为ScrollView增加圆角的三种方式，及自定义属性【在Linearlayout中新增ScrollView支持滚动 后续】

获取圆角的几种方案如下：
方案一：
通过shape来实现，给scrollView增加背景来实现
方案二：
通过自定义ScrollView，还要自定义属性，在dispatchDraw中不停的裁剪
方案三：
用Android 5.0新增的接口，给ScrollView添加setOutlineProvider监听来实现

【注意】：设置圆角时已经要给scrollview设置padding值，不然圆角没效果

demo：
方案一：

首先在res/drawable文件夹下，新建一个文件，命名为：shape_radius.xml

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" >
    <corners android:radius="@dimen/dialog_keyboard_setting_round"/>
    <solid android:color="#31e10a"/>

</shape>

然后给scrollview新增background为上面的文件就行了

eg：https://www.cnblogs.com/MianActivity/p/5867776.html

方案二：
自定义布局：

package com.smartisanos.sara.widget;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.view.View;
import android.widget.LinearLayout;
import com.smartisanos.sara.R;

public class RoundedRectLinearLayout extends LinearLayout {
    private Path mClip;
    private float mRadius;
    private float mRadiusMarginTop;
    private float mRadiusMarginLeft;
    private float mRadiusMargeinRight;
    private float mRadiusMargeinBottom;

    public RoundedRectLinearLayout(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs);
    }

    public RoundedRectLinearLayout(Context context, AttributeSet attrs,
            int defStyle) {
        super(context, attrs, defStyle);
        init(attrs);
    }

    private void init(AttributeSet attrs) {
        if (attrs != null) {
            TypedArray a = getContext().obtainStyledAttributes(attrs, R.styleable.RoundedRectListView, 0, 0);
            mRadius = a.getDimensionPixelSize(R.styleable.RoundedRectListView_radius, 0);
            mRadiusMarginTop = a.getDimensionPixelSize(R.styleable.RoundedRectListView_radius_marginTop, 0);
            mRadiusMarginLeft = a.getDimensionPixelSize(R.styleable.RoundedRectListView_radius_marginLeft, 0);
            mRadiusMargeinRight = a.getDimensionPixelSize(R.styleable.RoundedRectListView_radius_marginRight, 0);
            mRadiusMargeinBottom = a.getDimensionPixelSize(R.styleable.RoundedRectListView_radius_marginBottom, 0);
            a.recycle();
        }
        setLayerType(View.LAYER_TYPE_SOFTWARE, null);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (mRadius > 0) {
            mClip = new Path();
            RectF rectRound = new RectF(mRadiusMarginLeft, mRadiusMarginTop, w
                    - mRadiusMargeinRight, h - mRadiusMargeinBottom);
            mClip.addRoundRect(rectRound, mRadius, mRadius, Direction.CW);
        }
    }

    @Override
    protected void dispatchDraw(Canvas canvas) {
        int saveCount = canvas.save();
        if (mRadius > 0) {
            canvas.clipPath(mClip);
        }
        super.dispatchDraw(canvas);
        canvas.restoreToCount(saveCount);
    }
}

自定义属性：

在res/values/attrs.xml中

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="RoundedRectListView">
        <attr name="radius" format="dimension" />
        <attr name="radius_marginTop" format="dimension" />
        <attr name="radius_marginLeft" format="dimension" />
        <attr name="radius_marginRight" format="dimension" />
        <attr name="radius_marginBottom" format="dimension" />
    </declare-styleable>
</resources>

布局中：

把LinearLayout改为com.smartisanos.sara.widget.RoundedRectLinearLayout，同时：

<com.smartisanos.sara.widget.LocalSearchLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:id="@+id/result"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.smartisanos.sara.widget.RoundedRectLinearLayout
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="@drawable/search_result_bg"
        android:orientation="vertical"
        android:paddingTop="7dp"
        android:layout_marginLeft="6dp"
        android:layout_marginRight="6dp"
        app:radius="12dp"
        app:radius_marginLeft="@dimen/local_search_rect_margin"
        app:radius_marginRight="@dimen/local_search_rect_margin"
        app:radius_marginBottom="20dp" >

……

</com.smartisanos.sara.widget.RoundedRectLinearLayout>

</com.smartisanos.sara.widget.LocalSearchLayout>

方案三：

        mSettingRound = IMEContext.getContext().getResources().getDimensionPixelSize(R.dimen.dialog_keyboard_setting_round);
        mScrollView = (ScrollView) mRootView.findViewById(R.id.dialog_keyboard_setting_scroll);
        if (Build.VERSION.SDK_INT >= 21) {
            mScrollView.setOutlineProvider(new ViewOutlineProvider() {
                @Override
                public void getOutline(View view, Outline outline) {
                    if (Build.VERSION.SDK_INT >= 21) {
                        outline.setRoundRect(view.getLeft(), view.getTop(), view.getRight(), view.getBottom(), mSettingRound);
                    }
                }
            });
            mScrollView.setClipToOutline(true);
        }