# Vibrating rectangles

Vibrating rectangles is a draft programming task. It is not yet considered ready to be promoted as a complete task, for reasons that should be found in its talk page.
1. Draw at least 20 rectangles with a common center, to be more precise, the circumcenter of all the rectangles must coincide. None of the rectangles must touch or intersect any other rectangle.
2. Animate the colours of the rectangles by fading in the colour from the outermost rectangle to the innermost.
3. The animation loop can continue for a definite number of iterations or forever.

Create Vibrating rectangles

## C

Dimensions of the rectangles, their number and the animation delay can be configured. Requires the WinBGIm library.

` /*Abhishek Ghosh, 15th September 2018*/ #include<graphics.h> void vibratingRectangles(int winWidth,int winHeight,int leastLength,int leastWidth,int num, int msec){	int color = 1,i,x = winWidth/2, y = winHeight/2; 	while(!kbhit()){		setcolor(color++);		for(i=num;i>0;i--){			rectangle(x - i*leastLength,y - i*leastWidth,x + i*leastLength,y + i*leastWidth);			delay(msec);		} 		if(color>MAXCOLORS){			color = 1;		}	}} int main(){	initwindow(1000,1000,"Vibrating Rectangles..."); 	vibratingRectangles(1000,1000,30,15,20,500); 	closegraph(); 	return 0;} `

## EasyLang

`on timer  sz -= 2  if sz < 0    sz = 49    color random 1000  .  move 50 - sz 50 - sz  line 50 + sz 50 - sz  line 50 + sz 50 + sz  line 50 - sz 50 + sz  line 50 - sz 50 - sz  timer 0.2.timer 0.2`

## Factor

`USING: accessors calendar colors.constants combinators kernellocals math math.vectors opengl timers ui ui.gadgetsui.gadgets.worlds ui.pens.solid ui.render ;IN: rosetta-code.vibrating-squares TUPLE: vibrating < gadget    { old-color initial: COLOR: black }    { new-color initial: COLOR: red }    { frame initial: 0 } ; DEFER: on-tick : <vibrating-gadget> ( -- gadget )    vibrating new COLOR: black <solid> >>interior COLOR: red    >>new-color COLOR: black >>old-color dup [ on-tick ] curry f    250 milliseconds <timer> start-timer ; M: vibrating pref-dim* drop { 420 420 } ; : draw-squares ( loc dim n -- loc' dim' )    [ 2dup gl-rect [ { 10 10 } v+ ] [ { -20 -20 } v+ ] bi* ]    times ; M:: vibrating draw-gadget* ( GADGET -- )    GADGET frame>> 20 mod :> n    GADGET new-color>> gl-color    { 10 10 } { 400 400 } n draw-squares    GADGET old-color>> gl-color    20 n - draw-squares 2drop ; :: on-tick ( GADGET -- )    GADGET relayout-1    GADGET [ 1 + ] change-frame frame>> 20 mod zero? [        GADGET new-color>> GADGET old-color<<        GADGET new-color>> {            { COLOR: red [ COLOR: green ] }            { COLOR: green [ COLOR: blue ] }            [ drop COLOR: red ]        } case GADGET new-color<<    ] when ; MAIN-WINDOW: vibrating-squares    {        { title "Vibrating Squares" }        { window-controls            { normal-title-bar close-button minimize-button } }    } <vibrating-gadget> >>gadgets ;`

## Go

This uses Go's 'image' packages in its standard library to create an animated GIF.

When played this is somewhat similar to the Python entry except that it uses a 7 (rather than 6) color palette and repeats indefinitely.

Although the .gif works fine in Firefox it might not do so in EOG due to optimizations made during its creation. If so, then the following ImageMagick command should fix it:

```  \$ convert vibrating.gif -coalesce vibrating2.gif
\$ eog vibrating2.gif
```
`package main import (    "image"    "image/color"    "image/gif"    "log"    "os") var (    black   = color.RGBA{0, 0, 0, 255}    red     = color.RGBA{255, 0, 0, 255}    green   = color.RGBA{0, 255, 0, 255}    blue    = color.RGBA{0, 0, 255, 255}    magenta = color.RGBA{255, 0, 255, 255}    cyan    = color.RGBA{0, 255, 255, 255}    yellow  = color.RGBA{255, 255, 0, 255}    white   = color.RGBA{255, 255, 255, 255}) var palette = []color.Color{red, green, blue, magenta, cyan, yellow, white, black} func hline(img *image.Paletted, x1, y, x2 int, ci uint8) {    for ; x1 <= x2; x1++ {        img.SetColorIndex(x1, y, ci)    }} func vline(img *image.Paletted, x, y1, y2 int, ci uint8) {    for ; y1 <= y2; y1++ {        img.SetColorIndex(x, y1, ci)    }} func setBackgroundColor(img *image.Paletted, w, h int, ci uint8) {    for x := 0; x < w; x++ {        for y := 0; y < h; y++ {            img.SetColorIndex(x, y, ci)        }    }} func drawRectangle(img *image.Paletted, x1, y1, x2, y2 int, ci uint8) {    hline(img, x1, y1, x2, ci)    hline(img, x1, y2, x2, ci)    vline(img, x1, y1, y2, ci)    vline(img, x2, y1, y2, ci)} func main() {    const nframes = 140    const delay = 10 // 100ms    width, height := 500, 500    anim := gif.GIF{LoopCount: nframes}    rect := image.Rect(0, 0, width, height)    for c := uint8(0); c < 7; c++ {        for f := 0; f < 20; f++ {            img := image.NewPaletted(rect, palette)            setBackgroundColor(img, width, height, 7) // black background            for r := 0; r < 20; r++ {                ix := c                if r < f {                    ix = (ix + 1) % 7                }                x := width * (r + 1) / 50                y := height * (r + 1) / 50                w := width - x                h := height - y                drawRectangle(img, x, y, w, h, ix)            }            anim.Delay = append(anim.Delay, delay)            anim.Image = append(anim.Image, img)        }    }    file, err := os.Create("vibrating.gif")    if err != nil {        log.Fatal(err)    }    defer file.Close()     if err2 := gif.EncodeAll(file, &anim); err != nil {        log.Fatal(err2)    }   }`

## J

```   NB. warning: overwrites /tmp/10[0-3][0-9].jpg
NB.          and        /tmp/r.gif

NB. uses imagemagic convert and a browser to display the animation.
NB. works on linux

NB. https://rosettacode.org/wiki/Ulam_spiral_(for_primes)#J

require'jpeg'

spiral =: ,~ \$ [: /: }[email protected](2 # >:@[email protected]) +/\@# <:@+: \$ (, -)@(1&,)
ulamspiral =: *: - spiral

NB. Corners are the squares of every other odd number.
NB. Rectangles ulams with first column < and <: second column of CORNERS
[CORNERS=: *: 1 2 p. i. _20 2
5929 6241
5329 5625
4761 5041
4225 4489
3721 3969
3249 3481
2809 3025
2401 2601
2025 2209
1681 1849
1369 1521
1089 1225
841  961
625  729
441  529
289  361
169  225
81  121
25   49
1    9

NB. S is a sufficiently large Ulam spiral matrix
S=: ulamspiral 81

NB. A are 20 Boolean bitmaps of squares
A =: CORNERS ((> {.)~ *. (<: {:)~)"1 _ S

NB. B is a bitmap of all the squares
B =: +/ A

NB. C is a running sum.  first 6 upper left corners shown
<"2 ] 6 10 10 {. C =: B +"2 +/\ A
┌───────────────────┬───────────────────┬───────────────────┬───────────────────┬───────────────────┬───────────────────┐
│0 0 0 0 0 0 0 0 0 0│0 0 0 0 0 0 0 0 0 0│0 0 0 0 0 0 0 0 0 0│0 0 0 0 0 0 0 0 0 0│0 0 0 0 0 0 0 0 0 0│0 0 0 0 0 0 0 0 0 0│
│0 2 2 2 2 2 2 2 2 2│0 2 2 2 2 2 2 2 2 2│0 2 2 2 2 2 2 2 2 2│0 2 2 2 2 2 2 2 2 2│0 2 2 2 2 2 2 2 2 2│0 2 2 2 2 2 2 2 2 2│
│0 2 0 0 0 0 0 0 0 0│0 2 0 0 0 0 0 0 0 0│0 2 0 0 0 0 0 0 0 0│0 2 0 0 0 0 0 0 0 0│0 2 0 0 0 0 0 0 0 0│0 2 0 0 0 0 0 0 0 0│
│0 2 0 1 1 1 1 1 1 1│0 2 0 2 2 2 2 2 2 2│0 2 0 2 2 2 2 2 2 2│0 2 0 2 2 2 2 2 2 2│0 2 0 2 2 2 2 2 2 2│0 2 0 2 2 2 2 2 2 2│
│0 2 0 1 0 0 0 0 0 0│0 2 0 2 0 0 0 0 0 0│0 2 0 2 0 0 0 0 0 0│0 2 0 2 0 0 0 0 0 0│0 2 0 2 0 0 0 0 0 0│0 2 0 2 0 0 0 0 0 0│
│0 2 0 1 0 1 1 1 1 1│0 2 0 2 0 1 1 1 1 1│0 2 0 2 0 2 2 2 2 2│0 2 0 2 0 2 2 2 2 2│0 2 0 2 0 2 2 2 2 2│0 2 0 2 0 2 2 2 2 2│
│0 2 0 1 0 1 0 0 0 0│0 2 0 2 0 1 0 0 0 0│0 2 0 2 0 2 0 0 0 0│0 2 0 2 0 2 0 0 0 0│0 2 0 2 0 2 0 0 0 0│0 2 0 2 0 2 0 0 0 0│
│0 2 0 1 0 1 0 1 1 1│0 2 0 2 0 1 0 1 1 1│0 2 0 2 0 2 0 1 1 1│0 2 0 2 0 2 0 2 2 2│0 2 0 2 0 2 0 2 2 2│0 2 0 2 0 2 0 2 2 2│
│0 2 0 1 0 1 0 1 0 0│0 2 0 2 0 1 0 1 0 0│0 2 0 2 0 2 0 1 0 0│0 2 0 2 0 2 0 2 0 0│0 2 0 2 0 2 0 2 0 0│0 2 0 2 0 2 0 2 0 0│
│0 2 0 1 0 1 0 1 0 1│0 2 0 2 0 1 0 1 0 1│0 2 0 2 0 2 0 1 0 1│0 2 0 2 0 2 0 2 0 1│0 2 0 2 0 2 0 2 0 2│0 2 0 2 0 2 0 2 0 2│
└───────────────────┴───────────────────┴───────────────────┴───────────────────┴───────────────────┴───────────────────┘

NB. D is C catenated to itself with the ones and twos swapped.
D=: (, ]`(0,2,:1"0)}) C

NB. E is the 40 matrices with ID, in 3 levels
E=: (;"2 0 (1000 + [email protected]#))@:(*&16b301070) D

NB. overwrite the files then get some help from the shell
[email protected]:(writejpeg('.jpg' ,~ '/tmp/' , ":))&>/"1 E
2!:0'convert -resize 600%  /tmp/10[0-3][0-9].jpg -delay 10 -loop 0 /tmp/r.gif'

echo 'please view the animation /tmp/r.gif in chrome browser'
```

## JavaScript

HTML you'll need for testing

```<!DOCTYPE html>
<html>
<meta charset="utf-8" />
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Vibrating rectangles</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
body{background-color:black;text-align:center;margin-top:150px}
</style>
<script src="vibRects.js"></script>
<div id='wnd'></div>
</body>
</html>
```
` const SIZE = 400, WAIT = .025;class VibRects {    constructor() {        this.wait = WAIT;        this.colorIndex = 0;        this.dimension = 5;        this.lastTime = 0;        this.accumulator = 0;        this.deltaTime = 1 / 60;        this.colors = ["#ff0000", "#ff8000", "#ffff00", "#80ff00", "#00ff00", "#00ff80",                        "#00ffff", "#0080ff", "#0000ff", "#8000ff", "#ff00ff", "#ff0080"];        this.canvas = document.createElement('canvas');        this.canvas.width = SIZE;        this.canvas.height = SIZE;        const d = document.getElementById("wnd");        d.appendChild(this.canvas);        this.ctx = this.canvas.getContext('2d');        for(let d = this.dimension; d < SIZE / 2; d += 10) {            this.draw("#404040", d);        }    }    draw(clr, d) {        this.ctx.strokeStyle = clr;        this.ctx.beginPath();        this.ctx.moveTo(d, d);        this.ctx.lineTo(SIZE - d, d);        this.ctx.lineTo(SIZE - d, SIZE - d);        this.ctx.lineTo(d, SIZE - d);        this.ctx.closePath();        this.ctx.stroke();    }    update(dt) {        if((this.wait -= dt) < 0) {            this.draw(this.colors[this.colorIndex], this.dimension);            this.wait = WAIT;            if((this.dimension += 10) > SIZE / 2) {                this.dimension = 5;                this.colorIndex = (this.colorIndex + 1) % this.colors.length;            }        }    }    start() {        this.loop = (time) => {            this.accumulator += (time - this.lastTime) / 1000;            while(this.accumulator > this.deltaTime) {                this.accumulator -= this.deltaTime;                this.update(Math.min(this.deltaTime));            }            this.lastTime = time;            requestAnimationFrame(this.loop);        }        this.loop(0);    }}function start() {    const vibRects = new VibRects();    vibRects.start();} `

## Julia

`using Gtk, Graphics, Colors const height, width, x0, y0 = 480, 640, 320, 240const can = @GtkCanvas()const win = GtkWindow(can, "Vibrating Rectangles", width, height)const colrs = colormap("rdBu")const sizes = collect(2:4:div(width, 2))const params = [1, 2] draw(can) do widget    ctx = getgc(can)    set_line_width(ctx, 1)    c = colrs[params[1]]    set_source_rgb(ctx, c.r, c.g, c.b)    i = sizes[params[2]]    rectangle(ctx, x0 - i, y0 - i, 2i, div(8i, 3))    stroke(ctx)end while true    params[1] = params[1] % 99 + 1    params[2] = params[2] % (length(sizes) - 1) + 1    draw(can)    show(can)    sleep(0.25)end `

## Objeck

Uses SLD2 libraries and 80's neon colors.

`use Game.SDL2;use Game.Framework; class Vibrating {  @framework : GameFramework;  @rec_offset : Int;  @rec_colors : Color[];  @rec_color_index : Int;   function : Main(args : String[]) ~ Nil {    vibrating := Vibrating->New();    vibrating->Run();  }   New() {    @framework := GameFramework->New(GameConsts->SCREEN_WIDTH, GameConsts->SCREEN_HEIGHT, "Vibrating Rectangles");    @framework->SetClearColor(Color->New(0, 0, 0));    @rec_colors := Color->New[5];    @rec_colors[0] := Color->New(255, 240, 1);     @rec_colors[1] := Color->New(253, 25, 153);     @rec_colors[2] := Color->New(153, 252, 32);      @rec_colors[3] := Color->New(0, 230, 254);    @rec_colors[4] := Color->New(161, 14, 236);  }   method : Run() ~ Nil {    if(@framework->IsOk()) {      e := @framework->GetEvent();       frame_count := 0;      quit := false;      while(<>quit) {        @framework->FrameStart();         # process input        while(e->Poll() <> 0) {          if(e->GetType() = EventType->SDL_QUIT) {            quit := true;          };        };         Render(frame_count);         @framework->FrameEnd();         frame_count += 1;        if(frame_count >= @framework->GetFps()) {          frame_count := 0;        };      };    }    else {      "--- Error Initializing Environment ---"->ErrorLine();      return;    };     leaving {      @framework->Quit();    };  }   method : Render(frame_count : Int) ~ Nil {    # rectangle offsets    if(frame_count % GameConsts->REC_REFRESH = 0) {      @rec_offset += 1;      if(@rec_offset >= GameConsts->REC_MAX) {        @rec_offset := 0;        @rec_color_index += 1;      };    };     # rectangle colors    first_color := @rec_colors[@rec_color_index];    second_color : Color;    if(@rec_color_index + 1 < @rec_colors->Size()) {      second_color := @rec_colors[@rec_color_index + 1];    }    else {      second_color := @rec_colors[0];      @rec_color_index := 0;    };     @framework->Clear();     for(i := 1; i < GameConsts->REC_MAX; i += 1;) {      if(i < @rec_offset) {        DrawRectangle(i, first_color);      }      else {        DrawRectangle(i, second_color);      };    };     @framework->Show();  }   method : DrawRectangle(step : Int, color : Color) ~ Nil {    x := step * GameConsts->REC_DIST; w := GameConsts->SCREEN_WIDTH - x * 2;    y := step * GameConsts->REC_DIST; h := GameConsts->SCREEN_HEIGHT - y * 2;     renderer := @framework->GetRenderer();    renderer->SetDrawColor(color->GetR(), color->GetG(), color->GetB(), 0);    renderer->DrawRect(Rect->New(x, y, w, h));    renderer->DrawRect(Rect->New(x + 1, y + 1, w - 2, h - 2));    renderer->DrawRect(Rect->New(x + 2, y + 2, w - 4, h - 4));  }} consts GameConsts {  SCREEN_WIDTH := 640,  SCREEN_HEIGHT := 480,  REC_DIST := 12,  REC_MAX := 20,  REC_REFRESH := 15} `

## Perl

Using the core module `Time::HiRres` to get sub-second sleep

Translation of: Perl 6
`use utf8;binmode STDOUT, ":utf8";use Time::HiRes qw(sleep); %r = ('tl' => qw<┌>, 'tr' => qw<┐>, 'h' => qw<─>, 'v' => qw<│>, 'bl' => qw<└>, 'br' => qw<┘>);@colors = ("\e[1;31m", "\e[1;32m", "\e[1;33m", "\e[1;34m", "\e[1;35m", "\e[1;36m"); print "\e[?25l"; # hide the cursor \$SIG{INT} = sub { print "\e[0H\e[0J\e[?25h"; exit; }; # clean up on exit while (1) {    @c = palette() unless \$n % 16;    rect(\$_, 31-\$_) for 0..15;    display(@vibe);    sleep .20;    push @c, \$c[0]; shift @c;    \$n++;} sub palette {    my @c = sort { -1 + 2*int(rand 2) } @colors;    (\$c[0], \$c[1], \$c[2]) x 12;} sub rect {    my (\$b, \$e) = @_;    my \$c = \$c[\$b % @c];    my @bb = (\$c.\$r{tl}, ((\$r{h})x(\$e-\$b-1)), \$r{tr}."\e[0m");    my @ee = (\$c.\$r{bl}, ((\$r{h})x(\$e-\$b-1)), \$r{br}."\e[0m");    \$vibe[\$b][\$_] = shift @bb for \$b .. \$e;    \$vibe[\$e][\$_] = shift @ee for \$b .. \$e;    \$vibe[\$_][\$b] = \$vibe[\$_][\$e] = \$c.\$r{v}."\e[0m" for \$b+1 .. \$e-1;} sub display {    my(@rect) = @_;    print "\e[0H\e[0J\n\n";    for my \$row (@rect) {        print "\t\t\t";        print \$_ // ' ' for @\$row;        print "\n";    }}`

## Perl 6

Works with: Rakudo version 2018.06

### ANSI graphics

Ok. The task description is essentially non-existent. In looking at the reference implementation (Ring) it seems like we are supposed to draw a series of concentric rectangles and then alter the colors step-wise. No actual vibration apparent.

Could fire up a GUI but WTH, let's try it at a command line with ANSI.

Draws a series of concentric rectangles then rotates through the color palette. Every three seconds, chooses new random palette colors and reverses rotation direction.

`# box drawing charactersmy %r = :tl<┌>, :h<─>, :tr<┐>, :v<│>, :bl<└>, :br<┘>; my @colors = « \e[1;31m \e[1;94m \e[1;33m \e[1;35m \e[1;36m \e[1;32m \e[1;34m »; # color palettemy @c = flat @colors[0] xx 12, @colors[3] xx 12, @colors[2] xx 12; print "\e[?25l"; # hide the cursor signal(SIGINT).tap: {    print "\e[0H\e[0J\e[?25h"; # clean up on exit    exit;} my \$rot = 1; my @vibe; loop {    rect(\$_, 31-\$_) for ^15;    display @vibe;    @c.=rotate(\$rot);    if ++\$ %% 30 {        @c = |@colors.pick(3);        @c = sort(flat @c xx 12);        \$rot *= -1;    }    sleep .1;} sub rect (\$b, \$e) {    @vibe[\$b;\$b..\$e] = @c[\$b % @c]~%r<tl>, |((%r<h>) xx (\$e - \$b - 1)), %r<tr>~"\e[0m";    @vibe[\$e;\$b..\$e] = @c[\$b % @c]~%r<bl>, |((%r<h>) xx (\$e - \$b - 1)), %r<br>~"\e[0m";    (\$b ^..^ \$e).map: { @vibe[\$_;\$b] = @vibe[\$_;\$e] = @c[\$b % @c]~%r<v>~"\e[0m" }} sub display (@rect) {    print "\e[0H\e[0J\n\n";    for @rect -> @row {        print "\t\t\t";        print \$_ // ' ' for @row;        print "\n";    }}`

See: Vibrating rectangles (.gif image)

### SDL Animation

Fully animated SDL2 graphics lib version. Will adjust rendered rectangles to fill resized windows. Hit the space bar to toggle palette rotation direction.

`use SDL2::Raw; my \$width  = 1200;my \$height = 800; SDL_Init(VIDEO); my \$window = SDL_CreateWindow(    'Vibrating rectangles',    SDL_WINDOWPOS_CENTERED_MASK,    SDL_WINDOWPOS_CENTERED_MASK,    \$width, \$height,    RESIZABLE); my \$render = SDL_CreateRenderer(\$window, -1, ACCELERATED +| PRESENTVSYNC); my \$event = SDL_Event.new; enum KEY_CODES (    K_SPACE  => 44,); my \$num = 80;my @rgb = palette(\$num);my (\$cx, \$cy);my \$dir = 1; main: loop {    while SDL_PollEvent(\$event) {        my \$casted_event = SDL_CastEvent(\$event);        given \$casted_event {            when *.type == QUIT { last main }            when *.type == WINDOWEVENT {                if .event == 5 {                    \$width  = .data1;                    \$height = .data2;                }            }            when *.type == KEYDOWN {                if KEY_CODES(.scancode) -> \$comm {                    given \$comm {                        when 'K_SPACE'  { \$dir *= -1; }                    }                }                #say .scancode; # unknown key pressed            }        }    }    (\$cx, \$cy) = \$width div 2, \$height div 2;     for 1..^\$num {        my (\$x, \$y) = (\$cx - (\$width/2/\$num*\$_), \$cy - (\$height/2/\$num*\$_))».round;        my (\$w, \$h) = (\$width/\$num*\$_, \$height/\$num*\$_)».round;        SDL_SetRenderDrawColor(\$render, |@rgb[\$_], 255);        SDL_RenderDrawRect(\$render, SDL_Rect.new(:x(\$x), :y(\$y), :w(\$w), :h(\$h)));    }    @rgb.=rotate(\$dir);    SDL_RenderPresent(\$render);    SDL_SetRenderDrawColor(\$render, 0, 0, 0, 0);    SDL_RenderClear(\$render);} SDL_Quit(); sub palette (\$l) { (^\$l).map: { hsv2rgb((\$_ * 360/\$l % 360)/360, 1, 1).list } }; sub hsv2rgb ( \$h, \$s, \$v ){ # inputs normalized 0-1    my \$c = \$v * \$s;    my \$x = \$c * (1 - abs( ((\$h*6) % 2) - 1 ) );    my \$m = \$v - \$c;    my (\$r, \$g, \$b) = do given \$h {        when   0..^(1/6) { \$c, \$x, 0 }        when 1/6..^(1/3) { \$x, \$c, 0 }        when 1/3..^(1/2) { 0, \$c, \$x }        when 1/2..^(2/3) { 0, \$x, \$c }        when 2/3..^(5/6) { \$x, 0, \$c }        when 5/6..1      { \$c, 0, \$x }    }    ( \$r, \$g, \$b ).map: ((*+\$m) * 255).Int}`

## Phix

`-- demo\rosetta\vibrect.exw----  Draws concentric rectangles in random colours to simulate vibration.--  Press +/- to increase/decrease the number of rectangles being drawn.--  Resizing the window, as it turns out, achieves much the same effect --  as +/-, only much quicker (by increasing/decreasing the spacing).--integer numrects = 125  -- (max non-touching for a height of 500) include pGUI.e Ihandle dlg, canvascdCanvas cddbuffer, cdcanvas function redraw_cb(Ihandle /*ih*/, integer /*posx*/, integer /*posy*/)    integer {w,h} = IupGetIntInt(canvas, "DRAWSIZE")    atom dw = w/(numrects*2+1),         dh = h/(numrects*2+1)     cdCanvasActivate(cddbuffer)    for i=1 to numrects do        cdCanvasSetForeground(cddbuffer,rand(#FFFFFF))        atom wd = i*dw,             hd = i*dh        cdCanvasRect(cddbuffer, wd, w-wd, hd, h-hd)     end for     cdCanvasFlush(cddbuffer)    return IUP_DEFAULTend function function map_cb(Ihandle ih)    cdcanvas = cdCreateCanvas(CD_IUP, ih)    cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)    cdCanvasSetBackground(cddbuffer, CD_WHITE)    cdCanvasSetForeground(cddbuffer, CD_BLACK)    return IUP_DEFAULTend function function timer_cb(Ihandle /*ih*/)    IupUpdate(canvas)    return IUP_IGNOREend function function esc_close(Ihandle /*ih*/, atom c)    if c=K_ESC then return IUP_CLOSE end if    if c='+' or (c='-' and numrects>3) then        numrects -= c-','        cdCanvasClear(cddbuffer)        IupUpdate(canvas)    end if    return IUP_CONTINUEend function procedure main()    IupOpen()     canvas = IupCanvas(NULL)    IupSetAttribute(canvas, "RASTERSIZE", "602x502") -- initial size    IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))     dlg = IupDialog(canvas)    IupSetAttribute(dlg, "TITLE", "Vibrating Rectangles")    IupSetCallback(dlg, "K_ANY",     Icallback("esc_close"))    IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))     IupMap(dlg)    IupSetAttribute(canvas, "RASTERSIZE", NULL) -- release the minimum limitation    IupShowXY(dlg,IUP_CENTER,IUP_CENTER)    Ihandle timer = IupTimer(Icallback("timer_cb"), 40)    IupMainLoop()    IupClose()end proceduremain()`

## Python

`import turtlefrom itertools import cyclefrom time import sleep def rect(t, x, y):    x2, y2 = x/2, y/2    t.setpos(-x2, -y2)    t.pendown()    for pos in [(-x2, y2), (x2, y2), (x2, -y2), (-x2, -y2)]:         t.goto(pos)    t.penup() def rects(t, colour, wait_between_rect=0.1):    for x in range(550, 0, -25):        t.color(colour)        rect(t, x, x*.75)        sleep(wait_between_rect) tl=turtle.Turtle()screen=turtle.Screen()screen.setup(620,620)screen.bgcolor('black')screen.title('Rosetta Code Vibrating Rectangles')tl.pensize(3)tl.speed(0)tl.penup()tl.ht() colours = 'red green blue orange white yellow'.split()for colour in cycle(colours):    rects(tl, colour)    sleep(0.5) `
Output:

Hmm, maybe this?

## Racket

Via big-bang.

`#lang racket (require 2htdp/image         2htdp/universe) (define N 20)(define SIZE 400)(define OFFSET 80)(define RATE 0.2) ;; a state is a pair of color index and position (define colors '(red orange yellow green blue indigo violet))(define (mod x) (modulo x (length colors))) (big-bang (cons 0 (sub1 N))  [on-tick   (match-lambda     [(cons m 0) (cons (mod (add1 m)) (sub1 N))]     [(cons m n) (cons m (sub1 n))])   RATE]  [to-draw   (match-lambda     [(cons m n)       (apply       overlay       (append        (for/list ([i (in-range N 0 -1)])          (square (* i (/ (- SIZE OFFSET) N))                  'outline                  (if (> i n)                      (list-ref colors (mod (add1 m)))                      (list-ref colors m))))        (list (empty-scene SIZE SIZE 'black))))])])`

## Ring

` # Project : Vibrating rectangles Load "guilib.ring" color1  = new qcolor() { setrgb( 255,0,0,255 ) }pen1    = new qpen()   { setcolor(color1)  setwidth(2) } color2  = new qcolor() { setrgb( 0,255,0,255 ) }pen2    = new qpen()   { setcolor(color2)  setwidth(2) } color3  = new qcolor() { setrgb( 0,0,255,255 ) }pen3    = new qpen()   { setcolor(color3)  setwidth(2) } penArray = [pen1, pen2, pen3]penNbr   =  1 New qapp{   win1 =  new qwidget()    {              setwindowtitle("Drawing using QPixMap")              setgeometry(100,100,500,500)              label1 = new qlabel(win1)              {                           setgeometry(10,10,500,500)                           settext("")              }                     Canvas = new qlabel(win1)             {                                          MonaLisa = new qPixMap2( 500,500)                              color = new qcolor(){ setrgb(255,0,0,255) }                            daVinci = new qpainter()                            {                                         begin(MonaLisa)                                          }                         setpixmap(MonaLisa)                      }       	nCounter = 0	oTimer = new qTimer(win1) {		setinterval(500)		settimeoutevent("DrawCounter()")		start()	}        show()          }   exec()}DrawCounter() func DrawCounter()        nCounter++        if nCounter < 15           Draw(penArray[penNbr])        elseif nCounter % 15 = 0            nCounter = 0            penNbr++            if penNbr > 3               penNbr = 1            ok                   Draw(penArray[penNbr])        okreturn Func Draw(pen1)         daVinci.setpen(penArray[penNbr])         daVinci.drawrect(50+nCounter*10, 50+nCounter*10, 300-nCounter*20, 300-nCounter*20)         Canvas.setpixmap(MonaLisa)               win1.show()                     return `

Output: