kev/Drawer/Module/GeoSigmaViewer/DrawToolChord.cs

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

namespace GeoSigmaViewer
{
    public class DrawToolChord : DrawTool
    {
        private MouseMoveResult mmResult;
        private int clockCount;
        public DrawToolChord()
        {
            ToolCursor = DrawCursors.Range;
            ItemType = DrawItemType.ITEM_ARC;
            clockCount = 0;
            mmResult = new MouseMoveResult();
        }

        public override void Start() 
        {
            drawer.Cursor = DrawCursors.Range;
            drawer.Geo.Arc_SetType(1);
        }

        public override void End()
        {
            drawer.Cursor = DrawCursors.Select;
        }

        public override void OnLButtonDown(Drawer drawArea, MouseEventArgs e)
        {
            clockCount++;
            clockCount = clockCount % 3;
            drawArea.Geo.OnLButtonDown(e.X, e.Y);
        }

        public override void OnMouseMove(Drawer drawArea, MouseEventArgs e)
        {  
            if (clockCount != 0)
            {
                Graphics g = drawArea.CreateGraphics();
                drawArea.Geo.ItemMouseMove(g.GetHdc(), e.X, e.Y, ref mmResult);
            }
        }

        public override void OnLButtonUp(Drawer drawArea, MouseEventArgs e)
        {
            drawArea.Geo.OnLButtonUp(e.X, e.Y);
            drawArea.Geo.EnableRedraw(true);
            drawArea.ReDraw();
        }
    }
}