Android ImageSwitcher

该例子来自APIDemo


/*
* Copyright (C) 2007 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
*      http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/

package com.example.android.apis.view;

import com.example.android.apis.R;

import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.Window;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.Gallery.LayoutParams;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher;


public class ImageSwitcher1 extends Activity implements
        AdapterView.OnItemSelectedListener, ViewSwitcher.ViewFactory {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_NO_TITLE);

        setContentView(R.layout.image_switcher_1);

        mSwitcher = (ImageSwitcher) findViewById(R.id.switcher);
        //提供显示图片的地方
        mSwitcher.setFactory(this);

       //系统的anim中的fade_in.xml
        mSwitcher.setInAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_in));
        //系统的anim中的fade_out.xml
        mSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this,
                android.R.anim.fade_out));

        Gallery g = (Gallery) findViewById(R.id.gallery);
        g.setAdapter(new ImageAdapter(this));
        g.setOnItemSelectedListener(this);
    }

    public void onItemSelected(AdapterView parent, View v, int position, long id) {
        mSwitcher.setImageResource(mImageIds[position]);
    }

    public void onNothingSelected(AdapterView parent) {
    }

//设置ImgaeSwitcher的为IamgeView的变化并且设置其属性，除此之外可以设置第一次加载的时候ImageSwitcher显示的图片默认第一张
    public View makeView() {
        ImageView i = new ImageView(this);
        i.setBackgroundColor(0xFF000000);
        i.setScaleType(ImageView.ScaleType.FIT_CENTER);
        i.setLayoutParams(new ImageSwitcher.LayoutParams(LayoutParams.FILL_PARENT,
                LayoutParams.FILL_PARENT));
        return i;
    }

    private ImageSwitcher mSwitcher;

    public class ImageAdapter extends BaseAdapter {
        public ImageAdapter(Context c) {
            mContext = c;
        }

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

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

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

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

            i.setImageResource(mThumbIds[position]);
            i.setAdjustViewBounds(true);
            i.setLayoutParams(new Gallery.LayoutParams(
                    LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));
            i.setBackgroundResource(R.drawable.picture_frame);
            return i;
        }

        private Context mContext;

    }

    private Integer[] mThumbIds = {
            R.drawable.sample_thumb_0, R.drawable.sample_thumb_1,
            R.drawable.sample_thumb_2, R.drawable.sample_thumb_3,
            R.drawable.sample_thumb_4, R.drawable.sample_thumb_5,
            R.drawable.sample_thumb_6, R.drawable.sample_thumb_7};

    private Integer[] mImageIds = {
            R.drawable.sample_0, R.drawable.sample_1, R.drawable.sample_2,
            R.drawable.sample_3, R.drawable.sample_4, R.drawable.sample_5,
            R.drawable.sample_6, R.drawable.sample_7};

}



//frameworks\base\core\res\res\anim\fade_in.xml

<alpha xmlns:android="http://schemas.android.com/apk/res/android" android:interpolator="@anim/accelerate_interpolator" 
    android:fromAlpha="1.0"
    android:toAlpha="0.0"
    android:duration="@android:integer/config_mediumAnimTime" 
/>

//frameworks\base\core\res\res\anim\fade_out.xml

<alpha xmlns:android="http://schemas.android.com/apk/res/android"
        android:interpolator="@anim/decelerate_interpolator"
        android:fromAlpha="0.0" android:toAlpha="1.0"
        android:duration="@android:integer/config_longAnimTime" />

显示效果


总结
TextSwitcher与ImageSwitcher差不多，不过ImageSwitcher规定的view为ImageView,而TextSwitcher为TextView。(这个在public View makeView()这个里面设置）。若是ImageSwitcher则在makeView()里面定义的是IamgeView并且将其返回给IamgeSwitcher, 而TextSwitcher则在makeView里面定义的是TextView并且将其返回给TextSwitcher.

java.lang.Object
   ↳ android.view.View
   ↳ android.view.ViewGroup
   ↳ android.widget.FrameLayout
   ↳ android.widget.ViewAnimator
   ↳ android.widget.ViewSwitcher
   ↳                    android.widget.TextSwitcher




java.lang.Object
   ↳ android.view.View
   ↳ android.view.ViewGroup
   ↳ android.widget.FrameLayout
   ↳ android.widget.ViewAnimator
   ↳ android.widget.ViewSwitcher
   ↳ android.widget.ImageSwitcher