Raster bars

From Rosetta Code
Revision as of 12:04, 28 August 2022 by Thundergnat (talk | contribs) (syntax highlighting fixup automation)
Raster bars 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.
Task

Display bars of color,   moving up and down across the screen for horizontal raster bars,   or left and right across the screen for vertical raster bars,   making the raster bars move as stated by swaying side-to-side the respective way if possible.

Use multiple colors in succession and carefully make a gradient between the colors   (if possible)   to achieve an effect of metallic-looking horizontal bars.

Horizontal and/or vertical raster bars are acceptable.

Ada

Library: SDLAda
with Ada.Numerics.Elementary_Functions;

with SDL.Video.Windows.Makers;
with SDL.Video.Renderers.Makers;
with SDL.Video.Palettes;
with SDL.Events.Events;

procedure Raster_Bars is

   Width   : constant := 1200;
   Height  : constant := 600;

   Window   : SDL.Video.Windows.Window;
   Renderer : SDL.Video.Renderers.Renderer;

   function Check_Quit return Boolean is
      use type SDL.Events.Event_Types;
      Event : SDL.Events.Events.Events;
   begin
      while SDL.Events.Events.Poll (Event) loop
         if Event.Common.Event_Type = SDL.Events.Quit then
            return True;
         end if;
      end loop;
      return False;
   end Check_Quit;

   procedure Draw_Raster_Bar (Y : Integer) is
      use SDL.Video.Palettes;
      use SDL.C;
      Cc : Colour_Component;
   begin
      for I in 0 .. 10 loop
         Cc := Colour_Component (50 + 20 * I);
         Renderer.Set_Draw_Colour ((Cc, Cc, Cc, 255));
         Renderer.Draw (Line => ((0,     C.int (Y + I)),
                                 (Width, C.int (Y + I))));
      end loop;
   end Draw_Raster_Bar;

   procedure Draw_Raster_Bar_V (X : Integer) is
      use SDL.Video.Palettes;
      use SDL.C;
      Cc : Colour_Component;
   begin
      for I in 0 .. 10 loop
         Cc := Colour_Component (250 - 20 * I);
         Renderer.Set_Draw_Colour ((Cc, Cc, Cc, 255));
         Renderer.Draw (Line => ((C.int (X + I), 0),
                                 (C.int (X + I), Height)));
      end loop;
   end Draw_Raster_Bar_V;

   procedure Raster_Bars is
      use Ada.Numerics.Elementary_Functions;
      Xc  : constant Integer := 800;
      Yc  : constant Integer := 200;
      XA  : constant Float   := 40.0;
      YA  : constant Float   := 30.0;
      N : Float := 0.0;
   begin
      loop
         Renderer.Set_Draw_Colour ((0, 0, 0, 255));
         Renderer.Fill (Rectangle => (0, 0, Width, Height));
         Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 00.0, 360.0)));
         Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 25.0, 360.0)));
         Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 50.0, 360.0)));
         Draw_Raster_Bar (Yc + Integer (YA * Sin (N + 75.0, 360.0)));
         Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 00.0, 360.0)));
         Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 90.0, 360.0)));
         Draw_Raster_Bar_V (Xc + Integer (XA * Sin (0.6 * N + 180.0, 360.0)));
         Window.Update_Surface;
         if Check_Quit then
            exit;
         end if;
         delay 0.010;
         N := N + 4.0;
      end loop;
   end Raster_Bars;

begin
   if not SDL.Initialise (Flags => SDL.Enable_Screen) then
      return;
   end if;

   SDL.Video.Windows.Makers.Create (Win      => Window,
                                    Title    => "Raster bar",
                                    Position => SDL.Natural_Coordinates'(X => 10, Y => 10),
                                    Size     => SDL.Positive_Sizes'(Width, Height),
                                    Flags    => 0);
   SDL.Video.Renderers.Makers.Create (Renderer, Window.Get_Surface);

   Raster_Bars;

   Window.Finalize;
   SDL.Finalise;
end Raster_Bars;

Go

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

After each 20 frames, it switches between horizontal and vertical bars and repeats the whole process 10 times.

WARNING: If you have problems with flashing images, either switch to a longer delay than 150ms between 'sways' or don't run it at all.

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 raster_bars.gif -coalesce raster_bars2.gif
  $ eog raster_bars2.gif

package main

import (
    "image"
    "image/color"
    "image/gif"
    "log"
    "os"
)

var (
    c0 = color.RGBA{166, 124, 0, 255}
    c1 = color.RGBA{191, 155, 48, 255}
    c2 = color.RGBA{255, 191, 0, 255}
    c3 = color.RGBA{255, 207, 64, 255}
    c4 = color.RGBA{255, 220, 115, 255}
)

var palette = []color.Color{c0, c1, c2, c3, c4}

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 drawHbar(img *image.Paletted, x1, y1, x2, y2 int, ci uint8) {
    for ; y1 <= y2; y1++ {
        hline(img, x1, y1, x2, ci)
    }
}

func drawVbar(img *image.Paletted, x1, y1, x2, y2 int, ci uint8) {
    for ; x1 <= x2; x1++ {
        vline(img, x1, y1, y2, ci)
    }
}

func main() {
    const nframes = 40
    const delay = 15 // 150ms
    width, height := 500, 500
    anim := gif.GIF{LoopCount: 9} // repeats 9 + 1 times
    rect := image.Rect(0, 0, width, height)

    for f := 0; f < nframes; f++ {
        img := image.NewPaletted(rect, palette)
        c := uint8(f % 2)
        if f < nframes/2 {
            for y := 0; y < height; y += 20 {
                drawHbar(img, 0, y, width, y+19, c)
                c++
                if c == 5 {
                    c = 0
                }
            }
        } else {
            for x := 0; x < width; x += 20 {
                drawVbar(img, x, 0, x+19, height, c)
                c++
                if c == 5 {
                    c = 0
                }
            }
        }
        anim.Delay = append(anim.Delay, delay)
        anim.Image = append(anim.Image, img)
    }

    file, err := os.Create("raster_bars.gif")
    if err != nil {
        log.Fatal(err)
    }
    defer file.Close()
    if err2 := gif.EncodeAll(file, &anim); err != nil {
        log.Fatal(err2)
    }
}


Julia

using Colors, Cairo, Gtk

const can = GtkCanvas()
const win = GtkWindow(can, "Raster Bar Demo", 500, 500)
const pallete_index = [1]
const horizontal = [true]
const palette = [  # colors from the Go example
    colorant"rgba(166, 124, 0, 1.0)",
    colorant"rgba(191, 155, 48, 1.0)",
    colorant"rgba(255, 191, 0, 1.0)",
    colorant"rgba(255, 207, 64, 1.0)",
    colorant"rgba(255, 220, 115, 1.0)",
]

function line(ctx, x1, y1, x2, y2, colr, width=1)
    set_source(ctx, colr)
    set_line_width(ctx, width)
    move_to(ctx, x1, y1)
    line_to(ctx, x2, y2)
    stroke(ctx)
end
hline(ctx, x1, y, x2, c) = line(ctx, x1, y, x2, y, c)
hbar(ctx, x1, y1, x2, y2, c) = foreach(y -> hline(ctx, x1, y, x2, c), y1:y2)
vline(ctx, x, y1, y2, c) = line(ctx, x, y1, x, y2, c)
vbar(ctx, x1, y1, x2, y2, c) = foreach(x -> vline(ctx, x, y1, y2, c), x1:x2)

draw(can) do widget
    ctx = Gtk.getgc(can)
    height, width = Gtk.height(can), Gtk.width(can)
    if horizontal[1]
        for i in 1:3:height
            hbar(ctx, 0, i, width, i + 3, palette[pallete_index[1]])
            pallete_index[1] = mod1(pallete_index[1] + 1, 5)
        end
    else
        for i in 1:3:width
            vbar(ctx, i, 0, i + 3, height, palette[pallete_index[1]])
            pallete_index[1] = mod1(pallete_index[1] + 1, 5)
        end
    end
end

set_gtk_property!(can, :expand, true)
for i in 1:typemax(Int)
    sleep(0.1)
    draw(can)
    showall(win)
    pallete_index[1] = mod1(pallete_index[1] + 2, 5)
    if i % 30 == 29
        horizontal[1] = !horizontal[1]
    end
end

Nim

Translation of: Julia
Library: gintro
import gintro/[gobject, glib, gdk, gtk, gio, cairo]


const Palette = [[166.0, 124.0,   0.0],
                 [191.0, 155.0,  48.0],
                 [255.0, 191.0,   0.0],
                 [255.0, 207.0,  64.0],
                 [255.0, 220.0, 115.0]]

type

  # Description of the simulation.
  Simulation = ref object
    area: DrawingArea
    horizontal: bool
    paletteIndex: Natural
    count: int

  Color = array[3, float]


#---------------------------------------------------------------------------------------------------

proc newSimulation(area: DrawingArea): Simulation {.noInit.} =
  ## Allocate and initialize the simulation object.
  Simulation(area: area, horizontal: true, paletteIndex: 0, count: 0)

#---------------------------------------------------------------------------------------------------

proc bar(ctx: cairo.Context; x1, y1, x2, y2: int; c: Color) =
  ## Draw a bar.
  ctx.setSource(c)
  ctx.rectangle(x1.toFloat, y1.toFloat, (x2 - x1 + 1).toFloat, (y2 - y1 + 1).toFloat)
  ctx.fill()

#---------------------------------------------------------------------------------------------------

proc draw(sim: Simulation; ctx: cairo.Context) =
  ## Draw the bars.

  let width = sim.area.window.width()
  let height = sim.area.window.height()

  if sim.horizontal:
    for i in countup(0, height - 4, 3):
      ctx.bar(0, i, width - 1, i + 3, Palette[sim.paletteIndex])
      sim.paletteIndex = (sim.paletteIndex + 1) mod 5

  else:
    for i in countup(0, width - 4, 3):
      ctx.bar(i, 0, i + 3, height - 1, Palette[sim.paletteIndex])
      sim.paletteIndex = (sim.paletteIndex + 1) mod 5

#---------------------------------------------------------------------------------------------------

proc update(sim: Simulation): gboolean =
  ## Update the simulation state.

  sim.draw(sim.area.window.cairoCreate())
  sim.area.showAll()
  sim.paletteIndex = (sim.paletteIndex + 2) mod 5
  inc sim.count
  if sim.count mod 30 == 29:
    sim.horizontal = not sim.horizontal
  result = gboolean(1)

#---------------------------------------------------------------------------------------------------

proc activate(app: Application) =
  ## Activate the application.

  let window = app.newApplicationWindow()
  window.setSizeRequest(500, 500)
  window.setTitle("Raster Bar Demo")

  let area = newDrawingArea()
  window.add(area)

  let sim = newSimulation(area)
  timeoutAdd(50, update, sim)

  window.showAll()

#———————————————————————————————————————————————————————————————————————————————————————————————————

let app = newApplication(Application, "Rosetta.rasterbars")
discard app.connect("activate", activate)
discard app.run()

Phix

Some grey bars that vaguely shimmer as they march up the screen... (did not turn out quite as well as hoped) 

-- demo\rosetta\Raster_bars.exw
with javascript_semantics
constant title = "Raster bars",
         N = 10,
         nColours = floor(255/N)
integer offset = 0, clast = nColours

include pGUI.e
 
Ihandle dlg, canvas
cdCanvas cddbuffer, cdcanvas
 
function colour(integer i)
    integer g = i*N
    return  cdEncodeColorAlpha(g, g, g, 255)
end function

function redraw_cb(Ihandle /*ih*/, integer /*posx*/, /*posy*/)
    cdCanvasActivate(cddbuffer)
    cdCanvasSetBackground(cddbuffer, colour(clast))
    cdCanvasClear(cddbuffer)
    integer {width, height} = IupGetIntInt(canvas, "DRAWSIZE"),
            h = floor(height/(nColours-1)),
            y = height+offset
    cdCanvasSetInteriorStyle(cddbuffer, CD_SOLID)
    for i=2 to nColours do
        integer c = clast+i-1
        if c>nColours then c -= nColours end if
        cdCanvasSetForeground(cddbuffer, colour(c))
        cdCanvasBox(cddbuffer, 0, width, y-h, y)
        y -= h
    end for
    cdCanvasFlush(cddbuffer)
    offset += 1
    if offset>=h then
        offset = 0
        clast += 1
        if clast>nColours then clast = 1 end if
    end if
    return IUP_DEFAULT
end function
 
function map_cb(Ihandle ih)
    cdcanvas = cdCreateCanvas(CD_IUP, ih)
    cddbuffer = cdCreateCanvas(CD_DBUFFER, cdcanvas)
    return IUP_DEFAULT
end function
 
function unmap_cb(Ihandle /*ih*/)
    cdKillCanvas(cddbuffer)
    cdKillCanvas(cdcanvas)
    return IUP_DEFAULT
end function
 
function timer_cb(Ihandle /*ih*/)
    IupRedraw(dlg) 
    return IUP_DEFAULT
end function

procedure main()
    IupOpen()
    canvas = IupCanvas("RASTERSIZE=600x400")
    IupSetCallbacks(canvas, {"MAP_CB", Icallback("map_cb"),
                             "UNMAP_CB", Icallback("unmap_cb"),
                             "ACTION", Icallback("redraw_cb")})
    dlg = IupDialog(canvas,`TITLE="%s"`, {title})
    Ihandle hTimer = IupTimer(Icallback("timer_cb"), 10)
    IupShow(dlg)
    IupSetAttribute(canvas, "RASTERSIZE", NULL)
 
    if platform()!=JS then
        IupMainLoop()
        IupClose()
    end if
end procedure
 
main()

Raku

(formerly Perl 6)

Works with: Rakudo version 2019.03

As there is no reference implementation, and rather sketchy task instructions, this may or may not fulfill the original task authors intent.

Not really sure what is meant by "swaying", perhaps this will suffice.

Generate random colored bars and display them. (They ended up looking more plastic than metallic; ah well.)

  • Use Up / Down arrows to change the scroll speed.
  • Use Left / Right arrows to adjust the gap between the raster bars.
  • Use Pg Up / Pg Dn to adjust raster bar height.
  • Use Z / X to change the angle of the raster bars.
  • Use Space bar to pause / resume scrolling.
  • Use Left Ctrl to toggle the scroll direction.
  • Press R to toggle Randomize on / off.
  • If Randomize is active, adjust the randomize delay with < / >
  • Press S to toggle Swaying on / off.
  • If Swaying is active, adjust the period with D / F
  • Press Q to exit.
unit sub MAIN (
    Int :b(:$bar-height) is copy = 60; #= Height of the individual "Raster bars", minimum 32 (pixels)
    Int :d(:$dir) is copy        = -1; #= Scroll direction: -1 is "up" 1 is "down"
    Int :s(:$step) is copy       = 4;  #= Scroll speed (pixels per step
    Int :g(:$gap) is copy        = $bar-height + 50; #= Gap between bars (pixels)
    Int :a(:$angle) is copy      = 0; #= Angle to orient bars off horizontal (-60 to 60 degrees)
    Int :sw(:$sway) is copy      = 0; #= Swaying on / off
    Real :r(:$rnd) is copy       = 0; #= Delay between randomize events
);

say q:to/END/;

    Use Up / Down arrows to change the scroll speed.
    Use Left / Right arrows to adjust the gap between the raster bars.
    Use Pg Up / Pg Dn to adjust raster bar height.
    Use Z / X to change the angle of the raster bars.
    Use Space bar to pause / resume scrolling.
    Use Left Ctrl to toggle the scroll direction.
    Press R to toggle Randomize on / off.
    If Randomize is active, adjust the randomize delay with < / >
    Press S to toggle Swaying on / off.
    If Swaying is active, adjust the period with D / F
    Press Q to exit.
    END

use SDL2::Raw;
use Cairo;

my $width  = 800;
my $height = 800;

SDL_Init(VIDEO);

my $window = SDL_CreateWindow(
    'Raster Bars - Raku',
    SDL_WINDOWPOS_CENTERED_MASK,
    SDL_WINDOWPOS_CENTERED_MASK,
    $width, $height, RESIZABLE
);

my $render = SDL_CreateRenderer($window, -1, ACCELERATED +| PRESENTVSYNC);

my @bars = (^128).map: { gen-bar( rand xx 3 ) };

my $event = SDL_Event.new;

enum KEY_CODES (
    K_UP     => 82,
    K_DOWN   => 81,
    K_LEFT   => 80,
    K_RIGHT  => 79,
    K_SPACE  => 44,
    K_PGUP   => 75,
    K_PGDN   => 78,
    K_LCTRL  => 224,
    K_Z      => 29,
    K_X      => 27,
    K_Q      => 20,
    K_R      => 21,
    K_S      => 22,
    K_D      => 7,
    K_F      => 9,
    K_LT     => 54,
    K_GT     => 55,
);

my $port  = +@bars * $gap;
my $y     = $dir > 0 ?? $height - $port !! $height ;
my $now   = now;
my $period = 2;

main: loop {
    handle-event($event) while SDL_PollEvent($event);

    randomize if $rnd and now - $now > $rnd;

    if $dir > 0 {
        $y = $height - $port if $y > 0 - ceiling $height / cos(π * $angle / 180).abs
    } else {
        $y = 0 - ceiling $height / cos(π * $angle / 180).abs if $y < $height - $port
    }

    $y = $step * $dir + $y;

    $angle = (((now * $period) % τ).sin * 35).Int if $sway;

    for ^@bars {
        my $offset = $sway ?? $gap !! ceiling $gap / cos(π * $angle / 180).abs;
        SDL_RenderCopyEx( $render, @bars[$_], Nil,
          SDL_Rect.new( -($width*4), $y + $offset * $_, $width * 10, $bar-height),
          $angle.Num, SDL_Point.new(:x((4.5*$width).Int),:y($y + $offset * $_)), 0

        )
    }

    SDL_RenderPresent($render);

    SDL_RenderClear($render);

    print fps;
}

put '';

SDL_Quit();

sub gen-bar (@color) {
    my $bar = Cairo::Image.create( Cairo::FORMAT_ARGB32, 1, 128 );
    given Cairo::Context.new($bar) {
        my Cairo::Pattern::Gradient::Linear $lpat .= create(0.0, 0.0,  0.0, 128.0);
        $lpat.add_color_stop_rgba(  1, |(@color »*» .3), 1);
        $lpat.add_color_stop_rgba( .2, |(@color),        1);
        $lpat.add_color_stop_rgba(.75, |(@color),        1);
        $lpat.add_color_stop_rgba(  0, |(@color »+» .5), 1);
        .rectangle(0, 0, 1, 128);
        .pattern($lpat);
        .fill;
        $lpat.destroy;
    }

    my $bar_texture = SDL_CreateTexture(
        $render, %PIXELFORMAT<ARGB8888>,
        STATIC, 1, 128
    );

    SDL_UpdateTexture(
        $bar_texture,
        SDL_Rect.new(:x(0), :y(0), :w(1), :h(128)),
        $bar.data, $bar.stride // 1
    );

    $bar_texture
}

sub handle-event ($event) {
    my $casted_event = SDL_CastEvent($event);
    given $casted_event {
        when *.type == QUIT    { last main }
        when *.type == KEYDOWN {
            if KEY_CODES(.scancode) -> $comm {
                given $comm {
                    when 'K_UP'     { $step += 1 }
                    when 'K_DOWN'   { $step -= 1 if $step > 1 }
                    when 'K_LEFT'   { $gap = $gap < 32 ?? $gap !! $gap - 1; $port = +@bars * $gap; }
                    when 'K_RIGHT'  { $gap++; $port += +@bars; }
                    when 'K_PGUP'   { $bar-height += 2 }
                    when 'K_PGDN'   { $bar-height = $bar-height >= 34 ?? $bar-height - 2 !! $bar-height }
                    when 'K_SPACE'  { $step = $step ?? 0 !! 1 }
                    when 'K_LCTRL'  { $dir  *= -1 }
                    when 'K_Z'      { $angle = $angle > -45 ?? $angle - 5 !! $angle }
                    when 'K_X'      { $angle = $angle <  45 ?? $angle + 5 !! $angle }
                    when 'K_R'      { $rnd = $rnd ?? 0 !! 1 }
                    when 'K_S'      { $sway xor= 1 }
                    when 'K_F'      { $period += .1 }
                    when 'K_D'      { $period = $period - .1 max .1;  }
                    when 'K_GT'     { $rnd += .2 }
                    when 'K_LT'     { $rnd = $rnd > .2 ?? $rnd -.2 !! .2 }
                    when 'K_Q'      { last main }
                }
            } #else { say .scancode, "\n" }
        }
        when *.type == WINDOWEVENT {
            if .event == RESIZED {
                $width  = .data1;
                $height = .data2 + $bar-height;
            }
        }
    }
}

sub randomize {
    $dir   = (-1,1).pick;
    $step  = (4..8).pick;
    $bar-height   = (32..200).pick;
    $gap   = $bar-height + (1..100).pick;
    $angle = (-45, *+5 ... 45).pick;

    $port = +@bars * $gap;

    if $dir > 0 {
        $y = $height - $port;
    } else {
        $y = 0 - ceiling ($height max $width) / cos(π * $angle / 180).abs;
    }
    $now = now;
}

sub fps {
    state $fps-frames = 0;
    state $fps-now    = now;
    state $fps        = '';
    $fps-frames++;
    if now - $fps-now >= 1 {
        $fps = [~] "\b" x 40, ' ' x 20, "\b" x 20 ,
            sprintf "FPS: %5.2f  ", ($fps-frames / (now - $fps-now)).round(.01);
        $fps-frames = 0;
        $fps-now = now;
    }
    $fps
}

Screenshot still of typical run: (offsite .png image)

(Small) Moving gif of swaying bars: (offsite .gif image)

Rust

extern crate minifb;

use std::iter::repeat;

use minifb::{Key, Window, WindowOptions};

const WIDTH: usize = 640;
const HEIGHT: usize = 360;

struct Bar {
    color: [f32; 3],
    height: u32,
    position: f32,
    speed: f32,
}

impl Bar {

    fn draw_column(&self, column_buffer: &mut [u32]) {
        let start_row = (self.position.round() as i32).clamp(0, HEIGHT as i32) as usize;
        let end_row = (start_row + self.height as usize).clamp(0, HEIGHT);

        column_buffer[start_row..end_row].iter_mut().enumerate()
            .for_each(|(row_index, color)| {
                *color = self.row_color(row_index as i32);
            });
    }

    fn row_color(&self, y: i32) -> u32 {
        let yy = y as f32 / (self.height - 1) as f32;
        let yy = 1.0 - 2.0 * (yy - 0.5).abs();

        let r = (25.0 + yy.powf((2.0 - 2.0 * self.color[0]).exp()) * 230.0).round() as u8;
        let g = (25.0 + yy.powf((2.0 - 2.0 * self.color[1]).exp()) * 230.0).round() as u8;
        let b = (25.0 + yy.powf((2.0 - 2.0 * self.color[2]).exp()) * 230.0).round() as u8;

        u32::from_be_bytes([255, r, g, b])
    }

    fn update_position(&mut self) {
        self.position += self.speed;

        if let Some(position) = self.bounce_position() {
            self.position = position;
            self.speed = -self.speed;
        }
    }

    fn bounce_position(&self) -> Option<f32> {
        if self.speed > 0.0 {
            let limit = (HEIGHT as i32 - self.height as i32) as f32;
            (self.position >= limit).then(|| limit - (self.position - limit))
        } else {
            (self.position <= 0.0).then(|| -self.position)
        }
    }

}

fn main() {

    let mut window = Window::new(
        "Raster Bars",
        WIDTH,
        HEIGHT,
        WindowOptions::default(),
    )
    .unwrap_or_else(|e| {
        panic!("{}", e);
    });

    // Limit to max ~60 fps update rate
    window.limit_update_rate(Some(std::time::Duration::from_micros(16600)));

    let mut bars = Vec::new();

    bars.push(Bar { color: [1.0, 1.0, 0.0], height: 20, position: 0.0, speed: 3.1 });
    bars.push(Bar { color: [1.0, 0.0, 0.0], height: 25, position: 0.0, speed: 0.2 });
    bars.push(Bar { color: [0.0, 1.0, 0.0], height: 7, position: 0.0, speed: 0.4 });
    bars.push(Bar { color: [0.0, 0.0, 1.0], height: 30, position: 0.0, speed: 1.0 });

    while window.is_open() && !window.is_key_down(Key::Escape) {

        let mut column_buffer = vec![0x_00_00_00_u32; HEIGHT];
        for bar in &mut bars {
            bar.draw_column(&mut column_buffer);
            bar.update_position();
        }

        let buffer: Vec<u32> = column_buffer.iter()
            .flat_map(|&row_color| repeat(row_color).take(WIDTH))
            .collect();

        window
            .update_with_buffer(&buffer, WIDTH, HEIGHT)
            .unwrap();
    }
}


Wren

Translation of: Go
Library: DOME

Unlike the Go example, repeats indefinitely until the window is closed.

As DOME has no facility to create an animated .gif file, the moving image is displayed but not saved. 

import "dome" for Window
import "graphics" for Canvas, Color

var c0 = Color.rgb(166, 124,   0, 255)
var c1 = Color.rgb(191, 155,  48, 255)
var c2 = Color.rgb(255, 191,   0, 255)
var c3 = Color.rgb(255, 207,  64, 255)
var c4 = Color.rgb(255, 220, 115, 255)

var Palette = [c0, c1, c2, c3, c4]

class RasterBars {
    construct new(width, height) {
        Window.resize(width, height)
        Canvas.resize(width, height)
        Window.title = "Raster bars"
        _width = width
        _height = height
    }

    init() {
        _f = 0
        _nframes = 320
        _draw = false
        _c = false
    }

    hline(x1, y, x2, ci) {
        while (x1 <= x2) {
            Canvas.pset(x1, y, Palette[ci])
            x1 = x1 + 1
        }
    }

    vline(x, y1, y2, ci) {
        while (y1 <= y2) {
            Canvas.pset(x, y1, Palette[ci])
            y1 = y1 + 1
        }
    }

    drawHBar(x1, y1, x2, y2, ci) {
        while (y1 <= y2) {
            hline(x1, y1, x2, ci)
            y1 = y1 + 1
        }
    }

    drawVBar(x1, y1, x2, y2, ci) {
        while (x1 <= x2) {
            vline(x1, y1, y2, ci)
            x1 = x1 + 1
        }
    }

    update() {
        _f = _f + 1
        if (_f % 8 == 0) {
            _draw = true
            _c = !_c   
        } else {
            _draw = false
        }
        if (_f == _nframes) _f = 0
    }

    draw(alpha) {
        if (!_draw) return
        var c = _c ? 0 : 1
        if (_f < _nframes / 2) {
            var y = 0
            while (y < _height) {
                drawHBar(0, y, _width, y+19, c)
                c = (c < 4) ? c + 1 : 0
                y = y + 20
            }
        } else {
            var x = 0
            while (x < _width) {
                drawVBar(x, 0, x+19, _height, c)
                c = (c < 4) ? c + 1 : 0
                x = x + 20
            }
        }
    }
}

var Game = RasterBars.new(500, 500)
Retrieved from "https://rosettacode.org/wiki/Raster_bars?oldid=328251"