重写HorizontalScrollView实现代码控制水平滚动定位

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#滚动定位 #水平scroll

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重写HorizontalScrollView实现代码控制水平滚动定位
CenterShowHorizontalScrollView.java

package com.aldx.hccraftsman.view;

import android.content.Context;
import android.util.AttributeSet;
import android.view.Gravity;
import android.view.View;
import android.widget.HorizontalScrollView;
import android.widget.LinearLayout;

import com.aldx.hccraftsman.R;
import com.aldx.hccraftsman.utils.Utils;

/**
 * author: chenzheng
 * created on: 2017/5/10 16:26
 * description:
 */

public class CenterShowHorizontalScrollView extends HorizontalScrollView {
    private LinearLayout mShowLinear;
    private Context context;

    public CenterShowHorizontalScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.context = context;
        mShowLinear = new LinearLayout(context);
        mShowLinear.setOrientation(LinearLayout.HORIZONTAL);
        HorizontalScrollView.LayoutParams params = new HorizontalScrollView.LayoutParams(
                LayoutParams.WRAP_CONTENT, LayoutParams.MATCH_PARENT);
        mShowLinear.setGravity(Gravity.CENTER_VERTICAL);
        this.addView(mShowLinear, params);
    }

    public void onClicked(View v) {
        if (v.getTag(R.id.item_position) != null) {
            int position = (Integer) v.getTag(R.id.item_position);
            View itemView = mShowLinear.getChildAt(position);
            int itemWidth = itemView.getWidth();
            int screenWidth = Utils.getScreenW(context);

            smoothScrollTo(itemView.getLeft() - (screenWidth / 2 - itemWidth / 2), 0);
        }
    }

    public void onClicked(int position) {
        View itemView = mShowLinear.getChildAt(position);
        int itemWidth = itemView.getWidth();
        int screenWidth = Utils.getScreenW(context);

        smoothScrollTo(itemView.getLeft() - (screenWidth / 2 - itemWidth / 2), 0);
    }

    public LinearLayout getLinear() {
        return mShowLinear;
    }

    public void addItemView(View itemView, int position) {
        itemView.setTag(R.id.item_position, position);
        mShowLinear.addView(itemView);
    }


}

<com.aldx.hccraftsman.view.CenterShowHorizontalScrollView
        android:id="@+id/tab_horizontalscrollView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#e5e5e5"
        android:scrollbars="none" />

CenterShowHorizontalScrollView内部已经添加过LinearLayout所以不需要再重复添加了，直接将子view添加进去即可：

mHScrollView.addItemView(itemView, i);

代码控制滚动定位：

mHScrollView.onClicked(view);

或

mHScrollView.onClicked(position);

注:
如果你再oncreate方法里就想调用滚动定位，是看不到效果的，因为这时控件的宽度还没有被测量出来，解决方法：

mHScrollView.getViewTreeObserver().addOnGlobalLayoutListener(
                new ViewTreeObserver.OnGlobalLayoutListener() {
                    @Override
                    public void onGlobalLayout() {
                        if(tempViewList.size()>0) {
                            mHScrollView.onClicked(temp_tab);
                        }
                        mHScrollView.getViewTreeObserver()
                                .removeGlobalOnLayoutListener(this);
                    }
                });