自定义View2 刮刮卡效果_class { private boolean ; private int width; priva-优快云博客

本文介绍了一种在Android中实现刮刮卡效果的方法，并提供了一个自定义View的示例代码。通过使用PorterDuffXfermode实现XOR效果，可以达到刮刮卡的视觉效果。文中还包含了如何保存生成的Bitmap到本地。

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效果如下图：

这里需要用到上一节中PorterDuffXfermode（把传递改头换面的服务员） xfermode

内容请参考http://note.youdao.com/share/?id=3f61125240ed4553df90532d42192ccb&type=note

刮刮需要用到的是Xor的效果。

刮刮卡的自定义view

public class GuaGuaView extends View{
    private Bitmap mBitmap;
    private Paint mPaintRect;
    private Paint mPaintLine;
    private int width;
    private int height;
    private Canvas mCanvasBitmap;
    private Bitmap mBitMapBackground;
    private float x;
    private float y;
    private Path mPhth;
    private int mLastX;
    private int mLastY;
    public GuaGuaView(Context context) {
        super(context);
    }

    public GuaGuaView(Context context, AttributeSet attrs) {
        super(context, attrs);
        TypedArray a = context.obtainStyledAttributes(attrs,R.styleable.GuaGuaView);
        int paintwidth = a.getDimensionPixelOffset(R.styleable.GuaGuaView_guaguaview_paintwidth, 30);
        BitmapDrawable dra = (BitmapDrawable) a.getDrawable(R.styleable.GuaGuaView_guaguaview_background);
        if(dra!=null){
            mBitMapBackground = dra.getBitmap();
        }else {
            mBitMapBackground = BitmapFactory.decodeResource(getResources(), R.mipmap.aa);
        }
        mPaintRect = new Paint();
        mPaintRect.setColor(Color.GREEN);
        mPaintLine = new Paint();
        mPaintLine.setColor(Color.YELLOW);
        mPaintLine.setStrokeWidth(paintwidth);
        PorterDuffXfermode xfermode = new PorterDuffXfermode(PorterDuff.Mode.XOR);
        mPaintLine.setAntiAlias(true);
        mPaintLine.setDither(true);
        mPaintLine.setStyle(Paint.Style.STROKE);
        mPaintLine.setStrokeJoin(Paint.Join.ROUND); // 圆角 连接点使用的样式
        mPaintLine.setStrokeCap(Paint.Cap.ROUND); // 圆角   覆盖时使用的样式
        mPaintLine.setXfermode(xfermode);
        mPhth= new Path();
    }

    @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;
                mPhth.moveTo(mLastX, mLastY);
                break;
            case MotionEvent.ACTION_MOVE:
                int dx = Math.abs(x - mLastX);
                int dy = Math.abs(y - mLastY);
                if (dx > 5 || dy > 5)
                   mPhth.lineTo(x, y);

                mLastX = x;
                mLastY = y;
                break;
        }

        invalidate();
        return true;
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        width = mBitMapBackground.getWidth();
        height = mBitMapBackground.getHeight();
        mBitmap = Bitmap.createBitmap(width,height, Bitmap.Config.ARGB_8888);
        setMeasuredDimension(width, height);       //设置view的宽和高
        mCanvasBitmap = new Canvas(mBitmap);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawBitmap(mBitMapBackground, new Rect(0, 0, mBitMapBackground.getWidth(), mBitMapBackground.getHeight()),
                new Rect(0, 0, mBitMapBackground.getWidth(), mBitMapBackground.getHeight()), null);
        mCanvasBitmap.drawRect(0, 0, mBitMapBackground.getWidth(), mBitMapBackground.getHeight(), mPaintRect);
        mCanvasBitmap.drawPath(mPhth,mPaintLine);
        canvas.drawBitmap(mBitmap,0,0,null);
    }
}

如何保存Bitmap

mButtonSave.setOnClickListener(new View.OnClickListener() {
    @Override
    public void onClick(View v) {
        mGuaGuaView.setDrawingCacheEnabled(true);
        Bitmap bitmap = mGuaGuaView.getDrawingCache(true);
        File file = new File(Environment.getExternalStorageDirectory(),System.currentTimeMillis()+".jpg");
        if (!file.exists()){
            try {
                file.createNewFile();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        try {
            bitmap.compress(Bitmap.CompressFormat.JPEG,100,new FileOutputStream(file));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }
});