Android自定义View过程解析

 <!-- 可以使用view的公共属性,例如背景 -->
 <com.niuli.view.MyView 
  android:layout_width="match_parent"
  android:layout_height="match_parent"
  android:background="#ffff00"
  />

public class MyView extends View {

 Bitmap bitmap;

 public MyView(Context context) {
  super(context);
  /**
   * getResources()可以获取当前资源内的资源
   */
  bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
 }

 public MyView(Context context, AttributeSet attrs) {
  super(context, attrs);
  bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
 }
 /**
  * 绘制是通过Canvas来承载,其就相当于一块画布
  * 更多的学习将在不断的做小东西中更新
  */
 @Override
 protected void onDraw(Canvas canvas) {
  super.onDraw(canvas);
  /**
   * Paint相当于一只画笔,可以画文字,几何图形,bit图片等
   */
  Paint paint = new Paint();
  //设置绘制的颜色,是否空心之类的都是对画笔的设计
  paint.setColor(Color.BLUE);

  //绘画文字
  paint.setTextSize(30);
  canvas.drawText("这是一个自定义view", 0, 30, paint);
  //绘画直线
  canvas.drawLine(0, 60, 100, 60, paint);
  //绘画圆角矩形方法之一
  //设置空心
  paint.setStyle(paint.getStyle().STROKE);

  RectF rec = new RectF(0, 90, 100, 190);
  canvas.drawRoundRect(rec, 20, 20, paint);
  //绘制图片
  canvas.drawBitmap(bitmap, 0, 350, paint);
 }

}

public class MyViewtwo extends View {

 //定义画笔
 private Paint paint = new Paint();
 private int x;
 private float sweepAngle;
 private control thread;
 private Random random = new Random();

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

 public MyViewtwo(Context context) {
  super(context);
 }

 @Override
 protected void onDraw(Canvas canvas) {
  paint.setTextSize(80);
  //绘制文字
  canvas.drawText("七夕快乐", x, 70, paint);
  //绘制图形
  RectF rect = new RectF(0 ,80 ,100, 160);
  canvas.drawArc(rect, 0, sweepAngle, true, paint);

  //启动线程
  if (thread ==null) {
   thread = new control();
   thread.start();
  }
 }
 public class control extends Thread{
  @Override
  public void run() {
   while(true){
    x +=3;
    sweepAngle++;
    if (x>getWidth()) {
     x = (int) (0 - paint.measureText("七夕快乐"));
    }
    //控制圆的的旋转
    if (sweepAngle>360) {
     sweepAngle = 0;
    }
    //设置画笔颜色
    paint.setARGB(255, random.nextInt(255), random.nextInt(255), random.nextInt(255));

    //相当于刷新画布
    postInvalidate();

    try {
     sleep(30);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
   }
  }
 }

public abstract class MyViewtwo extends View {

 private control thread;

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

 public MyViewtwo(Context context) {
  super(context);
 }
 //封装,构造画面,子类继承后需要重写
 protected abstract void drawsub(Canvas canvas);

 @Override
 protected final void onDraw(Canvas canvas) {

  //启动线程
  if (thread ==null) {
   thread = new control();
   thread.start();
  }else {
   drawsub(canvas);
  }
 }
 //封装移动方法,子类继承后需要重写
 protected abstract void move();

 public class control extends Thread{
  @Override
  public void run() {
   while(true){
    move();
    //相当于刷新画布
    postInvalidate();

    try {
     sleep(30);
    } catch (InterruptedException e) {
     e.printStackTrace();
    }
   }
  }
 }

}

<?xml version="1.0" encoding="utf-8"?>
<resources>
 <declare-styleable name="NumText">
  <attr name="lineNum" format="integer"/>
  <attr name="xScroll" format="boolean" />
 </declare-styleable>
</resources>

<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 xmlns:nt="http://schemas.android.com/apk/res/com.jikexueyuan.myview"
 android:id="@+id/container"
 android:layout_width="match_parent"
 android:layout_height="match_parent" >

 <com.jikexueyuan.myview.v4.NumText 
  android:layout_width="match_parent"
  android:layout_height="match_parent" 
  nt:lineNum="6"
  nt:xScroll="true"/>

</FrameLayout>

public NumText(Context context, AttributeSet attrs) {
  super(context, attrs);

  TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.NumText);
  lineNum = ta.getInt(R.styleable.NumText_lineNum, 1);
  xScroll = ta.getBoolean(R.styleable.NumText_xScroll, false);
  ta.recycle();
 }