这篇文章主要介绍了Android中如何使用CoordinatorLayout+AppBarLayout实现拉伸顶部图片功能，具有一定借鉴价值，感兴趣的朋友可以参考下，希望大家阅读完这篇文章之后大有收获，下面让小编带着大家一起了解一下。
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直接上布局文件代码
上java代码
package com.ce.myscrollimg;import androidx.appcompat.app.AppCompatActivity;import androidx.fragment.app.Fragment;import androidx.viewpager.widget.ViewPager;import android.graphics.Typeface;import android.os.Bundle;import android.util.TypedValue;import android.view.LayoutInflater;import android.view.View;import android.view.ViewGroup;import android.widget.LinearLayout;import android.widget.TextView;import com.google.android.material.tabs.TabLayout;import java.util.ArrayList;import java.util.List;public class MainActivity extends AppCompatActivity { private TabLayout toolbar_tab; private NoScrollViewPager vp_content; private ViewPagerAdapter vpAdapter; private List listFragment = new ArrayList<>(); @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); initView(); } //初始化view private void initView(){ //tab toolbar_tab = findViewById(R.id.toolbar_tab); // vp_content = findViewById(R.id.vp_content); vpAdapter = new ViewPagerAdapter(getSupportFragmentManager(),listFragment); vp_content.setAdapter(vpAdapter); vp_content.setOffscreenPageLimit(2); toolbar_tab.setupWithViewPager(vp_content); for(int i=0;i<12;i++){ listFragment.add(CeshiFragment.newInstance("第"+i+"页")); } vpAdapter.notifyDataSetChanged(); for(int i=0;i重点在于设置AppBarLayout的Behavior这里自定义AppBarLayoutOverScrollViewBehavior，下面贴出代码
package com.ce.myscrollimg;import android.animation.Animator;import android.animation.ValueAnimator;import android.content.Context;import android.util.AttributeSet;import android.view.View;import android.view.ViewGroup;import androidx.appcompat.widget.Toolbar;import androidx.coordinatorlayout.widget.CoordinatorLayout;import androidx.core.view.ViewCompat;import com.google.android.material.appbar.AppBarLayout;/** * Created by gjm on 2017/5/24. * 目前包括的事件： * 图片放大回弹 * 个人信息布局的top和botoom跟随图片位移 * toolbar背景变色 */public class AppBarLayoutOverScrollViewBehavior extends AppBarLayout.Behavior { private static final String TAG = "overScroll"; private static final String TAG_TOOLBAR = "toolbar"; private static final String TAG_MIDDLE = "middle"; private static final float TARGET_HEIGHT = 1500; private View mTargetView; private int mParentHeight; private int mTargetViewHeight; private float mTotalDy; private float mLastScale; private int mLastBottom; private boolean isAnimate; private Toolbar mToolBar; private ViewGroup middleLayout;//个人信息布局 private int mMiddleHeight; private boolean isRecovering = false;//是否正在自动回弹中 private final float MAX_REFRESH_LIMIT = 0.3f;//达到这个下拉临界值就开始刷新动画 public AppBarLayoutOverScrollViewBehavior() { } public AppBarLayoutOverScrollViewBehavior(Context context, AttributeSet attrs) { super(context, attrs); } @Override public boolean onLayoutChild(CoordinatorLayout parent, AppBarLayout abl, int layoutDirection) { boolean handled = super.onLayoutChild(parent, abl, layoutDirection); if (mToolBar == null) { mToolBar = parent.findViewWithTag(TAG_TOOLBAR); } if (middleLayout == null) { middleLayout = (ViewGroup) parent.findViewWithTag(TAG_MIDDLE); } // 需要在调用过super.onLayoutChild()方法之后获取 if (mTargetView == null) { mTargetView = parent.findViewById(R.id.iv_bg); if (mTargetView != null) { initial(abl); } } abl.addOnOffsetChangedListener(new AppBarLayout.OnOffsetChangedListener() { @Override public final void onOffsetChanged(AppBarLayout appBarLayout, int i) { mToolBar.setAlpha(Float.valueOf(Math.abs(i)) / Float.valueOf(appBarLayout.getTotalScrollRange())); } }); return handled; } @Override public boolean onStartNestedScroll(CoordinatorLayout parent, AppBarLayout child, View directTargetChild, View target, int nestedScrollAxes, int x) { isAnimate = true; if (target instanceof DisInterceptNestedScrollView) return true;//这个布局就是middleLayout return super.onStartNestedScroll(parent, child, directTargetChild, target, nestedScrollAxes,x); } @Override public void onNestedPreScroll(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, int dx, int dy, int[] consumed, int x) { if (!isRecovering) { if (mTargetView != null && ((dy < 0 && child.getBottom() >= mParentHeight) || (dy > 0 && child.getBottom() > mParentHeight))) { scale(child, target, dy); return; } } super.onNestedPreScroll(coordinatorLayout, child, target, dx, dy, consumed,x); } @Override public boolean onNestedPreFling(CoordinatorLayout coordinatorLayout, AppBarLayout child, View target, float velocityX, float velocityY) { if (velocityY > 100) {//当y速度>100,就秒弹回 isAnimate = false; } return super.onNestedPreFling(coordinatorLayout, child, target, velocityX, velocityY); } @Override public void onStopNestedScroll(CoordinatorLayout coordinatorLayout, AppBarLayout abl, View target, int x) { recovery(abl); super.onStopNestedScroll(coordinatorLayout, abl, target,x); } private void initial(AppBarLayout abl) { abl.setClipChildren(false); mParentHeight = abl.getHeight(); mTargetViewHeight = mTargetView.getHeight(); mMiddleHeight = middleLayout.getHeight(); } private void scale(AppBarLayout abl, View target, int dy) { mTotalDy += -dy; mTotalDy = Math.min(mTotalDy, TARGET_HEIGHT); mLastScale = Math.max(1f, 1f + mTotalDy / TARGET_HEIGHT); ViewCompat.setScaleX(mTargetView, mLastScale); ViewCompat.setScaleY(mTargetView, mLastScale); mLastBottom = mParentHeight + (int) (mTargetViewHeight / 2 * (mLastScale - 1)); abl.setBottom(mLastBottom); target.setScrollY(0); middleLayout.setTop(mLastBottom - mMiddleHeight); middleLayout.setBottom(mLastBottom); if (onProgressChangeListener != null) { float progress = Math.min((mLastScale - 1) / MAX_REFRESH_LIMIT, 1);//计算0~1的进度 onProgressChangeListener.onProgressChange(progress, false); } } public interface onProgressChangeListener { /** * 范围 0~1 * * @param progress * @param isRelease 是否是释放状态 */ void onProgressChange(float progress, boolean isRelease); } public void setOnProgressChangeListener(AppBarLayoutOverScrollViewBehavior.onProgressChangeListener onProgressChangeListener) { this.onProgressChangeListener = onProgressChangeListener; } onProgressChangeListener onProgressChangeListener; private void recovery(final AppBarLayout abl) { if (isRecovering) return; if (mTotalDy > 0) { isRecovering = true; mTotalDy = 0; if (isAnimate) { ValueAnimator anim = ValueAnimator.ofFloat(mLastScale, 1f).setDuration(200); anim.addUpdateListener( new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { float value = (float) animation.getAnimatedValue(); ViewCompat.setScaleX(mTargetView, value); ViewCompat.setScaleY(mTargetView, value); abl.setBottom((int) (mLastBottom - (mLastBottom - mParentHeight) * animation.getAnimatedFraction())); middleLayout.setTop((int) (mLastBottom - (mLastBottom - mParentHeight) * animation.getAnimatedFraction() - mMiddleHeight)); if (onProgressChangeListener != null) { float progress = Math.min((value - 1) / MAX_REFRESH_LIMIT, 1);//计算0~1的进度 onProgressChangeListener.onProgressChange(progress, true); } } } ); anim.addListener(new Animator.AnimatorListener() { @Override public void onAnimationStart(Animator animation) { } @Override public void onAnimationEnd(Animator animation) { isRecovering = false; } @Override public void onAnimationCancel(Animator animation) { } @Override public void onAnimationRepeat(Animator animation) { } }); anim.start(); } else { ViewCompat.setScaleX(mTargetView, 1f); ViewCompat.setScaleY(mTargetView, 1f); abl.setBottom(mParentHeight); middleLayout.setTop(mParentHeight - mMiddleHeight);// middleLayout.setBottom(mParentHeight); isRecovering = false; if (onProgressChangeListener != null) onProgressChangeListener.onProgressChange(0, true); } } }}感谢你能够认真阅读完这篇文章，希望小编分享的“Android中如何使用CoordinatorLayout+AppBarLayout实现拉伸顶部图片功能”这篇文章对大家有帮助，同时也希望大家多多支持创新互联，关注创新互联行业资讯频道，更多相关知识等着你来学习!
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