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(); }