitmap = BitmapFactory.New(2048, 2048);

        public MainWindow()
        {
            InitializeComponent();

            RenderOptions.SetBitmapScalingMode(img, BitmapScalingMode.NearestNeighbor);
            RenderOptions.SetEdgeMode(img, EdgeMode.Aliased);

            for(int x = 0; x < wBitmap.Height; x++)
            {
                for (int y = 0; y < wBitmap.Width; y++)
                {
                    wBitmap.SetPixel(x, y, 255, 255, 255);
                }
            }
            img.Source = wBitmap;
        }

        private void clrPicker_SelectedColorChanged(object sender, RoutedPropertyChangedEventArgs<System.Windows.Media.Color?> e)
        {

        }

        private void image_MouseDown(object sender, MouseButtonEventArgs e)
        {
            prevX = (int)(e.GetPosition(img).X);
            prevY = (int)(e.GetPosition(img).Y);
            paint = true;
        }

        private void image_MouseUp(object sender, MouseButtonEventArgs e)
        {
            prevX = 0;
            prevY = 0;
            paint = false;
        }

        private void image_MouseMove(object sender, MouseEventArgs e)
        {
            if (paint)
            {
                if (brushTool)
                {
                    DrawPixel(e);
                }
            }
        }

        private void DrawPixel(MouseEventArgs e)
        {
            int column = (int)e.GetPosition(img).X;
            int row = (int)e.GetPosition(img).Y;

            try
            {
                // Reserve the back buffer for updates.
                wBitmap.Lock();

                unsafe
                {
                    // Get a pointer to the back buffer.
                    IntPtr pBackBuffer = wBitmap.BackBuffer;

                    // Find the address of the pixel to draw.
                    pBackBuffer += row * wBitmap.BackBufferStride;
                    pBackBuffer += column * 4;

                    // Compute the pixel's color.
                    int color_data = 0 << 0; // R
                    color_data |= 0 << 0;   // G
                    color_data |= 0 << 0;   // B

                    // Assign the color data to the pixel.
                    *((int*)pBackBuffer) = color_data;
                }

                // Specify the area of the bitmap that changed.
                wBitmap.AddDirtyRect(new Int32Rect(column, row, 1, 1));
            }
            finally
            {
                // Release the back buffer and make it available for display.
                wBitmap.Unlock();
            }
        }

    }
}