improve:端点吸附

避免点线和虚线吸附

Ink Canvas/MainWindow_cs/MW_SimulatePressure&InkToShape.cs

@@ -18,21 +18,19 @@ namespace Ink_Canvas
     {
         private StrokeCollection newStrokes = new StrokeCollection();
         private List<Circle> circles = new List<Circle>();
-        private const double LINE_STRAIGHTEN_THRESHOLD = 0.20; // 默认灵敏度阈值，与UI默认值对应
+        private const double LINE_STRAIGHTEN_THRESHOLD = 0.20;
 
-        // 矩形参考线系统
         private List<RectangleGuideLine> rectangleGuideLines = new List<RectangleGuideLine>();
-        private const double RECTANGLE_ENDPOINT_THRESHOLD = 30.0; // 端点相交判断阈值
-        private const double RECTANGLE_ANGLE_THRESHOLD = 15.0; // 角度判断阈值（度）
+        private const double RECTANGLE_ENDPOINT_THRESHOLD = 30.0;
+        private const double RECTANGLE_ANGLE_THRESHOLD = 15.0;
 
-        // 矩形参考线数据结构
         private class RectangleGuideLine
         {
             public Stroke OriginalStroke { get; set; }
             public Point StartPoint { get; set; }
             public Point EndPoint { get; set; }
             public DateTime CreatedTime { get; set; }
-            public double Angle { get; set; } // 直线角度（弧度）
+            public double Angle { get; set; }
             public bool IsHorizontal { get; set; }
             public bool IsVertical { get; set; }
 
@@ -64,7 +62,6 @@ namespace Ink_Canvas
                 var startPoint = e.Stroke.StylusPoints.Count > 0 ? e.Stroke.StylusPoints[0].ToPoint() : new Point();
                 var endPoint = e.Stroke.StylusPoints.Count > 0 ? e.Stroke.StylusPoints[e.Stroke.StylusPoints.Count - 1].ToPoint() : new Point();
 
-                // 确保InkCanvas保持Ink编辑模式，防止自动切换到鼠标模式
                 if (inkCanvas.EditingMode != InkCanvasEditingMode.Ink)
                 {
                     inkCanvas.EditingMode = InkCanvasEditingMode.Ink;
@@ -80,19 +77,15 @@ namespace Ink_Canvas
                     LogHelper.WriteLogToFile("StrokeCollected: 墨迹渐隐管理器为空，无法添加墨迹", LogHelper.LogType.Error);
                 }
 
-                // 延迟移除墨迹，避免立即移除导致模式切换
-                // 使用Dispatcher.BeginInvoke确保在UI线程上异步执行
                 Dispatcher.BeginInvoke(new Action(() =>
                 {
                     try
                     {
-                        // 再次确保InkCanvas保持Ink编辑模式
                         if (inkCanvas.EditingMode != InkCanvasEditingMode.Ink)
                         {
                             inkCanvas.EditingMode = InkCanvasEditingMode.Ink;
                         }
 
-                        // 从InkCanvas中移除墨迹，因为我们要用渐隐管理器来管理它
                         if (inkCanvas.Strokes.Contains(e.Stroke))
                         {
                             inkCanvas.Strokes.Remove(e.Stroke);
@@ -104,21 +97,18 @@ namespace Ink_Canvas
                     }
                 }), DispatcherPriority.Background);
 
-                // 墨迹渐隐模式下不参与墨迹纠正和其他处理，直接返回
                 return;
             }
 
             // 标记是否进行了直线拉直
             bool wasStraightened = false;
 
-            // 禁用原有的FitToCurve，使用新的高级贝塞尔曲线平滑
             if (Settings.Canvas.FitToCurve) drawingAttributes.FitToCurve = false;
 
             try
             {
                 inkCanvas.Opacity = 1;
 
-                // 应用屏蔽压感功能 - 如果启用，所有笔画都使用统一粗细
                 if (Settings.Canvas.DisablePressure)
                 {
                     var uniformPoints = new StylusPointCollection();
@@ -129,13 +119,11 @@ namespace Ink_Canvas
                     }
                     e.Stroke.StylusPoints = uniformPoints;
                 }
-                // 应用压感触屏模式 - 如果启用并且检测到触屏输入
                 else if (Settings.Canvas.EnablePressureTouchMode)
                 {
                     bool isTouchInput = true;
                     foreach (StylusPoint point in e.Stroke.StylusPoints)
                     {
-                        // 检测是否为压感笔输入（压感笔的PressureFactor不等于0.5或0）
                         if ((point.PressureFactor > 0.501 || point.PressureFactor < 0.5) && point.PressureFactor != 0)
                         {
                             isTouchInput = false;
@@ -143,7 +131,6 @@ namespace Ink_Canvas
                         }
                     }
 
-                    // 如果是触屏输入，则应用模拟压感
                     if (isTouchInput)
                     {
                         switch (Settings.Canvas.InkStyle)
@@ -1551,11 +1538,66 @@ namespace Ink_Canvas
             return distance;
         }
 
+        /// <summary>
+        /// 判断一个 stroke 是否是直线（排除虚线和点线）
+        /// </summary>
+        /// <param name="stroke">要检查的 stroke</param>
+        /// <returns>如果是直线返回 true，否则返回 false</returns>
+        private bool IsStraightLine(Stroke stroke)
+        {
+            if (stroke == null || stroke.StylusPoints.Count == 0)
+                return false;
+
+            int pointCount = stroke.StylusPoints.Count;
+
+            if (pointCount == 1)
+                return false;
+
+            // 最简单的直线：只有2个点
+            if (pointCount == 2)
+            {
+                Point p1 = stroke.StylusPoints[0].ToPoint();
+                Point p2 = stroke.StylusPoints[1].ToPoint();
+                double lineLength = GetDistance(p1, p2);
+                
+                if (lineLength < 10)
+                    return false;
+
+                return true;
+            }
+
+            if (pointCount > 3)
+                return false;
+
+            // 对于3个点的情况，检查它们是否基本在一条直线上
+            if (pointCount == 3)
+            {
+                Point p1 = stroke.StylusPoints[0].ToPoint();
+                Point p2 = stroke.StylusPoints[1].ToPoint();
+                Point p3 = stroke.StylusPoints[2].ToPoint();
+
+                double totalLength = GetDistance(p1, p3);
+                if (totalLength < 10)
+                    return false;
+
+                // 计算点到直线的距离
+                // 使用 p1 和 p3 作为直线端点，检查 p2 是否在这条直线上
+                double distance = DistanceFromLineToPoint(p1, p3, p2);
+
+                // 如果点到直线的距离相对于线段长度很小，认为是直线
+                // 使用相对误差阈值（比如 1%）
+                if (totalLength > 0 && distance / totalLength < 0.01)
+                    return true;
+
+                return false;
+            }
+
+            return false;
+        }
+
         // New method: Attempts to snap endpoints to existing stroke endpoints
         private Point[] GetSnappedEndpoints(Point start, Point end)
         {
-            // 如果端点吸附功能关闭，直接返回null
-            // 这里不再返回原始点，因为调用此方法的地方会判断返回值是否为null
             if (!Settings.Canvas.LineEndpointSnapping)
                 return null;
 
@@ -1572,6 +1614,10 @@ namespace Ink_Canvas
             {
                 if (stroke.StylusPoints.Count == 0) continue;
 
+                // 只对直线进行端点吸附，跳过虚线和点线
+                if (!IsStraightLine(stroke))
+                    continue;
+
                 // Get stroke endpoints
                 Point strokeStart = stroke.StylusPoints.First().ToPoint();
                 Point strokeEnd = stroke.StylusPoints.Last().ToPoint();