话不多说先看效果:
小米商店效果图:
个人实现效果图:
前几天小米手机应用商店更新,看到这样的效果,之后看到其他app也有这样的效果,闲来无事搞一下。
首先怎么实现呢?
思路:不考虑滑动,先要实现全屏,而且上方状态栏显示,之后重写Scrollview,监听滑动事件,当滑动一定距离时不断更新action bar的透明度。
第一步实现全屏:全屏样式实现参考
主要代码:
protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState) supportRequestWindowFeature(Window.FEATURE_ACTION_BAR_OVERLAY) setContentView(R.layout.activity_nac) if (Build.VERSION.SDK_INT >= 21) { View decorView = getWindow().getDecorView() int option = View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE decorView.setSystemUiVisibility(option) getWindow().setNavigationBarColor(Color.TRANSPARENT) getWindow().setStatusBarColor(Color.TRANSPARENT) } ActionBar actionBar = getSupportActionBar() actionBar.hide() }
然后就是重写ScrollView:
import android.content.Context;import android.util.AttributeSet;import android.util.Log;import android.util.LogPrinter;import android.view.MotionEvent;import android.view.View;import android.widget.ScrollView;/** * Created by ZHL on 2016/12/19. */public class FadingScrollView extends ScrollView { private static String TAG = "-----------FadingScrollView----------"; private View fadingView; private View fadingHeightView; private int oldY; private int fadingHeight = 500; public FadingScrollView(Context context) { super(context); } public FadingScrollView(Context context, AttributeSet attrs) { super(context, attrs); } public FadingScrollView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public void setFadingView(View view){this.fadingView = view;} public void setFadingHeightView(View v){this.fadingHeightView = v;} @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if(fadingHeightView != null) fadingHeight = fadingHeightView.getMeasuredHeight(); } @Override protected void onScrollChanged(int l, int t, int oldl, int oldt) { super.onScrollChanged(l, t, oldl, oldt); float fading = t>fadingHeight ? fadingHeight : (t > 30 ? t : 0); updateActionBarAlpha( fading / fadingHeight); } void updateActionBarAlpha(float alpha){ try { setActionBarAlpha(alpha); } catch (Exception e) { e.printStackTrace(); } } public void setActionBarAlpha(float alpha) throws Exception{ if(fadingView==null){ throw new Exception("fadingView is null..."); } fadingView.setAlpha(alpha); }}
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布局文件:
<?xml version="1.0" encoding="utf-8"?><RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_nac" android:layout_width="match_parent" android:layout_height="match_parent" tools:context="com.qienanxiang.activity.NacActivity"> <com.qienanxiang.widget.FadingScrollView android:id="@+id/nac_root" android:overScrollMode="never" android:scrollbars="none" android:layout_width="match_parent" android:layout_height="wrap_content"> <LinearLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="vertical"> <ImageView android:id="@+id/nac_image" android:layout_width="match_parent" android:layout_height="300dp" android:scaleType="fitXY" android:src="@mipmap/icon_bg2"/> <TextView android:layout_width="match_parent" android:layout_height="100dp" android:gravity="center" android:textSize="22dp" android:text="其他布局:最好是listview、recycleView"/> <! 建议这里放置listview 或者 recycleView ,LZ为了省事直接放了多个textview来撑起ScrollView。。。 </LinearLayout> </com.qienanxiang.widget.FadingScrollView> <FrameLayout android:layout_width="match_parent" android:layout_height="70dp" android:background="@android:color/transparent"> <View android:id="@+id/nac_layout" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@color/colorPrimary"/> <TextView android:layout_marginRight="@dimen/activity_horizontal_margin" android:layout_marginLeft="@dimen/activity_horizontal_margin" android:layout_marginTop="25dp" android:layout_marginBottom="10dp" android:layout_width="match_parent" android:layout_height="match_parent" android:gravity="center" android:background="#FFFFFF" android:text="自定义布局"/> </FrameLayout></RelativeLayout>
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activity 使用:
public class NacActivity extends AppCompatActivity { private View layout; private FadingScrollView fadingScrollView; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); supportRequestWindowFeature(Window.FEATURE_ACTION_BAR_OVERLAY); setContentView(R.layout.activity_nac); if (Build.VERSION.SDK_INT >= 21) { View decorView = getWindow().getDecorView(); int option = View.SYSTEM_UI_FLAG_LAYOUT_HIDE_NAVIGATION | View.SYSTEM_UI_FLAG_LAYOUT_FULLSCREEN | View.SYSTEM_UI_FLAG_LAYOUT_STABLE; decorView.setSystemUiVisibility(option); getWindow().setNavigationBarColor(Color.TRANSPARENT); getWindow().setStatusBarColor(Color.TRANSPARENT); } ActionBar actionBar = getSupportActionBar(); actionBar.hide(); layout = findViewById(R.id.nac_layout); layout.setAlpha(0); fadingScrollView = (FadingScrollView)findViewById(R.id.nac_root); fadingScrollView.setFadingView(layout); fadingScrollView.setFadingHeightView(findViewById(R.id.nac_image)); }}
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说一下上方所谓的action bar,这里并没有直接使用actionbar,而是使用自己的布局,因为使用action bar ,就要在activity中对它进行声明设置一些属性,而要实现状态栏透明 这样的效果,代码中已经设置actionbar hide,可能会起冲突,所以在写demo时就直接放弃了actionbar。
这样就大功告成了,如果有说的不正确的地方,欢迎留言一起讨论!