How to use CoordinatorLayout+AppBarLayout to realize the function of stretching the top picture in Android

This article mainly introduces how to use CoordinatorLayout+AppBarLayout in Android to achieve the function of stretching the top picture, which has a certain reference value, and interested friends can refer to it. I hope you can learn a lot after reading this article.

Go directly to the layout file code

Java code

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 ();} / / initialize 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 iTunes 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) {/ / when y speed > 100, 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); / / calculate the progress of onProgressChangeListener.onProgressChange (progress, false) }} public interface onProgressChangeListener {/ * * @ param progress * @ param isRelease is released * / 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); / / calculate the progress of 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) Thank you for reading this article carefully. 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