Android营造雪花和雨滴浪漫效果

package com.example.snowflake.view; 
 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.util.AttributeSet; 
import android.view.View; 
 
/** 
 * 雪花视图, DELAY时间重绘, 绘制NUM_SNOWFLAKES个雪花 
 */ 
public class SnowView extends View { 
 
 private static final int NUM_SNOWFLAKES = 150; // 雪花数量 
 private static final int DELAY = 5; // 延迟 
 private SnowFlake[] mSnowFlakes; // 雪花 
 
 public SnowView(Context context) { 
 super(context); 
 } 
 
 public SnowView(Context context, AttributeSet attrs) { 
 super(context, attrs); 
 } 
 
 public SnowView(Context context, AttributeSet attrs, int defStyleAttr) { 
 super(context, attrs, defStyleAttr); 
 } 
 
 @Override 
 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
 super.onSizeChanged(w, h, oldw, oldh); 
 if (w != oldw || h != oldh) { 
  initSnow(w, h); 
 } 
 } 
 
 private void initSnow(int width, int height) { 
 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); // 抗锯齿 
 paint.setColor(Color.WHITE); // 白色雪花 
 paint.setStyle(Paint.Style.FILL); // 填充; 
 mSnowFlakes = new SnowFlake[NUM_SNOWFLAKES]; 
 //mSnowFlakes所有的雪花都生成放到这里面 
 for (int i = 0; i 

package com.example.snowflake.view; 
 
import com.example.snowflake.RandomGenerator; 
 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.graphics.Point; 
 
/** 
 * 雪花的类, 移动, 移出屏幕会重新设置位置. 
 */ 
public class SnowFlake { 
 // 雪花的角度 
 private static final float ANGE_RANGE = 0.1f; // 角度范围 
 private static final float HALF_ANGLE_RANGE = ANGE_RANGE / 2f; // 一般的角度 
 private static final float HALF_PI = (float) Math.PI / 2f; // 半PI 
 private static final float ANGLE_SEED = 25f; // 角度随机种子 
 private static final float ANGLE_DIVISOR = 10000f; 
 // 雪花的移动速度 
 private static final float INCREMENT_LOWER = 2f; 
 private static final float INCREMENT_UPPER = 4f; 
 
 // 雪花的大小 
 private static final float FLAKE_SIZE_LOWER = 7f; 
 private static final float FLAKE_SIZE_UPPER = 20f; 
 
 private final RandomGenerator mRandom; // 随机控制器 
 private final Point mPosition; // 雪花位置 
 private float mAngle; // 角度 
 private final float mIncrement; // 雪花的速度 
 private final float mFlakeSize; // 雪花的大小 
 private final Paint mPaint; // 画笔 
 
 private SnowFlake(RandomGenerator random, Point position, float angle, float increment, float flakeSize, Paint paint) { 
 mRandom = random; 
 mPosition = position; 
 mIncrement = increment; 
 mFlakeSize = flakeSize; 
 mPaint = paint; 
 mAngle = angle; 
 } 
 
 public static SnowFlake create(int width, int height, Paint paint) { 
 RandomGenerator random = new RandomGenerator(); 
 int x = random.getRandom(width); 
 int y = random.getRandom(height); 
 Point position = new Point(x, y); 
 float angle = random.getRandom(ANGLE_SEED) / ANGLE_SEED * ANGE_RANGE + HALF_PI - HALF_ANGLE_RANGE; 
 float increment = random.getRandom(INCREMENT_LOWER, INCREMENT_UPPER); 
 float flakeSize = random.getRandom(FLAKE_SIZE_LOWER, FLAKE_SIZE_UPPER); 
 return new SnowFlake(random, position, angle, increment, flakeSize, paint); 
 } 
 
 // 绘制雪花 
 public void draw(Canvas canvas) { 
 int width = canvas.getWidth(); 
 int height = canvas.getHeight(); 
 move(width, height); 
 canvas.drawCircle(mPosition.x, mPosition.y, mFlakeSize, mPaint); 
 } 
 
 // 移动雪花 
 private void move(int width, int height) { 
 //x水平方向，那么需要晃动，主要设置这个值就可以，现在取消晃动了 
 //如果 mPosition.x不加上后面那个值，就不会晃动了 
 double x = mPosition.x + (mIncrement * Math.cos(mAngle)); 
 //y是竖直方向，就是下落 
 double y = mPosition.y + (mIncrement * Math.sin(mAngle)); 
 
 mAngle += mRandom.getRandom(-ANGLE_SEED, ANGLE_SEED) / ANGLE_DIVISOR; 
 //这个是设置雪花位置，如果在很短时间内刷新一次，就是连起来的动画效果 
 mPosition.set((int) x, (int) y); 
 
 // 移除屏幕, 重新开始 
 if (!isInside(width, height)) { 
  // 重置雪花 
  reset(width); 
 } 
 } 
 
 // 判断是否在其中 
 private boolean isInside(int width, int height) { 
 int x = mPosition.x; 
 int y = mPosition.y; 
 return x > mFlakeSize -5 && x + mFlakeSize <= width && y >= -mFlakeSize - 1 && y - mFlakeSize 

package com.example.raindrop.view; 
 
import com.example.raindrop.R; 
 
import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Paint; 
import android.util.AttributeSet; 
import android.view.View; 
 
/** 
 * 雨滴视图, DELAY时间重绘, 绘制NUM_SNOWFLAKES个雨滴 
 */ 
public class RainView extends View { 
 
 private static final int NUM_SNOWFLAKES = 150; // 雨滴数量 
 private static final int DELAY = 5; // 延迟 
 private RainFlake[] mSnowFlakes; // 雨滴 
 
 public RainView(Context context) { 
 super(context); 
 } 
 
 public RainView(Context context, AttributeSet attrs) { 
 super(context, attrs); 
 } 
 
 public RainView(Context context, AttributeSet attrs, int defStyleAttr) { 
 super(context, attrs, defStyleAttr); 
 } 
 
 @Override 
 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
 super.onSizeChanged(w, h, oldw, oldh); 
 if (w != oldw || h != oldh) { 
  initSnow(w, h); 
 } 
 } 
 
 private void initSnow(int width, int height) { 
 Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG); // 抗锯齿 
 paint.setColor(getResources().getColor(R.color.colorWater)); // 雨滴的颜色 
 paint.setStyle(Paint.Style.FILL); // 填充; 
 mSnowFlakes = new RainFlake[NUM_SNOWFLAKES]; 
 //mSnowFlakes所有的雨滴都生成放到这里面 
 for (int i = 0; i 

package com.example.raindrop.view; 
 
import com.example.raindrop.RandomGenerator; 
 
import android.graphics.Canvas; 
import android.graphics.Paint; 
 
/** 
 * 雨滴的类, 移动, 移出屏幕会重新设置位置. 
 */ 
public class RainFlake { 
 
 // 雨滴的移动速度 
 private static final float INCREMENT_LOWER = 6f; 
 private static final float INCREMENT_UPPER = 8f; 
 
 // 雨滴的大小 
 private static final float FLAKE_SIZE_LOWER = 2f; 
 private static final float FLAKE_SIZE_UPPER = 5f; 
 
 private final float mIncrement; // 雨滴的速度 
 private final float mFlakeSize; // 雨滴的大小 
 private final Paint mPaint; // 画笔 
 
 private Line mLine; // 雨滴 
 
 private RandomGenerator mRandom; 
 
 private RainFlake(RandomGenerator random,Line line, float increment, float flakeSize, Paint paint) { 
 mRandom = random; 
 mLine = line; 
 mIncrement = increment; 
 mFlakeSize = flakeSize; 
 mPaint = paint; 
 } 
 
 //生成雨滴 
 public static RainFlake create(int width, int height, Paint paint) { 
 RandomGenerator random = new RandomGenerator(); 
 int [] nline; 
 nline = random.getLine(width, height); 
  
 Line line = new Line(nline[0], nline[1], nline[2], nline[3]); 
 float increment = random.getRandom(INCREMENT_LOWER, INCREMENT_UPPER); 
 float flakeSize = random.getRandom(FLAKE_SIZE_LOWER, FLAKE_SIZE_UPPER); 
 return new RainFlake(random,line, increment, flakeSize, paint); 
 } 
 
 // 绘制雨滴 
 public void draw(Canvas canvas) { 
 int width = canvas.getWidth(); 
 int height = canvas.getHeight(); 
 drawLine(canvas, width, height); 
 } 
 
 /** 
 * 改成线条，类似于雨滴效果 
 * @param canvas 
 * @param width 
 * @param height 
 */ 
 private void drawLine(Canvas canvas, int width, int height) { 
 //设置线宽 
 mPaint.setStrokeWidth(mFlakeSize); 
 //y是竖直方向，就是下落 
 double y1 = mLine.y1 + (mIncrement * Math.sin(1.5)); 
 double y2 = mLine.y2 + (mIncrement * Math.sin(1.5)); 
 
 //这个是设置雨滴位置，如果在很短时间内刷新一次，就是连起来的动画效果 
 mLine.set(mLine.x1,(int) y1,mLine.x2 ,(int) y2); 
  
 if (!isInsideLine(height)) { 
  resetLine(width,height); 
 } 
  
 canvas.drawLine(mLine.x1, mLine.y1, mLine.x2, mLine.y2, mPaint); 
 } 
 
 // 判断是否在其中 
 private boolean isInsideLine(int height) { 
 return mLine.y1