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. package com.example.circletextview;
   import android.content.Context;
   import android.graphics.Canvas;
   import android.graphics.Color;
   import android.graphics.Paint;
   import android.graphics.PaintFlagsDrawFilter;
   import android.util.AttributeSet;
   import android.widget.TextView;
   public class CircleView extends TextView {
       private Paint mBgPaint = new Paint();
       PaintFlagsDrawFilter pfd = new PaintFlagsDrawFilter(0, Paint.ANTI_ALIAS_FLAG|Paint.FILTER_BITMAP_FLAG); 
       public CircleView(Context context, AttributeSet attrs, int defStyle) {
           super(context, attrs, defStyle);
       }
       public CircleView(Context context, AttributeSet attrs) {
           super(context, attrs);
           mBgPaint.setColor(Color.WHITE);
           mBgPaint.setAntiAlias(true);
       }
       public CircleView(Context context) {
           super(context);
           mBgPaint.setColor(Color.WHITE);
           mBgPaint.setAntiAlias(true);
       }
       @Override
       protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
           super.onMeasure(widthMeasureSpec, heightMeasureSpec);
           int measuredWidth = getMeasuredWidth();
           int measuredHeight = getMeasuredHeight();
           int max = Math.max(measuredWidth, measuredHeight);
           setMeasuredDimension(max, max);
       }
       @Override
       public void setBackgroundColor(int color) {
           mBgPaint.setColor(color);
       }
       /**
        * 设置通知个数显示
        * @param text
        */
       public void setNotifiText(int text){
           setText(text+"");
       }
       @Override
       public void draw(Canvas canvas) {
           canvas.setDrawFilter(pfd);//给Canvas加上抗锯齿标志
           canvas.drawCircle(getWidth()/2, getHeight()/2, Math.max(getWidth(), getHeight())/2, mBgPaint);
           super.draw(canvas);
       }
   }

github:

https://github.com/soyoungboy/MyCircleTextView