VYOMA_DRAW Display Protocol

Apps with display = true in their manifest can draw to the framebuffer by writing commands to stdout. The supervisor parses these commands and renders them to the compositor.

Color format

Colors are packed u32 values: (R << 24) | (G << 16) | (B << 8) | A, printed as decimal.

const WHITE: u32 = 0xFFFFFFFF;  // 4294967295
const BLACK: u32 = 0x000000FF;  // 255
const RED:   u32 = 0xFF0000FF;  // 4278190335
const BG:    u32 = 0x1E1E2EFF;  // Catppuccin-like dark background

Core commands (v1)

fill_rect

Fill a rectangle with a solid color.

VYOMA_DRAW:fill_rect:<x>,<y>,<w>,<h>,<rgba>

draw_text

Draw text at a position with a given size.

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

Sizes: s = 4x8, m = 8x16, l = 16x32

draw_text_wrap

Draw text with word wrapping at a maximum width.

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

flush

Commit the current frame to the display. Nothing appears on screen until flush is called.

VYOMA_DRAW:flush

Extended commands (v2)

fill_rect_r

Draw a rounded rectangle.

VYOMA_DRAW:fill_rect_r:<x>,<y>,<w>,<h>,<rgba>,<radius>

draw_glyph

Draw a single Unicode glyph by codepoint.

VYOMA_DRAW:draw_glyph:<x>,<y>,<rgba>,<size>,<codepoint>

draw_image

Draw an inline image (base64-encoded).

VYOMA_DRAW:draw_image:<x>,<y>,<w>,<h>,<format>,<base64data>

Format is png or raw.

Example: drawing a simple UI

fn main() {
    let bg: u32 = 0x1E1E2EFF;
    let white: u32 = 0xFFFFFFFF;
    let accent: u32 = 0x89B4FAFF;

    // Clear background
    println!("VYOMA_DRAW:fill_rect:0,0,480,360,{bg}");

    // Title bar
    println!("VYOMA_DRAW:fill_rect:0,0,480,32,{accent}");
    println!("VYOMA_DRAW:draw_text:8,8,{bg},m,My App");

    // Body text
    println!("VYOMA_DRAW:draw_text:16,48,{white},m,Hello, VyomaOS!");

    // Rounded button
    println!("VYOMA_DRAW:fill_rect_r:16,80,120,32,{accent},8");
    println!("VYOMA_DRAW:draw_text:40,88,{bg},m,Click me");

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

Notes

• All coordinates are relative to the app's window, not the screen
• The compositor handles window positioning, decorations, and z-ordering
• Apps should call flush after completing a full frame
• Drawing without flush queues commands but displays nothing