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

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