Android使用HorizontalScrollView实现水平滚动-创新互联

HorizontalScrollView 和 ScrollView 都是由 FrameLayout 派生出来的。它们就是一个用于为普通组件添加滚动条的组件。且 HorizontalScrollView 和 ScrollView 里面最多只能包含一个组件（当然组件里面还可以嵌套组件）。它们不同的是 HorizontalScrollView 用于添加水平滚动，而 ScrollView 用于添加垂直滚动。

突然间想到 做一个屏幕下方水平滑动，屏幕上方并作出相应的反应的效果。只是在下方滚动时，屏幕上方没有作出理想的反应，点击事件倒是实现了。最终只能在网上搜索，终于找到了一个。于是作出的效果如下：

只是这个效果还有所缺陷，加载了 13 张图片，在屏幕下方水平滚动到最后一页时，第 9 张的图片并没有在上面的显示出来(原作者的也有这个问题)；如果图片的数量小于或者等于 4 张时则不能运行。

本例的难点主要在于 MyHorizontalView 类中，并且还有收集而来的注解。

MainActivity.java :

package com.crazy.horizontalscrollviewtest;
 
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;
 
import com.crazy.horizontalscrollviewtest.MyHorizontalView.CurrentImageChangeListener;
import com.crazy.horizontalscrollviewtest.MyHorizontalView.OnItemClickListener;
 
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.ImageView;
import android.support.v7.app.AppCompatActivity;
 
 
public class MainActivity extends AppCompatActivity {
 
  private ImageView mImageView;
  private MyHorizontalView myHorizontalView;
  private List bitmapList;
  private MyAdapter adapter;
 
  @Override
  protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
 
    init();
  }
 
  private void init() {
    mImageView = (ImageView)findViewById(R.id.imageView);
 
    bitmapList = new ArrayList<>(Arrays.asList(
        readBitMap(this, R.drawable.bricks),
        readBitMap(this, R.drawable.dog),
        readBitMap(this, R.drawable.flower),
        readBitMap(this, R.drawable.grass),
        readBitMap(this, R.drawable.stones),
        readBitMap(this, R.drawable.wood),
        readBitMap(this, R.drawable.bg_01),
        readBitMap(this, R.drawable.bg_02),
        readBitMap(this, R.drawable.bg_03),
        readBitMap(this, R.drawable.bg_04),
        readBitMap(this, R.drawable.bg_05),
        readBitMap(this, R.drawable.bg_06),
        readBitMap(this, R.drawable.bg_07)
    ));
 
    myHorizontalView = (MyHorizontalView)findViewById(R.id.my_horizontal);
    adapter = new MyAdapter(this, bitmapList);
 
    //设置适配器
    myHorizontalView.initDatas(adapter);
 
    //添加滚动回调
    myHorizontalView
        .setCurrentImageChangeListener(new CurrentImageChangeListener() {
          @Override
          public void onCurrentImgChanged(int position, View viewIndicator) {
            Log.e("==============","===============  " + position);
            mImageView.setImageBitmap(bitmapList.get(position));
            viewIndicator.setBackgroundColor(Color.parseColor("#AA024DA4"));
          }
        });
 
    //添加点击回调
    myHorizontalView.setOnItemClickListener(new OnItemClickListener() {
      @Override
      public void onItemClick(View view, int position) {
 
        mImageView.setImageBitmap(bitmapList.get(position));
        view.setBackgroundColor(Color.parseColor("#AA024DA4"));
      }
    });
  }
 
  public static Bitmap readBitMap(Context mContext, int resId) {
    BitmapFactory.Options opt = new BitmapFactory.Options();
    opt.inPreferredConfig = Bitmap.Config.RGB_565;
    opt.inPurgeable = true;
    opt.inInputShareable = true;
 
    InputStream is = mContext.getResources().openRawResource(resId);
    return BitmapFactory.decodeStream(is, null, opt);
  }
 
}