107 lines
		
	
	
		
			4.8 KiB
		
	
	
	
		
			C#
		
	
	
	
	
	
			
		
		
	
	
			107 lines
		
	
	
		
			4.8 KiB
		
	
	
	
		
			C#
		
	
	
	
	
	
using System;
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using System.Collections.Generic;
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using System.Linq;
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using System.Runtime.CompilerServices;
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using System.Text;
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using System.Threading.Tasks;
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using System.Windows;
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using System.Windows.Controls;
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using System.Windows.Documents;
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using System.Windows.Media;
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namespace Future.Contract
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{
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    /// <summary>
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    /// 拖动辅助装饰器
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    /// </summary>
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    public class DragDropAdorner : Adorner
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    {
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        #region   静态变量区
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        private static DragDropAdorner sAdorner;            //装饰器:拖放过程中所有效果绘制使用的装饰器对象,结束后会释放
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        private static AdornerLayer sLayer;                 //装饰层:用于放置拖放效果装饰器,拖放过程结束后会清除对象引用
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        private static UIElement sOrigin;                   //拖起目标:被拖动的源对象
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        private static UIElement sTarget;                   //放置目标:在拖动过程中用于放置拖动源的目标,随拖动过程而变化
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        private static Canvas sCanvas;                      //拖放画布:整个拖放过程的完整区域,是拖起目标与放置目标的祖辈
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        private static Border sShadow;                      //鼠标拖起阴影:用于将托起目标尺寸按照相同缩放比缩放后变成阴影
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        private static Canvas sEffect;                      //鼠标拖动效果:用于提示放置的参考点位置,左、上、右、下,中。
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        private static Dock sPosition;                      //参考放置位置:为放置目标的位置提供参考,左、上、右、下,中。
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        /// <summary>
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        /// 放置的参考点
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        /// </summary>
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        public static Dock DropPosition { get => sPosition; }
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        #endregion
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        #region   静态方法区
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        /// <summary>
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        /// 设定完整拖放效果区域以及被拖动的对象,或是等效对象来起动拖放事件
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        /// </summary>
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        /// <param name="area">完整的拖放区域,必须是拖起目标与放置目标的共同祖先节点</param>
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        /// <param name="origin">被拖动的可视化目标,或是其等效目标</param>
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        /// <returns></returns>
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        public static DragDropEffects DoDragDrop(UIElement area, UIElement dragSource, object data, DragDropEffects allowedEffects)
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        {
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            DragDropEffects dragDropEffects = allowedEffects;
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            //TODO:准备拖放,生成阴影,监听拖动执行区域中的拖动事件
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            dragDropEffects = DragDrop.DoDragDrop(dragSource, data, dragDropEffects);
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            //TODO:拖拽操作完成,释放装饰器以及过程中使用的所有资源
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            sLayer.Remove(sAdorner);
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            return dragDropEffects;
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        }
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        private static void OnDragEnter(UIElement target, DragEventArgs args)
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        {
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            sTarget= target;
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            target.MouseMove += Target_MouseMove;
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            //TODO:更换目标对象,监听目标对象的鼠标事件,规制“阴影”与“效果”
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        }
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        private static void Target_MouseMove(object sender, System.Windows.Input.MouseEventArgs e)
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        {
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            //TODO:计算鼠标位置,移动效果与阴影
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        }
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        //public static void OnDragOver(UIElement target, DragEventArgs args)
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        //{
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        //    //TODO:计算鼠标位置,移动效果与阴影
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        //}
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        public static void OnDragLeave(UIElement target, DragEventArgs args)
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        { 
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            //TODO:清除目标对象,清除对鼠标事件的监听,清除“阴影”与“效果”
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            target.MouseMove -= Target_MouseMove;
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        }
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        public static void DropCompleted(UIElement target, DragEventArgs args)
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        {
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            //TODO:清除静态存储区中所使用过的数据,清除装饰器
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        }
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        #endregion
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        private readonly VisualCollection mVisuals;
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        private DragDropAdorner(UIElement adornedElement) : base(adornedElement)
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        {
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            mVisuals = new VisualCollection(this);
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            sCanvas = new Canvas
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            {
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                Background=Brushes.Transparent
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            };
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            mVisuals.Add(sCanvas);
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            sLayer = AdornerLayer.GetAdornerLayer(adornedElement);
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            sLayer?.Add(this);
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        }
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        protected override int VisualChildrenCount => mVisuals.Count;
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        protected override Visual GetVisualChild(int index) => mVisuals[index];
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        protected override Size ArrangeOverride(Size finalSize)
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        {
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            //var bubbleSize = _bubble.DesiredSize;
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            //var location = new Point(finalSize.Width + 10, (finalSize.Height - bubbleSize.Height) / 2);
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            //_bubble.Arrange(new Rect(location, DesiredSize));
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            sCanvas.Arrange(new Rect(new Point(), finalSize));
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            return finalSize;
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        }
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    }
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}
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