aistudio-wpf-diagram/AIStudio.Wpf.DiagramDesigner/ViewModels/DrawingViewModel/Erasable/DrawingDesignerItemViewModelBase.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Media3D;
using System.Windows.Shapes;
using System.Windows.Controls;

namespace AIStudio.Wpf.DiagramDesigner
{
    public class DrawingDesignerItemViewModelBase : DesignerItemViewModelBase
    {
        public DrawingDesignerItemViewModelBase() : this(null)
        {

        }

        public DrawingDesignerItemViewModelBase(IDiagramViewModel root) : base(root)
        {

        }

        public DrawingDesignerItemViewModelBase(IDiagramViewModel root, DrawMode drawMode, Point startPoint, bool erasable) : this(root, drawMode, new List<Point> { startPoint }, erasable)
        {
          
        }

        public DrawingDesignerItemViewModelBase(IDiagramViewModel root, DrawMode drawMode, List<Point> points, bool erasable) : base(root)
        {
            DrawMode = drawMode;
            Points = points;
            Erasable = erasable;
        }

        public virtual bool OnMouseMove(IInputElement sender, MouseEventArgs e)
        {
            return true;
        }

        public virtual bool OnMouseDown(IInputElement sender, MouseButtonEventArgs e)
        {
            return true;
        }

        public virtual bool OnMouseUp(IInputElement sender, MouseButtonEventArgs e)
        {
            if (IsFinish)
            {
                UpdateLocation();

                Geometry.Transform = new TranslateTransform(0 - Left, 0 - Top);

                if (Erasable)
                {
                    var aPen = new Pen(ColorObject.ToBrush(ColorViewModel.LineColor), ColorViewModel.LineWidth);                   
                    Geometry = Geometry.GetWidenedPathGeometry(aPen); //可擦除，需要把Geometry转成几何图像，所以不能有填充色
                }
               
            }
            return true;
        }

        public virtual bool Erase(Geometry erase)
        {
            if (Erasable)
            {
                erase.Transform = new TranslateTransform(0 - Left, 0 - Top);
                Geometry = Geometry.Combine(Geometry, erase, GeometryCombineMode.Exclude, null);

                if (Geometry.IsEmpty())
                    return true;
            }
            else
            {
                //var area = erase.GetArea();
                //if (area > 10)
                //{
                    return true;
                //}
            }
            return false;
        }

        public bool Erasable
        {
            get;set;
        }

        private Geometry _geometry;
        public Geometry Geometry
        {
            get
            {
                return _geometry;
            }
            set
            {
                SetProperty(ref _geometry, value);
            }
        }

        public bool IsFinish
        {
            get; set;
        }

        private List<Point> _points;
        public List<Point> Points
        {
            get
            {
                return _points;
            }
            set
            {
                SetProperty(ref _points, value);
            }
        }
        public DrawMode DrawMode
        {
            get; set;
        }

        public void UpdateLocation()
        {
            ItemWidth = Geometry.Bounds.Width + ColorViewModel.LineWidth;
            ItemHeight = Geometry.Bounds.Height + ColorViewModel.LineWidth;
            Left = Geometry.Bounds.Left;
            Top = Geometry.Bounds.Top;
        }

        protected override void Init(IDiagramViewModel root, bool initNew)
        {
            base.Init(root, initNew);
            IsHitTestVisible = false;
        }

        protected override void InitNew()
        {
            ClearConnectors();
        }

    }
}