Android-水平滑动容器HorizontalScrollView

摘自：

Android 自定义 HorizontalScrollView 打造再多图片（控件）也不怕 OOM 的横向滑动效果

自定义view：

思想：

1、首先根据屏幕的大小和Item的大小，计算可以一个屏幕最多可以加载多少个Item，然后加载该数量Item。

2、当用户右滑（从右向左），滑动到一定距离时，加载下一张，删除第一张

3、当用户左滑（从左向右），滑动到一定距离时，加载上一张，删除最后一张

package com.example.lenovo.myapplication.shuiping;

import java.util.HashMap;
import java.util.Map;

import android.content.Context;
import android.graphics.Color;
import android.util.AttributeSet;
import android.util.DisplayMetrics;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.WindowManager;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;

public class MyHorizontalScrollView extends HorizontalScrollView implements OnClickListener {

/**
* 图片滚动时的回调接口
*
* @author zhy
*/
public interface CurrentImageChangeListener {
void onCurrentImgChanged(int position, View viewIndicator);
}

/**
* 条目点击时的回调
*
* @author zhy
*/
public interface OnItemClickListener {
void onClick(View view, int pos);
}

private CurrentImageChangeListener mListener;

private OnItemClickListener mOnClickListener;

private static final String TAG = "MyHorizontalScrollView";

/**
* HorizontalListView中的LinearLayout
*/
private LinearLayout mContainer;

/**
* 子元素的宽度
*/
private int mChildWidth;
/**
* 子元素的高度
*/
private int mChildHeight;
/**
* 当前最后一张图片的index
*/
private int mCurrentIndex;
/**
* 当前第一张图片的下标
*/
private int mFristIndex;
/**
* 当前第一个View
*/
private View mFirstView;
/**
* 数据适配器
*/
private HorizontalScrollViewAdapter mAdapter;
/**
* 每屏幕最多显示的个数
*/
private int mCountOneScreen;
/**
* 屏幕的宽度
*/
private int mScreenWitdh;

/**
* 保存View与位置的键值对
*/
private Map<View, Integer> mViewPos = new HashMap<View, Integer>();

public MyHorizontalScrollView(Context context, AttributeSet attrs) {
super(context, attrs);
// 获得屏幕宽度
WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
DisplayMetrics outMetrics = new DisplayMetrics();
wm.getDefaultDisplay().getMetrics(outMetrics);
mScreenWitdh = outMetrics.widthPixels;
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
mContainer = (LinearLayout) getChildAt(0);
}

/**
* 加载下一张图片
*/
protected void loadNextImg() {
// 数组边界值计算
if (mCurrentIndex == mAdapter.getCount() - 1) {
return;
}
//移除第一张图片，且将水平滚动位置置0
scrollTo(0, 0);
mViewPos.remove(mContainer.getChildAt(0));
mContainer.removeViewAt(0);

//获取下一张图片，并且设置onclick事件，且加入容器中
View view = mAdapter.getView(++mCurrentIndex, null, mContainer);
view.setOnClickListener(this);
mContainer.addView(view);
mViewPos.put(view, mCurrentIndex);

//当前第一张图片小标
mFristIndex++;
//如果设置了滚动监听则触发
if (mListener != null) {
notifyCurrentImgChanged();
}

}

/**
* 加载前一张图片
*/
protected void loadPreImg() {
//如果当前已经是第一张，则返回
if (mFristIndex == 0)
return;
//获得当前应该显示为第一张图片的下标
int index = mCurrentIndex - mCountOneScreen;
if (index >= 0) {
//          mContainer = (LinearLayout) getChildAt(0);
//移除最后一张
int oldViewPos = mContainer.getChildCount() - 1;
mViewPos.remove(mContainer.getChildAt(oldViewPos));
mContainer.removeViewAt(oldViewPos);

//将此View放入第一个位置
View view = mAdapter.getView(index, null, mContainer);
mViewPos.put(view, index);
mContainer.addView(view, 0);
view.setOnClickListener(this);
//水平滚动位置向左移动view的宽度个像素
scrollTo(mChildWidth, 0);
//当前位置--，当前第一个显示的下标--
mCurrentIndex--;
mFristIndex--;
//回调
if (mListener != null) {
notifyCurrentImgChanged();

}
}
}

/**
* 滑动时的回调
*/
public void notifyCurrentImgChanged() {
//先清除所有的背景色，点击时会设置为蓝色
for (int i = 0; i < mContainer.getChildCount(); i++) {
mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
}

mListener.onCurrentImgChanged(mFristIndex, mContainer.getChildAt(0));

}

/**
* 初始化数据，设置数据适配器
*
* @param mAdapter
*/
public void initDatas(HorizontalScrollViewAdapter mAdapter) {
this.mAdapter = mAdapter;
mContainer = (LinearLayout) getChildAt(0);
// 获得适配器中第一个View
final View view = mAdapter.getView(0, null, mContainer);
mContainer.addView(view);

// 强制计算当前View的宽和高
if (mChildWidth == 0 && mChildHeight == 0) {
int w = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
int h = MeasureSpec.makeMeasureSpec(0,
MeasureSpec.UNSPECIFIED);
view.measure(w, h);
mChildHeight = view.getMeasuredHeight();
mChildWidth = view.getMeasuredWidth();
Log.e(TAG, view.getMeasuredWidth() + "," + view.getMeasuredHeight());
mChildHeight = view.getMeasuredHeight();
// 计算每次加载多少个View
mCountOneScreen = (mScreenWitdh / mChildWidth == 0) ? mScreenWitdh / mChildWidth + 1 : mScreenWitdh / mChildWidth + 2;

Log.e(TAG, "mCountOneScreen = " + mCountOneScreen + " ,mChildWidth = " + mChildWidth);

}
//初始化第一屏幕的元素
initFirstScreenChildren(mCountOneScreen);
}

/**
* 加载第一屏的View
*
* @param mCountOneScreen
*/
public void initFirstScreenChildren(int mCountOneScreen) {
mContainer = (LinearLayout) getChildAt(0);
mContainer.removeAllViews();
mViewPos.clear();

for (int i = 0; i < mCountOneScreen; i++) {
View view = mAdapter.getView(i, null, mContainer);
view.setOnClickListener(this);
mContainer.addView(view);
mViewPos.put(view, i);
mCurrentIndex = i;
}

if (mListener != null) {
notifyCurrentImgChanged();
}

}

@Override
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_MOVE:
//          Log.e(TAG, getScrollX() + "");

int scrollX = getScrollX();
// 如果当前scrollX为view的宽度，加载下一张，移除第一张
if (scrollX >= mChildWidth) {
loadNextImg();
}
// 如果当前scrollX = 0， 往前设置一张，移除最后一张
if (scrollX == 0) {
loadPreImg();
}
break;
}
return super.onTouchEvent(ev);
}

@Override
public void onClick(View v) {
if (mOnClickListener != null) {
for (int i = 0; i < mContainer.getChildCount(); i++) {
mContainer.getChildAt(i).setBackgroundColor(Color.WHITE);
}
mOnClickListener.onClick(v, mViewPos.get(v));
}
}

public void setOnItemClickListener(OnItemClickListener mOnClickListener) {
this.mOnClickListener = mOnClickListener;
}

public void setCurrentImageChangeListener(CurrentImageChangeListener mListener) {
this.mListener = mListener;
}

}

自定义适配器：

package com.example.lenovo.myapplication.shuiping;

import java.util.List;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.lenovo.myapplication.R;

public class HorizontalScrollViewAdapter {

private Context mContext;
private LayoutInflater mInflater;
private List<Integer> mDatas;

public HorizontalScrollViewAdapter(Context context, List<Integer> mDatas) {
this.mContext = context;
mInflater = LayoutInflater.from(context);
this.mDatas = mDatas;
}

public int getCount() {
return mDatas.size();
}

public Object getItem(int position) {
return mDatas.get(position);
}

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

public View getView(int position, View convertView, ViewGroup parent) {
ViewHolder viewHolder = null;
if (convertView == null) {
viewHolder = new ViewHolder();
convertView = mInflater.inflate(R.layout.activity_index_gallery_item, parent, false);
viewHolder.mImg = (ImageView) convertView.findViewById(R.id.id_index_gallery_item_image);
viewHolder.mText = (TextView) convertView.findViewById(R.id.id_index_gallery_item_text);

convertView.setTag(viewHolder);
} else {
viewHolder = (ViewHolder) convertView.getTag();
}
viewHolder.mImg.setImageResource(mDatas.get(position));
viewHolder.mText.setText("some info ");

return convertView;
}

private class ViewHolder {
ImageView mImg;
TextView mText;
}

}

item布局：activity_index_gallery_item

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="120dp"
android:layout_height="130dp"
android:background="@android:color/white" >

<ImageView
android:id="@+id/id_index_gallery_item_image"
android:layout_width="80dp"
android:layout_height="80dp"
android:layout_alignParentTop="true"
android:layout_centerHorizontal="true"
android:layout_margin="5dp"
android:scaleType="centerCrop" />

<TextView
android:id="@+id/id_index_gallery_item_text"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/id_index_gallery_item_image"
android:layout_centerHorizontal="true"
android:layout_marginBottom="5dp"
android:layout_marginTop="5dp"
android:textColor="#ff0000"
android:textSize="12dp" />

</RelativeLayout>

使用：

package com.example.lenovo.myapplication.shuiping;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

import android.app.Activity;
import android.graphics.Color;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.ImageView;

import com.example.lenovo.myapplication.R;
import com.example.lenovo.myapplication.activity.MyApplication;
import com.squareup.leakcanary.RefWatcher;

public class MainActivity extends Activity {

private MyHorizontalScrollView mHorizontalScrollView;
private HorizontalScrollViewAdapter mAdapter;
private ImageView mImg;
private List<Integer> mDatas = new ArrayList<Integer>(Arrays.asList(
R.drawable.a, R.drawable.b, R.drawable.c, R.drawable.d,
R.drawable.e, R.drawable.f, R.drawable.g, R.drawable.h,
R.drawable.l));

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
setContentView(R.layout.activity_main1);

mImg = (ImageView) findViewById(R.id.id_content);

mHorizontalScrollView = (MyHorizontalScrollView) findViewById(R.id.id_horizontalScrollView);
mAdapter = new HorizontalScrollViewAdapter(this, mDatas);
//添加滚动回调
mHorizontalScrollView.setCurrentImageChangeListener(new MyHorizontalScrollView.CurrentImageChangeListener() {
@Override
public void onCurrentImgChanged(int position, View viewIndicator) {
mImg.setImageResource(mDatas.get(position));
viewIndicator.setBackgroundColor(Color.parseColor("#AA024DA4"));
}
});
//添加点击回调
mHorizontalScrollView.setOnItemClickListener(new MyHorizontalScrollView.OnItemClickListener() {

@Override
public void onClick(View view, int position) {
mImg.setImageResource(mDatas.get(position));
view.setBackgroundColor(Color.parseColor("#AA024DA4"));
}
});
//设置适配器
mHorizontalScrollView.initDatas(mAdapter);
}

@Override
protected void onDestroy() {
super.onDestroy();

RefWatcher refWatcher = MyApplication.getRefWatcher(this);
refWatcher.watch(this);
}
}

布局：activity_main1

HorizontalScrollView内部有个水平方向的LinearLayout。

<LinearLayout 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:background="@android:color/white"
android:orientation="vertical">

<FrameLayout
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1">

<ImageView
android:id="@+id/id_content"
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:layout_gravity="center"
android:layout_margin="10dp"
android:scaleType="centerCrop"
android:src="@drawable/ic_launcher" />
</FrameLayout>

<com.example.lenovo.myapplication.shuiping.MyHorizontalScrollView
android:id="@+id/id_horizontalScrollView"
android:layout_width="wrap_content"
android:layout_height="150dp"
android:layout_gravity="bottom"
android:background="@android:color/white"
android:scrollbars="none">

<LinearLayout
android:id="@+id/id_gallery"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center_vertical"
android:orientation="horizontal"/>
</com.example.lenovo.myapplication.shuiping.MyHorizontalScrollView>

</LinearLayout>