public class GuaGuaLe extends View{ /**中獎(jiǎng)文本變量*/ private String mText;//顯示文本 private Paint mTextPaint;//繪制文本的畫筆 private Rect mTextBounds;//文本的邊界 public GuaGuaLe(Context context) { this(context, null); } public GuaGuaLe(Context context, AttributeSet attrs) { super(context, attrs); initView(); } /**初始化一些實(shí)例變量*/ private void initView() { setTextMessage();//實(shí)例化文本的一些變量 } private void setTextMessage() { mText = "謝謝惠顧"; mTextBounds = new Rect(); mTextPaint = new Paint(); mTextPaint.setAntiAlias(true); mTextPaint.setColor(Color.DKGRAY); mTextPaint.setTextSize(22); mTextPaint.getTextBounds(mText,0,mText.length(),mTextBounds);//獲取到繪制文本的長寬 } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); } @Override protected void onDraw(Canvas canvas) { //繪制文本 canvas.drawText(mText,getWidth()/2 - mTextBounds.width()/2,getHeight()/2 + mTextBounds.height()/2,mTextPaint); }}

 /**畫板變量*/ private Canvas mCanvas;//緩沖畫板 private Bitmap mLayerBimtap;//圖層圖片 private Bitmap mBitmap;//畫板上的畫紙 private Paint mPaint;//畫筆 @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); setCanvasMessage(getMeasuredWidth(),getMeasuredHeight());//實(shí)例化緩存畫板的一些變量 } /*** * 雙緩沖技術(shù) * 1.創(chuàng)建一個(gè)與屏幕繪制區(qū)域一致的Canvas對(duì)象 * 2.先將圖形繪制到內(nèi)存中 * 3.再一次性將對(duì)象上的圖形拷貝到屏幕上 * @param width * @param height */ private void setCanvasMessage(int width,int height) { mPaint = new Paint(); mPaint.setAntiAlias(true); mPaint.setStyle(Paint.Style.FILL); mPaint.setStrokeWidth(3); mPaint.setColor(Color.parseColor("#c0c0c0")); mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);//創(chuàng)建一個(gè)空白的位圖 mCanvas = new Canvas(mBitmap);//在此Bitmap上作畫 //mCanvas.drawColor(Color.parseColor("#c0c0c0"));//繪制背景顏色 mCanvas.drawRoundRect(new RectF(0, 0, width, height), 20, 20, mPaint);//繪制圓角矩形 mLayerBimtap = BitmapFactory.decodeResource(getResources(), R.mipmap.fg_guaguaka); mCanvas.drawBitmap(mLayerBimtap, null, new RectF(0, 0, width, height), null);//繪制圖層圖片 @Override protected void onDraw(Canvas canvas) { //繪制文本 canvas.drawText(mText,getWidth()/2 - mTextBounds.width()/2,getHeight()/2 + mTextBounds.height()/2,mTextPaint); //繪制圖層 //canvas.drawBitmap(mBitmap,0,0,null); //繪制圖層圖片 canvas.drawBitmap(mBitmap,0,0,null); } }

 /**路徑變量*/ private Path mPath; private Paint mPathPaint; private int mLastX;//記錄上一次X坐標(biāo) private int mLastY;//記錄上一次Y坐標(biāo) /**初始化一些實(shí)例變量*/ private void initView() { setTextMessage();//實(shí)例化文本的一些變量 setPathMessage();//實(shí)例化路徑的一些變量 } @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); //獲取手指在屏幕上的坐標(biāo) int x = (int) event.getX(); int y = (int) event.getY(); switch (action){  case MotionEvent.ACTION_DOWN:  mLastX = x;  mLastY = y;  mPath.moveTo(mLastX,mLastY);  break;  case MotionEvent.ACTION_MOVE:  int dx = Math.abs(x - mLastX);  int dy = Math.abs(y - mLastY);  if(dx > 3 || dy >3){   mPath.lineTo(x, y);  }  mLastX = x;  mLastY = y;  break;  case MotionEvent.ACTION_UP:  break;  default:  break; } invalidate();//主線程中刷新 return true;//截取事件向下分發(fā) } @Override protected void onDraw(Canvas canvas) { //繪制文本 canvas.drawText(mText,getWidth()/2 - mTextBounds.width()/2,getHeight()/2 + mTextBounds.height()/2,mTextPaint); //繪制路徑 drawPath(); //繪制圖片【圖層背景顏色】 //canvas.drawBitmap(mBitmap,0,0,null); //繪制圖片【圖層圖片】 canvas.drawBitmap(mBitmap, 0, 0, null); } //返回給系統(tǒng)的canvas是一幅帶有路徑的位圖 private void drawPath() { //這之前是設(shè)置了圖層圖片 mPathPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT)); mCanvas.drawPath(mPath,mPathPaint); }

 /**擦除是否完成*/ private volatile boolean isComplete; /**回調(diào)接口*/ private OnCompleteListener mOnCompleteListener; public interface OnCompleteListener{ void complete(); } //對(duì)外設(shè)置調(diào)用的公開方法 public void setmOnCompleteListener(OnCompleteListener mOnCompleteListener){ this.mOnCompleteListener = mOnCompleteListener; } case MotionEvent.ACTION_UP:  //開啟一個(gè)線程去計(jì)算擦除的面積  new Thread(new Runnable() {   @Override   public void run() {   int width = getWidth();   int height = getHeight();   int area = 0;//記錄被擦數(shù)的范圍大小   int percent ;   for(int i=0;i<width;i++)    for(int j = 0;j<height;j++){    if(mBitmap.getPixel(i,j) == 0){     area ++;    }    }   if(area > 0){    percent = area *100/(width*height);    if(percent > 20){    isComplete = true;    postInvalidate();//在子線程中刷新，可能比較耗時(shí)操作    }   }   }  }).start(); @Override protected void onDraw(Canvas canvas) { //繪制文本 canvas.drawText(mText, getWidth() / 2 - mTextBounds.width() / 2, getHeight() / 2 + mTextBounds.height() / 2, mTextPaint); if(isComplete){  if(mOnCompleteListener != null){  mOnCompleteListener.complete();//接口回調(diào)，在主線程中  } } if(!isComplete){  //繪制路徑  drawPath();  //繪制圖片【圖層背景顏色】  //canvas.drawBitmap(mBitmap,0,0,null);  //繪制圖片【圖層圖片】  canvas.drawBitmap(mBitmap, 0, 0, null); } }public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); GuaGuaLe guaguaLeView = (GuaGuaLe) findViewById(R.id.guaguale); //注冊了一個(gè)觀察者 guaguaLeView.setmOnCompleteListener(new GuaGuaLe.OnCompleteListener() {  @Override  public void complete() {  Toast.makeText(MainActivity.this, "用戶繪制了大部分", Toast.LENGTH_SHORT).show();  } }); }}

在values/attrs.xml中定義 <declare-styleable name="GuaGuaLe"> <attr name="text" format="string"></attr> <attr name="textSize" format="dimension"></attr> <attr name="textColor" format="color"></attr> </declare-styleable>在布局文件中定義屬性 <zlll.bg.com.example.cn.myapplication.view.GuaGuaLe  android:id="@+id/guaguale"  android:layout_width="350dp"  android:layout_height="200dp"  app:text="$5,000"  app:textColor="#c02040"  app:textSize="22sp"  android:layout_centerInParent="true"/>在主界面中定義Text文本public class MainActivity extends AppCompatActivity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); GuaGuaLe guaguaLeView = (GuaGuaLe) findViewById(R.id.guaguale); //注冊了一個(gè)觀察者 guaguaLeView.setmOnCompleteListener(new GuaGuaLe.OnCompleteListener() {  @Override  public void complete() {  Toast.makeText(MainActivity.this, "用戶繪制了大部分", Toast.LENGTH_SHORT).show();  } }); guaguaLeView.setTextByUser("Android 新技能Get"); }} /**中獎(jiǎng)文本變量*/ private String mText;//顯示文本 private Paint mTextPaint;//繪制文本的畫筆 private Rect mTextBounds;//文本的邊界 //以下兩個(gè)是新增的 private int mTextSize;//文本大小 private int mTextColor;//文本顏色 //對(duì)外設(shè)置調(diào)用的設(shè)置文本公開方法 public void setTextByUser(String text){ mText = text; mTextPaint.getTextBounds(mText,0,mText.length(),mTextBounds);//重新計(jì)算文本的范圍 }在構(gòu)造函數(shù)中定義 public GuaGuaLe(Context context, AttributeSet attrs) { super(context, attrs); //獲取自定義屬性的值 TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.GuaGuaLe); mText = a.getString(R.styleable.GuaGuaLe_text); mTextColor = a.getColor(R.styleable.GuaGuaLe_textColor, Color.parseColor("#c0c0c0")); //TypedValue.applyDimension內(nèi)部就是將sp,dp轉(zhuǎn)化為px mTextSize = a.getDimensionPixelSize(R.styleable.GuaGuaLe_textSize, (int) TypedValue.applyDimension  (TypedValue.COMPLEX_UNIT_SP,22,getResources().getDisplayMetrics())); a.recycle(); initView(); }