关于Gallery的一点问题

[李狗蛋52635]

各位好
　　小弟最近在写一个Gallery的例子，想实现的功能是在横屏上放置一个gallery，处于最中间的一幅图设置一个比较大的背景，左右两边的图都设置比较小的背景，整个gallery一直保持这样的格局。
　　gallery是顺便地实现了，但在动态地设置背景时，出现了问题，在我的OnItemSelectedListener中，为左右两边的图设置背景时，有时根据index竟然找不到....汗一个，请教各位大虾这是为什么呢?

OnItemSelectedListener的代码如下：

gallery.setOnItemSelectedListener(new OnItemSelectedListener() {
			@Override
			public void onItemSelected(AdapterView<?> arg0, View arg1,
					int arg2, long arg3) {
				Log.v("", "------------------------------------------------------");
				Log.v("", "----- pic : " + arg2 + " is selected. Child count: " + arg0.getChildCount());
				arg1.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_center));
				View preView = arg0.getChildAt(arg2-1);
				if(preView!=null){
					preView.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_left));
					Log.v("", "----- left pic : " + (arg2 - 1) + " 背景替换ok");
				}
				View nextView = arg0.getChildAt(arg2+1);
				if(nextView!=null){
					nextView.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_right));
					Log.v("", "----- right pic : " + (arg2 + 1) + " 背景替换ok");
				}
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
			}
		});

请各位不吝赐教，先谢谢了。

[李狗蛋52635]

自己顶下
我只是想获得当前被选中view的前一个／后一个view，用getChildAt不对吗？

[ihrthk]

能否贴出全代码，你是怎么"放置一个gallery，处于最中间的一幅图设置一个比较大的背景，左右两边的图都设置比较小的背景"...

[李狗蛋52635]

package com.weektask01;

import java.io.IOException;

import android.app.Activity;
import android.app.WallpaperManager;
import android.content.Context;
import android.os.Bundle;
import android.os.IBinder;
import android.util.Log;
import android.view.ContextMenu;
import android.view.LayoutInflater;
import android.view.MenuItem;
import android.view.View;
import android.view.ViewGroup;
import android.view.ContextMenu.ContextMenuInfo;
import android.view.View.OnClickListener;
import android.view.View.OnFocusChangeListener;
import android.view.ViewGroup.LayoutParams;
import android.webkit.MimeTypeMap;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Button;
import android.widget.Gallery;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;
import android.widget.Toast;
import android.widget.AdapterView.AdapterContextMenuInfo;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.AdapterView.OnItemSelectedListener;

public class Wallpaper extends Activity {
	
	private int curWallpaper;
	
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.wallpaper);

        Gallery g = (Gallery) findViewById(R.id.gallery1);
        // Set the adapter to our custom adapter (below)
        g.setAdapter(new ImageAdapter(this));
        g.setSpacing(0);
        // g.setClickable(false);
        
        // Set a item click listener, and just Toast the clicked position
//        g.setOnItemClickListener(new OnItemClickListener() {
//            public void onItemClick(AdapterView parent, View v, int position, long id) {
//                Toast.makeText(Wallpaper.this, "" + position, Toast.LENGTH_SHORT).show();
//            }
//        });
        
        g.setOnItemSelectedListener(new OnItemSelectedListener() {
			@Override
			public void onItemSelected(AdapterView<?> arg0, View arg1, int arg2, long arg3) {
				curWallpaper = arg2;
				TextView page = (TextView) findViewById(R.id.pageText);
				page.setText((arg2 + 1) + "/" + arg0.getCount());
				Log.v("", "");
				Log.v("", "----- pic : " + arg2 + " is selected. " + arg0.getPositionForView(arg0.getSelectedView()));
				arg1.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_center));
				
//				View preView = arg0.focusSearch(arg1, AdapterView.FOCUS_LEFT);
				View preView = arg0.getChildAt(arg2 - 1);
				if(preView!=null){
					preView.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_left));
					Log.v("", "----- left pic 背景替换ok");
				}
				
				View nextView = arg0.getChildAt(arg2 + 1);
				if(nextView!=null){
					nextView.setBackgroundDrawable(getResources().getDrawable(R.drawable.ic_wallpaper_right));
					Log.v("", "----- right pic 背景替换ok");
				}
			}

			@Override
			public void onNothingSelected(AdapterView<?> arg0) {
			}
		});
        
        // We also want to show context menu for longpressed items in the gallery
        registerForContextMenu(g);
        
        final WallpaperManager wallpaperManager = WallpaperManager.getInstance(this);
        
        Button setWallpaper = (Button) findViewById(R.id.application);
        setWallpaper.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				try {
					wallpaperManager.setResource(mImageIds[curWallpaper]);
					finish();
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
		});
        
        Button preview = (Button) findViewById(R.id.preview);
        preview.setOnClickListener(new OnClickListener() {
			@Override
			public void onClick(View v) {
				finish();
			}
		});
        
    }

    @Override
    public void onCreateContextMenu(ContextMenu menu, View v, ContextMenuInfo menuInfo) {
        menu.add(R.string.app_name);
    }
    
    @Override
    public boolean onContextItemSelected(MenuItem item) {
        AdapterContextMenuInfo info = (AdapterContextMenuInfo) item.getMenuInfo();
        Toast.makeText(this, "Longpress: " + info.position, Toast.LENGTH_SHORT).show();
        return true;
    }
    
    // --------------------------- ImageAdapter --------------------------- 
    public class ImageAdapter extends BaseAdapter {
        int mGalleryItemBackground;
        
        private LayoutInflater mInflater;
        
        private int curpos;
        
        public ImageAdapter(Context c) {
            mContext = c;
            mInflater = LayoutInflater.from(mContext);
            Log.v("ImageAdapter is defined!-----", mContext.toString());
            curpos = 0;
            // See res/values/attrs.xml for the <declare-styleable> that defines
            // Gallery1.
//            TypedArray a = obtainStyledAttributes(R.styleable.Gallery1);
//            mGalleryItemBackground = a.getResourceId(
//                    R.styleable.Gallery1_android_galleryItemBackground, 0);
//            a.recycle();
        }

        public int getCount() {
            return mImageIds.length;
        }

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

        public long getItemId(int position) {
            return position;
        }
        
        public View getView(int position, View convertView, ViewGroup parent) {
        	ViewHolder holder = null;
            if (convertView == null) {
                convertView = mInflater.inflate(R.layout.pic_center, null);
                
                holder = new ViewHolder();
                holder.text = (TextView) convertView.findViewById(R.id.text);
                holder.image = (ImageView) convertView.findViewById(R.id.pic);
                holder.rootLayout = (LinearLayout) convertView.findViewById(R.id.rootLayout);

                convertView.setTag(holder);
            } else {
                holder = (ViewHolder) convertView.getTag();
            }
            holder.text.setText(myText[position]);
            holder.image.setImageResource(mImageIds[position]);
            Log.v("", "----- Pic at position: " + position + " is created!");
            return convertView;
        }
        
        
        private class ViewHolder {
        	LinearLayout rootLayout;
            ImageView image;
            TextView text;
        }
        
        private Context mContext;
        
    }
    
    // image resources
    private Integer[] mImageIds = {
    		R.drawable.wallpaper02,
    		R.drawable.wallpaper03,
    		R.drawable.wallpaper04,
    		R.drawable.wallpaper05,
    		R.drawable.wallpaper06,
    		R.drawable.wallpaper07,
    		R.drawable.wallpaper08,
    		R.drawable.wallpaper09,
    		R.drawable.wallpaper10,
    		R.drawable.wallpaper11
    };
    // text resources        
    private String[] myText = {
    		"Grass Road",
    		"Desert Road",
    		"Fishing Port",
    		"Black Wave",
    		"Red And Black",
    		"Waving",
    		"Universe",
    		"Drops On Grass",
    		"Purple Flowers",
    		"Wheet"
    };
}

代码在此，gallery很平常的啊，和BaseAdapter配合使用，其中pic_center.xml文件如下:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/rootLayout"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:gravity="center"
  android:orientation="vertical">
	  <ImageView
		  android:id="@+id/pic"
		  android:layout_height="100dip"
		  android:layout_width="100dip"
		  android:layout_gravity="center"
	  	></ImageView>
	  <TextView
		  android:id="@+id/text"
		  android:layout_height="wrap_content"
		  android:layout_width="wrap_content"
		  android:text=""
	  	></TextView>
</LinearLayout>

[李狗蛋52635]

这个问题已经解决，将思路改变，不在OnItemSelectedListener中进行处理，而是记录下当前的position，在getView中进行处理。

[thekingo_oflove]

楼主，我也遇到这问题啊，从SD卡获取所有图片，gallery显示，menu设置背景找不到图片ID，要怎么记录当前显示的图片的ID，求教。