效果图

刮刮卡自定义控件

import android.content.Context;
import android.graphics.Bitmap;
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.graphics.Rect;
import android.graphics.RectF;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.View;
/**
 * 描述：
 * 作者： shawn
 * 时间： 2024/5/2711:20
 */
public class ScratchView extends View {
    /**
     * 绘制线条的画笔
     */
    private Paint mOutterPaint = new Paint();
    /**
     * 遮层画笔
     */
    private Paint mMaskPaint = new Paint();
    /**
     * 最下面画笔
     */
    private Paint mBackPint = new Paint();
    /**
     * mCanvas绘制内容在其上
     */
    private Bitmap mBitmap;
    /**
     * 记录用户绘制的Path
     */
    private Path mPath = new Path();
    /**
     * 内存中创建的Canvas
     */
    private Canvas mCanvas;
    private boolean isComplete;
    private Rect mTextBound = new Rect();
    private String mText = "￥500,0000";
    private int mLastX;
    private int mLastY;
    private int measuredWidth;
    private int measuredHeight;
    public GuaGuaKaView(Context context) {
        this(context, null);
    }
    public GuaGuaKaView(Context context, AttributeSet attrs) {
        this(context, attrs, 0);
    }
    public GuaGuaKaView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }
    private void init() {
        mPath = new Path();
        setUpOutPaint();
        setUpBackPaint();
    }
    /**
     * 初始化canvas的绘制用的画笔
     */
    private void setUpBackPaint() {
        mBackPint.setStyle(Paint.Style.FILL);
        mBackPint.setTextScaleX(2f);
        mBackPint.setColor(Color.DKGRAY);
        mBackPint.setTextSize(32);
        mBackPint.getTextBounds(mText, 0, mText.length(), mTextBound);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        if (!isComplete) {
            drawPath();
            canvas.drawBitmap(mBitmap, 0, 0, null);
        } else {
            this.setVisibility(GONE);
        }
    }
    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        measuredWidth = getMeasuredWidth();//宽高和父view的相同
        measuredHeight = getMeasuredHeight();
        // 初始化bitmap
        mBitmap = Bitmap.createBitmap(measuredWidth, measuredHeight, Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
        mMaskPaint.setColor(Color.parseColor("#000000"));//遮层透明
        mMaskPaint.setStyle(Paint.Style.FILL);
        mCanvas.drawRoundRect(new RectF(0, 0, measuredWidth, measuredHeight), 0, 0, mMaskPaint);
//        mCanvas.drawBitmap(BitmapFactory.decodeResource(getResources(),
//                R.drawable.bg_withdraw_history), null, new RectF(0, 0, measuredWidth, measuredHeight), null);//遮层
    }
    /**
     * 设置画笔的一些参数
     */
    private void setUpOutPaint() {
        // 设置画笔
//         mOutterPaint.setAlpha(0);
        mOutterPaint.setColor(Color.parseColor("#c0c0c0"));
        mOutterPaint.setAntiAlias(true);
        mOutterPaint.setDither(true);
        mOutterPaint.setStyle(Paint.Style.STROKE);
        mOutterPaint.setStrokeJoin(Paint.Join.ROUND); // 圆角
        mOutterPaint.setStrokeCap(Paint.Cap.ROUND); // 圆角
        // 设置画笔宽度
        mOutterPaint.setStrokeWidth(50);
    }
    /**
     * 绘制线条
     */
    private void drawPath() {
        mOutterPaint.setStyle(Paint.Style.STROKE);
        mOutterPaint
                .setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));//取俩者的交集
        mCanvas.drawPath(mPath, mOutterPaint);
    }
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        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;
                new Thread(mRunnable).start();
                break;
            case MotionEvent.ACTION_UP:
                new Thread(mRunnable).start();
                break;
        }
        invalidate();
        return true;
    }
    /**
     * 统计擦除区域任务
     */
    private Runnable mRunnable = new Runnable() {
        private int[] mPixels;
        @Override
        public void run() {
            int w = getWidth();
            int h = getHeight();
            float wipeArea = 0;
            float totalArea = w * h;
            Bitmap bitmap = mBitmap;
            mPixels = new int[w * h];
            /**
             * 拿到所有的像素信息
             */
            bitmap.getPixels(mPixels, 0, w, 0, 0, w, h);
            /**
             * 遍历统计擦除的区域
             */
            for (int i = 0; i < w; i++) {
                for (int j = 0; j < h; j++) {
                    int index = i + j * w;
                    if (mPixels[index] == 0) {
                        wipeArea++;
                    }
                }
            }
            /**
             * 根据所占百分比，进行一些操作
             */
            if (wipeArea > 0 && totalArea > 0) {
                int percent = (int) (wipeArea * 100 / totalArea);
                Log.e("TAG", "清除区域 = " + percent);
                if (percent > 75) {
                    isComplete = true;
                    postInvalidate();
                }
            }
        }
    };
    /**
     * 将布局转换成bitmap
     * @param addViewContent
     * @return
     */
    private Bitmap getViewBitmap(View addViewContent) {
        addViewContent.setDrawingCacheEnabled(true);
        addViewContent.measure(
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED),
                View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED));
        addViewContent.layout(0, 0,
                addViewContent.getMeasuredWidth(),
                addViewContent.getMeasuredHeight());
        addViewContent.buildDrawingCache();
        Bitmap cacheBitmap = addViewContent.getDrawingCache();
        Bitmap bitmap = Bitmap.createBitmap(cacheBitmap);
        return bitmap;
    }
}

 如何使用？

<RelativeLayout>
<!-- 显示层 -->
<ImageView
            android:id="@+id/iv_holder"
            android:layout_width="0dp"
            android:layout_height="100dp"
            android:layout_marginStart="14dp"
            android:layout_marginTop="60dp"
            android:layout_marginEnd="14dp"
            android:scaleType="fitXY"
            android:src="@drawable/bg_drama_top"
            app:layout_constraintLeft_toLeftOf="parent"
            app:layout_constraintRight_toRightOf="parent"
            app:layout_constraintTop_toTopOf="parent" />
<!-- 刮奖层 -->
<ScratchView
            app:layout_constraintTop_toTopOf="@id/iv_holder"
            app:layout_constraintBottom_toBottomOf="@id/iv_holder"
            app:layout_constraintStart_toStartOf="@id/iv_holder"
            app:layout_constraintEnd_toEndOf="@id/iv_holder"
            android:layout_width="0dp"
            android:layout_height="0dp"/>
</RelativeLayout>