Display Protocol

Apps render to the screen by writing VYOMA_DRAW: commands to stdout. The supervisor intercepts these commands and renders them to the DRM/virtio-gpu framebuffer.

Protocol Format

Each command is a single line written to stdout:

VYOMA_DRAW:<command>:<parameters>

Commands are processed in order. Nothing appears on screen until flush is called.

Commands

fill_rect

Fill a rectangle with a solid color.

VYOMA_DRAW:fill_rect:<x>,<y>,<width>,<height>,<rgba>

Parameter	Type	Description
x	integer	Left edge (pixels)
y	integer	Top edge (pixels)
width	integer	Width (pixels)
height	integer	Height (pixels)
rgba	u32	Color as (R<<24)|(G<<16)|(B<<8)|A printed as decimal

draw_text

Draw a single line of text.

VYOMA_DRAW:draw_text:<x>,<y>,<rgba>,<size>,<text>

Parameter	Type	Description
x	integer	Left edge (pixels)
y	integer	Top edge (pixels)
rgba	u32	Text color
size	char	s = 4x8, m = 8x16, l = 16x32
text	string	Text content (rest of line)

draw_text_wrap

Draw text with automatic word wrapping.

VYOMA_DRAW:draw_text_wrap:<x>,<y>,<max_width>,<rgba>,<size>,<text>

Parameter	Type	Description
x	integer	Left edge (pixels)
y	integer	Top edge (pixels)
max_width	integer	Maximum width before wrapping (pixels)
rgba	u32	Text color
size	char	s, m, or l
text	string	Text content

flush

Commit the current frame to the framebuffer. Nothing is visible until this is called.

VYOMA_DRAW:flush

Color Format

Colors are packed as a u32 in RGBA format:

(Red << 24) | (Green << 16) | (Blue << 8) | Alpha

Printed as a decimal integer in the protocol string.

Common Colors

Color	Decimal	Hex
White	4294967295	0xFFFFFFFF
Black	255	0x000000FF
Red	4278190335	0xFF0000FF
Green	16744703	0x00FF00FF
Blue	65535	0x0000FFFF
Catppuccin BG	505290495	0x1E1E2EFF

In Rust, define colors as constants:

const WHITE: u32 = 0xFFFFFFFF;
const BG:    u32 = 0x1E1E2EFF;
const RED:   u32 = 0xFF0000FF;

Font Sizes

Size code	Pixel dimensions	Use case
s	4x8	Fine detail, status bars
m	8x16	Default body text
l	16x32	Headers, titles

Example: Complete App Frame

const WHITE: u32  = 0xFFFFFFFF;
const BG: u32     = 0x1E1E2EFF;
const PURPLE: u32 = 0x7C3AEDFF;
const GRAY: u32   = 0x64748BFF;

fn draw_frame() {
    // Clear background
    println!("VYOMA_DRAW:fill_rect:0,0,960,700,{BG}");

    // Header bar
    println!("VYOMA_DRAW:fill_rect:0,0,960,40,{PURPLE}");
    println!("VYOMA_DRAW:draw_text:10,12,{WHITE},m,My Application");

    // Body text
    println!("VYOMA_DRAW:draw_text:10,60,{WHITE},m,Welcome to VyomaOS!");
    println!("VYOMA_DRAW:draw_text:10,80,{GRAY},s,Press any key to continue...");

    // Commit to screen
    println!("VYOMA_DRAW:flush");
}

Window Chrome

The supervisor automatically adds window chrome around each app’s drawing area:

• Title bar with app name and deterministic accent color
• Focus border (2px) around the active window
• Status strip showing app name and uptime

Apps don’t need to account for chrome in their coordinates — the supervisor handles offsetting.

Performance

The supervisor tracks per-app flush rate and logs FPS every 5 seconds. To maintain smooth rendering, apps should aim for consistent flush intervals rather than flooding with draw commands.