Android 简易刮刮卡实现

本文代码出自鸿洋大神博客，查看具体介绍可参照http://blog.youkuaiyun.com/lmj623565791/article/details/40162163

话不多说，直接上代码

刮刮卡实现类：

public class GuaGuaKa extends View {

	/**
	 * 绘制线条的Paint,即用户手指绘制Path
	 */
	private Paint mOutterPaint = new Paint();
	/**
	 * 记录用户绘制的Path
	 */
	private Path mPath = new Path();
	/**
	 * 内存中创建的Canvas
	 */
	private Canvas mCanvas;
	/**
	 * mCanvas绘制内容在其上
	 */
	private Bitmap mBitmap;

	private Bitmap mBackBitmap;

	private int mLastX;
	private int mLastY;

	private Rect mTextBound = new Rect();
	private String mText = "500,0000,000";
	private Paint mBackPint = new Paint();
	private GuaGuaKa mKa;

	public GuaGuaKa(Context context) {
		this(context, null);
	}

	public GuaGuaKa(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public GuaGuaKa(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		// Resources res = context.getResources();
		// mBackBitmap = BitmapFactory.decodeResource(res, R.drawable.bg_login);
		init();
		mKa = this;
	}

	private void init() {
		mPath = new Path();
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);

		int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		int widthSize = MeasureSpec.getSize(widthMeasureSpec);
		int heightMode = MeasureSpec.getMode(heightMeasureSpec);
		int heightSize = MeasureSpec.getSize(heightMeasureSpec);
		int width;
		int height;
		Rect mBounds = new Rect();
		if (widthMode == MeasureSpec.EXACTLY) {
			width = widthSize;
		} else {
			mBackPint.getTextBounds(mText, 0, mText.length(), mBounds);
			float textWidth = mBounds.width();
			int desired = (int) (getPaddingLeft() + textWidth + getPaddingRight());
			width = desired;
		}

		if (heightMode == MeasureSpec.EXACTLY) {
			height = heightSize;
		} else {
			mBackPint.getTextBounds(mText, 0, mText.length(), mBounds);
			float textHeight = mBounds.height();
			int desired = (int) (getPaddingTop() + textHeight + getPaddingBottom());
			height = desired;
		}
		setMeasuredDimension(width, height);
		// 初始化bitmap
		mBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888);
		mCanvas = new Canvas(mBitmap);
		setUpOutPaint();
		// 绘制这改成
		mCanvas.drawColor(Color.parseColor("#c0c0c0"));
	}

	public void setUpOutPaint() {
		// 设置画笔
		mOutterPaint.setColor(Color.RED);
		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(80);
		mBackPint.setStyle(Style.FILL);
		mBackPint.setTextScaleX(2f);
		mBackPint.setColor(Color.DKGRAY);
		mBackPint.setTextSize(22);
		mBackPint.getTextBounds(mText, 0, mText.length(), mTextBound);
	}

	@Override
	protected void onDraw(Canvas canvas) {
		// canvas.drawBitmap(mBackBitmap, 0, 0, null);
		canvas.drawText(mText, getWidth() / 2 - mTextBound.width() / 2,
				getHeight() / 2 + mTextBound.height() / 2, mBackPint);
		drawPath();
		canvas.drawBitmap(mBitmap, 0, 0, null);
	}

	/**
	 * 绘制线条
	 */
	private void drawPath() {
		mOutterPaint
				.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_OUT));
		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;
			break;
		}
		invalidate();
		return true;
	}
}

MainActivity的调用：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

    <com.example.myviewdemo.GuaGuaKa  
        android:layout_width="wrap_content"  
        android:layout_height="wrap_content" 
        android:layout_centerInParent="true"
        android:padding="20dp"/> 

</RelativeLayout>

本文主要介绍了一个简易的刮刮卡实现，可自行进行扩展，完整Demo下载链接：链接: https://pan.baidu.com/s/1o8cFJuU 密码: 6hr8