Andriod实现刮刮卡的效果，andriod实现刮刮卡,思想： 将一个View设

Andriod实现刮刮卡的效果，andriod实现刮刮卡,思想： 将一个View设

思想：

将一个View设计成多层，内层（包括中奖信息）和外层（用于刮奖），外层的图层用Canvas与一个Bitmap关联，用这个关联的Bitmap来处理手势的滑动，类似于刮奖的动作。 使用paint.setXfermode来进行消除手势滑动区域```javaimport 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.view.MotionEvent;
import android.view.View;

/* * Created by Administrator on 2015/7/29. /
public class GuaView extends View {
private Path mPath;
private Paint mInnerPaint; //内层图层Paint
private Paint mOuterPaint; //外层图层Paint
private Bitmap mGuaBitmap; //用于处理刮奖的Bitmap
private Bitmap mOuterBitmap; //外层图层Bitmap
private Canvas mCanvas;

private int mWidth, mHeight;private float mLastX;  private float mLastY;private String mText;public GuaView(Context context, AttributeSet attrs) {      super(context, attrs);      init();  }private void init() {      mPath = new Path();      mOuterPaint = new Paint();      mInnerPaint = new Paint();    //创建外层图层      mOuterBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.guaguaka).copy(Bitmap.Config.ARGB_8888, true);      mText = "¥500";  }@Override  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {      super.onMeasure(widthMeasureSpec, heightMeasureSpec);    mWidth = mOuterBitmap.getWidth();      mHeight = mOuterBitmap.getHeight();    //创建内层图层      mGuaBitmap = Bitmap.createBitmap(mWidth, mHeight, Bitmap.Config.ARGB_8888);      mCanvas = new Canvas(mGuaBitmap);      mCanvas.drawBitmap(mOuterBitmap, 0, 0, null); //将mOuterBitmap画到mCanvas上，与mGuaBitmap关联    setOuterPaint();      setInnerPaint();  }private void setInnerPaint() {      mInnerPaint.setColor(Color.RED);      mInnerPaint.setStyle(Paint.Style.STROKE);      mInnerPaint.setStrokeCap(Paint.Cap.ROUND);      mInnerPaint.setStrokeJoin(Paint.Join.ROUND);      mInnerPaint.setAntiAlias(true);      mInnerPaint.setDither(true); //防抖      mInnerPaint.setStrokeWidth(5);      mInnerPaint.setTextSize(100);      mInnerPaint.setTextAlign(Paint.Align.CENTER);  }private void setOuterPaint() {      mOuterPaint.setColor(Color.GREEN);      mOuterPaint.setStyle(Paint.Style.STROKE);      mOuterPaint.setStrokeCap(Paint.Cap.ROUND);      mOuterPaint.setStrokeJoin(Paint.Join.ROUND);      mOuterPaint.setAntiAlias(true);      mOuterPaint.setDither(true); //防抖      mOuterPaint.setStrokeWidth(20);  }@Override  //Path  public boolean onTouchEvent(MotionEvent event) {      float x = event.getX();      float y = event.getY();      switch (event.getAction()) {          case MotionEvent.ACTION_DOWN:              mLastX = x;              mLastY = y;              mPath.moveTo(x, y);              break;          case MotionEvent.ACTION_MOVE:              float deltaX = Math.abs(x - mLastX);              float deltaY = Math.abs(y - mLastY);              if (deltaX > 5 || deltaY > 5) {                  mPath.lineTo(x, y);              }              mLastX = x;              mLastY = y;              break;          case MotionEvent.ACTION_UP:              break;      }      invalidate();      return true;  }@Override  protected void onDraw(Canvas canvas) {      super.onDraw(canvas);    canvas.drawColor(Color.parseColor("#bbbbbb")); //背景底色  灰色      canvas.drawText(mText, mWidth / 2, mHeight / 4 * 3, mInnerPaint); //绘制文本      canvas.drawBitmap(mGuaBitmap, 0, 0, null); //绘制外层Bitmap, 将mBitmap显示在界面上      drawPath();  }private void drawPath() {      //使用该mode：dst和src相交后， 只保留dst，且除去相交的部份      mOuterPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));      mCanvas.drawPath(mPath, mOuterPaint);  }

}
```