滑动 ViewDragHelper DrawerLayout

时间：2017-05-17 12:02:26 阅读：213 评论：0 收藏：0 [点我收藏+]

标签：flags color origin event order oid ups roc tab

参考：http://blog.csdn.net/lmj623565791/article/details/46858663

API文档：https://developer.android.google.cn/reference/android/support/v4/widget/ViewDragHelper.html

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

ViewDragHelper is a utility class for writing custom ViewGroups. 
It offers a number of useful operations and state tracking 
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

/**
 * 最基础的使用，不做任何特殊处理
 * @author 白乾涛
 */
public class VDHLayout extends LinearLayout {
	private ViewDragHelper mDragger;
	public VDHLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
		mDragger = ViewDragHelper.create(this, //当前的ViewGroup
				1.0f, //越大，mTouchSlop的值就会越小，主要用于设置 helper.mTouchSlop = (int) (helper.mTouchSlop * (1 / sensitivity));
				new ViewDragHelper.Callback() {//在用户的触摸过程中会回调相关方法
					@Override
					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
						return true;
					}
					@Override
					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
						return left;
					}
					@Override
					public int clampViewPositionVertical(View child, int top, int dy) {
						return top;
					}
				});
	}
	@Override
	public boolean onInterceptTouchEvent(MotionEvent event) {
		return mDragger.shouldInterceptTouchEvent(event);//使用mDragger来决定我们是否应该拦截当前的事件
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		mDragger.processTouchEvent(event);//通过mDragger.processTouchEvent(event)处理事件。必须返回true
		return true;
	}
}

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

public class DragLayout2 extends LinearLayout {
	private ViewDragHelper mDragger;
	private View mDragView;//第一个View，就是演示简单的移动 
	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） 
	private View mEdgeTrackerView;//第三个View，边界移动时对View进行捕获
	private Point mAutoBackOriginPos = new Point();
	public DragLayout2(Context context, AttributeSet attrs) {
		super(context, attrs);
		mDragger = ViewDragHelper.create(this, 1.0f, new ViewDragHelper.Callback() {
			@Override
			public boolean tryCaptureView(View child, int pointerId) {//可以通过ID或pointerId判断
				if (new Random().nextBoolean()) return child == mDragView || child == mAutoBackView;//mEdgeTrackerView禁止直接移动
				else return pointerId == 0 || pointerId == 1;
			}
			@Override
			public int clampViewPositionHorizontal(View child, int left, int dx) {
				final int leftBound = getPaddingLeft();
				final int rightBound = getWidth() - child.getWidth() - leftBound;
				return Math.min(Math.max(left, leftBound), rightBound);//不超过父控件的区域
			}
			public int clampViewPositionVertical(View child, int top, int dy) {
				final int topBound = getPaddingTop();
				final int bottomBound = getHeight() - child.getHeight() - topBound;
				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
			}
			@Override
			public void onViewReleased(View releasedChild, float xvel, float yvel) {//手指释放的时候回调
				if (releasedChild == mAutoBackView) {
					mDragger.settleCapturedViewAt(mAutoBackOriginPos.x, mAutoBackOriginPos.y);//mAutoBackView在手指释放时可以自动回去
					invalidate();
				}
			}
			@Override
			public void onEdgeDragStarted(int edgeFlags, int pointerId) {//在边界拖动时回调
				//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
				mDragger.captureChildView(mEdgeTrackerView, pointerId);
			}
		});
		mDragger.setEdgeTrackingEnabled(ViewDragHelper.EDGE_ALL);//设置边界检测区域
	}
	@Override
	public boolean onInterceptTouchEvent(MotionEvent event) {
		return mDragger.shouldInterceptTouchEvent(event);
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		mDragger.processTouchEvent(event);
		return true;
	}
	@Override
	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
		if (mDragger.continueSettling(true)) invalidate();
	}
	@Override
	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
		super.onLayout(changed, l, t, r, b);
		mAutoBackOriginPos.x = mAutoBackView.getLeft();
		mAutoBackOriginPos.y = mAutoBackView.getTop();
	}
	@Override
	protected void onFinishInflate() {
		super.onFinishInflate();
		mAutoBackView = getChildAt(1);
		mEdgeTrackerView = getChildAt(2);
	}
}

点击冲突与回调方法

public class DragLayout3 extends RelativeLayout {
	private ViewDragHelper mDragger;
	private View mDragView;//仅此View支持移动
	public DragLayout3(Context context, AttributeSet attrs) {
		super(context, attrs);
		mDragger = ViewDragHelper.create(this, 10.0f, new ViewDragHelper.Callback() {
			@Override
			public boolean tryCaptureView(View child, int pointerId) {
				Log.i("bqt", "【tryCaptureView】");
				return mDragView != null && child == mDragView;//仅支持mDragView移动
			}
			@Override
			public int clampViewPositionHorizontal(View child, int left, int dx) {
				Log.i("bqt", "【clampViewPositionHorizontal】");
				final int leftBound = getPaddingLeft();
				final int rightBound = getWidth() - child.getWidth() - leftBound;
				return Math.min(Math.max(left, leftBound + 5), rightBound - 5);//自定义区域
			}
			public int clampViewPositionVertical(View child, int top, int dy) {
				Log.i("bqt", "【clampViewPositionVertical】");
				final int topBound = getPaddingTop();
				final int bottomBound = getHeight() - child.getHeight() - topBound;
				return Math.min(Math.max(top, topBound + 5), bottomBound - 5);//自定义区域
			}
			//*********************************************get回调*********************************************
			@Override
			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
				Log.i("bqt", "【getViewHorizontalDragRange】");
				return getMeasuredWidth() - child.getMeasuredWidth();
			}
			@Override
			public int getViewVerticalDragRange(View child) {
				Log.i("bqt", "【getViewVerticalDragRange】");
				return getMeasuredHeight() - child.getMeasuredHeight();
			}
			@Override
			public int getOrderedChildIndex(int index) {//改变同一个坐标去寻找captureView位置
				Log.i("bqt", "【getOrderedChildIndex】");
				return super.getOrderedChildIndex(index);
			}
			//*********************************************on回调*********************************************
			@Override
			public boolean onEdgeLock(int edgeFlags) {//true的时候会锁住当前的边界，false则unLock。
				Log.i("bqt", "【onEdgeLock】");
				return super.onEdgeLock(edgeFlags);
			}
			@Override
			public void onEdgeDragStarted(int edgeFlags, int pointerId) {//在边界拖动时回调
				super.onEdgeDragStarted(edgeFlags, pointerId);
				Log.i("bqt", "【onEdgeDragStarted】");
			}
			@Override
			public void onEdgeTouched(int edgeFlags, int pointerId) {//当触摸到边界时回调
				super.onEdgeTouched(edgeFlags, pointerId);
				Log.i("bqt", "【onEdgeTouched】");
			}
			@Override
			public void onViewCaptured(View capturedChild, int activePointerId) {//当captureview被捕获时回调
				super.onViewCaptured(capturedChild, activePointerId);
				Log.i("bqt", "【onViewCaptured】");
			}
			@Override
			public void onViewDragStateChanged(int state) {//当ViewDragHelper状态发生变化时回调（IDLE,DRAGGING,SETTING[自动滚动时]）
				super.onViewDragStateChanged(state);
				Log.i("bqt", "【onViewDragStateChanged】");
			}
			@Override
			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
				super.onViewPositionChanged(changedView, left, top, dx, dy);
				Log.i("bqt", "【onViewPositionChanged】");
			}
			@Override
			public void onViewReleased(View releasedChild, float xvel, float yvel) {//手指释放的时候回调
				super.onViewReleased(releasedChild, xvel, yvel);
				Log.i("bqt", "【onViewReleased】");
			}
		});
	}
	@Override
	public boolean onInterceptTouchEvent(MotionEvent event) {
		return mDragger.shouldInterceptTouchEvent(event);
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		mDragger.processTouchEvent(event);
		return true;
	}
	@Override
	protected void onFinishInflate() {
		super.onFinishInflate();
		mDragView = findViewById(R.id.dragview);
	}
}

最简单实用的案例

/**
 * 仅id为dragview的可以移动
 * @author 白乾涛
 */
public class MyDragLayout extends RelativeLayout {
	private ViewDragHelper mDragger;
	private View mDragView;//仅此View支持移动
	public MyDragLayout(Context context, AttributeSet attrs) {
		super(context, attrs);
		mDragger = ViewDragHelper.create(this, 10.0f, new ViewDragHelper.Callback() {
			@Override
			public boolean tryCaptureView(View child, int pointerId) {
				Log.i("bqt", "【tryCaptureView】");
				return mDragView != null && child == mDragView;//仅支持mDragView移动
			}
			@Override
			public int clampViewPositionHorizontal(View child, int left, int dx) {
				Log.i("bqt", "【clampViewPositionHorizontal】");
				final int leftBound = getPaddingLeft();
				final int rightBound = getWidth() - child.getWidth() - leftBound;
				return Math.min(Math.max(left, leftBound + 5), rightBound - 5);//自定义区域
			}
			public int clampViewPositionVertical(View child, int top, int dy) {
				Log.i("bqt", "【clampViewPositionVertical】");
				final int topBound = getPaddingTop();
				final int bottomBound = getHeight() - child.getHeight() - topBound;
				return Math.min(Math.max(top, topBound + 5), bottomBound - 5);//自定义区域
			}
			//*********************************************get回调*********************************************
			@Override
			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
				Log.i("bqt", "【getViewHorizontalDragRange】");
				return getMeasuredWidth() - child.getMeasuredWidth();
			}
			@Override
			public int getViewVerticalDragRange(View child) {
				Log.i("bqt", "【getViewVerticalDragRange】");
				return getMeasuredHeight() - child.getMeasuredHeight();
			}
		});
	}
	@Override
	public boolean onInterceptTouchEvent(MotionEvent event) {
		return mDragger.shouldInterceptTouchEvent(event);
	}
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		mDragger.processTouchEvent(event);
		return true;
	}
	@Override
	protected void onFinishInflate() {
		super.onFinishInflate();
		mDragView = findViewById(R.id.dragview);
	}
}

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滑动 ViewDragHelper DrawerLayout

标签：flags color origin event order oid ups roc tab

原文地址：http://www.cnblogs.com/baiqiantao/p/6866356.html

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