Android之雪花飘落的动画特效
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之前有搜索过相关的信息，但是都不是最全的，下面我们来直接了解这个特效吧：
下面我们来看一看代码的实现吧：
三个工具类：其中主函数中不需要写代码，只需布局有相应的控件即可，雪花的大小、颜色和数量等可以自己设置
1.***********************************SnowFlake.java*************************************
import android.graphics.Canvas;
import android.graphics.Paint;
import android.graphics.Point;
import me.chunyu.spike.wcl_snowfall_demo.RandomGenerator;
/**
* 雪花的类, 移动, 移出屏幕会重新设置位置.
* <p/>
* Created by wangchenlong on 16/1/24.
*/
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; // 角度的分母
// 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)
double x = mPosition.x + (mIncrement * Math.cos(mAngle));
double y = mPosition.y + (mIncrement * Math.sin(mAngle));
mAngle += mRandom.getRandom(-ANGLE_SEED, ANGLE_SEED) / ANGLE_DIVISOR; // 随机晃动
mPosition.set((int) x, (int) y);
// 移除屏幕, 重新开始
if (!isInside(width, height))
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 - 1 && 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.***********************************SnowView.java*************************************
import android.annotation.TargetApi;
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
* <p/>
* Created by wangchenlong on 16/1/24.
*/
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];
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 (SnowFlake s : mSnowFlakes)
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()
invalidate();
;
3.*******************************RandomGenerator.java*****************************************
import java.util.Random;
/**
* 随机生成器
* <p/>
* Created by wangchenlong on 16/1/24.
*/
public class RandomGenerator
private static final Random RANDOM = new Random();
// 区间随机
public float getRandom(float lower, float upper)
float min = Math.min(lower, upper);
float max = Math.max(lower, upper);
return getRandom(max - min) + min;
// 上界随机
public float getRandom(float upper)
return RANDOM.nextFloat() * upper;
// 上界随机
public int getRandom(int upper)
return RANDOM.nextInt(upper);
一个布局：
4.*******************************activity_main.xml*****************************************
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent">
<FrameLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:contentDescription="@null"
android:scaleType="centerCrop"
android:src="@drawable/christmas"/>
<me.chunyu.spike.wcl_snowfall_demo.views.SnowView
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</FrameLayout>
</RelativeLayout>
OK
觉得不错的话，记得打赏一下：
https://blog.csdn.net/shenggaofei/article/details/105873568
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