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识别目标View在HorizontalScrollView可见区域

2017.12.13 12:49 2531浏览

完成需求的时候涉及到这个所以撸了一下
本文章是本人原创,转载请带原地址连接

先放效果图('霁雪清虹"是目标):

TIM图片20171213124705.png

  1. 首先需要一个自定义HorizontalScrollView,复写一个View的onScrollChanged方法,用于监听滑动变化
    代码如下:
import android.content.Context;
import android.util.AttributeSet;
import android.widget.HorizontalScrollView;

/**
 * Created by 霁雪清虹 on 2016/9/29.
 */

public class MyHorizontalScrollView extends HorizontalScrollView {

    private MyScrollListener myScrollListener;
    public MyHorizontalScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (myScrollListener != null) {
            myScrollListener.onScrollChanged();
        }
    }

    public void setMyScrollListener(MyScrollListener myScrollListener) {
        this.myScrollListener = myScrollListener;
    }

    public interface MyScrollListener {
        void onScrollChanged();
    }

}

然后就是MainActivity的onScrollChanged中的代码就是重点了
代码如下:


import android.graphics.Point;
import android.graphics.Rect;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.TextView;
import android.widget.Toast;

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

public class MainActivity extends AppCompatActivity implements View.OnClickListener, MyHorizontalScrollView.MyScrollListener {

    protected TextView targetTextView;
    private final static String NAME = "霁雪清虹";
    protected MyHorizontalScrollView horizontalScrollView;
    private Rect rect;
    private Rect globalRect;
    private Point globalOffset;
    private List<String> contentList = new ArrayList();

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        super.setContentView(R.layout.activity_main);
        initView();
        bindDataToUi();
        rect = new Rect();
        globalRect = new Rect();
        globalOffset = new Point();
    }

    private void bindDataToUi() {
        contentList.add("天涯");
        contentList.add("兰亭书序");
        contentList.add("天涯");
        contentList.add("兰亭书序");
        contentList.add("晨曦");
        contentList.add("虹猫");
        contentList.add("天涯");
        contentList.add("兰亭书序");
        contentList.add("霁雪清虹");
        contentList.add("懵逼虹");
        contentList.add("小逗比");
        contentList.add("若冰");
        contentList.add("晨曦");
        contentList.add("虹猫");
        contentList.add("天涯");
        contentList.add("兰亭书序");

        for (String str : contentList) {
            RelativeLayout contentPanel = (RelativeLayout) LayoutInflater.from(this).inflate(R.layout.content, null);
            ((LinearLayout) horizontalScrollView.getChildAt(0)).addView(contentPanel);
            TextView text = (TextView) contentPanel.findViewById(R.id.text);
            if (NAME.equals(str)) {
                targetTextView = text;
            }
            text.setText(str);
        }
    }

    @Override
    public void onClick(View view) {
    }

    private void initView() {
        horizontalScrollView = (MyHorizontalScrollView) findViewById(R.id.horizontalScrollView);
        horizontalScrollView.setMyScrollListener(this);
    }

    private boolean isFirstBack;

    @Override
    public void onBackPressed() {
        if (isFirstBack) {
            super.onBackPressed();
        }
        isFirstBack = true;
        Toast.makeText(this, "再按一次退出程序", Toast.LENGTH_SHORT).show();
    }

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

    @Override
    public void onScrollChanged() {
        targetTextView.getGlobalVisibleRect(globalRect, globalOffset);
     /*   Log.e("TAG","globalRect is "+globalRect.toString());
        Log.e("TAG","globalOffset is "+globalOffset.toString());
        Log.e("TAG","reat width is "+reat.toString());*/
        if (targetTextView.getLocalVisibleRect(rect)) {
            //左可见
            if (globalOffset.x < 0 && rect.width()< targetTextView.getWidth()

                    ) {
                Log.e("TAG", "目标霁雪清虹左半边可见");
            } else if (globalOffset.x > 0 && rect.width() < targetTextView.getWidth()
                    ) {
                Log.e("TAG", "目标霁雪清虹右半边可见");
            } else {
                Log.e("TAG", "目标霁雪清虹全可见");
            }
        } else {
            Log.e("TAG", "目标霁雪清虹不可见");
        }
    }
}

下面是Activity的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:id="@+id/activity_main"
    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.jiawei11.animationdemo.MainActivity">

    <MyHorizontalScrollView
        android:id="@+id/horizontalScrollView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        >

        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:paddingLeft="5dp"
            android:paddingRight="5dp">
        </LinearLayout>
    </MyHorizontalScrollView>
</RelativeLayout>

下面是 content.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
                android:layout_width="match_parent"
                android:layout_height="match_parent"
                android:paddingLeft="5dp"
                android:paddingRight="5dp">

    <TextView
        android:id="@+id/text"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
</RelativeLayout>
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本文原创发布于慕课网 ,转载请注明出处,谢谢合作

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