Android刮刮卡效果

                    

 

不多说，直接上代码：

 

  1 package com.example.test;

  2 

  3 import android.app.Activity;

  4 import android.content.Context;

  5 import android.graphics.Bitmap;

  6 import android.graphics.Bitmap.Config;

  7 import android.graphics.Canvas;

  8 import android.graphics.Color;

  9 import android.graphics.Paint;

 10 import android.graphics.Paint.Cap;

 11 import android.graphics.Paint.Join;

 12 import android.graphics.Paint.Style;

 13 import android.graphics.Path;

 14 import android.graphics.PorterDuff.Mode;

 15 import android.graphics.PorterDuffXfermode;

 16 import android.graphics.drawable.BitmapDrawable;

 17 import android.os.Bundle;

 18 import android.util.DisplayMetrics;

 19 import android.view.MotionEvent;

 20 import android.view.View;

 21 

 22 public class GuaGuaKaActivity extends Activity {

 23     int screenWidth = 0;

 24     int screenHeight = 0;

 25     @Override

 26     protected void onCreate(Bundle savedInstanceState) {

 27         super.onCreate(savedInstanceState);

 28         

 29         DisplayMetrics dm  = new DisplayMetrics();

 30         getWindowManager().getDefaultDisplay().getMetrics(dm);

 31         screenWidth = dm.widthPixels;

 32         screenHeight = dm.heightPixels;

 33         

 34         setContentView(new GuaGuaKa(this));

 35     }

 36     class GuaGuaKa extends View{

 37         private Canvas mCanvas = null;

 38         private Path mPath = null;

 39         private Paint mPaint = null;

 40         private Bitmap bitmap = null;

 41         public GuaGuaKa(Context context) {

 42             super(context);

 43             init(context);

 44         }

 45         

 46         private void init(Context context) {

 47             setBackground();

 48             

 49             mPath = new Path();

 50             bitmap = Bitmap.createBitmap(screenWidth, screenHeight, Config.ARGB_8888);

 51             mPaint = new Paint();

 52             mPaint.setFlags(Paint.ANTI_ALIAS_FLAG);

 53             mPaint.setAntiAlias(true);

 54             mPaint.setDither(true);

 55             mPaint.setStyle(Style.STROKE);

 56             mPaint.setStrokeWidth(10);

 57             mPaint.setStrokeCap(Cap.ROUND);

 58             mPaint.setStrokeJoin(Join.ROUND);

 59             mPaint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));

 60             mPaint.setAlpha(0);

 61             

 62             mCanvas = new Canvas(bitmap);

 63             mCanvas.drawColor(Color.GRAY);

 64         }

 65         

 66         private void setBackground() {

 67             Paint paint = new Paint();

 68             Bitmap bitmap = Bitmap.createBitmap(screenWidth,screenHeight,Config.ARGB_8888);

 69             paint.setTextSize(30);

 70             paint.setColor(Color.BLACK);

 71             paint.setFlags(Paint.ANTI_ALIAS_FLAG);

 72             paint.setAntiAlias(true);

 73             

 74             Canvas canvas = new Canvas(bitmap);

 75             canvas.drawColor(Color.WHITE);

 76             canvas.drawText("谢谢惠顾", 100, 100, paint);

 77             canvas.drawText("再来10瓶", 100, 250, paint);

 78             setBackgroundDrawable(new BitmapDrawable(getResources(), bitmap));

 79             

 80         }

 81 

 82         @Override

 83         protected void onDraw(Canvas canvas) {

 84             super.onDraw(canvas);

 85             mCanvas.drawPath(mPath, mPaint);

 86             canvas.drawBitmap(bitmap, 0, 0, null);

 87         }

 88         int x = 0;

 89         int y = 0;

 90         @Override

 91         public boolean onTouchEvent(MotionEvent event) {

 92             int action = event.getAction();

 93             int currX = (int) event.getX();

 94             int currY = (int) event.getY();

 95             switch(action){

 96                 case MotionEvent.ACTION_DOWN:{

 97                     mPath.reset();

 98                     x = currX;

 99                     y = currY;

100                     mPath.moveTo(x, y);

101                 }break;

102                 case MotionEvent.ACTION_MOVE:{

103                     mPath.quadTo(x, y, currX, currY);

104                     x = currX;

105                     y = currY;

106                     postInvalidate();

107                 }break;

108                 case MotionEvent.ACTION_UP:

109                 case MotionEvent.ACTION_CANCEL:{

110                     mPath.reset();

111                 }break;

112             }

113             return true;

114         }

115     }

116 }

参考：

1、Android中Path类的lineTo方法和quadTo方法画线的区别：http://blog.csdn.net/stevenhu_223/article/details/9229337

2、android.graphics.Paint方法setXfermode ：http://my.oschina.net/smalant/blog/40328