Raster bars
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 accepted.
Ada
<lang Ada>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;</lang>
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
<lang go>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)
}
}</lang>
Perl 6
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".
Generate random colored bars and display them. (They ended up looking more plastic than metallic; ah well.)
- Use Up / Down to change the scroll speed.
- Use Pg Up / Pg Dn to adjust raster bar height.
- Use Left / Right to adjust the gap between the raster bars.
- Use Space bar to pause / resume scrolling.
- Use Left Ctrl to reverse scroll direction.
- Use Z / X to change the angle of the raster bars.
- Press Q to exit.
<lang perl6>use SDL2::Raw; use Cairo;
my $width = 800; my $height = 800;
SDL_Init(VIDEO);
my $window = SDL_CreateWindow(
'Raster Bars - Perl 6', SDL_WINDOWPOS_CENTERED_MASK, SDL_WINDOWPOS_CENTERED_MASK, $width, $height, RESIZABLE
);
my $render = SDL_CreateRenderer($window, -1, ACCELERATED +| PRESENTVSYNC);
my @bars = (^256).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,
);
my $dir = -1; my $step = 5; my $incr = 1; my $gap = 100; my $bh = 64; $height += 32; my $port = +@bars * $gap; my $y = $dir > 0 ?? $height - $port !! $height; my $angle = 0;
main: loop {
handle-event($event) while SDL_PollEvent($event);
$y = $step * $dir + $y;
if $dir > 0 {
$y = $height - $port if $y > 0
} else {
$y = 0 if $y < $height - $port
}
for ^@bars {
my $offset = $gap / cos(π * $angle / 180);
SDL_RenderCopyEx( $render, @bars[$_], Nil,
SDL_Rect.new( -$gap, $y + $offset * $_, $width * 2, $bh),
$angle.Num, SDL_Point.new(:x(0),:y(0)), 0
)
}
SDL_RenderPresent($render);
SDL_RenderClear($render);
}
SDL_Quit();
sub gen-bar (@color) {
my $bar = Cairo::Image.create( Cairo::FORMAT_ARGB32, 1, 32 );
given Cairo::Context.new($bar) {
my Cairo::Pattern::Gradient::Linear $lpat .= create(0.0, 0.0, 0.0, 32.0);
$lpat.add_color_stop_rgba( 1, |(@color »*» .3), 1);
$lpat.add_color_stop_rgba( .2, |(@color), 1);
$lpat.add_color_stop_rgba( .8, |(@color), 1);
$lpat.add_color_stop_rgba( 0, |(@color »+» .8), 1);
.rectangle(0, 0, 1, 32);
.pattern($lpat);
.fill;
$lpat.destroy;
}
my $bar_texture = SDL_CreateTexture(
$render, %PIXELFORMAT<ARGB8888>,
STATIC, 1, 32
);
SDL_UpdateTexture(
$bar_texture,
SDL_Rect.new(:x(0), :y(0), :w(1), :h(32)),
$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 += $incr }
when 'K_DOWN' { $step -= $incr if $step > $incr }
when 'K_LEFT' { $gap = $gap < 32 ?? $gap !! $gap - 1; $port = +@bars * $gap; }
when 'K_RIGHT' { $gap++; $port += +@bars; }
when 'K_PGUP' { $bh += 2 }
when 'K_PGDN' { $bh = $bh >= 34 ?? $bh - 2!! $bh }
when 'K_SPACE' { $step = $step ?? 0 !! $incr }
when 'K_LCTRL' { $dir *= -1 }
when 'K_Z' { $angle = $angle > -45 ?? $angle - 1 !! $angle }
when 'K_X' { $angle = $angle < 45 ?? $angle + 1 !! $angle }
when 'K_Q' { last main }
}
}
}
when *.type == WINDOWEVENT {
if .event == 5 {
$width = .data1;
$height = .data2 + 32;
}
}
}
}</lang>
Screenshot still of typical run: (offsite .png image)
Phix
Some grey bars that vaguely shimmer as they march up the screen... (did not turn out quite as well as hoped) <lang Phix>-- demo\rosetta\Raster_bars.exw constant 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*/, integer /*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(NULL)
IupSetAttribute(canvas, "RASTERSIZE", "600x400")
IupSetCallback(canvas, "MAP_CB", Icallback("map_cb"))
IupSetCallback(canvas, "UNMAP_CB", Icallback("unmap_cb"))
dlg = IupDialog(canvas)
IupSetAttribute(dlg, "TITLE", "Raster bars")
IupSetCallback(canvas, "ACTION", Icallback("redraw_cb"))
IupCloseOnEscape(dlg)
Ihandle hTimer = IupTimer(Icallback("timer_cb"), 10)
IupMap(dlg)
IupSetAttribute(canvas, "RASTERSIZE", NULL)
IupShowXY(dlg,IUP_CENTER,IUP_CENTER)
IupMainLoop()
IupClose()
end procedure
main()</lang>