NGUI 源码分析- UIWidgetInspector

NGUI Version 3.9.0

//----------------------------------------------
//            NGUI: Next-Gen UI kit
// Copyright © 2011-2015 Tasharen Entertainment
//----------------------------------------------

using UnityEngine;
using UnityEditor;
using System.Collections.Generic;

/// <summary>
/// Inspector class used to edit UIWidgets.
/// </summary>

[CanEditMultipleObjects]
[CustomEditor(typeof(UIWidget), true)]
public class UIWidgetInspector : UIRectEditor
{
	static public new UIWidgetInspector instance; // 

	public enum Action // YUTODO这个什么作用？
	{
		None,
		Move, // 移动
		Scale,// 缩放
		Rotate,
	}

	Action mAction = Action.None;
	Action mActionUnderMouse = Action.None;
	bool mAllowSelection = true;

	protected UIWidget mWidget; // 保存一个widget

	static protected bool mUseShader = false;// 默认不使用shader

    // GUIStyle 是什么鬼？
    // 各种颜色的点
	static GUIStyle mBlueDot = null; //  蓝点？
	static GUIStyle mYellowDot = null;
	static GUIStyle mRedDot = null;
	static GUIStyle mOrangeDot = null;
	static GUIStyle mGreenDot = null;
	static GUIStyle mGreyDot = null;
	static MouseCursor mCursor = MouseCursor.Arrow; // 还能控制鼠标光标？666

    // 枢轴点
	static public UIWidget.Pivot[] pivotPoints =
	{
		UIWidget.Pivot.BottomLeft,
		UIWidget.Pivot.TopLeft,
		UIWidget.Pivot.TopRight,
		UIWidget.Pivot.BottomRight,
		UIWidget.Pivot.Left,
		UIWidget.Pivot.Top,
		UIWidget.Pivot.Right,
		UIWidget.Pivot.Bottom,
	};

    //
	static int s_Hash = "WidgetHash".GetHashCode();

    // 坐标
	Vector3 mLocalPos = Vector3.zero;
	Vector3 mWorldPos = Vector3.zero;

    // 起始宽高
	int mStartWidth = 0;
	int mStartHeight = 0;

    // 起始拖动和鼠标？
	Vector3 mStartDrag = Vector3.zero;
	Vector2 mStartMouse = Vector2.zero;

    // 起始方向和旋转角度
	Vector3 mStartRot = Vector3.zero;
	Vector3 mStartDir = Vector3.right;

    // 起始的上下左右？
	Vector2 mStartLeft = Vector2.zero;
	Vector2 mStartRight = Vector2.zero;
	Vector2 mStartBottom = Vector2.zero;
	Vector2 mStartTop = Vector2.zero;

    // 拖动枢轴点 默认为中心
	UIWidget.Pivot mDragPivot = UIWidget.Pivot.Center;

    /// <summary>
    /// Raycast into the screen.
    /// 判断当前鼠标是否射中传入的平面
    /// </summary>
    /// <param name="corners">传入待检测平面的三个点</param>
    /// <param name="hit">射到的点的坐标</param>
    /// <returns>射到返回true</returns>
	static public bool Raycast (Vector3[] corners, out Vector3 hit)
	{
		Plane plane = new Plane(corners[0], corners[1], corners[2]); // 三点确定一个平面
        Ray ray = HandleUtility.GUIPointToWorldRay(Event.current.mousePosition); // 转换2D GUI位置到世界空间的ray
		float dist = 0f;
		bool isHit = plane.Raycast(ray, out dist); // 检查射线有没有射中平面
		hit = isHit ? ray.GetPoint(dist) : Vector3.zero; // GetPoint 返回离射线距离为 dist 的那个点的位置。
		return isHit;
	}

	/// <summary>
	/// Color used by the handles based on the current color scheme.
	/// 根据当前颜色主题返回颜色
	/// </summary>

	static public Color handlesColor
	{
		get
		{
			if (NGUISettings.colorMode == NGUISettings.ColorMode.Orange)
			{
				return new Color(1f, 0.5f, 0f);
			}
			else if (NGUISettings.colorMode == NGUISettings.ColorMode.Green)
			{
				return Color.green;
			}
			return Color.white;
		}
	}

	/// <summary>
	/// Draw a control dot at the specified world position.
	/// 在世界坐标绘制控制点
	/// </summary>

	static public void DrawKnob (Vector3 point, bool selected, bool canResize, int id)
	{
        // TODO 这是一种什么赋值方法？
		if (mGreyDot == null) mGreyDot = "sv_label_0"; // 一种内置的编辑器风格
		if (mBlueDot == null) mBlueDot = "sv_label_1";
		if (mGreenDot == null) mGreenDot = "sv_label_3";
		if (mYellowDot == null) mYellowDot = "sv_label_4";
		if (mOrangeDot == null) mOrangeDot = "sv_label_5";
		if (mRedDot == null) mRedDot = "sv_label_6";

        //
		Vector2 screenPoint = HandleUtility.WorldToGUIPoint(point);

        // 矩阵
#if UNITY_4_3 || UNITY_4_5 || UNITY_4_6
		Rect rect = new Rect(screenPoint.x - 7f, screenPoint.y - 7f, 14f, 14f);
#else
		Rect rect = new Rect(screenPoint.x - 5f, screenPoint.y - 9f, 14f, 14f);
#endif

        // 根据传入的状态判断显示的颜色
		if (selected)
		{
			if (NGUISettings.colorMode == NGUISettings.ColorMode.Orange)
			{
				mRedDot.Draw(rect, GUIContent.none, id);
			}
			else
			{
				mOrangeDot.Draw(rect, GUIContent.none, id);
			}
		}
		else if (canResize)
		{
			if (NGUISettings.colorMode == NGUISettings.ColorMode.Orange)
			{
				mOrangeDot.Draw(rect, GUIContent.none, id);
			}
			else if (NGUISettings.colorMode == NGUISettings.ColorMode.Green)
			{
				mGreenDot.Draw(rect, GUIContent.none, id);
			}
			else
			{
				mBlueDot.Draw(rect, GUIContent.none, id);
			}
		}
		else mGreyDot.Draw(rect, GUIContent.none, id); //
	}

	/// <summary>
	/// Screen-space distance from the mouse position to the specified world position.
	/// 屏幕空间下 鼠标到某点的距离
	/// </summary>

	static public float GetScreenDistance (Vector3 worldPos, Vector2 mousePos)
	{
		Vector2 screenPos = HandleUtility.WorldToGUIPoint(worldPos);
		return Vector2.Distance(mousePos, screenPos);
	}

	/// <summary>
	/// Closest screen-space distance from the mouse position to one of the specified world points.
	/// 屏幕空间下 在鼠标到各点的距离中取最小距离
	/// </summary>

	static public float GetScreenDistance (Vector3[] worldPoints, Vector2 mousePos, out int index)
	{
		float min = float.MaxValue;
		index = 0;

		for (int i = 0; i < worldPoints.Length; ++i)
		{
			float distance = GetScreenDistance(worldPoints[i], mousePos);

			if (distance < min)
			{
				index = i;
				min = distance;
			}
		}
		return min;
	}

	/// <summary>
	/// Set the mouse cursor rectangle, refreshing the screen when it gets changed.
	/// 鼠标光标类型发生改变时重新设置它的矩形区域
	/// </summary>

	static public void SetCursorRect (Rect rect, MouseCursor cursor)
	{
		EditorGUIUtility.AddCursorRect(rect, cursor);

		if (Event.current.type == EventType.MouseMove)
		{
			if (mCursor != cursor)
			{
				mCursor = cursor;
				Event.current.Use();
			}
		}
	}

    /// <summary>
    ///
    /// </summary>
	protected override void OnDisable ()
	{
		base.OnDisable();
		NGUIEditorTools.HideMoveTool(false);
		instance = null;
	}

	/// <summary>
	/// Convert the specified 4 corners into 8 pivot points (adding left, top, right, bottom -- in that order).
	/// 把四个角落的坐标数组扩展为八个点的坐标数组
	/// </summary>

	static public Vector3[] GetHandles (Vector3[] corners)
	{
		Vector3[] v = new Vector3[8];

		v[0] = corners[0];
		v[1] = corners[1];
		v[2] = corners[2];
		v[3] = corners[3];

		v[4] = (corners[0] + corners[1]) * 0.5f;
		v[5] = (corners[1] + corners[2]) * 0.5f;
		v[6] = (corners[2] + corners[3]) * 0.5f;
		v[7] = (corners[0] + corners[3]) * 0.5f;

		return v;
	}

	/// <summary>
	/// Determine what kind of pivot point is under the mouse and update the cursor accordingly.
	/// 通过鼠标的位置判断应当进行什么样的操作。
	/// 默认返回 center 锚点，能够缩放时返回 目标锚点
	/// </summary>

	static public UIWidget.Pivot GetPivotUnderMouse (Vector3[] worldPos, Event e, bool[] resizable, bool movable, ref Action action)
	{
		// Time to figure out what kind of action is underneath the mouse
		UIWidget.Pivot pivotUnderMouse = UIWidget.Pivot.Center;// 初始化为 锚点中心

        //
		if (action == Action.None)
		{
			int index = 0;
			float dist = GetScreenDistance(worldPos, e.mousePosition, out index); // 获取最小的距离，并记录最小距离对应点的下标
			bool alt = (e.modifiers & EventModifiers.Alt) != 0; // 判断是不是按了组合键

            //
			if (resizable[index] && dist < 10f) // 如果这个位置能动，并且距离小于10f
			{
				pivotUnderMouse = pivotPoints[index]; //鼠标点到的枢轴点是index标示出的index
				action = Action.Scale;// 进行缩放动作
			}
			else if (!alt && NGUIEditorTools.SceneViewDistanceToRectangle(worldPos, e.mousePosition) == 0f) // 没有按组合键并且鼠标点在矩形框里面
			{
				action = movable ? Action.Move : Action.Rotate; // 能移动仅进行移动，不能移动就进行旋转
			}
			else if (dist < 30f)
			{
				action = Action.Rotate; // 其他情况就进行旋转
			}
		}

		// Change the mouse cursor to a more appropriate one
        //
		Vector2[] screenPos = new Vector2[8];
		for (int i = 0; i < 8; ++i) screenPos[i] = HandleUtility.WorldToGUIPoint(worldPos[i]);

		Bounds b = new Bounds(screenPos[0], Vector3.zero); // 给定中心点和大小。，后面那个大小代表（width,height,depth）
		for (int i = 1; i < 8; ++i) b.Encapsulate(screenPos[i]);// 包含八个点的最小矩形框，在这里八个点都恰好在矩形框的边上。

        Vector2 min = b.min;// min = center - extents; extents 是 size 的一半。例如中心点为（0，0，0），extents（2，3，5），那么min（-2，-3，-5）
		Vector2 max = b.max;

        // 在原来的基础上扩展 30f。depth 没用到所以这里没处理
		min.x -= 30f;
		max.x += 30f;
		min.y -= 30f;
		max.y += 30f;

		Rect rect = new Rect(min.x, min.y, max.x - min.x, max.y - min.y); // 获取矩形框

        // 根据动作的状态 显示鼠标光标的形状
		if (action == Action.Rotate)
		{
			SetCursorRect(rect, MouseCursor.RotateArrow);
		}
		else if (action == Action.Move)
		{
			SetCursorRect(rect, MouseCursor.MoveArrow);
		}
		else if (action == Action.Scale)
		{
			SetCursorRect(rect, MouseCursor.ScaleArrow);
		}
		else SetCursorRect(rect, MouseCursor.Arrow);

		return pivotUnderMouse;
	}

	/// <summary>
	/// Draw the specified anchor point.
	/// 绘制黄色的锚点以及连接线、距离标签
	/// </summary>

	static public void DrawAnchorHandle (UIRect.AnchorPoint anchor, Transform myTrans, Vector3[] myCorners, int side, int id)
	{
		if (!anchor.target) return; // 没有定锚点就不用画了

		int i0, i1;

        //矩形四个点在数组中的序列与相对位置的关系如下
        //12
        //03

        //根据是哪边的锚点来选出决定那条边的两个顶点
		if (side == 0)
		{
			// Left
			i0 = 0;
			i1 = 1;
		}
		else if (side == 1)
		{
			// Top
			i0 = 1;
			i1 = 2;
		}
		else if (side == 2)
		{
			// Right
			i0 = 3;
			i1 = 2;
		}
		else
		{
			// Bottom
			i0 = 0;
			i1 = 3;
		}

        //
		Vector3 myPos = (myCorners[i0] + myCorners[i1]) * 0.5f; // 锚点相关位置是对应边的中点

		Vector3[] sides = null; // 目标对象矩形的四个节点

		if (anchor.rect != null)
		{
			sides = anchor.rect.worldCorners;
		}
		else
		{
#if UNITY_4_3 || UNITY_4_5 || UNITY_4_6
			Camera cam = anchor.target.camera; // 获取锚点目标的 camera
#else
			Camera cam = anchor.target.GetComponent<Camera>();
#endif
			if (cam != null) sides = cam.GetWorldCorners(); // 获取相机的边界
		}

		Vector3 theirPos; // 黄点位置，必然在目标矩形上面

		if (sides != null)
		{
			Vector3 v0, v1;

			if (side == 0 || side == 2)
			{
				// Left or right
				v0 = Vector3.Lerp(sides[0], sides[3], anchor.relative); // 在两个向量V0、V1间做线性插值，根据第三个参数t决定返回某个插值。例如 t=0 返回V0，t=0.5 返回V0、V1的中间插值。
				v1 = Vector3.Lerp(sides[1], sides[2], anchor.relative); //
			}
			else
			{
				// Top or bottom
				v0 = Vector3.Lerp(sides[0], sides[1], anchor.relative);
				v1 = Vector3.Lerp(sides[3], sides[2], anchor.relative);
			}

            // 黄点是 myPos 在 v0 和 v1 连接线上的投影点，如果超过v0v1线段，则黄点设置为v0或v1。
			theirPos = HandleUtility.ProjectPointLine(myPos, v0, v1);
		}
		else
		{
			theirPos = anchor.target.position;
		}

        // 画连接线
		NGUIHandles.DrawShadowedLine(myCorners, myPos, theirPos, Color.yellow);

        // 位置偏离的时候在一定条件下绘制一个标记负值距离的标签
		if (Event.current.GetTypeForControl(id) == EventType.Repaint) // 控制ID id 当前事件类型如果是重绘
		{
			Vector2 screenPoint = HandleUtility.WorldToGUIPoint(theirPos);

#if UNITY_4_3 || UNITY_4_5 || UNITY_4_6
			Rect rect = new Rect(screenPoint.x - 7f, screenPoint.y - 7f, 14f, 14f);
#else
			Rect rect = new Rect(screenPoint.x - 5f, screenPoint.y - 9f, 14f, 14f);
#endif
			if (mYellowDot == null) mYellowDot = "sv_label_4";

			Vector3 v0 = HandleUtility.WorldToGUIPoint(myPos);
			Vector3 v1 = HandleUtility.WorldToGUIPoint(theirPos);

			Handles.BeginGUI(); // 开始一个 2D 绘制块

			mYellowDot.Draw(rect, GUIContent.none, id); // 绘制黄点

			Vector3 diff = v1 - v0;
			bool isHorizontal = Mathf.Abs(diff.x) > Mathf.Abs(diff.y);// 判断是否为水平线
			float mag = diff.magnitude; // 获取线的长度

			if ((isHorizontal && mag > 60f) || (!isHorizontal && mag > 30f)) // 长度超过 60 的水平线或者长度大于 30 的竖直线
			{
				Vector3 pos = (myPos + theirPos) * 0.5f; //
				string text = anchor.absolute.ToString();// 

				GUI.color = Color.yellow;

				if (side == 0)
				{
                    if (theirPos.x < myPos.x) //如果目标点的位置比出发点的位置还要靠左，那么显示一个标记距离的label
						NGUIHandles.DrawCenteredLabel(pos, text);
				}
				else if (side == 1)
				{
					if (theirPos.y > myPos.y)
						NGUIHandles.DrawCenteredLabel(pos, text);
				}
				else if (side == 2)
				{
					if (theirPos.x > myPos.x)
						NGUIHandles.DrawCenteredLabel(pos, text);
				}
				else if (side == 3)
				{
					if (theirPos.y < myPos.y)
						NGUIHandles.DrawCenteredLabel(pos, text);
				}
				GUI.color = Color.white;
			}
			Handles.EndGUI();
		}
	}

	/// <summary>
	/// Draw the on-screen selection, knobs, and handle all interaction logic.
	///
	/// </summary>

	public void OnSceneGUI ()
	{
		if (Selection.objects.Length > 1) return;  // 选中了多个对象，返回
		NGUIEditorTools.HideMoveTool(true); // 隐藏移动工具
		if (!UIWidget.showHandles) return; // 没有需要显示的 handles，返回

		mWidget = target as UIWidget; // 把选中对象作为一个 UIWidget 组件处理

		Transform t = mWidget.cachedTransform; // 获取对象的 transform

		Event e = Event.current;               //
		int id = GUIUtility.GetControlID(s_Hash, FocusType.Passive); // 获取一个控制ID，这个控制不能获取键盘焦点
		EventType type = e.GetTypeForControl(id); // 获取控制ID的事件类型

		Action actionUnderMouse = mAction; // 移动、缩放或是旋转
		Vector3[] handles = GetHandles(mWidget.worldCorners); // 获取组件的八个枢轴点点

        // 绘制矩形框
		NGUIHandles.DrawShadowedLine(handles, handles[0], handles[1], handlesColor);
		NGUIHandles.DrawShadowedLine(handles, handles[1], handles[2], handlesColor);
		NGUIHandles.DrawShadowedLine(handles, handles[2], handles[3], handlesColor);
		NGUIHandles.DrawShadowedLine(handles, handles[0], handles[3], handlesColor);

		// If the widget is anchored, draw the anchors
        // 组件有锚点的话就绘制锚点
		if (mWidget.isAnchored)
		{
			DrawAnchorHandle(mWidget.leftAnchor, mWidget.cachedTransform, handles, 0, id);
			DrawAnchorHandle(mWidget.topAnchor, mWidget.cachedTransform, handles, 1, id);
			DrawAnchorHandle(mWidget.rightAnchor, mWidget.cachedTransform, handles, 2, id);
			DrawAnchorHandle(mWidget.bottomAnchor, mWidget.cachedTransform, handles, 3, id);
		}

        // 需要时显示细节
		if (type == EventType.Repaint)
		{
			bool showDetails = (mAction == UIWidgetInspector.Action.Scale) || NGUISettings.drawGuides; // 进行缩放时显示细节
			if (mAction == UIWidgetInspector.Action.None && e.modifiers == EventModifiers.Control) showDetails = true;
			if (NGUITools.GetActive(mWidget) && mWidget.parent == null) showDetails = true;
			if (showDetails) NGUIHandles.DrawSize(handles, mWidget.width, mWidget.height);
		}

		// Presence of the legacy stretch component prevents resizing
        // TODO 显示原来的轨迹组件放置重绘 ？？

		bool canResize = (mWidget.GetComponent<UIStretch>() == null); // 没有这个组件说明是可以自由缩放的
		bool[] resizable = new bool[8]; // 

		resizable[4] = canResize;	// left
		resizable[5] = canResize;	// top
		resizable[6] = canResize;	// right
		resizable[7] = canResize;	// bottom

		UILabel lbl = mWidget as UILabel; // 如果这个 widget 组件实际上是个一个 Label 组件

		if (lbl != null)
		{
			if (lbl.overflowMethod == UILabel.Overflow.ResizeFreely) // 如果 label 设置为可以随意缩放，那么其锚点都定住
			{
				resizable[4] = false;	// left
				resizable[5] = false;	// top
				resizable[6] = false;	// right
				resizable[7] = false;	// bottom
			}
			else if (lbl.overflowMethod == UILabel.Overflow.ResizeHeight) // 如果是高度可以自由缩放，那么上下两个锚点也定住
			{
				resizable[5] = false;	// top
				resizable[7] = false;	// bottom
			}
		}

		if (mWidget.keepAspectRatio == UIWidget.AspectRatioSource.BasedOnHeight) // 基于高度变换，那么左右锚点就不需要设置了
		{
			resizable[4] = false;
			resizable[6] = false;
		}
		else if (mWidget.keepAspectRatio == UIWidget.AspectRatioSource.BasedOnWidth)
		{
			resizable[5] = false;
			resizable[7] = false;
		}

        // 角落的锚点情况根据上下左右的可用情况设置
		resizable[0] = resizable[7] && resizable[4]; // bottom-left
		resizable[1] = resizable[5] && resizable[4]; // top-left
		resizable[2] = resizable[5] && resizable[6]; // top-right
		resizable[3] = resizable[7] && resizable[6]; // bottom-right

        // 获取锚点，没有的话返回 center
		UIWidget.Pivot pivotUnderMouse = GetPivotUnderMouse(handles, e, resizable, true, ref actionUnderMouse);

		switch (type)
		{
			case EventType.Repaint: // 绘制控制点
			{
				Vector3 v0 = HandleUtility.WorldToGUIPoint(handles[0]);
				Vector3 v2 = HandleUtility.WorldToGUIPoint(handles[2]);

				if ((v2 - v0).magnitude > 60f) // 斜边 长度大于 60 才绘制控制点
				{
					Vector3 v1 = HandleUtility.WorldToGUIPoint(handles[1]);
					Vector3 v3 = HandleUtility.WorldToGUIPoint(handles[3]);

                    Handles.BeginGUI();
					{
						for (int i = 0; i < 4; ++i)
							DrawKnob(handles[i], mWidget.pivot == pivotPoints[i], resizable[i], id);

						if ((v1 - v0).magnitude > 80f)
						{
							if (mWidget.leftAnchor.target == null || mWidget.leftAnchor.absolute != 0)
								DrawKnob(handles[4], mWidget.pivot == pivotPoints[4], resizable[4], id);

							if (mWidget.rightAnchor.target == null || mWidget.rightAnchor.absolute != 0)
								DrawKnob(handles[6], mWidget.pivot == pivotPoints[6], resizable[6], id);
						}

						if ((v3 - v0).magnitude > 80f)
						{
							if (mWidget.topAnchor.target == null || mWidget.topAnchor.absolute != 0)
								DrawKnob(handles[5], mWidget.pivot == pivotPoints[5], resizable[5], id);

							if (mWidget.bottomAnchor.target == null || mWidget.bottomAnchor.absolute != 0)
								DrawKnob(handles[7], mWidget.pivot == pivotPoints[7], resizable[7], id);
						}
					}
					Handles.EndGUI();
				}
			}
			break;

			case EventType.MouseDown:
			{
				if (actionUnderMouse != Action.None)
				{
					mStartMouse = e.mousePosition; // 记录鼠标起始位置
					mAllowSelection = true; // 标记拖动的开始，拖动过程中无法再次选中

					if (e.button == 1) //
					{
						if (e.modifiers == 0) // 没有用组合键
						{
							GUIUtility.hotControl = GUIUtility.keyboardControl = id;
							e.Use(); // 使用该事件，用于表示这个事件已经处理过了
						}
					}
					else if (e.button == 0 && actionUnderMouse != Action.None && Raycast(handles, out mStartDrag)) // 鼠标左键&&能够操作&&点到了这个平面 // TODO 不知道为什么需要这么多判断
					{
						mWorldPos = t.position;
						mLocalPos = t.localPosition;
						mStartRot = t.localRotation.eulerAngles;
						mStartDir = mStartDrag - t.position; // 用向量来表示角度，鼠标与中点连线的夹角
						mStartWidth = mWidget.width;
						mStartHeight = mWidget.height;
                        // TODO 上下左右，
						mStartLeft.x = mWidget.leftAnchor.relative;
						mStartLeft.y = mWidget.leftAnchor.absolute;
						mStartRight.x = mWidget.rightAnchor.relative;
						mStartRight.y = mWidget.rightAnchor.absolute;
						mStartBottom.x = mWidget.bottomAnchor.relative;
						mStartBottom.y = mWidget.bottomAnchor.absolute;
						mStartTop.x = mWidget.topAnchor.relative;
						mStartTop.y = mWidget.topAnchor.absolute;

                        //
						mDragPivot = pivotUnderMouse;
						mActionUnderMouse = actionUnderMouse;
                        //
						GUIUtility.hotControl = GUIUtility.keyboardControl = id;
						e.Use();
					}
				}
			}
			break;

			case EventType.MouseDrag:
			{
				// Prevent selection once the drag operation begins
                // 如果已经进行了拖动操作，那么无法再进行选中了
				bool dragStarted = (e.mousePosition - mStartMouse).magnitude > 3f;
				if (dragStarted) mAllowSelection = false;

				if (GUIUtility.hotControl == id) // 如果热键控制 与 id 一致
				{
					e.Use(); // TODO 这个为什么设置在前面？

					if (mAction != Action.None || mActionUnderMouse != Action.None) //
					{
						Vector3 pos;

						if (Raycast(handles, out pos))
						{
                            // 拖动开始时进行数据记录
							if (mAction == Action.None && mActionUnderMouse != Action.None) // 前面的 mAction 用于标记是否是拖动刚开始
							{
								// Wait until the mouse moves by more than a few pixels
								if (dragStarted)
								{
									if (mActionUnderMouse == Action.Move) //
									{
										NGUISnap.Recalculate(mWidget); // 重新计算
									}
									else if (mActionUnderMouse == Action.Rotate) //
									{
										mStartRot = t.localRotation.eulerAngles; // 返回欧垃角
										mStartDir = mStartDrag - t.position; // 旋转的角度
									}
									else if (mActionUnderMouse == Action.Scale)
									{
										mStartWidth = mWidget.width;
										mStartHeight = mWidget.height;
										mDragPivot = pivotUnderMouse;
									}
									mAction = actionUnderMouse;
								}
							}

                            //
							if (mAction != Action.None)
							{
                                // 设置撤销点
								NGUIEditorTools.RegisterUndo("Change Rect", t);
								NGUIEditorTools.RegisterUndo("Change Rect", mWidget);

								// Reset the widget before adjusting anything
                                // 在进行任何调整前先进行重置
								t.position = mWorldPos;
								mWidget.width = mStartWidth;
								mWidget.height = mStartHeight;
                                // widget 的上下左右锚点都重置为初始值
								mWidget.leftAnchor.Set(mStartLeft.x, mStartLeft.y);
								mWidget.rightAnchor.Set(mStartRight.x, mStartRight.y);
								mWidget.bottomAnchor.Set(mStartBottom.x, mStartBottom.y);
								mWidget.topAnchor.Set(mStartTop.x, mStartTop.y);

                                // 移动操作
								if (mAction == Action.Move)
								{
									// Move the widget
                                    t.position = mWorldPos + (pos - mStartDrag); // t.position = t.positon + (pos - mStartDrag);//mWorldPos 和 mStartDrag 应该是同一个值，不知道为什么要分开来
									Vector3 after = t.localPosition; // 

									bool snapped = false; //
									Transform parent = t.parent; 

									if (parent != null)
									{
										UIGrid grid = parent.GetComponent<UIGrid>(); // 

                                        // 如果说这个widget的父节点具有 Grid 组件，并且按照 CellSnap 的布局方式进行布局
                                        // 那么根据grid的cell大小进行对齐操作。
										if (grid != null && grid.arrangement == UIGrid.Arrangement.CellSnap)
										{
											snapped = true;
											if (grid.cellWidth > 0) after.x = Mathf.Round(after.x / grid.cellWidth) * grid.cellWidth;
											if (grid.cellHeight > 0) after.y = Mathf.Round(after.y / grid.cellHeight) * grid.cellHeight;
										}
									}

                                    // 如果还没对齐过，进行对齐
									if (!snapped)
									{
										// Snap the widget
										after = NGUISnap.Snap(after, mWidget.localCorners, e.modifiers != EventModifiers.Control);
									}

									// Calculate the final delta
                                    // 本地坐标的变化量
									Vector3 localDelta = (after - mLocalPos);

									// Restore the position
									t.position = mWorldPos; // 恢复坐标位置

									// Adjust the widget by the delta
                                    // 根据 delta 来移动 Widget 。 // TODO 这跟直接移动 postion 有什么区别？
									NGUIMath.MoveRect(mWidget, localDelta.x, localDelta.y);
								}
								else if (mAction == Action.Rotate)
								{
                                    // 这部分代码不是太懂呢。。
									Vector3 dir = pos - t.position;
									float angle = Vector3.Angle(mStartDir, dir);

									if (angle > 0f)
									{
										float dot = Vector3.Dot(Vector3.Cross(mStartDir, dir), t.forward);
										if (dot < 0f) angle = -angle;
										angle = mStartRot.z + angle; // 为什么要加 z 值
										angle = (NGUISnap.allow && e.modifiers != EventModifiers.Control) ?
											Mathf.Round(angle / 15f) * 15f : Mathf.Round(angle);
                                        // 计算欧拉角
										t.localRotation = Quaternion.Euler(mStartRot.x, mStartRot.y, angle);
									}
								}
								else if (mAction == Action.Scale)
								{
									// Move the widget
                                    //
									t.position = mWorldPos + (pos - mStartDrag);

									// Calculate the final delta
									Vector3 localDelta = (t.localPosition - mLocalPos);

									// Restore the position
									t.position = mWorldPos;

									// Adjust the widget's position and scale based on the delta, restricted by the pivot
                                    // 以枢轴点为中心进行缩放
									NGUIMath.ResizeWidget(mWidget, mDragPivot, localDelta.x, localDelta.y, 2, 2);
									ReEvaluateAnchorType();
								}
							}
						}
					}
				}
			}
			break;

                // 释放鼠标
			case EventType.MouseUp:
			{
				if (e.button == 2) break; // 中键不处理

				if (GUIUtility.hotControl == id)
				{
                    // 收尾处理
					GUIUtility.hotControl = 0;
					GUIUtility.keyboardControl = 0;

                    //
					if (e.button < 2)
					{
						bool handled = false; 

                        //
						if (e.button == 1)
						{
							// Right-click: Open a context menu listing all widgets underneath
							NGUIEditorTools.ShowSpriteSelectionMenu(e.mousePosition);
							handled = true;
						}
						else if (mAction == Action.None)
						{
                            // 选择对象
							if (mAllowSelection)
							{
								// Left-click: Select the topmost widget
								NGUIEditorTools.SelectWidget(e.mousePosition);
								handled = true;
							}
						}
						else
						{
							// Finished dragging something
							Vector3 pos = t.localPosition;
							pos.x = Mathf.Round(pos.x);
							pos.y = Mathf.Round(pos.y);
							pos.z = Mathf.Round(pos.z);
							t.localPosition = pos; //对相对位置进行圆整
							handled = true;
						}

						if (handled) e.Use(); // 如果处理过了，那么该事件结束
					}

					// Clear the actions
					mActionUnderMouse = Action.None;
					mAction = Action.None;
				}
				else if (mAllowSelection) // 没控制但是允许选中，那么选择第一个 widget
				{
					List<UIWidget> widgets = NGUIEditorTools.SceneViewRaycast(e.mousePosition);
					if (widgets.Count > 0) Selection.activeGameObject = widgets[0].gameObject;
				}
				mAllowSelection = true;
			}
			break;

            // 上下左右键对矩形框进行移动
			case EventType.KeyDown:
			{
				if (e.keyCode == KeyCode.UpArrow)
				{
					NGUIEditorTools.RegisterUndo("Nudge Rect", t);
					NGUIEditorTools.RegisterUndo("Nudge Rect", mWidget);
					NGUIMath.MoveRect(mWidget, 0f, 1f);
					e.Use();
				}
				else if (e.keyCode == KeyCode.DownArrow)
				{
					NGUIEditorTools.RegisterUndo("Nudge Rect", t);
					NGUIEditorTools.RegisterUndo("Nudge Rect", mWidget);
					NGUIMath.MoveRect(mWidget, 0f, -1f);
					e.Use();
				}
				else if (e.keyCode == KeyCode.LeftArrow)
				{
					NGUIEditorTools.RegisterUndo("Nudge Rect", t);
					NGUIEditorTools.RegisterUndo("Nudge Rect", mWidget);
					NGUIMath.MoveRect(mWidget, -1f, 0f);
					e.Use();
				}
				else if (e.keyCode == KeyCode.RightArrow)
				{
					NGUIEditorTools.RegisterUndo("Nudge Rect", t);
					NGUIEditorTools.RegisterUndo("Nudge Rect", mWidget);
					NGUIMath.MoveRect(mWidget, 1f, 0f);
					e.Use();
				}
				else if (e.keyCode == KeyCode.Escape)
				{
					if (GUIUtility.hotControl == id)
					{
						if (mAction != Action.None)
							Undo.PerformUndo();

						GUIUtility.hotControl = 0;
						GUIUtility.keyboardControl = 0;

						mActionUnderMouse = Action.None;
						mAction = Action.None;
						e.Use();
					}
					else Selection.activeGameObject = null;
				}
			}
			break;
		}
	}

	/// <summary>
	/// Cache the reference.
	/// 记录引用
	/// </summary>

	protected override void OnEnable ()
	{
		base.OnEnable();
		instance = this;
		mWidget = target as UIWidget; // 在对 mWidget 进行操作时为什么不需要判空？
	}

	/// <summary>
	/// All widgets have depth, color and make pixel-perfect options
    /// 所有组件都有 depth，color和 pixel-perfect 选项
	/// </summary>

    protected override void DrawCustomProperties ()
	{
		if (NGUISettings.unifiedTransform) // 这个不知道是哪里设置的。。如果是统一的transform，某些部分就不需要显示了。
		{
			DrawColor(serializedObject, mWidget);
		}
		else DrawInspectorProperties(serializedObject, mWidget, true); // 在检视器中显示Widget组件的操作面板
	}

	/// <summary>
	/// Draw common widget properties that can be shown as a part of the Transform Inspector.
	/// 在检视器中显示通用的 widget 属性，不显示颜色部分
	/// </summary>

	public void DrawWidgetTransform () { DrawInspectorProperties(serializedObject, mWidget, false); }

	/// <summary>
	/// Draw the widget's color.
	/// 在检视器中显示，设置 widget 的颜色和透明度
	/// </summary>

	static public void DrawColor (SerializedObject so, UIWidget w)
	{
		if ((w.GetType() != typeof(UIWidget)))
		{
			NGUIEditorTools.DrawProperty("Color Tint", so, "mColor", GUILayout.MinWidth(20f));
		}
		else if (so.isEditingMultipleObjects)
		{
			NGUIEditorTools.DrawProperty("Alpha", so, "mColor.a", GUILayout.Width(120f));
		}
		else
		{
			GUI.changed = false;
			float alpha = EditorGUILayout.Slider("Alpha", w.alpha, 0f, 1f);

			if (GUI.changed)
			{
				NGUIEditorTools.RegisterUndo("Alpha change", w);
				w.alpha = alpha;
			}
		}
	}

	/// <summary>
	/// Draw common widget properties.
	/// 在检视器中显示通用 widget 属性
	/// </summary>

	static public void DrawInspectorProperties (SerializedObject so, UIWidget w, bool drawColor)
	{
		if (drawColor)
		{
			DrawColor(so, w);
			GUILayout.Space(3f);
		}

		PrefabType type = PrefabUtility.GetPrefabType(w.gameObject); // TODO 为什么要辨别出 prefab 的类型？有些情况不需要显示？

		if (NGUIEditorTools.DrawHeader("Widget")) // 包裹起来
		{
			NGUIEditorTools.BeginContents();
			if (NGUISettings.minimalisticLook) NGUIEditorTools.SetLabelWidth(70f);

			DrawPivot(so, w); //枢轴点
			DrawDepth(so, w, type == PrefabType.Prefab);// 深度
			DrawDimensions(so, w, type == PrefabType.Prefab);// 大小
			if (NGUISettings.minimalisticLook) NGUIEditorTools.SetLabelWidth(70f); 

			SerializedProperty ratio = so.FindProperty("aspectRatio");
			SerializedProperty aspect = so.FindProperty("keepAspectRatio");

			GUILayout.BeginHorizontal();
			{
				if (!aspect.hasMultipleDifferentValues && aspect.intValue == 0) // 单个或多个对象选中时 aspect 都是第一种情况
				{
					EditorGUI.BeginDisabledGroup(true); // 设置为禁用
					NGUIEditorTools.DrawProperty("Aspect", ratio, false, GUILayout.Width(130f));
					EditorGUI.EndDisabledGroup();
				}
				else NGUIEditorTools.DrawProperty("Aspect", ratio, false, GUILayout.Width(130f));

				NGUIEditorTools.DrawProperty("", aspect, false, GUILayout.MinWidth(20f));
			}
			GUILayout.EndHorizontal();

            // 编辑多个对象或者对象存在 碰撞盒的时候显示
			if (so.isEditingMultipleObjects || w.hasBoxCollider)
			{
				GUILayout.BeginHorizontal();
				{
					NGUIEditorTools.DrawProperty("Collider", so, "autoResizeBoxCollider", GUILayout.Width(100f));
					GUILayout.Label("auto-adjust to match");
				}
				GUILayout.EndHorizontal();
			}
			NGUIEditorTools.EndContents();
		}
	}

	/// <summary>
	/// Draw widget's dimensions.
	/// </summary>

	static void DrawDimensions (SerializedObject so, UIWidget w, bool isPrefab)
	{
		GUILayout.BeginHorizontal();
		{
			bool freezeSize = so.isEditingMultipleObjects;

			UILabel lbl = w as UILabel;

			if (!freezeSize && lbl) freezeSize = (lbl.overflowMethod == UILabel.Overflow.ResizeFreely);

			if (freezeSize)
			{
				EditorGUI.BeginDisabledGroup(true);
				NGUIEditorTools.DrawProperty("Size", so, "mWidth", GUILayout.MinWidth(100f));
				EditorGUI.EndDisabledGroup();
			}
			else
			{
				GUI.changed = false;
				int val = EditorGUILayout.IntField("Size", w.width, GUILayout.MinWidth(100f));

				if (GUI.changed)
				{
					NGUIEditorTools.RegisterUndo("Dimensions Change", w);
					w.width = val;
				}
			}

			if (!freezeSize && lbl)
			{
				UILabel.Overflow ov = lbl.overflowMethod;
				freezeSize = (ov == UILabel.Overflow.ResizeFreely || ov == UILabel.Overflow.ResizeHeight);
			}

			NGUIEditorTools.SetLabelWidth(12f);

			if (freezeSize)
			{
				EditorGUI.BeginDisabledGroup(true);
				NGUIEditorTools.DrawProperty("x", so, "mHeight", GUILayout.MinWidth(30f));
				EditorGUI.EndDisabledGroup();
			}
			else
			{
				GUI.changed = false;
				int val = EditorGUILayout.IntField("x", w.height, GUILayout.MinWidth(30f));

				if (GUI.changed)
				{
					NGUIEditorTools.RegisterUndo("Dimensions Change", w);
					w.height = val;
				}
			}

			NGUIEditorTools.SetLabelWidth(80f);

			if (isPrefab)
			{
				GUILayout.Space(70f);
			}
			else
			{
				EditorGUI.BeginDisabledGroup(so.isEditingMultipleObjects);

				if (GUILayout.Button("Snap", GUILayout.Width(60f)))
				{
					foreach (GameObject go in Selection.gameObjects)
					{
						UIWidget pw = go.GetComponent<UIWidget>();

						if (pw != null)
						{
							NGUIEditorTools.RegisterUndo("Snap Dimensions", pw);
							NGUIEditorTools.RegisterUndo("Snap Dimensions", pw.transform);
							pw.MakePixelPerfect();
						}
					}
				}
				EditorGUI.EndDisabledGroup();
			}
		}
		GUILayout.EndHorizontal();
	}

	/// <summary>
	/// Draw widget's depth.
	/// </summary>

	static void DrawDepth (SerializedObject so, UIWidget w, bool isPrefab)
	{
		if (isPrefab) return;

		GUILayout.Space(2f);
		GUILayout.BeginHorizontal();
		{
			EditorGUILayout.PrefixLabel("Depth");

			if (GUILayout.Button("Back", GUILayout.MinWidth(46f)))
			{
				foreach (GameObject go in Selection.gameObjects)
				{
					UIWidget pw = go.GetComponent<UIWidget>();
					if (pw != null) pw.depth = w.depth - 1;
				}
			}

			NGUIEditorTools.DrawProperty("", so, "mDepth", GUILayout.MinWidth(20f));

			if (GUILayout.Button("Forward", GUILayout.MinWidth(60f)))
			{
				foreach (GameObject go in Selection.gameObjects)
				{
					UIWidget pw = go.GetComponent<UIWidget>();
					if (pw != null) pw.depth = w.depth + 1;
				}
			}
		}
		GUILayout.EndHorizontal();

		int matchingDepths = 1;

		UIPanel p = w.panel;

		if (p != null)
		{
			for (int i = 0, imax = p.widgets.Count; i < imax; ++i)
			{
				UIWidget pw = p.widgets[i];
				if (pw != w && pw.depth == w.depth)
					++matchingDepths;
			}
		}

		if (matchingDepths > 1)
		{
			EditorGUILayout.HelpBox(matchingDepths + " widgets are sharing the depth value of " + w.depth, MessageType.Info);
		}
	}

	/// <summary>
	/// Draw the widget's pivot.
	/// </summary>

	static void DrawPivot (SerializedObject so, UIWidget w)
	{
		SerializedProperty pv = so.FindProperty("mPivot");

		if (pv.hasMultipleDifferentValues)
		{
			// TODO: Doing this doesn't keep the widget's position where it was. Another approach is needed.
			NGUIEditorTools.DrawProperty("Pivot", so, "mPivot");
		}
		else
		{
			// Pivot point -- the new, more visual style
			GUILayout.BeginHorizontal();
			GUILayout.Label("Pivot", GUILayout.Width(NGUISettings.minimalisticLook ? 66f : 76f));
			Toggle(w, "\u25C4", "ButtonLeft", UIWidget.Pivot.Left, true);
			Toggle(w, "\u25AC", "ButtonMid", UIWidget.Pivot.Center, true);
			Toggle(w, "\u25BA", "ButtonRight", UIWidget.Pivot.Right, true);
			Toggle(w, "\u25B2", "ButtonLeft", UIWidget.Pivot.Top, false);
			Toggle(w, "\u258C", "ButtonMid", UIWidget.Pivot.Center, false);
			Toggle(w, "\u25BC", "ButtonRight", UIWidget.Pivot.Bottom, false);

			GUILayout.EndHorizontal();
			pv.enumValueIndex = (int)w.pivot;
		}
	}

	/// <summary>
	/// Draw a toggle button for the pivot point.
	/// </summary>

	static void Toggle (UIWidget w, string text, string style, UIWidget.Pivot pivot, bool isHorizontal)
	{
		bool isActive = false;

		switch (pivot)
		{
			case UIWidget.Pivot.Left:
			isActive = IsLeft(w.pivot);
			break;

			case UIWidget.Pivot.Right:
			isActive = IsRight(w.pivot);
			break;

			case UIWidget.Pivot.Top:
			isActive = IsTop(w.pivot);
			break;

			case UIWidget.Pivot.Bottom:
			isActive = IsBottom(w.pivot);
			break;

			case UIWidget.Pivot.Center:
			isActive = isHorizontal ? pivot == GetHorizontal(w.pivot) : pivot == GetVertical(w.pivot);
			break;
		}

		if (GUILayout.Toggle(isActive, text, style) != isActive)
			SetPivot(w, pivot, isHorizontal);
	}

	static bool IsLeft (UIWidget.Pivot pivot)
	{
		return pivot == UIWidget.Pivot.Left ||
			pivot == UIWidget.Pivot.TopLeft ||
			pivot == UIWidget.Pivot.BottomLeft;
	}

	static bool IsRight (UIWidget.Pivot pivot)
	{
		return pivot == UIWidget.Pivot.Right ||
			pivot == UIWidget.Pivot.TopRight ||
			pivot == UIWidget.Pivot.BottomRight;
	}

	static bool IsTop (UIWidget.Pivot pivot)
	{
		return pivot == UIWidget.Pivot.Top ||
			pivot == UIWidget.Pivot.TopLeft ||
			pivot == UIWidget.Pivot.TopRight;
	}

	static bool IsBottom (UIWidget.Pivot pivot)
	{
		return pivot == UIWidget.Pivot.Bottom ||
			pivot == UIWidget.Pivot.BottomLeft ||
			pivot == UIWidget.Pivot.BottomRight;
	}

	static UIWidget.Pivot GetHorizontal (UIWidget.Pivot pivot)
	{
		if (IsLeft(pivot)) return UIWidget.Pivot.Left;
		if (IsRight(pivot)) return UIWidget.Pivot.Right;
		return UIWidget.Pivot.Center;
	}

	static UIWidget.Pivot GetVertical (UIWidget.Pivot pivot)
	{
		if (IsTop(pivot)) return UIWidget.Pivot.Top;
		if (IsBottom(pivot)) return UIWidget.Pivot.Bottom;
		return UIWidget.Pivot.Center;
	}

	static UIWidget.Pivot Combine (UIWidget.Pivot horizontal, UIWidget.Pivot vertical)
	{
		if (horizontal == UIWidget.Pivot.Left)
		{
			if (vertical == UIWidget.Pivot.Top) return UIWidget.Pivot.TopLeft;
			if (vertical == UIWidget.Pivot.Bottom) return UIWidget.Pivot.BottomLeft;
			return UIWidget.Pivot.Left;
		}

		if (horizontal == UIWidget.Pivot.Right)
		{
			if (vertical == UIWidget.Pivot.Top) return UIWidget.Pivot.TopRight;
			if (vertical == UIWidget.Pivot.Bottom) return UIWidget.Pivot.BottomRight;
			return UIWidget.Pivot.Right;
		}
		return vertical;
	}

	static void SetPivot (UIWidget w, UIWidget.Pivot pivot, bool isHorizontal)
	{
		UIWidget.Pivot horizontal = GetHorizontal(w.pivot);
		UIWidget.Pivot vertical = GetVertical(w.pivot);

		pivot = isHorizontal ? Combine(pivot, vertical) : Combine(horizontal, pivot);

		if (w.pivot != pivot)
		{
			NGUIEditorTools.RegisterUndo("Pivot change", w);
			w.pivot = pivot;
		}
	}

	protected override void OnDrawFinalProperties ()
	{
		if (mAnchorType == AnchorType.Advanced || !mWidget.isAnchored) return;

		SerializedProperty sp = serializedObject.FindProperty("leftAnchor.target");

		if (!IsRect(sp))
		{
			GUILayout.Space(3f);
			GUILayout.BeginHorizontal();
			GUILayout.Space(6f);
			NGUIEditorTools.DrawProperty("", serializedObject, "hideIfOffScreen", GUILayout.Width(18f));
			GUILayout.Label("Hide if off-screen", GUILayout.MinWidth(20f));
			GUILayout.EndHorizontal();
		}
	}
}