Android 圖像滑塊

Android圖像滑塊將一個完整的屏幕滑動到另一個屏幕。愛掏網(wǎng) - it200.com圖像滑塊由支持庫提供的 ViewPager 創(chuàng)建。愛掏網(wǎng) - it200.com要實現(xiàn)圖像滑塊，您需要繼承擴展了PagerAdapter的ViewPager類。愛掏網(wǎng) - it200.com

圖像滑塊示例

讓我們看一個Android圖像滑塊的示例。愛掏網(wǎng) - it200.com

activity_main.xml

在activity_main.xml文件中，我們將ViewPager包裝在RelativeLayout中。愛掏網(wǎng) - it200.com

文件：activity_main.xml

<?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="fill_parent"
    android:layout_height="fill_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.test.imageslider.MainActivity">


    <android.support.v4.view.ViewPager
        android:id="@+id/viewPage"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent" />

</RelativeLayout>

Activity類

文件: MainActivity.java

package com.example.test.imageslider;

import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        ViewPager mViewPager = (ViewPager) findViewById(R.id.viewPage);
        ImageAdapter adapterView = new ImageAdapter(this);
        mViewPager.setAdapter(adapterView);
    }
}

圖像適配器類

現(xiàn)在創(chuàng)建一個繼承自 PagerAdapter 的圖像適配器類，用于 Android 圖像滑塊。愛掏網(wǎng) - it200.com

將一些圖像放在 drawable 文件夾中，這些圖像將用于滑動。愛掏網(wǎng) - it200.com

文件: ImageAdapter.java

package com.example.test.imageslider;

import android.content.Context;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ImageView;

public class ImageAdapter extends PagerAdapter{
    Context mContext;

    ImageAdapter(Context context) {
        this.mContext = context;
    }

    @Override
    public boolean isViewFromObject(View view, Object object) {
        return view == ((ImageView) object);
    }

    private int[] sliderImageId = new int[]{
            R.drawable.image1, R.drawable.image2, R.drawable.image3,R.drawable.image4, R.drawable.image5,
    };

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        ImageView imageView = new ImageView(mContext);
        imageView.setScaleType(ImageView.ScaleType.CENTER_CROP);
        imageView.setImageResource(sliderImageId[position]);
        ((ViewPager) container).addView(imageView, 0);
        return imageView;
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        ((ViewPager) container).removeView((ImageView) object);
    }

    @Override
    public int getCount() {
        return sliderImageId.length;
    }
}

我們需要覆蓋PagerAdapter類的以下方法。愛掏網(wǎng) - it200.com

1. isViewFromObject(View, Object): 此方法檢查視圖是否與鍵關聯(lián)，并由instantiateItem()返回。愛掏網(wǎng) - it200.com
2. instantiateItem(ViewGroup, int): 此方法創(chuàng)建傳遞作為參數(shù)的頁面位置。愛掏網(wǎng) - it200.com
3. destroyItem(ViewGroup, int, Object): 它從容器中刪除當前位置的頁面。愛掏網(wǎng) - it200.com在此示例中，我們只是使用removeView()來移除對象。愛掏網(wǎng) - it200.com
4. getCount(): 它返回ViewPager中可用視圖的數(shù)量。愛掏網(wǎng) - it200.com

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