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：