代码如下:
import android.content.Context;
import android.os.Parcelable;
import android.support.annotation.IntDef;
import android.support.design.widget.CoordinatorLayout;
import android.support.v4.view.WindowInsetsCompat;
import android.util.AttributeSet;
import android.view.View;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
/**
* Created by JokAr on 2017/3/2.
*/
public
abstract class VerticalScrollingBehavior <V extends View> extends
CoordinatorLayout.Behavior<V> {
private int mTotalDyUnconsumed =
0;
private int mTotalDy =
0;
@ScrollDirection
private int mOverScrollDirection = ScrollDirection.SCROLL_NONE;
@ScrollDirection
private int mScrollDirection = ScrollDirection.SCROLL_NONE;
public VerticalScrollingBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
}
public VerticalScrollingBehavior() {
super();
}
@Retention(RetentionPolicy.SOURCE)
@IntDef({ScrollDirection.SCROLL_DIRECTION_UP, ScrollDirection.SCROLL_DIRECTION_DOWN})
public
@interface ScrollDirection {
int SCROLL_DIRECTION_UP =
1;
int SCROLL_DIRECTION_DOWN = -
1;
int SCROLL_NONE =
0;
}
@ScrollDirection
public int getOverScrollDirection() {
return mOverScrollDirection;
}
/**
* @return Scroll direction: SCROLL_DIRECTION_UP,
* SCROLL_DIRECTION_DOWN, SCROLL_NONE
*/
@ScrollDirection
public int getScrollDirection() {
return mScrollDirection;
}
/**
* @param coordinatorLayout
* @param child
* @param direction Direction of the overscroll: SCROLL_DIRECTION_UP, SCROLL_DIRECTION_DOWN
* @param currentOverScroll Unconsumed value, negative or positive based on the direction;
* @param totalOverScroll Cumulative value for current direction
*/
public
abstract void onNestedVerticalOverScroll(CoordinatorLayout coordinatorLayout,
V child,
@ScrollDirection int direction,
int currentOverScroll, int totalOverScroll);
/**
* @param scrollDirection Direction of the overscroll: SCROLL_DIRECTION_UP, SCROLL_DIRECTION_DOWN
*/
public
abstract void onDirectionNestedPreScroll(CoordinatorLayout coordinatorLayout, V child,
View target, int dx, int dy, int[] consumed,
@ScrollDirection int scrollDirection);
@Override
public boolean onStartNestedScroll(CoordinatorLayout coordinatorLayout, V child,
View directTargetChild, View target,
int nestedScrollAxes) {
return (nestedScrollAxes & View.SCROLL_AXIS_VERTICAL) !=
0;
}
@Override
public void onNestedScrollAccepted(CoordinatorLayout coordinatorLayout, V child,
View directTargetChild, View target, int nestedScrollAxes) {
super.onNestedScrollAccepted(coordinatorLayout, child, directTargetChild, target, nestedScrollAxes);
}
@Override
public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, V child, View target) {
super.onStopNestedScroll(coordinatorLayout, child, target);
}
@Override
public void onNestedScroll(CoordinatorLayout coordinatorLayout, V child,
View target, int dxConsumed, int dyConsumed,
int dxUnconsumed, int dyUnconsumed) {
super.onNestedScroll(coordinatorLayout, child, target, dxConsumed, dyConsumed,
dxUnconsumed, dyUnconsumed);
if (dyUnconsumed >
0 && mTotalDyUnconsumed <
0) {
mTotalDyUnconsumed =
0;
mOverScrollDirection = ScrollDirection.SCROLL_DIRECTION_UP;
}
else if (dyUnconsumed <
0 && mTotalDyUnconsumed >
0) {
mTotalDyUnconsumed =
0;
mOverScrollDirection = ScrollDirection.SCROLL_DIRECTION_DOWN;
}
mTotalDyUnconsumed += dyUnconsumed;
onNestedVerticalOverScroll(coordinatorLayout, child, mOverScrollDirection,
dyConsumed, mTotalDyUnconsumed);
}
@Override
public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, V child,
View target, int dx, int dy, int[] consumed) {
super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed);
if (dy >
0 && mTotalDy <
0) {
mTotalDy =
0;
mScrollDirection = ScrollDirection.SCROLL_DIRECTION_UP;
}
else if (dy <
0 && mTotalDy >
0) {
mTotalDy =
0;
mScrollDirection = ScrollDirection.SCROLL_DIRECTION_DOWN;
}
mTotalDy += dy;
onDirectionNestedPreScroll(coordinatorLayout, child, target, dx,
dy, consumed, mScrollDirection);
}
@Override
public boolean onNestedFling(CoordinatorLayout coordinatorLayout, V child, View target,
float velocityX, float velocityY, boolean consumed) {
super.onNestedFling(coordinatorLayout, child, target, velocityX, velocityY, consumed);
mScrollDirection = velocityY >
0 ? ScrollDirection.SCROLL_DIRECTION_UP
: ScrollDirection.SCROLL_DIRECTION_DOWN;
return onNestedDirectionFling(coordinatorLayout, child, target, velocityX,
velocityY, mScrollDirection);
}
protected abstract boolean onNestedDirectionFling(CoordinatorLayout coordinatorLayout, V child,
View target, float velocityX, float velocityY,
@ScrollDirection int scrollDirection);
@Override
public boolean onNestedPreFling(CoordinatorLayout coordinatorLayout, V child, View target,
float velocityX, float velocityY) {
return super.onNestedPreFling(coordinatorLayout, child, target, velocityX, velocityY);
}
@Override
public WindowInsetsCompat onApplyWindowInsets(CoordinatorLayout coordinatorLayout, V child,
WindowInsetsCompat insets) {
return super.onApplyWindowInsets(coordinatorLayout, child, insets);
}
@Override
public Parcelable onSaveInstanceState(CoordinatorLayout parent, V child) {
return super.onSaveInstanceState(parent, child);
}
}
import android.content.Context;
import android.content.res.TypedArray;
import android.os.Build;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.support.design.widget.CoordinatorLayout;
import android.support.design.widget.Snackbar;
import android.support.v4.view.ViewCompat;
import android.support.v4.view.ViewPropertyAnimatorCompat;
import android.support.v4.view.animation.LinearOutSlowInInterpolator;
import android.util.AttributeSet;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Interpolator;
public class BottomNavigationBehavior<V extends View> extends VerticalScrollingBehavior<V> {
private static final Interpolator INTERPOLATOR =
new LinearOutSlowInInterpolator();
private final BottomNavigationWithSnackbar mWithSnackBarImpl
= Build.VERSION.SDK_INT >= Build.VERSION_CODES.LOLLIPOP
?
new LollipopBottomNavWithSnackBarImpl() :
new PreLollipopBottomNavWithSnackBarImpl();
private boolean isTablet;
private int mTabLayoutId;
private boolean hidden =
false;
private ViewPropertyAnimatorCompat mOffsetValueAnimator;
private ViewGroup mTabLayout;
private View mTabsHolder;
private int mSnackbarHeight = -
1;
private boolean scrollingEnabled =
true;
private boolean hideAlongSnackbar =
false;
int[] attrsArray =
new int[]{
android.R.attr.id};
public BottomNavigationBehavior() {
super();
}
public BottomNavigationBehavior(Context context, AttributeSet attrs) {
super(context, attrs);
TypedArray a = context.obtainStyledAttributes(attrs,
attrsArray);
mTabLayoutId = a.getResourceId(
0, View.NO_ID);
a.recycle();
}
public static <V extends View> BottomNavigationBehavior<V>
from(@NonNull V view) {
ViewGroup.LayoutParams
params = view.getLayoutParams();
if (!(
params instanceof CoordinatorLayout.LayoutParams)) {
throw new IllegalArgumentException(
"The view is not a child of CoordinatorLayout");
}
CoordinatorLayout.Behavior behavior = ((CoordinatorLayout.LayoutParams)
params)
.getBehavior();
if (!(behavior instanceof BottomNavigationBehavior)) {
throw new IllegalArgumentException(
"The view is not associated with BottomNavigationBehavior");
}
return (BottomNavigationBehavior<V>) behavior;
}
@Override
public boolean
layoutDependsOn(CoordinatorLayout parent, V child, View dependency) {
mWithSnackBarImpl.updateSnackbar(parent, dependency, child);
return dependency instanceof Snackbar.SnackbarLayout;
}
@Override
public void onDependentViewRemoved(CoordinatorLayout parent, V child, View dependency) {
updateScrollingForSnackbar(dependency, child,
true);
super.onDependentViewRemoved(parent, child, dependency);
}
private void updateScrollingForSnackbar(View dependency, V child, boolean enabled) {
if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
scrollingEnabled = enabled;
if (!hideAlongSnackbar && ViewCompat.getTranslationY(child) !=
0) {
ViewCompat.setTranslationY(child,
0);
hidden =
false;
hideAlongSnackbar =
true;
}
else if (hideAlongSnackbar) {
hidden =
true;
animateOffset(child, -child.getHeight());
}
}
}
@Override
public boolean
onDependentViewChanged(CoordinatorLayout parent, V child, View dependency) {
updateScrollingForSnackbar(dependency, child,
false);
return super.onDependentViewChanged(parent, child, dependency);
}
@Override
public boolean
onLayoutChild(CoordinatorLayout parent, V child,
int layoutDirection) {
boolean layoutChild = super.onLayoutChild(parent, child, layoutDirection);
if (mTabLayout ==
null && mTabLayoutId != View.NO_ID) {
mTabLayout = findTabLayout(child);
getTabsHolder();
}
return layoutChild;
}
@Nullable
private ViewGroup
findTabLayout(@NonNull View child) {
if (mTabLayoutId ==
0)
return null;
return (ViewGroup) child.findViewById(mTabLayoutId);
}
@Override
public void onNestedVerticalOverScroll(CoordinatorLayout coordinatorLayout, V child,
@ScrollDirection
int direction,
int currentOverScroll,
int totalOverScroll) {
}
@Override
public void onDirectionNestedPreScroll(CoordinatorLayout coordinatorLayout, V child, View target,
int dx,
int dy,
int[] consumed, @ScrollDirection
int scrollDirection) {
handleDirection(child, scrollDirection);
}
private void handleDirection(V child, @ScrollDirection
int scrollDirection) {
if (!scrollingEnabled)
return;
if (scrollDirection == ScrollDirection.SCROLL_DIRECTION_DOWN && hidden) {
hidden =
false;
animateOffset(child,
0);
}
else if (scrollDirection == ScrollDirection.SCROLL_DIRECTION_UP && !hidden) {
hidden =
true;
animateOffset(child, child.getHeight());
}
}
@Override
protected boolean
onNestedDirectionFling(CoordinatorLayout coordinatorLayout, V child, View target,
float velocityX,
float velocityY,
@ScrollDirection
int scrollDirection) {
handleDirection(child, scrollDirection);
return true;
}
private void animateOffset(final V child, final
int offset) {
ensureOrCancelAnimator(child);
mOffsetValueAnimator.translationY(offset).start();
animateTabsHolder(offset);
}
private void animateTabsHolder(
int offset) {
if (mTabsHolder !=
null) {
offset = offset >
0 ?
0 :
1;
ViewCompat.animate(mTabsHolder).alpha(offset).setDuration(
200).start();
}
}
private void ensureOrCancelAnimator(V child) {
if (mOffsetValueAnimator ==
null) {
mOffsetValueAnimator = ViewCompat.animate(child);
mOffsetValueAnimator.setDuration(
100);
mOffsetValueAnimator.setInterpolator(INTERPOLATOR);
}
else {
mOffsetValueAnimator.cancel();
}
}
private void getTabsHolder() {
if (mTabLayout !=
null) {
mTabsHolder = mTabLayout.getChildAt(
0);
}
}
public boolean
isScrollingEnabled() {
return scrollingEnabled;
}
public void setScrollingEnabled(boolean scrollingEnabled) {
this.scrollingEnabled = scrollingEnabled;
}
public void setHidden(V view, boolean bottomLayoutHidden) {
if (!bottomLayoutHidden && hidden) {
animateOffset(view,
0);
}
else if (bottomLayoutHidden && !hidden) {
animateOffset(view, -view.getHeight());
}
hidden = bottomLayoutHidden;
}
private interface BottomNavigationWithSnackbar {
void updateSnackbar(CoordinatorLayout parent, View dependency, View child);
}
private class PreLollipopBottomNavWithSnackBarImpl implements BottomNavigationWithSnackbar {
@Override
public void updateSnackbar(CoordinatorLayout parent, View dependency, View child) {
if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
if (mSnackbarHeight == -
1) {
mSnackbarHeight = dependency.getHeight();
}
int targetPadding = child.getMeasuredHeight();
int shadow = (
int) ViewCompat.getElevation(child);
ViewGroup.MarginLayoutParams layoutParams = (ViewGroup.MarginLayoutParams) dependency.getLayoutParams();
layoutParams.bottomMargin = targetPadding - shadow;
child.bringToFront();
if (Build.VERSION.SDK_INT < Build.VERSION_CODES.KITKAT) {
child.getParent().requestLayout();
((View) child.getParent()).invalidate();
}
}
}
}
private class LollipopBottomNavWithSnackBarImpl implements BottomNavigationWithSnackbar {
@Override
public void updateSnackbar(CoordinatorLayout parent, View dependency, View child) {
if (!isTablet && dependency instanceof Snackbar.SnackbarLayout) {
if (mSnackbarHeight == -
1) {
mSnackbarHeight = dependency.getHeight();
}
int targetPadding = (mSnackbarHeight +
child.getMeasuredHeight());
dependency.setPadding(dependency.getPaddingLeft(),
dependency.getPaddingTop(), dependency.getPaddingRight(), targetPadding
);
}
}
}
}
