自定义控件之--继承控件（圆形TextView）

师从郭大，自学于心，继承控件无疑就是继承自现有控件，保持继承的控件的属性并进行必要的扩展。

 

比如下面这个自定义控件，它就保持了TextView的属性，并对TextView的外观进行必要的修改该来适应自己的项目，主要实现的是一个圆形的TextView的功能。

 

三个构造方法：

onMesure(): onMeasure()方法顾名思义就是用于测量视图的大小的, 确定视图的宽度和高度的规格和大小 ;

draw():视图绘制， canvas.drawCircle(getWidth()/2, getHeight()/2,Math.max(getWidth(), getHeight())/2, mBgPaint); 绘制圆形 。

 

给Canvas加上抗锯齿标志:

PaintFlagsDrawFilter pfd =newPaintFlagsDrawFilter(0,Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG);

canvas.setDrawFilter(pfd);

 

绘制圆形的TextView:

canvas.drawCircle(getWidth()/2, getHeight()/2,Math.max(getWidth(), getHeight())/2, mBgPaint);


 

设置回调方法，然后控制组件的内容和背景：

 

setBackgroundColor

setNotifiText

1.  1 package com.example.circletextview;
    2 import android.content.Context;
    3 import android.graphics.Canvas;
    4 import android.graphics.Color;
    5 import android.graphics.Paint;
    6 import android.graphics.PaintFlagsDrawFilter;
    7 import android.util.AttributeSet;
    8 import android.widget.TextView;
    9 public class CircleView extends TextView {
   10     private Paint mBgPaint = new Paint();
   11     PaintFlagsDrawFilter pfd = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG); 
   12     public CircleView(Context context, AttributeSet attrs, int defStyle) {
   13         super(context, attrs, defStyle);
   14     }
   15     public CircleView(Context context, AttributeSet attrs) {
   16         super(context, attrs);
   17         mBgPaint.setColor(Color.WHITE);
   18         mBgPaint.setAntiAlias(true);
   19     }
   20     public CircleView(Context context) {
   21         super(context);
   22         mBgPaint.setColor(Color.WHITE);
   23         mBgPaint.setAntiAlias(true);
   24     }
   25     @Override
   26     protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
   27         super.onMeasure(widthMeasureSpec, heightMeasureSpec);
   28         int measuredWidth = getMeasuredWidth();
   29         int measuredHeight = getMeasuredHeight();
   30         int max = Math.max(measuredWidth, measuredHeight);
   31         setMeasuredDimension(max, max);
   32     }
   33     @Override
   34     public void setBackgroundColor(int color) {
   35         mBgPaint.setColor(color);
   36     }
   37     /**
   38      * 设置通知个数显示
   39      * @param text
   40      */
   41     public void setNotifiText(int text){
   42         setText(text+"");
   43     }
   44     @Override
   45     public void draw(Canvas canvas) {
   46         canvas.setDrawFilter(pfd);//给Canvas加上抗锯齿标志
   47         canvas.drawCircle(getWidth()/2, getHeight()/2, Math.max(getWidth(), getHeight())/2, mBgPaint);
   48         super.draw(canvas);
   49     }
   50 }

github:

https://github.com/soyoungboy/MyCircleTextView