滑动 ViewDragHelper DrawerLayout

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概述

官方在v4的支持包中提供了ViewDragHelper这样一个类来帮助我们方便的编写自定义ViewGroup
  1. ViewDragHelper is a utility class for writing custom ViewGroups. 
  2. It offers a number of useful operations and state tracking 
  3. for allowing a user to drag and reposition views within their parent ViewGroup.

ViewDragHelper.Callback的回调

  • int clampViewPositionHorizontal(View child, int left, int dx)    Restrict the motion of the dragged child view along the horizontal axis.
  • int clampViewPositionVertical(View child, int top, int dy)    Restrict the motion of the dragged child view along the vertical axis.
  • int getOrderedChildIndex(int index)    Called to determine the Z-order of child views.
  • int getViewHorizontalDragRange(View child)    Return the magnitude of a draggable child view‘s horizontal range of motion in pixels.
  • int getViewVerticalDragRange(View child)    Return the magnitude of a draggable child view‘s vertical range of motion in pixels.
  • void onEdgeDragStarted(int edgeFlags, int pointerId)    Called when the user has started a deliberate drag away from one of the subscribed edges in the parent view while no child view is currently captured.
  • boolean onEdgeLock(int edgeFlags)    Called when the given edge may become locked.
  • void onEdgeTouched(int edgeFlags, int pointerId)    Called when one of the subscribed edges in the parent view has been touched by the user while no child view is currently captured.
  • void onViewCaptured(View capturedChild, int activePointerId)    Called when a child view is captured for dragging or settling.
  • void onViewDragStateChanged(int state)    Called when the drag state changes.
  • void onViewPositionChanged(View changedView, int left, int top, int dx, int dy)    Called when the captured view‘s position changes as the result of a drag or settle.
  • void onViewReleased(View releasedChild, float xvel, float yvel)    Called when the child view is no longer being actively dragged.
  • abstract boolean tryCaptureView(View child, int pointerId)    Called when the user‘s input indicates that they want to capture the given child view with the pointer indicated by pointerId.

最基础的使用

  1. /**
  2.  * 最基础的使用，不做任何特殊处理
  3.  * @author 白乾涛
  4.  */
  5. public class VDHLayout extends LinearLayout {
  6. 	private ViewDragHelper mDragger;
  8. 	public VDHLayout(Context context, AttributeSet attrs) {
  9. 		super(context, attrs);
  10. 		mDragger = ViewDragHelper.create(this, //当前的ViewGroup
  11. 				1.0f, //越大，mTouchSlop的值就会越小，主要用于设置 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity));
  12. 				new ViewDragHelper.Callback() {//在用户的触摸过程中会回调相关方法
  13. 					@Override
  14. 					public boolean tryCaptureView(View child, int pointerId) {//返回ture则表示可以捕获该view，你可以根据传入的第一个view参数决定哪些可以捕获
  15. 						return true;
  16. 					}
  18. 					@Override
  19. 					public int clampViewPositionHorizontal(View child, int left, int dx) {//在该方法中对child移动的边界进行控制，left 为即将移动到的位置
  20. 						return left;
  21. 					}
  23. 					@Override
  24. 					public int clampViewPositionVertical(View child, int top, int dy) {
  25. 						return top;
  26. 					}
  27. 				});
  28. 	}
  30. 	@Override
  31. 	public boolean onInterceptTouchEvent(MotionEvent event) {
  32. 		return mDragger.shouldInterceptTouchEvent(event);//使用mDragger来决定我们是否应该拦截当前的事件
  33. 	}
  35. 	@Override
  36. 	public boolean onTouchEvent(MotionEvent event) {
  37. 		mDragger.processTouchEvent(event);//通过mDragger.processTouchEvent(event)处理事件。必须返回true
  38. 		return true;
  39. 	}
  40. }

功能增强

松手时自动返回到原本的位置，边界检测，控制在父控件中移动的区域
  1. public class DragLayout2 extends LinearLayout {
  2. 	private ViewDragHelper mDragger;
  3. 	private View mDragView;//第一个View，就是演示简单的移动 
  4. 	private View mAutoBackView;//第二个View，移动后，松手自动返回到原本的位置（注意你拖动的越快，返回的越快） 
  5. 	private View mEdgeTrackerView;//第三个View，边界移动时对View进行捕获
  6. 	private Point mAutoBackOriginPos = new Point();
  8. 	public DragLayout2(Context context, AttributeSet attrs) {
  9. 		super(context, attrs);
  10. 		mDragger = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {
  11. 			@Override
  12. 			public boolean tryCaptureView(View child, int pointerId) {//可以通过ID或pointerId判断
  13. 				if (new Random().nextBoolean()) return child == mDragView || child == mAutoBackView;//mEdgeTrackerView禁止直接移动
  14. 				else return pointerId == 0 || pointerId == 1;
  15. 			}
  17. 			@Override
  18. 			public int clampViewPositionHorizontal(View child, int left, int dx) {
  19. 				final int leftBound = getPaddingLeft();
  20. 				final int rightBound = getWidth() - child.getWidth() - leftBound;
  21. 				return Math.min(Math.max(left, leftBound), rightBound);//不超过父控件的区域
  22. 			}
  24. 			public int clampViewPositionVertical(View child, int top, int dy) {
  25. 				final int topBound = getPaddingTop();
  26. 				final int bottomBound = getHeight() - child.getHeight() - topBound;
  27. 				return Math.min(Math.max(top, topBound + 5), bottomBound - 10);//距离父控件上面的距离不超过5，距离父控件下面的距离不超过10
  28. 			}
  30. 			@Override
  31. 			public void onViewReleased(View releasedChild, float xvel, float yvel) {//手指释放的时候回调
  32. 				if (releasedChild == mAutoBackView) {
  33. 					mDragger.settleCapturedViewAt(mAutoBackOriginPos.x, mAutoBackOriginPos.y);//mAutoBackView在手指释放时可以自动回去
  34. 					invalidate();
  35. 				}
  36. 			}
  38. 			@Override
  39. 			public void onEdgeDragStarted(int edgeFlags, int pointerId) {//在边界拖动时回调
  40. 				//该方法可以绕过tryCaptureView，所以我们的tryCaptureView虽然并为返回true，但却不影响
  41. 				mDragger.captureChildView(mEdgeTrackerView, pointerId);
  42. 			}
  43. 		});
  44. 		mDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_ALL);//设置边界检测区域
  45. 	}
  47. 	@Override
  48. 	public boolean onInterceptTouchEvent(MotionEvent event) {
  49. 		return mDragger.shouldInterceptTouchEvent(event);
  50. 	}
  52. 	@Override
  53. 	public boolean onTouchEvent(MotionEvent event) {
  54. 		mDragger.processTouchEvent(event);
  55. 		return true;
  56. 	}
  58. 	@Override
  59. 	public void computeScroll() {//settleCapturedViewAt方法内部使用的是mScroller.startScroll，所以需要结合computeScroll方法一起使用
  60. 		if (mDragger.continueSettling(true)) invalidate();
  61. 	}
  63. 	@Override
  64. 	protected void onLayout(boolean changed, int l, int t, int r, int b) {//在onLayout之后保存最开始的位置信息
  65. 		super.onLayout(changed, l, t, r, b);
  66. 		mAutoBackOriginPos.x = mAutoBackView.getLeft();
  67. 		mAutoBackOriginPos.y = mAutoBackView.getTop();
  68. 	}
  70. 	@Override
  71. 	protected void onFinishInflate() {
  72. 		super.onFinishInflate();
  73. 		mAutoBackView = getChildAt(1);
  74. 		mEdgeTrackerView = getChildAt(2);
  75. 	}
  76. }

点击冲突与回调方法

  1. public class DragLayout3 extends RelativeLayout {
  2. 	private ViewDragHelper mDragger;
  4. 	private View mDragView;//仅此View支持移动
  6. 	public DragLayout3(Context context, AttributeSet attrs) {
  7. 		super(context, attrs);
  8. 		mDragger = ViewDragHelper.create(this, 10.0f, new ViewDragHelper.Callback() {
  9. 			@Override
  10. 			public boolean tryCaptureView(View child, int pointerId) {
  11. 				Log.i("bqt", "【tryCaptureView】");
  12. 				return mDragView != null && child == mDragView;//仅支持mDragView移动
  13. 			}
  15. 			@Override
  16. 			public int clampViewPositionHorizontal(View child, int left, int dx) {
  17. 				Log.i("bqt", "【clampViewPositionHorizontal】");
  18. 				final int leftBound = getPaddingLeft();
  19. 				final int rightBound = getWidth() - child.getWidth() - leftBound;
  20. 				return Math.min(Math.max(left, leftBound + 5), rightBound - 5);//自定义区域
  21. 			}
  23. 			public int clampViewPositionVertical(View child, int top, int dy) {
  24. 				Log.i("bqt", "【clampViewPositionVertical】");
  25. 				final int topBound = getPaddingTop();
  26. 				final int bottomBound = getHeight() - child.getHeight() - topBound;
  27. 				return Math.min(Math.max(top, topBound + 5), bottomBound - 5);//自定义区域
  28. 			}
  30. 			//*********************************************get回调*********************************************
  31. 			@Override
  32. 			public int getViewHorizontalDragRange(View child) {//方法的返回值是该childView横向或者纵向的移动的范围，当前如果只需要一个方向移动，可以只复写一个
  33. 				Log.i("bqt", "【getViewHorizontalDragRange】");
  34. 				return getMeasuredWidth() - child.getMeasuredWidth();
  35. 			}
  37. 			@Override
  38. 			public int getViewVerticalDragRange(View child) {
  39. 				Log.i("bqt", "【getViewVerticalDragRange】");
  40. 				return getMeasuredHeight() - child.getMeasuredHeight();
  41. 			}
  43. 			@Override
  44. 			public int getOrderedChildIndex(int index) {//改变同一个坐标去寻找captureView位置
  45. 				Log.i("bqt", "【getOrderedChildIndex】");
  46. 				return super.getOrderedChildIndex(index);
  47. 			}
  49. 			//*********************************************on回调*********************************************
  51. 			@Override
  52. 			public boolean onEdgeLock(int edgeFlags) {//true的时候会锁住当前的边界，false则unLock。
  53. 				Log.i("bqt", "【onEdgeLock】");
  54. 				return super.onEdgeLock(edgeFlags);
  55. 			}
  57. 			@Override
  58. 			public void onEdgeDragStarted(int edgeFlags, int pointerId) {//在边界拖动时回调
  59. 				super.onEdgeDragStarted(edgeFlags, pointerId);
  60. 				Log.i("bqt", "【onEdgeDragStarted】");
  61. 			}
  63. 			@Override
  64. 			public void onEdgeTouched(int edgeFlags, int pointerId) {//当触摸到边界时回调
  65. 				super.onEdgeTouched(edgeFlags, pointerId);
  66. 				Log.i("bqt", "【onEdgeTouched】");
  67. 			}
  69. 			@Override
  70. 			public void onViewCaptured(View capturedChild, int activePointerId) {//当captureview被捕获时回调
  71. 				super.onViewCaptured(capturedChild, activePointerId);
  72. 				Log.i("bqt", "【onViewCaptured】");
  73. 			}
  75. 			@Override
  76. 			public void onViewDragStateChanged(int state) {//当ViewDragHelper状态发生变化时回调（IDLE,DRAGGING,SETTING[自动滚动时]）
  77. 				super.onViewDragStateChanged(state);
  78. 				Log.i("bqt", "【onViewDragStateChanged】");
  79. 			}
  81. 			@Override
  82. 			public void onViewPositionChanged(View changedView, int left, int top, int dx, int dy) {//当captureview的位置发生改变时回调
  83. 				super.onViewPositionChanged(changedView, left, top, dx, dy);
  84. 				Log.i("bqt", "【onViewPositionChanged】");
  85. 			}
  87. 			@Override
  88. 			public void onViewReleased(View releasedChild, float xvel, float yvel) {//手指释放的时候回调
  89. 				super.onViewReleased(releasedChild, xvel, yvel);
  90. 				Log.i("bqt", "【onViewReleased】");
  91. 			}
  93. 		});
  94. 	}
  96. 	@Override
  97. 	public boolean onInterceptTouchEvent(MotionEvent event) {
  98. 		return mDragger.shouldInterceptTouchEvent(event);
  99. 	}
  101. 	@Override
  102. 	public boolean onTouchEvent(MotionEvent event) {
  103. 		mDragger.processTouchEvent(event);
  104. 		return true;
  105. 	}
  107. 	@Override
  108. 	protected void onFinishInflate() {
  109. 		super.onFinishInflate();
  110. 		mDragView = findViewById(R.id.dragview);
  111. 	}
  112. }

最简单实用的案例

  1. /**
  2.  * 仅id为dragview的可以移动
  3.  * @author 白乾涛
  4.  */
  5. public class MyDragLayout extends RelativeLayout {
  6. 	private ViewDragHelper mDragger;
  7. 	private View mDragView;//仅此View支持移动
  9. 	public MyDragLayout(Context context, AttributeSet attrs) {
  10. 		super(context, attrs);
  11. 		mDragger = ViewDragHelper.create(this, 10.0f, new ViewDragHelper.Callback() {
  12. 			@Override
  13. 			public boolean tryCaptureView(View child, int pointerId) {
  14. 				Log.i("bqt", "【tryCaptureView】");
  15. 				return mDragView != null && child == mDragView;//仅支持mDragView移动
  16. 			}
  18. 			@Override
  19. 			public int clampViewPositionHorizontal(View child, int left, int dx) {
  20. 				Log.i("bqt", "【clampViewPositionHorizontal】");
  21. 				final int leftBound = getPaddingLeft();
  22. 				final int rightBound = getWidth() - child.getWidth() - leftBound;
  23. 				return Math.min(Math.max(left, leftBound + 5), rightBound - 5);//自定义区域
  24. 			}
  26. 			public int clampViewPositionVertical(View child, int top, int dy) {
  27. 				Log.i("bqt", "【clampViewPositionVertical】");
  28. 				final int topBound = getPaddingTop();
  29. 				final int bottomBound = getHeight() - child.getHeight() - topBound;
  30. 				return Math.min(Math.max(top, topBound + 5), bottomBound - 5);//自定义区域
  31. 			}
  33. 			//*********************************************get回调*********************************************
  34. 			@Override
  35. 			public int getViewHorizontalDragRange(View child) {//方法的返回值是该childView横向或者纵向的移动的范围，当前如果只需要一个方向移动，可以只复写一个
  36. 				Log.i("bqt", "【getViewHorizontalDragRange】");
  37. 				return getMeasuredWidth() - child.getMeasuredWidth();
  38. 			}
  40. 			@Override
  41. 			public int getViewVerticalDragRange(View child) {
  42. 				Log.i("bqt", "【getViewVerticalDragRange】");
  43. 				return getMeasuredHeight() - child.getMeasuredHeight();
  44. 			}
  45. 		});
  46. 	}
  48. 	@Override
  49. 	public boolean onInterceptTouchEvent(MotionEvent event) {
  50. 		return mDragger.shouldInterceptTouchEvent(event);
  51. 	}
  53. 	@Override
  54. 	public boolean onTouchEvent(MotionEvent event) {
  55. 		mDragger.processTouchEvent(event);
  56. 		return true;
  57. 	}
  59. 	@Override
  60. 	protected void onFinishInflate() {
  61. 		super.onFinishInflate();
  62. 		mDragView = findViewById(R.id.dragview);
  63. 	}
  64. }






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