package com.example.guaguale;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.widget.TextView;

/**
 * Created by Administrator on 2017\10\6 0006.
 */

public class ScratchTextView extends TextView {
    private static final String TAG = "ScratchTextView";
    private Bitmap mbitmap;// 蓋在字上面的圖片
    private Canvas mCanvas; //畫線的畫布
    private Paint mPaint;//劃線的畫筆
    private Path mPath;//線
    private float mX, mY;
    private float TOUCH_TOLERANCE;
    private boolean isInited = false;//用於判斷時候覆蓋了textview的文字

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

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

    public ScratchTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    //onDraw初始化的時候調用一次，然invalidate()的時候調用，
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        if (isInited) {
            mCanvas.drawPath(mPath, mPaint);//把線畫到mCanvas上,mCanva會把線畫到mBitmap
            canvas.drawBitmap(mbitmap, 0, 0, null);// 把mBitmap畫到textview上 canvas是父textvie傳過來的。
        }
    }

    /**
     * 初始化刮刮卡
     *
     * @param bgColor          刮刮卡背景色，用於蓋住下面的字
     * @param paintStrokeWidth 擦除線寬
     * @param touchTolerance   畫線容差
     */
    public void initScratchCard(final int bgColor, final int paintStrokeWidth, float touchTolerance) {
        TOUCH_TOLERANCE = touchTolerance;
        mPaint = new Paint();//創建畫筆
        mPaint.setAlpha(240);
        mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));//
        mPaint.setAntiAlias(true);// 抗鋸齒        mPaint.setDither(true);// 防抖動        mPaint.setStyle(Paint.Style.STROKE);// 畫筆類型： STROKE空心 FILL實心 FILL_AND_STROKE用契形填充        mPaint.setStrokeJoin(Paint.Join.ROUND);// 畫筆接洽點類型        mPaint.setStrokeCap(Paint.Cap.ROUND);// 畫筆筆刷類型        mPaint.setStrokeWidth(paintStrokeWidth);// 畫筆筆刷寬度        mPath = new Path();        //建立一個空的Bit        mbitmap = Bitmap.createBitmap(100, 90, Bitmap.Config.ARGB_8888);//        mCanvas = new Canvas(mbitmap);//通過bitmap生成一個畫布        Paint paint = new Paint();//用於繪制生成的背景圖片的字體        paint.setTextSize(50);///字體大小        paint.setColor(Color.parseColor("#ff0717"));        mCanvas.drawColor(bgColor);//背景色        //.從資源文件中獲取圖片        Bitmap photo = BitmapFactory.decodeResource(this.getResources(), R.drawable.sss);        mCanvas.drawBitmap(photo, 0 , 1 , paint);//設置遮蓋層的圖片。比如說，衣服        //設置外層的文字。        mCanvas.drawText("不要嘛！！", getLayoutParams().width / 4, getLayoutParams().height / 2 + 15, paint);        isInited = true;    }    //該觸膜事件可以定義在調用的activity中實現    @Override    public boolean onTouchEvent(MotionEvent event) {        if (!isInited) {            return true;        }        switch (event.getAction()) {            case MotionEvent.ACTION_DOWN:                mPath.reset();        // 重置繪制路線，即隱藏之前繪制的軌跡                mPath.moveTo(event.getX(), event.getY());        // mPath繪制的繪制起點                mX = event.getX();                mY = event.getY();                invalidate();//更新界面                Log.d(TAG, mX + "|" + mY);                break;            case MotionEvent.ACTION_MOVE:                //x和y移動的距離                float dx = Math.abs(event.getX() - mX);                float dy = Math.abs(event.getY() - mY);                //x,y移動的距離大於畫線容差                if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {                    // 二次貝塞爾，實現平滑曲線；mX, mY為操作點，(x + mX) / 2, (y + mY) / 2為終點                    mPath.quadTo(mX, mY, (event.getX() + mX) / 2, (event.getY() + mY) / 2);                    // 第二次執行時，第一次結束調用的坐標值將作為第二次調用的初始坐標值                    mX = event.getX();                    mY = event.getY();                    Log.d(TAG, mX + "|" + mY);                    invalidate();                    break;                }        }        return true;    }}
 

ScratchTextView scratchTv;
 @Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
     scratchTv= (ScratchTextView) findViewById(R.id.scratchTv);
    String[] str_reward = {"討厭！", "舒服1000！", "真爽10000！","真爽10000！"};
    scratchTv.setText(str_reward[getRandom()]);
    scratchTv.initScratchCard(0xFFFFFFFF, 20, 1f);
}
private int getRandom() {
    Random random = new Random();
    int number = random.nextInt(5);
    return number;
}
 

<com.example.guaguale.ScratchTextView
    android:id="@+id/scratchTv"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

自定義view刮刮樂