Animation effect--snow in the sky

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Winter is coming, the snow is snowing, so cold.

Our application can also have some winter effect, teach you to do a snowy animation effect, reference.

Main
(1) Hide status bar , full screen display picture.
(2) Draw multiple points to achieve the movement effect.
(3) Recycle points, avoid duplicate creation.

I like to talk with comments, please pay more attention to the comments in the code.

Github

1. Snowflake class

The properties of snowflakes include: random amount, position, increment, size, angle, brush.
In the process of painting, the use angle moves the point position, each rate is different.
When the snowflake moves out of the screen, it is reused and is re-dropped at the top of the screen.
Algorithm reference.

/** * Snowflake class, move, move out of the screen will reset position. * <p/> * Created by Wangchenlong on 16/1/24. * * Public  class snowflake {    //Snowflake Angle    Private Static Final floatAnge_range =0.1F//Angle range    Private Static Final floatHalf_angle_range = Ange_range/2F//General angle    Private Static Final floatHALF_PI = (float) Math.PI/2F//semi-pi    Private Static Final floatAngle_seed = -F//Angle random seed    Private Static Final floatAngle_divisor =10000F//The denominator of the angle    //Snow movement speed    Private Static Final floatIncrement_lower =2FPrivate Static Final floatIncrement_upper =4F//size of snowflakes    Private Static Final floatFlake_size_lower =7FPrivate Static Final floatFlake_size_upper = -FPrivate FinalRandomgenerator Mrandom;//Random controller    Private FinalPoint Mposition;//Snowflake location    Private floatMAngle;//Angle    Private Final floatMincrement;//Speed of snowflakes    Private Final floatMflakesize;//size of snowflakes    Private FinalPaint Mpaint;//Brushes    Private Snowflake(Randomgenerator random, point position,floatAnglefloatIncrementfloatFlakesize, Paint paint) {mrandom = random;        Mposition = position;        Mincrement = increment;        Mflakesize = flakesize;        Mpaint = paint;    MAngle = angle; } Public StaticSnowflakeCreate(intWidthintHeight, paint paint) {randomgenerator random =NewRandomgenerator ();intx = random.getrandom (width);inty = random.getrandom (height); Point position =NewPoint (x, y);floatAngle = Random.getrandom (angle_seed)/angle_seed * ange_range + half_pi-half_angle_range;floatIncrement = Random.getrandom (Increment_lower, Increment_upper);floatFlakesize = Random.getrandom (Flake_size_lower, Flake_size_upper);return NewSnowflake (random, position, angle, increment, flakesize, paint); }//Draw Snowflakes     Public void Draw(Canvas canvas) {intwidth = Canvas.getwidth ();intHeight = canvas.getheight ();        Move (width, height);    Canvas.drawcircle (mposition.x, MPOSITION.Y, Mflakesize, Mpaint); }//Moving snowflakes    Private void Move(intWidthintHeight) {Doublex = mposition.x + (mincrement * Math.Cos (mAngle));Doubley = mposition.y + (mincrement * Math.sin (mAngle)); MAngle + = Mrandom.getrandom (-angle_seed, angle_seed)/angle_divisor;//Random shakingMposition.set ((int) x, (int) y);//Remove screen and start again        if(!isinside (width, height))        {Reset (width); }    }//Determine if the    Private Boolean Isinside(intWidthintHeight) {intx = mposition.x;inty = mposition.y;returnX >=-mflakesize-1&& x + mflakesize <= width && y >=-mflakesize-1&& y-mflakesize < height; }//Reset Snowflakes    Private void Reset(intwidth) {mposition.x = Mrandom.getrandom (width); MPOSITION.Y = (int) (-mflakesize-1);// TopMAngle = Mrandom.getrandom (angle_seed)/angle_seed * ange_range + half_pi-half_angle_range; }}

Random number generator with interval random and upper bound random.

/** * Random generator * <p/> * Created by Wangchenlong on 16/1/24. * * Public  class randomgenerator {    Private Static FinalRandom random =NewRandom ();//Interval random     Public float Getrandom(floatLowerfloatUpper) {floatmin = math.min (lower, upper);floatmax = Math.max (lower, upper);returnGetrandom (max-min) + min; }//upper bound random     Public float Getrandom(floatUpper) {returnRandom.nextfloat () * UPPER; }//upper bound random     Public int Getrandom(intUpper) {returnRandom.nextint (upper); }}

2. Snowflake View

Snowflake View, delay time redraw, draw num_snowflakes snowflakes.
Initialization is done in onsizechanged, and is plotted in OnDraw.

/** * Snowflake view, delay time redraw, draw num_snowflakes snowflakes * <p/> * Created by Wangchenlong on 16/1/24. */ Public  class snowview extends View {    Private Static Final intNum_snowflakes = Max;//Snowflake quantity    Private Static Final intDELAY =5;//Delay    PrivateSnowflake[] Msnowflakes;//Snowflake     Public Snowview(Context context) {Super(context); } Public Snowview(context context, AttributeSet attrs) {Super(context, attrs); } Public Snowview(context context, AttributeSet attrs,intDEFSTYLEATTR) {Super(Context, attrs, defstyleattr); }@TargetApi( +) Public Snowview(context context, AttributeSet attrs,intDefstyleattr,intDefstyleres) {Super(Context, Attrs, defstyleattr, defstyleres); }@Override protected void onsizechanged(intWintHintOLDW,intOLDH) {Super. onsizechanged (W, H, OLDW, OLDH);if(w! = OLDW | | h! = OLDH)        {Initsnow (W, h); }    }Private void Initsnow(intWidthintHeight) {Paint paint =NewPaint (Paint.anti_alias_flag);//anti-aliasingPaint.setcolor (Color.White);//White snowflakesPaint.setstyle (Paint.Style.FILL);//fill;Msnowflakes =NewSnowflake[num_snowflakes]; for(inti =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); }//Redraw once at a time, animation effectGetHandler (). postdelayed (runnable, DELAY); }//Redraw Threads    PrivateRunnable Runnable =NewRunnable () {@Override         Public void Run() {invalidate (); }    };}

Use the getHandler().postDelayed(runnable, DELAY); Refresh page.

3. Full-screen layout

Full Screen layout

<?xml version= "1.0" encoding= "Utf-8"?><android.support.design.widget.CollapsingToolbarLayoutxmlns:android="http// Schemas.android.com/apk/res/android "android:layout_width=" Match_parent "android: Layout_height="Match_parent">                <framelayoutandroid:layout_width="Match_parent"android:layout_height ="Match_parent">                        <ImageViewandroid: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.SnowViewandroid:layout_width="Match_ Parent "android:layout_height=" match_parent "/>                            </framelayout></android.support.design.widget.CollapsingToolbarLayout>

status barThe default is not to be transparent, need to use CollapsingToolbarLayout ,
Replace the style of the status bar, otherwise it will leave a certain height, even if transparency is not filled.

Style

<?xml version="1.0" encoding="utf-8"?><resources>    <style name="AppTheme.NoStatusBar">        <item name="android:windowTranslucentStatus">true</item>    </style></resources>

You can add something interesting to your app in the winter.
OK, that ' s all! Enjoy it!

Animation effect--snow in the sky