自定義控件之--繼承控件（圓形TextView）

師從郭大，自學於心，繼承控件無疑就是繼承自現有控件，保持繼承的控件的屬性並進行必要的擴展。

 

比如下面這個自定義控件，它就保持了TextView的屬性，並對TextView的外觀進行必要的修改該來適應自己的項目，主要實現的是一個圓形的TextView的功能。

 

三個構造方法：

onMesure(): onMeasure()方法顧名思義就是用於測量視圖的大小的, 確定視圖的寬度和高度的規格和大小 ;

draw():視圖繪制， canvas.drawCircle(getWidth()/2, getHeight()/2,Math.max(getWidth(), getHeight())/2, mBgPaint); 繪制圓形 。

 

給Canvas加上抗鋸齒標志:

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

canvas.setDrawFilter(pfd);

 

繪制圓形的TextView:

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


 

設置回調方法，然后控制組件的內容和背景：

 

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);
       }
       /**
        * 設置通知個數顯示
        * @param text
        */
       public void setNotifiText(int text){
           setText(text+"");
       }
       @Override
       public void draw(Canvas canvas) {
           canvas.setDrawFilter(pfd);//給Canvas加上抗鋸齒標志
           canvas.drawCircle(getWidth()/2, getHeight()/2, Math.max(getWidth(), getHeight())/2, mBgPaint);
           super.draw(canvas);
       }
   }

github:

https://github.com/soyoungboy/MyCircleTextView