Question

好的，我的问题类似于Background image in ListView entries spontaneously disappearing

但是这个问题是通过在普通的ImageView上使用setImageResource来解决的，但是我希望动画存在于列表的所有元素上，如果没有允许动画运行的自定义ImageView类，就无法做到这一点。有没有人知道为什么这些图像在列表视图中滚动后消失了，也许这是如何解决的？非常感谢！

这是我的ListAdapter：

    package com.mmgworldwide.layout.listadapters;

import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.ArrayList;

import com.mmgworldwide.R;
import com.mmgworldwide.customviews.SpinLoadingAnim;
import com.mmgworldwide.data.FWREvent;
import com.mmgworldwide.data.ImageThreadLoader;
import com.mmgworldwide.data.ImageThreadLoader.ImageLoadedListener;
import com.mmgworldwide.layout.ListDivider;
import com.mmgworldwide.data.Personality;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.drawable.AnimationDrawable;
import android.graphics.drawable.Drawable;
import android.text.SpannableString;
import android.text.style.UnderlineSpan;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.Animation;
import android.view.animation.AnimationUtils;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.TextView;

public class PersonalityListAdapter extends ArrayAdapter<Object>{

    private Context parentContext;
    public ArrayList<Object> items_list_ref;
    private ImageThreadLoader imageLoader = new ImageThreadLoader();

    public PersonalityListAdapter(Context context, int resource, int textViewResourceId, ArrayList<Object> items_list) {
        super(context, resource, textViewResourceId, items_list);
        items_list_ref = items_list;
        parentContext = context;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        Object node = (Object) items_list_ref.get(position);
        LayoutInflater inflater = (LayoutInflater) parentContext.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        if(node instanceof ListDivider){
            //make new div bar
            View div = inflater.inflate(R.layout.list_bar, parent, false);
            TextView div_label = (TextView) div.findViewById(R.id.div_label);
            div_label.setText(((ListDivider) node).label.toUpperCase());
            return div;
        }

        View row = inflater.inflate(R.layout.picture_list, parent, false);

        TextView name_txt = (TextView) row.findViewById(R.id.name_txt);
        TextView title_txt = (TextView) row.findViewById(R.id.title_txt);
        final ImageView portrait_img = (ImageView) row.findViewById(R.id.portrait);
        final ImageView load_cnt = (ImageView) row.findViewById(R.id.portrait_loadDisplay);

        name_txt.setText(((Personality) node).getName());
        SpannableString title_underlined = new SpannableString(((Personality) node).getTitle());
        title_underlined .setSpan(new UnderlineSpan(), 0, title_underlined.length(), 0);
        title_txt.setText(title_underlined);

        load_cnt.setVisibility(View.VISIBLE);

        return row;
    }

这是我的自定义ImageView类

package com.mmgworldwide.customviews;

import android.R;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.AnimationDrawable;
import android.util.AttributeSet;
import android.util.Log;
import android.widget.ImageView;

public class SpinLoadingAnim extends ImageView{

    AnimationDrawable animation;
    private final Integer FRAME_SPEED = 20;

    public SpinLoadingAnim(Context context, AttributeSet attrs){
        super(context, attrs);

         //setBackgroundColor(Color.GREEN);


        animation = new AnimationDrawable();
        animation.addFrame(context.getResources().getDrawable(com.mmgworldwide.R.drawable.spinner_00000), FRAME_SPEED);
        animation.addFrame(context.getResources().getDrawable(com.mmgworldwide.R.drawable.spinner_00001), FRAME_SPEED);
        animation.addFrame(context.getResources().getDrawable(com.mmgworldwide.R.drawable.spinner_00002), FRAME_SPEED);
        animation.addFrame(context.getResources().getDrawable(com.mmgworldwide.R.drawable.spinner_00003), FRAME_SPEED);

        animation.setOneShot(false);

        this.setBackgroundDrawable(animation);
        this.post(new Starter());
    }

    class Starter implements Runnable {
        public void run() {
            animation.start();

        }

    }

这是我的布局XML

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="match_parent"
  android:layout_height="wrap_content"
  android:background="#FFFFFF"
  android:gravity="center_vertical"
  android:paddingTop="10dp"
  android:paddingBottom="10dp"
  android:paddingLeft="10dp"
  android:paddingRight="10dp">
    <ImageView android:layout_width="60dp" android:layout_height="60dp" android:id="@+id/portrait" android:layout_centerVertical="true"></ImageView>


    <com.mmgworldwide.customviews.SpinLoadingAnim
        android:id="@+id/portrait_loadDisplay" 
        android:layout_width="20dp" android:layout_height="20dp"
        android:background="#939598"
        android:layout_centerVertical="true" android:layout_marginLeft="20dp"
        android:layout_alignParentBottom="true" 
        android:layout_alignParentLeft="true" />



    <ImageView android:layout_height="wrap_content" android:layout_width="wrap_content" android:layout_centerVertical="true" android:id="@+id/arrow" android:src="@drawable/list_arrow" android:layout_alignParentRight="true"></ImageView>
    <LinearLayout android:layout_toRightOf="@id/portrait" android:layout_toLeftOf="@id/arrow" android:layout_centerVertical="true" android:orientation="vertical" android:layout_height="wrap_content" android:layout_width="wrap_content" android:baselineAligned="true" android:paddingLeft="15dp" android:paddingRight="15dp">
        <TextView android:text="CHEF NAME" android:id="@+id/name_txt" android:layout_width="wrap_content" android:textColor="#000000" android:textStyle="bold" 
            android:layout_height="wrap_content" android:paddingBottom="2dp" android:textSize="15sp"></TextView>
        <TextView android:text="Chef Title" android:id="@+id/title_txt" android:layout_width="wrap_content" android:textColor="#000000" 
            android:layout_height="wrap_content" android:textSize="13sp"></TextView>
    </LinearLayout>


</RelativeLayout>

每隔5个“预加载器”图形仍在消失，但感谢Michele，这已经帮助了很多，并使事情变得更加清洁。

package com.mmgworldwide.layout;

import java.util.ArrayList;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.ImageView;
import android.widget.ListView;
import android.widget.TextView;

import com.mmgworldwide.R;
import com.mmgworldwide.data.DataConnection;
import com.mmgworldwide.data.ImageThreadLoader;
import com.mmgworldwide.data.Personality;

//http://code.google.com/p/and-conference/source/browse/trunk/src/com/totsp/conference/PresentationList.java

public class Personalities extends Activity{

    private ListView listView;
    private ArrayAdapter<Object> adapter;

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.personalities);

        listView = (ListView) findViewById(R.id.personalitylistview);
        listView.setDrawingCacheEnabled(false);


        addListAdapter();

        setFooterView("more");
    }

    private void addListAdapter(){
        ArrayList<Object> adaptList = makeAdaptList();

        adapter = new PersonalityListAdapter(this, 0, adaptList);
        listView.setAdapter(adapter);
    }

    private ArrayList<Object> makeAdaptList(){
        ArrayList<Object> adaptList = new ArrayList<Object>();
        String currentDivDate = " ";
        for(Personality aEvent : DataConnection.fwrInfo.getPersonalityList()){
            adaptList.add(aEvent);
        }

        return adaptList;
    }

    private void setFooterView(String highlight){
        Footer footer = (Footer) findViewById(R.id.footer);
        footer.setHighlight(highlight);
    }

    //***********************************************************************************************************************************************
    //ViewHolder
    //***********************************************************************************************************************************************
    static class ViewHolder {
        private TextView tView1;
        private TextView tView2;
        private ImageView iView1;
    }

    //***********************************************************************************************************************************************
    //PersonalityListAdapter
    //***********************************************************************************************************************************************
    private class PersonalityListAdapter extends ArrayAdapter<Object>{

        LayoutInflater vi = (LayoutInflater) Personalities.this.getSystemService(Context.LAYOUT_INFLATER_SERVICE);

        private Context parentContext;
        public ArrayList<Object> items_list_ref;
        private ImageThreadLoader imageLoader = new ImageThreadLoader();

        public PersonalityListAdapter(final Context context, final int resId, final ArrayList<Object> presentations) {
            super(context, resId, presentations);
            this.items_list_ref = presentations;
            parentContext = context;
        }

        @Override
    public int getCount() {
        return items_list_ref.size();
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

        @Override
        public View getView(int position, View convertView, ViewGroup parent) {
            //Log.d("TROY", "adding view");
            View v = convertView;

            if (v == null) {
                //Log.d("TROY", "inflation");
                v = vi.inflate(R.layout.picture_list, parent, false);
                ViewHolder viewHolder = new ViewHolder();

                viewHolder.tView1 = (TextView) v.findViewById(R.id.name_txt);
                viewHolder.tView2 = (TextView) v.findViewById(R.id.title_txt);
                viewHolder.iView1 = (ImageView) v.findViewById(R.id.portrait);

                v.setTag(viewHolder);
            }

            Object p = items_list_ref.get(position);

            if (p != null) {
                //Log.d("TROY", "setting stuff");
                ViewHolder viewHolder = (ViewHolder) v.getTag();
                viewHolder.tView1.setText("hi");
            }

            return v;
        }
    }

}

这是一个正在发生的事情的屏幕截图（为什么没有显示第5个预载图形？）：

enter image description here

编辑------

好的，我添加了getCount和getItemId覆盖，但仍然有相同的问题，我想我会从头开始一个项目并再次尝试使用listView，同样的问题，我已经建立了一个测试项目来证明这令人沮丧问题。在这个测试中，我甚至没有向适配器添加任何数据，并且动画仅适用于其中一些，就像我的主项目一样。

非常感谢你的耐心和帮助米歇尔，你一直非常棒。

http://faceonfire.com/temp/ListTester.zip

Answer 1

ListViews是高度优化的数据结构。您应该使用ViewHolders遵守列表规则并使系统的生命更容易。

当您滚动ListView时，系统会缓存持有者中的项目以提高性能。阅读How to load the Listview "smoothly" in android

你也可以尝试设置

yourListView.setDrawingCacheEnabled(false);

编辑：确定比尝试使用xml设置动画

http://developer.android.com/reference/android/graphics/drawable/AnimationDrawable.html

喜欢：

<!-- Animation frames are wheel0.png -- wheel5.png files inside the
 res/drawable/ folder -->
 <animation-list android:id="selected" android:oneshot="false">
    <item android:drawable="@drawable/wheel0" android:duration="50" />
    <item android:drawable="@drawable/wheel1" android:duration="50" />
    <item android:drawable="@drawable/wheel2" android:duration="50" />
    <item android:drawable="@drawable/wheel3" android:duration="50" />
    <item android:drawable="@drawable/wheel4" android:duration="50" />
    <item android:drawable="@drawable/wheel5" android:duration="50" />
 </animation-list>

edit2：请尝试实现getCount和getItemId，你的List的boundarys有问题，也许android无法找到列表滚动后的位置。哦，你可以用随机数据来测试它，而不是一直都是相同的项目（也许是一些奇怪的哈希（默认的getItemId实现？），它总是与相同的项目内容相同）。例如：

@Override
public int getCount() {
    return <yourdatastructure>.getSize();
}

@Override
public long getItemId(int position) {
    return position;
}

自定义图像视图从ListAdapter中消失

1 个答案: