using System;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Windows.Forms;

namespace Dongke.IBOSS.Basics.FlowSetting
{
    /// <summary>
    /// 画布容器（画板）
    /// </summary>
    internal partial class CanvasBox : UserControl
    {
        #region 成员变量

        /// <summary>
        /// 画布图片
        /// </summary>
        private Bitmap _canvasImage = null;
        /// <summary>
        /// 画布
        /// </summary>
        private Graphics _canvasGraphics = null;

        #endregion 成员变量

        #region 构造函数

        /// <summary>
        /// 构造函数
        /// </summary>
        public CanvasBox()
        {
            this.InitializeComponent();
            this.AutoScroll = true;
            this.flowCanvas.BackColor = System.Drawing.Color.White;

            this.txtRBFocus.ReadOnly = true;
            this.txtRBFocus.Size = Size.Empty;

            this.ClientSizeChanged += this.CanvasBox_ClientSizeChanged;
            this.MouseDown += this.CanvasBox_MouseDown;
            this.GotFocus += this.CanvasBox_GotFocus;

            this.flowCanvas.GotFocus += this.CanvasBox_GotFocus;
            this.flowCanvas.MouseDown += this.CanvasBox_MouseDown;
            this.flowCanvas.SizeChanged += this.flowCanvas_SizeChanged;
        }

        #endregion 构造函数

        #region 属性

        /// <summary>
        /// 获取处理键盘事件的控件
        /// </summary>
        public Control KeyControl
        {
            get
            {
                return this.txtRBFocus;
            }
        }

        /// <summary>
        /// 获取画布控件
        /// </summary>
        public Control CanvasControl
        {
            get
            {
                return this.flowCanvas;
            }
        }

        /// <summary>
        /// 获取画布尺寸
        /// </summary>
        public Size CanvasSize
        {
            get
            {
                return this.flowCanvas.Size;
            }
        }

        /// <summary>
        /// 获取画布图片
        /// </summary>
        public Bitmap CanvasImage
        {
            get
            {
                if (this._canvasImage == null)
                {
                    this._canvasImage = new Bitmap(this.flowCanvas.Size.Width, this.flowCanvas.Size.Height);
                }
                return this._canvasImage;
            }
        }

        /// <summary>
        /// 获取画布
        /// </summary>
        public Graphics Canvas
        {
            get
            {
                if (this._canvasGraphics == null)
                {
                    if (this._canvasImage == null)
                    {
                        this._canvasImage = new Bitmap(this.flowCanvas.Size.Width, this.flowCanvas.Size.Height);
                    }
                    this._canvasGraphics = this.GetGraphicsFromImage(this._canvasImage);
                }
                return this._canvasGraphics;
            }
        }

        /// <summary>
        /// 获取或设置画布背景
        /// </summary>
        public Image CanvasBackgroundImage
        {
            get
            {
                return this.flowCanvas.BackgroundImage;
            }
            set
            {
                this.flowCanvas.BackgroundImage = value;
            }
        }

        #endregion 属性

        #region 事件处理

        /// <summary>
        /// 改变画布大小
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void flowCanvas_SizeChanged(object sender, EventArgs e)
        {
            // TODO 优化 = null ，在使用时，会重新赋值。但是大小改变后要调用RefreshItems，要不是空白画布。
            //Bitmap bitmap = null;
            //if (this._canvasImage == null)
            //{
            //    bitmap = new Bitmap(this.flowCanvas.Size.Width, this.flowCanvas.Size.Height);
            //}
            //else
            //{
            //    bitmap = new Bitmap(this._canvasImage, this.flowCanvas.Size);
            //}

            //this._canvasImage = bitmap;
            //this._canvasGraphics = this.GetGraphicsFromImage(this._canvasImage);
            this._canvasImage = null;
            this._canvasGraphics = null;
        }

        /// <summary>
        /// 画板改变大小
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CanvasBox_ClientSizeChanged(object sender, EventArgs e)
        {
            this.SetCanvasLocation();
        }

        /// <summary>
        /// 获取焦点
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CanvasBox_MouseDown(object sender, MouseEventArgs e)
        {
            this.txtRBFocus.Focus();
        }

        /// <summary>
        /// 获取焦点
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        private void CanvasBox_GotFocus(object sender, EventArgs e)
        {
            this.txtRBFocus.Focus();
        }

        #endregion 事件处理

        #region 公有方法

        /// <summary>
        /// 设置画布尺寸
        /// </summary>
        /// <param name="value">画布尺寸</param>
        public void SetCanvasSize(Size value)
        {
            if (value.IsEmpty)
            {
                this.flowCanvas.Size = Consts.CANVAS_SIZE_MIN;
            }
            else
            {
                this.flowCanvas.Size = new Size(
                    Math.Max(value.Width, Consts.CANVAS_SIZE_MIN.Width),
                    Math.Max(value.Height, Consts.CANVAS_SIZE_MIN.Height));
            }

            this.SetCanvasLocation();
        }

        #endregion 公有方法

        #region 内部方法

        /// <summary>
        /// 设置画布呈现质量
        /// </summary>
        /// <param name="graphics"></param>
        internal void SetSmoothingMode(Graphics graphics)
        {
            graphics.SmoothingMode = SmoothingMode.HighQuality;
        }

        /// <summary>
        /// 设置Item的图片
        /// </summary>
        /// <param name="image">图片</param>
        internal void SetItemsImage(Image image)
        {
            this.flowCanvas.Image = image;
        }

        #endregion 内部方法

        #region 受保护方法

        /// <summary>
        /// 显示获得焦点的控件
        /// </summary>
        /// <param name="activeControl"></param>
        /// <returns></returns>
        protected override Point ScrollToControl(Control activeControl)
        {
            return this.DisplayRectangle.Location;
        }

        #endregion 受保护方法

        #region 私有方法

        /// <summary>
        /// 设置画布大小
        /// </summary>
        private void SetCanvasLocation()
        {
            int x = this.GetCanvasLeft();
            int y = this.GetCanvasTop();

            this.flowCanvas.Location = new Point(x, y);

            this.txtRBFocus.Location = new Point(
                this.flowCanvas.Right + Consts.CANVAS_MARGIN,
                this.flowCanvas.Bottom + Consts.CANVAS_MARGIN);

            //this.AutoScroll = true;
        }

        /// <summary>
        /// 获取画布位置Y
        /// </summary>
        /// <returns>位置Y</returns>
        private int GetCanvasTop()
        {
            int margin = this.ClientSize.Height
                       - this.flowCanvas.Height
                       - Consts.CANVAS_MARGIN
                       - Consts.CANVAS_MARGIN;

            if (0 < margin)
            {
                return Consts.CANVAS_MARGIN + (margin) / 2 + this.lblLeftTop.Top;
            }
            else
            {
                return Consts.CANVAS_MARGIN + this.lblLeftTop.Top;
            }
        }

        /// <summary>
        /// 获取画布位置X
        /// </summary>
        /// <returns>位置X</returns>
        private int GetCanvasLeft()
        {
            int margin = this.ClientSize.Width
                       - this.flowCanvas.Width
                       - Consts.CANVAS_MARGIN
                       - Consts.CANVAS_MARGIN;

            if (0 < margin)
            {
                return Consts.CANVAS_MARGIN + (margin) / 2 + this.lblLeftTop.Left;
            }
            else
            {
                return Consts.CANVAS_MARGIN + this.lblLeftTop.Left;
            }
        }

        /// <summary>
        /// 从图片获得Graphics
        /// </summary>
        /// <param name="image">片</param>
        /// <returns>Graphics</returns>
        private Graphics GetGraphicsFromImage(Image image)
        {
            Graphics g = Graphics.FromImage(image);
            this.SetSmoothingMode(g);
            return g;
        }

        #endregion 私有方法
    }
}