using System;
using System.Collections.Generic;
using System.Text;
using OpenTK;
using OpenTK.Graphics.OpenGL;
using OpenTK.Graphics;
using OpenTK.Input;
using System.Threading;
using System.Drawing;
using System.Drawing.Imaging;
using GlPixelFormat = OpenTK.Graphics.OpenGL.PixelFormat;
using SysPixelFormat = System.Drawing.Imaging.PixelFormat;
using System.IO;

namespace OpenTK建立一个窗体
{
    internal class Game : GameWindow
    {
        private Bitmap _bitmap = Image.FromFile(Directory.GetCurrentDirectory() + "\\logo.jpg") as Bitmap; 
        private int _texture;

        private string windowTitle="";
        private int frames = 0;

        public Game(int with, int height, string title)
            : base(with, height, GraphicsMode.Default, title)
        {
        }

        protected override void OnLoad(EventArgs e)
        {
            GL.ClearColor(Color.MidnightBlue);
            //GL.Enable(EnableCap.DepthTest);

            GL.Enable(EnableCap.Texture2D);
            GL.Hint(HintTarget.PerspectiveCorrectionHint, HintMode.Nicest);

            GL.GenTextures(1, out _texture);
            GL.BindTexture(TextureTarget.Texture2D, _texture);

            BitmapData bitmapData = _bitmap.LockBits(
                new Rectangle(0, 0, _bitmap.Width, _bitmap.Height),
                ImageLockMode.ReadOnly,
                SysPixelFormat.Format32bppArgb
            );

            GL.TexImage2D(
                TextureTarget.Texture2D,
                0,
                PixelInternalFormat.Rgba,
                bitmapData.Width,
                bitmapData.Height,
                0,
                GlPixelFormat.Bgra,
                PixelType.UnsignedByte,
                bitmapData.Scan0
            );

            _bitmap.UnlockBits(bitmapData);

            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMinFilter, (int)TextureMinFilter.Linear);
            GL.TexParameter(TextureTarget.Texture2D, TextureParameterName.TextureMagFilter, (int)TextureMinFilter.Linear);
        }
        protected override void OnUnload(EventArgs e)
        {
            //base.OnUnload(e);
            GL.DeleteTextures(1, ref _texture);
        }
        protected override void OnUpdateFrame(FrameEventArgs e)
        {
            base.OnUpdateFrame(e);

            KeyboardState input = Keyboard.GetState();
            if (input.IsKeyDown(Key.Escape))
            {
                Exit();
            }
            Title = $"{windowTitle} - FPS: {RenderFrequency:0.0} - Frames: {frames}";

        }
        protected override void OnRenderFrame(FrameEventArgs e)
        {
            frames++;

            GL.Clear(ClearBufferMask.ColorBufferBit);

            GL.MatrixMode(MatrixMode.Modelview);
            GL.LoadIdentity();
            GL.BindTexture(TextureTarget.Texture2D, _texture);

            GL.Begin(PrimitiveType.Quads);

            GL.TexCoord2(0.0f, 1.0f);
            GL.Vertex2(-0.6f, -0.4f);
            GL.TexCoord2(1.0f, 1.0f);
            GL.Vertex2(0.6f, -0.4f);
            GL.TexCoord2(1.0f, 0.0f);
            GL.Vertex2(0.6f, 0.4f);
            GL.TexCoord2(0.0f, 0.0f);
            GL.Vertex2(-0.6f, 0.4f);

            GL.End();

            SwapBuffers();

        }
        
    }
}