RecyclerView scoll落后

Question

我在RecyclerView内使用ViewPager，而ViewPager在NestedScrollView内，问题是滚动滞后，虽然不大，但并不完美。 我已经阅读了Android Document关于渲染性能的信息，而我的onBind方法大约花费了1毫秒或更短的时间，而我的customImageView中的setImageBitmap舍入位图大约需要2毫秒的时间。 从文档来看，我只需要16毫秒即可绘制框架，而我的时间却远远少于16毫秒，而且我很确定其他部分不会做任何与UI相关的事情。那么我该如何发现问题并解决问题呢？

我的活动布局：

<android.support.design.widget.CoordinatorLayout 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"
android:background="@color/gray_dark"
android:fitsSystemWindows="true"
android:orientation="vertical">

<android.support.design.widget.AppBarLayout
    android:id="@+id/app_bar"
    android:layout_width="match_parent"
    android:layout_height="@dimen/app_bar_height"
    android:fitsSystemWindows="true">

    <android.support.design.widget.CollapsingToolbarLayout
        android:id="@+id/toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:fitsSystemWindows="true"
        android:minHeight="56dp"
        app:contentScrim="@color/colorTransparent"
        app:layout_scrollFlags="scroll|exitUntilCollapsed"
        app:statusBarScrim="@color/colorTransparent">

        <ImageView
            android:id="@+id/headerImage"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:adjustViewBounds="true"
            android:contentDescription="@string/header_image"
            android:fitsSystemWindows="true"
            android:foreground="@color/gray_alpha"
            android:scaleType="centerCrop"
            app:layout_collapseMode="parallax" />


        <android.support.design.widget.TabLayout
            android:id="@+id/tablayout"
            android:layout_width="match_parent"
            android:layout_height="56dp"
            android:layout_alignParentBottom="true"
            android:layout_gravity="bottom"
            app:layout_collapseMode="pin"
            app:tabIndicatorColor="@color/pink"
            app:tabMode="scrollable"
            app:tabSelectedTextColor="@color/pink"
            app:tabTextColor="@color/white" />

    </android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>


<android.support.v4.widget.NestedScrollView
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fillViewport="true"
    app:layout_behavior="@string/appbar_scrolling_view_behavior">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/white"
        android:orientation="vertical">

        <android.support.v4.view.ViewPager
            android:id="@+id/viewPager"
            android:layout_width="match_parent"
            android:layout_height="wrap_content" />

    </LinearLayout>

</android.support.v4.widget.NestedScrollView>


</android.support.design.widget.CoordinatorLayout>

和我的片段布局代码：

<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:id="@+id/recycler"
android:layout_height="match_parent"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
android:background="@color/white"
android:orientation="vertical">

</android.support.v7.widget.RecyclerView>

我的ViewPager适配器是如此简单，只附加片段：

class MainPagerAdapter(fm: FragmentManager, val listener: FragmentGetter) : FragmentPagerAdapter(fm) {

private val arr = SparseArray<Fragment>()

override fun getItem(position: Int): Fragment {
    return when (position) {
        0 -> {
            if (arr[0] == null) arr.append(0, listener.getBeshnoFragment());arr[0]
        }
        1 -> {
            if (arr[1] == null) arr.append(1, listener.getPlaylistFragment()); arr[1]
        }
        2 -> {
            if (arr[2] == null) arr.append(2, listener.getMusicFragment())
            (arr[2] as MusicFragment).load(ALL_MUSICS, null)
            arr[2]
        }
        3 -> {
            if (arr[3] == null) arr.append(3, listener.getAlbumFragment()); arr[3]
        }
        4 -> {
            if (arr[4] == null) arr.append(4, listener.getArtistFragment()); arr[4]
        }
        else -> {
            if (arr[5] == null) arr.append(5, listener.getFoldersFragment()); arr[5]
        }
    }
}

override fun getPageTitle(position: Int): CharSequence? {
    return listener.getPageTitle(position)
}

override fun getCount(): Int {
    return TabLayoutData.items.size
}

interface FragmentGetter {
    fun getBeshnoFragment(): BeshnoFragment
    fun getMusicFragment(): MusicFragment
    fun getAlbumFragment(): AlbumFragment
    fun getArtistFragment(): ArtistFragment
    fun getPlaylistFragment(): PlaylistFragment
    fun getFoldersFragment(): FoldersFragment
    fun getPageTitle(pos: Int): String
}

}

这是我的RecyclerView适配器代码：

override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
    val holder = ViewHolder(
            LayoutInflater.from(parent.context).inflate(
                    R.layout.music_list_item, parent, false
            )
    )
    holder.menu.setOnClickListener {
        val pos = holder.adapterPosition
        if (menu != null) menu!!.dismiss()
        mCurrentMusic = musics[pos]
        menu = PopupMenu(holder.itemView.context, holder.menu)
        buildMenu()
        menu!!.show()
    }
    holder.itemView.setOnClickListener {
        val pos = holder.adapterPosition
        listener.playMusic(musics[pos])
    }

    holder.image.radius = UIUtils.convertDpToPixel(8f, parent.context).toInt()

    return holder
}

override fun onBindViewHolder(holder: ViewHolder, position: Int) {
    val t1 = System.currentTimeMillis()
    val music = musics[position]
    holder.name.text = music.title
    holder.album.text = music.album
    val path = music.imagePath
    MusicUtils.setMusicImageAsync(path, holder.image, MusicUtils.QUALITY_MED)
    Log.d(javaClass.simpleName, "adapter bind time: ${System.currentTimeMillis() - t1}")//this time takes less than 1 miliseconds
}

MusicUtils.setMusicImageAsync代码是：

fun setMusicImageAsync(album_ART: String?, cover: ImageView, quality: Int) {
        if (album_ART == null || album_ART.isEmpty() || !File(album_ART).exists()) {
            setPlaceHolder(cover)
            return
        }

        ImageLoaderTask(quality) { // on post execute
            if (it == null) {
                setPlaceHolder(cover)
            } else {
                val t1 = System.currentTimeMillis()
                cover.setImageBitmap(it)
                cover.setPadding(0, 0, 0, 0)
                Log.d("MusicImageLoader", "time is: ${System.currentTimeMillis() - t1}") //this time takes about 2 miliseconds
            }
        }.execute(album_ART)
    }

我还为RecyclerView使用了绘图缓存，但滚动滞后。

Answer 1

我认为这可以帮助您

recyclerView.setNestedScrollingEnabled(false)