自定义View的编写

在项目的时候，很多情况要用到自定义View来达到自己想要的效果，所有自定义View的编写很重要。

首先看看所要实现的效果：

最上面的一行字“LogicView”每次从左向右滚动，下面的圆从角度0到360不断变化。并且颜色随机地变化。

MainActivity.java

 package com.example.myview;

 import android.os.Bundle;

 import android.app.Activity;

 import android.view.Menu;

 public class MainActivity extends Activity {

     @Override

     protected void onCreate(Bundle savedInstanceState) {

         super.onCreate(savedInstanceState);

         setContentView(R.layout.activity_main);

         //setContentView(new Myview(this));

     }

 }

activity_main.xml

 <FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"

     xmlns:tools="http://schemas.android.com/tools"

     android:layout_width="match_parent"

     android:layout_height="match_parent"

     tools:context=".MainActivity" >

     <com.example.myview.TestClass

         android:layout_width="match_parent"

         android:layout_height="match_parent"

         />

 </FrameLayout>

TestClass.java

 package com.example.myview;

 import java.util.Random;

 import android.content.Context;

 import android.graphics.Canvas;

 import android.graphics.Paint;

 import android.graphics.RectF;

 import android.util.AttributeSet;

 import android.view.View;

 public  class TestClass extends View{

     private MyThread thread;

     private Paint paint = new Paint();

     private float rx = ;

     private RectF rectF = new RectF(,,,);

     private float sweepAngel = ;

     Random rand = new Random();

     public TestClass(Context context, AttributeSet attrs) {

         super(context, attrs);

     }

     public TestClass(Context context) {

         super(context);

     }

     private  void drawSub(Canvas canvas){

         paint.setTextSize();

         canvas.drawText("LogicView", rx, , paint);

         canvas.drawArc(rectF,,sweepAngel,true,paint);

     }

     protected void onDraw(Canvas canvas){

         if(thread==null){

             thread = new MyThread();

             thread.start();

         }else{

             drawSub(canvas);

         }

     }

     private void logic(){

         rx++;

         if(rx > getWidth()){

             rx =  - paint.measureText("LogicView");

         }

         sweepAngel ++ ;

         if(sweepAngel > ){

             sweepAngel = ;

         }

         int r = rand.nextInt();

         int g = rand.nextInt();

         int b = rand.nextInt();

         paint.setARGB(, r, g, b);

     }

     class MyThread extends Thread{

         @Override

         public void run() {

             while(true){

                 logic();

                 postInvalidate();

                 try {

                     Thread.sleep();

                 } catch (InterruptedException e) {

                     e.printStackTrace();

                 }

             }

         }

     }

 }