时间:2021-01-10 11:03:39 | 栏目:Android代码 | 点击:次
先来段Behavior代码,网上关于FloatingActionButton(以下简称FAB)滑动的代码很多了,参考一下。
public class FabBehavior extends FloatingActionButton.Behavior{ private static final Interpolator INTERPOLATOR = new FastOutSlowInInterpolator(); private boolean mIsAnimatingOut = false; public FabBehavior(Context context, AttributeSet attrs) { super(); } @Override public boolean onStartNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child, final View directTargetChild, final View target, final int nestedScrollAxes) { // Ensure we react to vertical scrolling return nestedScrollAxes == ViewCompat.SCROLL_AXIS_VERTICAL || super.onStartNestedScroll(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes); } @Override public void onNestedScroll(final CoordinatorLayout coordinatorLayout, final FloatingActionButton child, final View target, final int dxConsumed, final int dyConsumed, final int dxUnconsumed, final int dyUnconsumed) { super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed); if (dyConsumed > 0 && !this.mIsAnimatingOut && child.getVisibility() == View.VISIBLE) { // User scrolled down and the FAB is currently visible -> hide the FAB animateOut(child); } else if (dyConsumed < 0 && child.getVisibility() != View.VISIBLE) { // User scrolled up and the FAB is currently not visible -> show the FAB animateIn(child); } } // Same animation that FloatingActionButton.Behavior uses to hide the FAB when the AppBarLayout exits private void animateOut(final FloatingActionButton button) { if (Build.VERSION.SDK_INT >= 14) { ViewCompat.animate(button).translationY(button.getHeight() + getMarginBottom(button)).setInterpolator(INTERPOLATOR).withLayer() .setListener(new ViewPropertyAnimatorListener() { public void onAnimationStart(View view) { FabBehavior.this.mIsAnimatingOut = true; } public void onAnimationCancel(View view) { FabBehavior.this.mIsAnimatingOut = false; } public void onAnimationEnd(View view) { FabBehavior.this.mIsAnimatingOut = false; view.setVisibility(View.GONE); } }).start(); } else { } } // Same animation that FloatingActionButton.Behavior uses to show the FAB when the AppBarLayout enters private void animateIn(FloatingActionButton button) { button.setVisibility(View.VISIBLE); if (Build.VERSION.SDK_INT >= 14) { ViewCompat.animate(button).translationY(0) .setInterpolator(INTERPOLATOR).withLayer().setListener(null) .start(); } else { } } private int getMarginBottom(View v) { int marginBottom = 0; final ViewGroup.LayoutParams layoutParams = v.getLayoutParams(); if (layoutParams instanceof ViewGroup.MarginLayoutParams) { marginBottom = ((ViewGroup.MarginLayoutParams) layoutParams).bottomMargin; } return marginBottom; } }
这是自定义的一个Behavior类,主要在onNestedScroll中自定义了出现和消失的动画。使用的时候,在xml文件中给FAB加一个包含完整behavior类名的layout_behavior属性
app:layout_behavior="com.normalframe.widgets.view.FabBehavior"
这样FAB就会随着列表上滑消失,下滑出现。这个功能主要是要处理FAB的位置会使列表最后一项被挡住的问题,当上滑时,FAB隐藏,这样当到达列表底部最后一项时,由于刚刚的动作是上滑动作,所以FAB处于隐藏状态,不会遮挡到列表。
在写这个功能时,发现了一个问题:
上滑时FAB能够正常隐藏,但是下拉列表时,FAB就不出现了。
而一样的代码如果放到其它项目中,有些又可以正常实现功能。Debug的时候发现,上拉时会调用onNestedScroll,于是其中自定义的隐藏方法可以被调用,但下滑时,不调用onNestedScroll。