安卓自定义控件卡券CouponView

package com.example.couponview;

import android.content.Context;
import android.content.res.TypedArray;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.RelativeLayout;
/**
 * 卡券控件
 * @author wbl
 *
 */
public class CouponView extends RelativeLayout{

private Paint mPaint;
//边缘小半圆的半径
private float radius = 20;
//小半圆之间的间距
private float spacing = 20;
//左右边距
private float paddingLeft;
private float paddingRight;
//半圆的个数
private int numCircle;
//控件的高宽度
private int height;
private int width;

private float remain;

public CouponView(Context context, AttributeSet attrs, int defStyle) {
super(context, attrs, defStyle);
//initView(context);
}

public CouponView(Context context, AttributeSet attrs) {
super(context, attrs);
initView(context,attrs);
}

public CouponView(Context context) {
super(context);
//initView(context);
}

private void initView(Context context,AttributeSet attrs) {
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setColor(Color.WHITE);

TypedArray ta = context.obtainStyledAttributes(attrs,R.styleable.CouponView);
float radius = ta.getDimension(R.styleable.CouponView_radius,20);
float spacing = ta.getDimension(R.styleable.CouponView_spacing, 20);
setRadius(radius);
setSpacing(spacing);

ta.recycle();

paddingLeft = paddingRight = spacing;
}


private void setSpacing(float spacing) {
this.spacing = spacing;
}

private void setRadius(float radius) {
this.radius = radius;
}



@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
System.out.println("这里");
// getWidth在OnCreat的时候得到的是0. 当一个view对象创建时，android并不知道其大小，所以getWidth()和   getHeight()返回的结果是0，真正大小是在计算布局时才会计算.
width = this.getWidth();
height = this.getHeight();
//圆的数量始终比边距数量少一个，所以总长度减去左边距除以2*radius+spacing的值就是圆的数量
numCircle = (int) ((width-paddingLeft)/(2*radius+spacing));
//除以所有圆和边距的所余下的长度
remain = ((width-paddingLeft)%(2*radius+spacing));
System.out.println("圆的个数=="+numCircle);
System.out.println("remain=="+remain);
}

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
        //remain/2保证左右两边边距一样
float cx = (paddingLeft+radius+remain/2);
for(int i=0;i<numCircle;i++){
canvas.drawCircle(cx, 0, radius, mPaint);
canvas.drawCircle(cx, height, radius, mPaint);
cx = (int) (cx+(2*radius+spacing));
}
}



}

在values目录下创建attrs.xml文件

<?xml version="1.0" encoding="utf-8"?>
<resources>
    <declare-styleable name="CouponView">
        <attr name="radius" format="dimension"/>
        <attr name="spacing" format="dimension"/>      
    </declare-styleable>
</resources>

下面是布局文件

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:wbl="http://schemas.android.com/apk/res/com.example.couponview"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center_horizontal"
    android:background="@color/white"
    android:paddingTop="20dp"
     >

    <com.example.couponview.CouponView
        android:layout_width="280dp"
        android:layout_height="100dp"
        android:background="@color/blue"
        wbl:radius="10dp"
        wbl:spacing="10dp"
        android:gravity="center" >

        <TextView
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="卡劵"
            android:textColor="@color/white"
            android:textSize="30dp" />
    </com.example.couponview.CouponView>

</RelativeLayout>

以下是运行结果