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The Þog of 2024-01-01 — WebAssembly Applet Spec

WIP

Exports

AppletStart

export fn AppletStart() -> void

Called by the host to initialize the module.

AppletQuit

export fn AppletQuit() -> void

Called by the host to notify it's shutting down. (Currently not really that useful)

AppletRender

export fn AppletRender() -> void

Called by the host to tell the module to refresh its framebuffer.

AppletEvent

export fn AppletEvent(
    kind: i32,
    arg_1: i32,
    arg_2: i32,
    arg_3: i32
) -> i32

Called by the host in response to mouse or key events.

Kind 0x00: Key press (scancode, codepoint, modifiers)
Kind 0x01: Key release (scancode, codepoint, modifiers)
Kind 0x02: Mouse button press (x, y, button)
Kind 0x03: Mouse button release (x, y, button)
Kind 0x04: Absolute mouse position (x, y, buttons)
Kind 0x05: Mouse movement delta (x, y, buttons)

Key scancodes and modifiers are TBD.

AppletDisplayWidth

export fn AppletDisplayWidth() -> i32

Returns the module's display width. The host should only call this once at startup.

AppletDisplayHeight

export fn AppletDisplayHeight() -> i32

Returns the module's display height. The host should only call this once at startup.

AppletDisplayPtr

export fn AppletDisplayPtr -> *u32

Returns a pointer to an array of width*height RGBA bytes (ABGR as u32). The host may call this at any time.

Imports

Applet.Write

import fn Applet.Write(ptr: *u8, len: u32) -> void

A debugging aid. Writes UTF-8 text to an optional text buffer, without a newline.

Applet.SetCursorLock

import fn Applet.SetCursorLock(enable: i32) -> void

Requests the host to lock the cursor. Locked cursor movement gives mouse delta events instead of absolute position events.

Applet.Quit

import fn Applet.Quit(code: i32) -> noreturn

Requests the host to quit. The host should call AppletQuit, like in any other quit condition.