今天用AS学做了一个简单的图片切换小程序
其中用到了一个ImageSwitcher的类通过设置一个ViewFactory工厂,实现其makeView()方法来创建显示图片的View。和和一个叫做“画廊类”的Gallery类,来陈列图片资源;
方法setImageResource用来显示指定的图片资源。
1.声明所需的变量private Gallery gallery;private ImageSwitcher imageSwitcher;将7张图片放入/res/drawable目录下,声明一个数组把图片资源放到数组里private int[] res={R.drawable.grid_view_02,R.drawable.grid_view_03,R.drawable.grid_view_04,R.drawable.grid_view_05,R.drawable.grid_view_06,R.drawable.grid_view_12,R.drawable.grid_view_14};
2.MainActivity.java
package com.example.ch.imageswitchingandshowing;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.view.ViewGroup;
import android.view.animation.AnimationUtils;
import android.widget.AdapterView;
import android.widget.BaseAdapter;
import android.widget.Gallery;
import android.widget.ImageSwitcher;
import android.widget.ImageView;
import android.widget.ViewSwitcher;
import java.util.Iterator;
public class MainActivity extends AppCompatActivity {
private Gallery gallery;
private ImageSwitcher imageSwitcher;
private int[] res={R.drawable.grid_view_02,R.drawable.grid_view_03,R.drawable.grid_view_04,
R.drawable.grid_view_05,R.drawable.grid_view_06,R.drawable.grid_view_12,R.drawable.grid_view_14};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
gallery=(Gallery)findViewById(R.id.gallery);
imageSwitcher=(ImageSwitcher)findViewById(R.id.imageSwitcher);
//buju
imageSwitcher.setFactory(new ViewSwitcher.ViewFactory() {
@Override
public View makeView() {
ImageView imageView= new ImageView(MainActivity.this);
imageView.setBackgroundColor(0xff000000);
imageView.setScaleType(ImageView.ScaleType.FIT_CENTER);
imageView.setLayoutParams(new ImageSwitcher.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT,
ViewGroup.LayoutParams.MATCH_PARENT));
return imageView;
}
});
imageSwitcher.setInAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_in));//设置进入的动态效果,叠进
imageSwitcher.setOutAnimation(AnimationUtils.loadAnimation(this, android.R.anim.fade_out));
//下面这一步是准备Gallery工作,获得信息。
gallery.setAdapter(new BaseAdapter() {
@Override
//获得<span style="font-family: 宋体;">gallery里的图片个数(item)</span>
public int getCount() {
return res.length;
}
@Override
public Object getItem(int position) {
return position;
}
@Override
<span style="color: rgb(51, 51, 51); font-family: 宋体; font-size: 14px; line-height: 28px; text-indent: 28px; background-color: rgb(249, 249, 249);">//至于getItemId(int position),它返回的是该postion对应item的id</span>
public long getItemId(int position) {
return position;
}
@Override
//得到画廊中的一个图片
public View getView(int position, View convertView, ViewGroup parent) {
ImageView imageView = new ImageView(MainActivity.this);
imageView.setLayoutParams(new Gallery.LayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT));
imageView.setAdjustViewBounds(true);
imageView.setImageResource(res[position]);
return imageView;
}
});
//选中画廊中的item监听事件
gallery.setOnItemSelectedListener(new AdapterView.OnItemSelectedListener() {
@Override
//选中了就将图片给到<span style="font-family: 宋体;">imageSwitcher中</span>
public void onItemSelected(AdapterView<?> parent, View view, int position, long id) {
imageSwitcher.setImageResource(res[position]);
}
@Override
public void onNothingSelected(AdapterView<?> parent) {
}
});
}
}
layout布局文件:
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.example.ch.imageswitchingandshowing.MainActivity">
<ImageSwitcher
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="@+id/imageSwitcher"
android:layout_alignParentTop="true"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
<Gallery
android:layout_width="match_parent"
android:layout_height="60dp"
android:id="@+id/gallery"
android:spacing="20dp"//展览图片时,设置相邻图片的间距
android:gravity="center_vertical"
android:layout_alignBottom="@+id/imageSwitcher"
android:layout_alignParentLeft="true"
android:layout_alignParentStart="true" />
</RelativeLayout>
托这两个控件时不要使这两者的区域有重叠部分。效果如下所示: