GridView 多選功能

GridView多選功能在Android 3.0版本(API Level: 11)中得到了支持, 在該版本中添加了幾個函數和屬性:

mGridView.setChoiceMode(GridView.CHOICE_MODE_MULTIPLE_MODAL);
mGridView.setMultiChoiceModeListener(new MultiChoiceModeListener());

在3.0中的GridView要進入到多選模式,需要長按GridView,進入多選模式後,可以使用ActionMode來顯示相關的屬性.
在3.0中的示例代碼中已經展示了如何使用多選的GridView, 代碼目錄:

android-sdk-windows\samples\android-14\ApiDemos\src\com\example\android\apis\view\Grid3.java

在4.0系統上的截圖:

 

如何在3.0版本以前使用多選的GridVeiw呢?

這個可以通過GridView的 setOnItemClickListener() 函數來實現,當用戶點擊後來切換每個Item的狀態(選中或者沒選中),
如果選中則在繪制該Item的時候就標記為選中. 下面的示例代碼是在Android ApiDemos 的Grid1.java修改而來.

package org.goodev;

import android.app.Activity;
import android.content.Intent;
import android.content.pm.ResolveInfo;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.PixelFormat;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.AdapterView.OnItemClickListener;
import android.widget.BaseAdapter;
import android.widget.GridView;
import android.widget.ImageView;

import java.util.ArrayList;
import java.util.List;

//Need the following import to get access to the app resources, since this
//class is in a sub-package.

public class Grid1 extends Activity implements OnItemClickListener {

    GridView mGrid; 

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        loadApps(); // do this in onresume?

        setContentView(R.layout.grid_1);
        mGrid = (GridView) findViewById(R.id.myGrid);
        mGrid.setAdapter(new AppsAdapter());
        mGrid.setOnItemClickListener(this);
    }

    private List mApps;

    private boolean[] mAppsSelected;

    private void loadApps() {
        Intent mainIntent = new Intent(Intent.ACTION_MAIN, null);
        mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);

        mApps = getPackageManager().queryIntentActivities(mainIntent, 0);
        mAppsSelected = new boolean[mApps.size()];
    }

    public class AppsAdapter extends BaseAdapter {
        public AppsAdapter() {
        }

        public View getView(int position, View convertView, ViewGroup parent) {
            ImageView i;

            if (convertView == null) {
                i = new ImageView(Grid1.this);
                i.setScaleType(ImageView.ScaleType.FIT_CENTER);
                i.setLayoutParams(new GridView.LayoutParams(50, 50));
            } else {
                i = (ImageView) convertView;
            }

            ResolveInfo info = mApps.get(position);
            Drawable icon = info.activityInfo.loadIcon(getPackageManager());
            if (mAppsSelected[position]) {
                Bitmap bm = drawCheckStatus(icon);
                i.setImageBitmap(bm);
            } else {
                i.setImageDrawable(icon);
            }

            return i;
        }

        public final int getCount() {
            return mApps.size();
        }

        public final Object getItem(int position) {
            return mApps.get(position);
        }

        public final long getItemId(int position) {
            return position;
        }
    }

    public Bitmap drawCheckStatus(Drawable drawable) {
        Bitmap bitmap = Bitmap.createBitmap(drawable.getIntrinsicWidth(), drawable
                .getIntrinsicHeight(),
                drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                        : Bitmap.Config.RGB_565);
        Canvas canvas = new Canvas(bitmap);
        drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight());
        Bitmap check = BitmapFactory.decodeResource(getResources(), R.drawable.checkbox_on_bg1);
        drawable.draw(canvas);
        canvas.drawBitmap(check, drawable.getIntrinsicWidth()-check.getWidth(), 0, null);
        return bitmap;
    }

    @Override
    public void onItemClick(AdapterView parent, View v, int position, long id) {
        mAppsSelected[position] = !mAppsSelected[position];
        ImageView i = (ImageView) v;
        ResolveInfo info = mApps.get(position);
        Drawable icon = info.activityInfo.loadIcon(getPackageManager());
        if (mAppsSelected[position]) {
            Bitmap bm = drawCheckStatus(icon);
            i.setImageBitmap(bm);
        } else {
            i.setImageDrawable(icon);
        }
    }

}

在上面的代碼中, 當用戶選中一個Item後 就繪制一個選中的圖標. 對於多選的邏輯處理只是做了簡單的標記, 在實際應用中需要根據具體情況來處理.
截圖如下: