using System;
using System.Windows.Forms;
using SharpGL.Enumerations;
using SharpGL.Version;
using SharpGL;
using System.ComponentModel;

namespace JuicyGraphics {
    class canvas : Control, ISupportInitialize {

        protected OpenGL GL = new OpenGL();

        public canvas() {
            SetStyle(ControlStyles.AllPaintingInWmPaint, true);
            SetStyle(ControlStyles.UserPaint, true);
            InitializeOpenGL();
        }

        protected void InitializeOpenGL() {
            GL.Create(OpenGLVersion.OpenGL4_3, RenderContextType.NativeWindow, Width, Height, 32, this.Handle);
            GL.ShadeModel(OpenGL.GL_SMOOTH);
            GL.ClearDepth(1.0f);
            GL.Enable(OpenGL.GL_DEPTH_TEST);
            GL.DepthFunc(OpenGL.GL_LEQUAL);
            GL.Hint(OpenGL.GL_PERSPECTIVE_CORRECTION_HINT, OpenGL.GL_NICEST);
            GL.Viewport(0, 0, Width, Height);
        }

        bool renderingForDesigner() {
            if (this == null)
                return false;
            if (LicenseManager.UsageMode == LicenseUsageMode.Designtime)
                return true;
            Control p = this.Parent;
            while (p != null) {
                if (p.GetType().FullName.Contains(".DesignerFrame"))
                    return true;
                p = p.Parent;
            }
            return false;
        }

        protected override void OnPaintBackground(PaintEventArgs e) {
            if (renderingForDesigner()) { base.OnPaintBackground(e); }
            return;
        }

        protected override void OnPaint(PaintEventArgs e) {
            if (renderingForDesigner()) {
                SetStyle(ControlStyles.AllPaintingInWmPaint, true);
                SetStyle(ControlStyles.UserPaint, true);
                InitializeOpenGL();
            }
            GL.MakeCurrent();
            GL.ClearColor(0f, 0.3f, 0.7f, 1f);
            GL.Clear(OpenGL.GL_COLOR_BUFFER_BIT | OpenGL.GL_DEPTH_BUFFER_BIT);

            GL.Begin(BeginMode.Triangles);
            GL.Color(0.8, 0.1, 0.1);
            GL.Vertex(1.0, 1.0);
            GL.Vertex(-1.0, -1.0); GL.Vertex(-1.0, 1.0);
            GL.End();
            GL.Flush();

            var handleDeviceContext = e.Graphics.GetHdc();
            GL.Blit(handleDeviceContext);
            e.Graphics.ReleaseHdc(handleDeviceContext);
        }

        protected override void OnSizeChanged(EventArgs e) {
            if (GL.RenderContextProvider == null)
                return;
            GL.SetDimensions(Width, Height);
            GL.Viewport(0, 0, Width, Height);
            Invalidate();
        }

        public void BeginInit() { }

        public void EndInit() {
            InitializeOpenGL();
            OnSizeChanged(null);
        }
    }
}