Android 滑动Scrollview标题栏渐变效果(仿京东toolbar)

Scrollview标题栏滑动渐变

/** * @ClassName MyScrollView * @Author Rex * @Date 2021/1/27 17:38 */public class MyScrollView extends ScrollView { private TranslucentListener mTranslucentListener; public void setTranslucentListener(TranslucentListener translucentListener) { this.mTranslucentListener = translucentListener; } public MyScrollView(Context context) { this(context, null); } public MyScrollView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if (mTranslucentListener != null) { //ScrollView滑出高度 int scrollY = getScrollY(); //屏幕高度 int screenHeight = getContext().getResources().getDisplayMetrics().heightPixels; //有效滑动距离为屏幕2分之一 // alpha = 滑动高度/（screenHeight/3f） if (scrollY <= screenHeight / 2f) { Log.d('>>>>>>>>>', 'ScrollView划出高度：' + scrollY); Log.d('>>>>>>>>>', '屏幕高度：' + screenHeight); Log.d('>>>>>>>>>', '渐变值：' + (0 + scrollY / (screenHeight / 4f))); // 渐变的过程 1~0 mTranslucentListener.onTranslucent(0 + scrollY / (screenHeight /4f)); } } }}

Activity 设置

public class ToolbarActivity extends AppCompatActivity implements TranslucentListener { private Toolbar mToolBar; private MyScrollView mScrollView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_toobar); mToolBar = findViewById(R.id.id_toolbar); mScrollView = findViewById(R.id.id_scrollView); //初始化渐变为0 mToolBar.setAlpha(0); //设置渐变回调 mScrollView.setTranslucentListener(this); } @Override public void onTranslucent(float alpha) { mToolBar.setAlpha(alpha); }}

渐变回调接口

/** * @ClassName TranslucentListener * @Author rex * @Date 2021/1/27 17:38 */public interface TranslucentListener { /** * 透明度的回调监听 * * @param alpha 0~1 透明度 */ public void onTranslucent(float alpha);}

布局文件

<RelativeLayout xmlns:android='http://schemas.android.com/apk/res/android' xmlns:app='http://schemas.android.com/apk/res-auto' android:layout_width='match_parent' android:layout_height='match_parent'> <com.rex.rxhttpdemo.MyScrollView android: android:layout_width='match_parent' android:layout_height='match_parent' android:clipChildren='false' android:clipToPadding='false' > <LinearLayout android:layout_width='match_parent' android:layout_height='match_parent' android:orientation='vertical'> <Button android: android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button0' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button1' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button2' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button3' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button4' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button5' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> <Button android:layout_width='match_parent' android:layout_height='match_parent' android:text='Button' /> </LinearLayout> </com.rex.rxhttpdemo.MyScrollView> <androidx.appcompat.widget.Toolbar android: android:layout_width='match_parent' android:layout_height='wrap_content' android:background='@color/colorAccent' app:title='title' /></RelativeLayout>

下滑显示上滑渐变消失

/** * @ClassName MyScrollView * @Author Rex * @Date 2021/1/27 17:38 */public class MyScrollView extends ScrollView { private TranslucentListener mTranslucentListener; public void setTranslucentListener(TranslucentListener translucentListener) { this.mTranslucentListener = translucentListener; } public MyScrollView(Context context) { this(context, null); } public MyScrollView(Context context, AttributeSet attrs) { this(context, attrs, 0); } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); if (mTranslucentListener != null) { //ScrollView滑出高度 int scrollY = getScrollY(); //屏幕高度 int screenHeight = getContext().getResources().getDisplayMetrics().heightPixels; //有效滑动距离为屏幕2分之一 // alpha = 滑动高度/（screenHeight/3f） if (scrollY <= screenHeight / 2f) { Log.d('>>>>>>>>>', 'ScrollView划出高度：' + scrollY); Log.d('>>>>>>>>>', '屏幕高度：' + screenHeight); Log.d('>>>>>>>>>', '渐变值：' + (1 - scrollY / (screenHeight / 4f))); // 渐变的过程 1~0 mTranslucentListener.onTranslucent(1 - scrollY / (screenHeight /4f)); } } }}

注意: 这里只是更改了 mTranslucentListener.onTranslucent 里的 渐变值

Activty 里 把初始化 mToolBar.setAlpha(0); 去掉

XML

<com.rex.rxhttpdemo.MyScrollView android: android:layout_width='match_parent' android:layout_height='match_parent' android:clipChildren='false' android:clipToPadding='false' android:paddingTop='?attr/actionBarSize' > </com.rex.rxhttpdemo.MyScrollView>

xml 加入 paddingtop .

注意:android:clipChildren=“false”android:clipToPadding='false'这俩个属性 如果不加会有留白

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