android viewflow 从 sdcard 刷卡图像

Question

我正在做一个将一些图像保存到 sdcard 的项目，现在我必须创建 View 流来显示这些图像。我通过 sdCard 的 Id 获取图像，我现在的问题是如何在不同图像之间滑动。这是我正在使用的代码:

import java.io.File;
import java.util.ArrayList;

import android.app.Activity;
import android.content.Intent;
import android.content.res.Configuration;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageButton;

public class Cards extends Activity {

    public Cursor cursor;
    int position;
    int indexxx;
    Bitmap b;
    int objectId;
    int cardsId;

    private ViewFlow viewFlow;
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.circle_layout); 
        UserDatabaseHelper userDbHelper = new UserDatabaseHelper(this, null, 1);
        userDbHelper.initialize(this);


        final int cardId = getIntent().getIntExtra("card_id",0);
        Log.i("Card Id ","Card Id : "+cardId);
        final int collId = getIntent().getIntExtra("collection_id",0);
        Log.i("Collection Id ","Collection Id : "+collId);

        position = getIntent().getIntExtra("position",0);
        Log.i("position","position : "+position);

        String cardSQL = "SELECT cm.objectId "+
         "FROM cardmedias AS cm "+
         "INNER JOIN cards AS cd "+
         "ON (cm.cardId = cd.objectId) "+
         "WHERE cd.collectionId="+collId;

        Cursor cards = userDbHelper.executeSQLQuery(cardSQL);
        if (cards.getCount() == 0) {
            Log.i("", "No Image file");
            cards.close();
        } else if (cards.getCount() > 0) {
            for (cards.move(0); cards.moveToNext(); cards.isAfterLast()) {
                cardsId = Integer.parseInt(cards.getString(cards
                        .getColumnIndex("objectId")));
                Log.i("", "cards objectId : " + cardsId);

                String path = Environment.getExternalStorageDirectory()
                        + "/.Stampii/MediaCard/" + cardsId + ".png";
                Log.i("", "path : " + path);
            }
        }

        String sql = "SELECT objectId FROM cardmedias WHERE cardId=" + cardId
                + " LIMIT 1";
        Cursor cursor = userDbHelper.executeSQLQuery(sql);
        if (cursor.getCount() == 0) {
            Log.i("", "No Image file");
            cursor.close();
        } else if (cursor.getCount() > 0) {
            for (cursor.move(0); cursor.moveToNext(); cursor.isAfterLast()) {
                objectId = Integer.parseInt(cursor.getString(cursor
                        .getColumnIndex("objectId")));
                Log.i("", "objectId : " + objectId);
            }
        }



        Button info = (Button) findViewById(R.id.info_button);
        info.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Intent intent = new Intent(Cards.this, SingleCardInfo.class);
                intent.putExtra("card_id", cardId);
                intent.putExtra("collection_id", collId);
                startActivity(intent);
            }
        });

        Button back = (Button) findViewById(R.id.back_button);
        back.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                finish();
            }
        });

        final ArrayList<Bitmap> images = new ArrayList<Bitmap>();
        String path = Environment.getExternalStorageDirectory()+"/.Stampii/MediaCard/"+objectId+".png";

        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inTempStorage = new byte[16*1024];

        Bitmap b = BitmapFactory.decodeFile(path, options);
        images.add(b);

        viewFlow = (ViewFlow) findViewById(R.id.viewflow);
        viewFlow.setAdapter(new ImageAdapter(this, images),position);


        ImageButton prevBtn = (ImageButton) findViewById(R.id.previous_button);
        prevBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                indexxx = viewFlow.getSelectedItemPosition()-1;
                if (indexxx>=0) {
                    viewFlow.setAdapter(new ImageAdapter(Cards.this, images),indexxx);
                    viewFlow.setSelectedItemPosition(indexxx);
                    Log.i("indexxx", "indexxx : " + indexxx);
                }
            }
        });

        ImageButton nextBtn = (ImageButton) findViewById(R.id.next_button);
        nextBtn.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                indexxx = viewFlow.getSelectedItemPosition()+1;
                if (indexxx<=images.size()) {
                    viewFlow.setAdapter(new ImageAdapter(Cards.this, images),indexxx);
                    viewFlow.setSelectedItemPosition(indexxx);
                    Log.i("indexxx", "indexxx : " + indexxx);
                }
            }
        }); 

    }
    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        viewFlow.onConfigurationChanged(newConfig);
    }

}

这是我的 ImageAdapter 类:

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Bitmap;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;

public class ImageAdapter extends BaseAdapter {

    private LayoutInflater mInflater;
    private ArrayList<Bitmap> ids = new ArrayList<Bitmap>();
    private Bitmap bitmap;

    public ImageAdapter(Context context, ArrayList<Bitmap> images) {
        mInflater = (LayoutInflater) context.getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        ids = images;
    }

    @Override
    public int getCount() {
        return 1;
    }

    @Override
    public Object getItem(int position) {
        return position;
    }

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

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        if (convertView == null) {
            convertView = mInflater.inflate(R.layout.image_item, null);
        }
        ((ImageView) convertView.findViewById(R.id.imgView)).setImageBitmap(ids.get(position));
        return convertView;
    }

}

知道如何通过从数据库中获取图像 ID、找到具有该名称的图像并将其添加到 View 流和滑动来设置下一张或上一张图像。我不希望有人代替我编写代码...我一直在想我该怎么做...所以如果有人可以帮助我提供建议、想法或其他东西，那就去做吧。

提前致谢!

Answer 1

我认为您已经非常接近成功了。

getCount() 应该是这样的:

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

已编辑:
您应该只创建一个 ImageAdapter 实例，您正在 onClick 中创建新实例。您还应该使用 setSelection() 而不是 setSelectedItemPosition()。似乎后者是供内部使用的:

        @Override
        public void onClick(View v) {
            indexxx = viewFlow.getSelectedItemPosition()-1;
            if (indexxx>=0) {
                viewFlow.setSelection(indexxx);
                Log.i("indexxx", "indexxx : " + indexxx);
            }
        }
        /* ... */
        @Override
        public void onClick(View v) {
            indexxx = viewFlow.getSelectedItemPosition()+1;
            if (indexxx<images.size()) { // Should be <, you have a wrong boundary check here!!!
                viewFlow.setSelection(indexxx);
                Log.i("indexxx", "indexxx : " + indexxx);
            }
        }