此篇是自定义ViewGroup实现子View的padding、margin属性（https://blog.csdn.net/qiantanlong/article/details/82347850）的姊妹篇，在于实现自定义View（不包含子View）的padding属性，话不多说，直接看代码。

package hongzhen.com.defineviewdemo;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
/**
 * 开发者：hongzhen
 * 创建时间： 2018/9/3 13:54
 * 公司名称：
 * 类名：MyMarginViewGroup.java
 * 描述：实现View的padding属性的支持
 */
public class MyPaddingView extends View {

    private int mNomalSize=200;
    private int mWidth;
    private int mHeith;
    private int paddingLeft;
    private int paddingTop;
    private int paddingRight;
    private int paddingBottom;

    public MyPaddingView(Context context) {
        this(context,null);
    }

    public MyPaddingView(Context context, @Nullable AttributeSet attrs) {
        this(context, attrs,0);
    }

    public MyPaddingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {
        this(context, attrs, defStyleAttr,0);
    }

    public MyPaddingView(Context context, @Nullable AttributeSet attrs, int defStyleAttr, int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        init();
    }

    private void init() {

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        int widthMode = MeasureSpec.getMode(widthMeasureSpec);
        int widthSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightMode = MeasureSpec.getMode(heightMeasureSpec);
        int heightSize = MeasureSpec.getSize(heightMeasureSpec);
        float hScale = 1.0f;
        float vScale = 1.0f;
        if (widthMode != MeasureSpec.UNSPECIFIED && widthSize < mNomalSize) {
            hScale = (float) widthSize / (float) mNomalSize;
        }
        if (heightMode != MeasureSpec.UNSPECIFIED && heightSize < mNomalSize) {
            vScale = (float) heightSize / (float) mNomalSize;
        }

        float scale = Math.min(hScale, vScale);
        mWidth = resolveSizeAndState((int) (mNomalSize * scale), widthMeasureSpec, 0);
        mHeith = resolveSizeAndState((int) (mNomalSize * scale), heightMeasureSpec, 0);
        setMeasuredDimension(mWidth, mHeith);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint mPaint = new Paint();
        mPaint.setColor(Color.RED);
        //考虑自定义view设置的padding属性，由于layout_margin相关属性是viewgroup负责的，因此只有自定义
        //viewgroup时才需要考虑其子view的layout_margin熟悉生效，view无需考虑layout_margin属性
        paddingLeft = getPaddingLeft();
        paddingTop = getPaddingTop();
        paddingRight = getPaddingRight();
        paddingBottom = getPaddingBottom();
        Rect rect = new Rect();
        rect.left = 0 + paddingLeft;
        rect.top = 0 + paddingTop;
        rect.right = mWidth - paddingRight;
        rect.bottom = mHeith - paddingBottom;
        canvas.drawRect(rect,mPaint);
    }
}

布局：

<?xml version="1.0" encoding="utf-8"?>
<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:orientation="vertical"
    tools:context=".MainActivity">

    <hongzhen.com.defineviewdemo.MyPaddingView
        android:layout_width="300dp"
        android:layout_height="300dp"
        android:layout_margin="10dp"
        android:padding="10dp"/>

    <hongzhen.com.defineviewdemo.MyMarginViewGroup
        android:background="#aaa"
        android:padding="10dp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content">

        <hongzhen.com.defineviewdemo.MyPaddingView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="#ddd"
            android:padding="10dp"
            android:layout_margin="15dp"/>
        <hongzhen.com.defineviewdemo.MyPaddingView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:background="#ddd"
            android:padding="10dp"
            android:layout_margin="15dp"/>
    </hongzhen.com.defineviewdemo.MyMarginViewGroup>

</LinearLayout>

 效果：请忽略下方的MyMarginViewGroup控件