Android营造雪花和雨滴浪漫效果

本文在实现雪花效果的基础上，根据漫天飞舞雪花，实现下雨天场景的效果，使用eclipse android 版本，具体内容如下

雪花效果图：

具体代码：

1、漫天飞舞的雪花主要代码
SnowView

<span style="font-size:14px;">package com.ex</span>ample.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 < NUM_SNOWFLAKES; ++i) {
  mSnowFlakes[i] = SnowFlake.create(width, height, paint);
 }
 } 

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 //for返回SnowFlake
 for (SnowFlake s : mSnowFlakes) {
  //然后进行绘制
  s.draw(canvas);
 }
 // 隔一段时间重绘一次, 动画效果
 getHandler().postDelayed(runnable, DELAY);
 } 

 // 重绘线程
 private Runnable runnable = new Runnable() {
 @Override
 public void run() {
  //自动刷新
  invalidate();
 }
 };
} 

SnowFlake

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 < height;
 } 

 // 重置雪花
 private void reset(int width) {
 mPosition.x = mRandom.getRandom(width);
 mPosition.y = (int) (-mFlakeSize - 1); // 最上面
 mAngle = mRandom.getRandom(ANGLE_SEED) / ANGLE_SEED * ANGE_RANGE + HALF_PI - HALF_ANGLE_RANGE;
 }
}

2、实现下雨天效果代码
RainView

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 < NUM_SNOWFLAKES; ++i) {
  mSnowFlakes[i] = RainFlake.create(width, height, paint);
 }
 } 

 @Override
 protected void onDraw(Canvas canvas) {
 super.onDraw(canvas);
 //for返回SnowFlake
 for (RainFlake s : mSnowFlakes) {
  //然后进行绘制
  s.draw(canvas);
 }
 // 隔一段时间重绘一次, 动画效果
 getHandler().postDelayed(runnable, DELAY);
 } 

 // 重绘线程
 private Runnable runnable = new Runnable() {
 @Override
 public void run() {
  //自动刷新
  invalidate();
 }
 };
}

RainFlake

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 < height && mLine.y2 < height;
 } 

 // 重置雨滴
 private void resetLine(int width, int height) {
 int [] nline;
 nline = mRandom.getLine(width, height);
 mLine.x1 = nline[0];
 mLine.y1 = nline[1];
 mLine.x2 = nline[2];
 mLine.y2 = nline[3];
 } 

} 

雨滴效果图：

以上就是本文的全部内容，帮助大家轻松实现浪漫的雪花雨滴效果，大家可以把效果运用到自己的项目中，希望大家喜欢。