image.png

上代码

package com.nick.customview;

import android.content.Context;

import android.graphics.Canvas;

import android.graphics.Color;

import android.graphics.Paint;

import android.graphics.RectF;

import android.support.annotation.Nullable;

import android.support.v7.widget.AppCompatImageView;

import android.util.AttributeSet;

public class SimpleRectangle extends AppCompatImageView {

public SimpleRectangle(Context context) {

super(context);

}

public SimpleRectangle(Context context, @Nullable AttributeSet attrs) {

super(context, attrs);

}

public SimpleRectangle(Context context, @Nullable AttributeSet attrs, int defStyleAttr) {

super(context, attrs, defStyleAttr);

}

@Override

public void draw(Canvas canvas) {

Paint paint = new Paint();

paint.setColor(Color.BLUE);

paint.setStyle(Paint.Style.STROKE);

paint.setAlpha(250);

paint.setStrokeWidth(10.0f);

paint.setStrokeCap(Paint.Cap.ROUND);

RectF rectF = new RectF(80, 80, getWidth()- 80, getHeight()- 80);

canvas.drawRoundRect(rectF, 30, 30, paint);

canvas.drawLine(80, getHeight()/2, getWidth()- 80, getHeight()/2, paint);

canvas.drawLine(getWidth()/2, 80, getWidth()/2, getHeight()- 80, paint);

super.draw(canvas);

}

}

一开始遇到的问题是怎么让边框的角变成圆角，后来查到添加paint的一个属性就可以做到。看developers怎么介绍这个牛逼的属性的：

paint.setStrokeCap(Paint.Cap.ROUND);

image.png

当画笔paint的样式是描边或这描边填充时使用Cap参数来设置线头的样式。