using System;
using System.Collections.Generic;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Linq;
using System.Windows.Forms;

namespace CloudWaterNetwork
{
    partial class MapControl : Control
    {
        private Point backgroundImageOffset = Point.Empty;  // 背景图偏移量
        private Image backgroundImage;                      // 背景图片
        private RectangleF chartArea;                        // 直角坐标系范围
        private PointF origin;                               // 坐标轴原点
        private float zoomLevel = 1f;                        // 缩放级别

        private bool isPanning = false;                      // 是否正在平移
        private Point lastMousePosition = Point.Empty;       // 上一次鼠标位置
        private bool isSelecting = false;                    // 是否正在框选矩形
        private RectangleF selectionRect;                    // 框选矩形


        public MapControl()
        {
            this.DoubleBuffered = true;
        }

        public Image BackgroundImage
        {
            get { return this.backgroundImage; }
            set
            {
                this.backgroundImage = value;
                this.Invalidate();
            }
        }

        protected override void OnMouseDown(MouseEventArgs e)
        {
            base.OnMouseDown(e);

            if (e.Button == MouseButtons.Middle)
            {
                // 启动平移模式
                this.isPanning = true;
                this.lastMousePosition = e.Location;
            }
            else if (e.Button == MouseButtons.Left)
            {
                // 启动框选矩形模式
                this.isSelecting = true;
                this.selectionRect = new RectangleF(e.Location, SizeF.Empty);
            }
        }

        protected override void OnMouseMove(MouseEventArgs e)
        {
            base.OnMouseMove(e);

            if (this.isPanning)
            {
                // 平移坐标系范围和背景图片
                int dx = e.X - this.lastMousePosition.X;
                int dy = e.Y - this.lastMousePosition.Y;
                this.backgroundImageOffset.Offset(dx, dy);
                this.chartArea.Offset(dx / this.zoomLevel, -dy / this.zoomLevel);
                this.origin.X += dx;
                this.origin.Y += dy;
                //Offset(dx, dy);
                this.lastMousePosition = e.Location;
                this.Invalidate();
            }
            else if (this.isSelecting)
            {
                // 更新框选矩形范围
                this.selectionRect.Width = e.X - this.selectionRect.Left;
                this.selectionRect.Height = e.Y - this.selectionRect.Top;
                this.Invalidate();
            }
        }

        protected override void OnMouseUp(MouseEventArgs e)
        {
            base.OnMouseUp(e);

            if (this.isPanning)
            {
                // 停止平移模式
                this.isPanning = false;
            }
            else if (this.isSelecting)
            {
                // 停止框选矩形模式，并重新计算坐标系范围和原点位置
                this.isSelecting = false;

                float x1 = (this.selectionRect.Left - this.origin.X) * (this.chartArea.Width / this.ClientSize.Width) + this.chartArea.Left;
                float y1 = (this.ClientSize.Height - this.selectionRect.Bottom + this.origin.Y) * (this.chartArea.Height / this.ClientSize.Height) + this.chartArea.Top;
                float x2 = (this.selectionRect.Right - this.origin.X) * (this.chartArea.Width / this.ClientSize.Width) + this.chartArea.Left;
                float y2 = (this.ClientSize.Height - this.selectionRect.Top + this.origin.Y) * (this.chartArea.Height / this.ClientSize.Height) + this.chartArea.Top;

                this.chartArea = new RectangleF(x1, y1, x2 - x1, y2 - y1);
                this.origin = new PointF(this.chartArea.Left, this.chartArea.Bottom);

                this.Invalidate();
            }
        }

        protected override void OnMouseWheel(MouseEventArgs e)
        {
            base.OnMouseWheel(e);

            // 缩放坐标系范围和背景图片
            float factor = e.Delta > 0 ? 1.1f : 0.9f;
            float oldZoomLevel = this.zoomLevel;
            this.zoomLevel *= factor;
            if (this.zoomLevel < 0.1f)
            {
                this.zoomLevel = 0.1f;
            }
            if (this.zoomLevel > 10f)
            {
                this.zoomLevel = 10f;
            }
            float dx = (this.chartArea.Width / oldZoomLevel - this.chartArea.Width / this.zoomLevel) / 2;
            float dy = (this.chartArea.Height / oldZoomLevel - this.chartArea.Height / this.zoomLevel) / 2;
            this.backgroundImageOffset.Offset((int)(e.Location.X * dx), (int)(e.Location.Y * dy));
            this.chartArea.Inflate(dx, dy);
            this.origin = new PointF(this.chartArea.Left, this.chartArea.Bottom);

            this.Invalidate();
        }

        protected override void OnPaint(PaintEventArgs e)
        {
            base.OnPaint(e);

            // 绘制背景图片
            if (this.backgroundImage != null)
            {
                e.Graphics.DrawImage(this.backgroundImage, this.backgroundImageOffset);
            }

            // 绘制直角坐标系和矩形
            using (Pen axisPen = new Pen(Color.Black, 2))
            {
                e.Graphics.DrawLine(axisPen, this.origin.X, this.origin.Y, this.origin.X + this.chartArea.Width / this.zoomLevel, this.origin.Y);  // X轴
                e.Graphics.DrawLine(axisPen, this.origin.X, this.origin.Y, this.origin.X, this.origin.Y - this.chartArea.Height / this.zoomLevel);  // Y轴

                if (this.isSelecting)
                {
                    // 绘制框选矩形
                    using (Pen selectionPen = new Pen(Color.Red, 2))
                    {
                        selectionPen.DashStyle = DashStyle.Dot;
                        e.Graphics.DrawRectangle(selectionPen, Rectangle.Round(this.selectionRect));
                    }
                }
            }
        }

        protected override void OnResize(EventArgs e)
        {
            base.OnResize(e);

            // 初始化坐标系范围和原点位置
            float widthRatio = (float)this.ClientSize.Width / this.chartArea.Width;
            float heightRatio = (float)this.ClientSize.Height / this.chartArea.Height;
            float zoomRatio = Math.Min(widthRatio, heightRatio);
            this.chartArea = new RectangleF(0, 0, this.ClientSize.Width / zoomRatio, this.ClientSize.Height / zoomRatio);
            this.origin = new PointF(this.chartArea.Left, this.chartArea.Bottom);

            this.Invalidate();
        }
    }
}