Viewer

using System;
using System.Collections.Generic;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

namespace CanvasDemo.Canvas
{
public class Viewer
{
TimCanvas Canvas;
public Viewer(TimCanvas canvas)
{
Canvas = canvas;

        //默认图纸坐标
        Zero = new Point(0, 0);
        Viewport = new Rectangle(0 - Zero.X, 0 - Zero.Y, Canvas.Width, Canvas.Height);

    }

    /// <summary>
    /// 零点坐标（默认为画板中间）
    /// </summary>
    public Point Zero;//不能用属性，不然没法使用Offset之类函数

    /// <summary>
    /// 视口，当前用户可以看到的区域
    /// </summary>
    public Rectangle Viewport;//不能用属性，不然没法使用Offset之类函数

    // int DebugVX = 50, DebugVL = 100;//调试时故意减少视口，用于调试

    //缩放比例
    public float Zoom = 1;

    //最小比例
    private float MinZoom = 0.01f;
    //最大比例
    private float MaxZoom = 100;

    #region 视图调整

    //鼠标中键按下
    bool IsMouseMiddleDown = false;

    /// <summary>
    /// 移动前鼠标位置
    /// </summary>
    Point OldMousePoint;

    public void MouseDown(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Middle) IsMouseMiddleDown = true;
        OldMousePoint = e.Location;
    }

    public void MouseUp(MouseEventArgs e)
    {
        if (e.Button == MouseButtons.Middle) IsMouseMiddleDown = false;
    }


    public void MouseMove(MouseEventArgs e)
    {
        var newLocation = e.Location;

        if (IsMouseMiddleDown == true)
        {//鼠标中键移动图纸

            var x = (newLocation.X - OldMousePoint.X);
            var y = (newLocation.Y - OldMousePoint.Y);

            Zero.Offset(x, y);

            Viewport.X = (int)((0 - Zero.X) / Zoom);
            Viewport.Y = (int)((0 - Zero.Y) / Zoom);
        }

        OldMousePoint = newLocation;
    }

    public void MouseWheel(MouseEventArgs e)
    {
        //鼠标滚轮滚动图纸
        int tZeroX = 0;
        int tZeroY = 0;
        if (e.Delta > 0)
        {
            if (Zoom == MaxZoom) return;

            Zoom = Zoom * 1.25f;
            if (Zoom > MaxZoom) Zoom = MaxZoom;

            tZeroX = (int)((e.X - Zero.X) - (e.X - Zero.X) * 1.25f);
            tZeroY = (int)((e.Y - Zero.Y) - (e.Y - Zero.Y) * 1.25f);
        }
        else
        {
            if (Zoom == MinZoom) return;

            Zoom = Zoom * 0.8f;
            if (Zoom < MinZoom) Zoom = MinZoom;

            tZeroX = (int)((e.X - Zero.X) - (e.X - Zero.X) * 0.8f);
            tZeroY = (int)((e.Y - Zero.Y) - (e.Y - Zero.Y) * 0.8f);
        }

        //调整相对坐标位置
        Zero.Offset(tZeroX, tZeroY);

        //调整视口位置
        Viewport.X = (int)((0 - Zero.X) / Zoom);
        Viewport.Y = (int)((0 - Zero.Y) / Zoom);
        Viewport.Width = (int)((Canvas.Width) / Zoom);
        Viewport.Height = (int)((Canvas.Height) / Zoom);
    }

    /// <summary>
    /// 设置缩放
    /// </summary>
    /// <param name="zoom"></param>
    public void SetZoom(float zoom)
    {
        Zoom = zoom;
        Canvas.Refresh();
    }
    public void SetZero(int x,int y)
    {
        Zero.X = x;
        Zero.Y = y;
        //调整视口位置
        Viewport.X = (int)((0 - Zero.X) / Zoom);
        Viewport.Y = (int)((0 - Zero.Y) / Zoom);
    }


        /// <summary>
        /// 设置成完整显示
        /// </summary>
        public void SetFullDisplay()
    {
        var w = (float)Canvas.Width / (float)Canvas.BackgrounderSize.Width;
        var h = (float)Canvas.Height / (float)Canvas.BackgrounderSize.Height;
        Zoom = w < h ? w : h;
        MinZoom = Zoom;
        MaxZoom = Zoom * 100;

        Zero.X = Canvas.Width / 2;
        Zero.Y = Canvas.Height / 2;

        Viewport.X = (int)((0 - Zero.X) / Zoom);
        Viewport.Y = (int)((0 - Zero.Y) / Zoom);
        Viewport.Width = (int)(Canvas.Width / Zoom);
        Viewport.Height = (int)(Canvas.Height / Zoom);

        Canvas.Refresh();
    }

    #endregion

    #region 控制是否绘制，用于优化性能

    /// <summary>
    /// 是否在区域中用于优化性能，这个涉及到性能优化
    /// </summary>
    /// <param name="element"></param>
    /// <returns></returns>
    public bool IsInZone(Element element)
    {
        return Viewport.IntersectsWith(element.Rect);
    }

    public bool IsInZone(Rectangle rect)
    {
        return Viewport.IntersectsWith(rect);
    }

    #endregion

    #region  本地坐标转世界坐标

    /// <summary>
    /// 本地（图纸）矩形变换到显示矩形
    /// </summary>
    public Rectangle LocalToShow(Rectangle rect)
    {
        //要清晰的确定本地和世界的关系
        var r = new Rectangle(rect.Location, rect.Size);

        //计算缩放坐标
        r.X = (int)(r.X * Zoom) + Zero.X;
        r.Y = (int)(r.Y * Zoom) + Zero.Y;

        //调整矩形大小
        r.Width = (int)Math.Round(rect.Width * Zoom, 0);
        r.Height = (int)Math.Round(rect.Height * Zoom, 0);

        return r;
    }

    public Point LocalToShow(Point point)
    {
        return new Point((int)(point.X * Zoom) + Zero.X, (int)(point.Y * Zoom) + Zero.Y);
    }

    public Rectangle LocalToShow(int x, int y, int width, int height)
    {
        return new Rectangle(
            (int)(x * Zoom) + Zero.X,
            (int)(y * Zoom) + Zero.Y,
            (int)Math.Round(width * Zoom, 0),
            (int)Math.Round(height * Zoom, 0)
         );
    }

    public int ToShowX(int x)
    {
        return (int)(x * Zoom) + Zero.X;
    }
    public int ToShowY(int y)
    {
        return (int)(y * Zoom) + Zero.Y;
    }

    /// <summary>
    /// 本地尺寸变换到显示的尺寸
    /// </summary>
    /// <param name="size"></param>
    /// <returns></returns>
    public Size LocalToShow(Size size)
    {
        return new Size((int)Math.Round(size.Width * Zoom, 0), (int)Math.Round(size.Height * Zoom, 0));
    }

    /// <summary>
    /// 鼠标坐标点变换到显示坐标点
    /// </summary>
    /// <param name="point"></param>
    /// <returns></returns>
    public Point MousePointToLocal(Point point)
    {
        return new Point((int)Math.Round((point.X - Zero.X) / Zoom, 0), (int)Math.Round((point.Y - Zero.Y) / Zoom, 0));
    }

    #endregion
}

}