Generated Code

The Slint SC compiler translates a .slint file into Rust code that depends only on the slint-sc runtime crate.[sls.gen.output]

The Component Struct

The generated code contains a struct named after the exported component.[sls.gen.component]

An exported component shall inherit Window.[sls.gen.window-root]

new()

pub fn new(size: slint_sc::Size) -> Self

rust

Creates an instance of the component for a window of size, a slint_sc::Size in pixels.[sls.gen.new]

render_rgb8()

pub fn render_rgb8(&self, frame_buffer: &mut [u8]) -> Result<(), slint_sc::RenderError>

rust

Renders the window into frame_buffer as described in Rendering: width * height pixels of the size the window was created with, in row-major order, each pixel three bytes — red, green, blue.[sls.gen.render-rgb8]

let instance = Foo::new(slint_sc::Size::new(320, 240));
let mut frame_buffer = [0u8; 320 * 240 * 3];
instance.render_rgb8(&mut frame_buffer)?;

rust

When the length of frame_buffer isn’t width * height * 3 for that size, render_rgb8 returns Err(RenderError::InvalidFrameBufferSize) and paints nothing.[sls.gen.render-error]

Properties

The generated component holds the value of each property declared on the root element.[sls.gen.prop.values.meta]

Kebab-case property names become snake_case in the generated names: the accessors of a property foo-bar are get_foo_bar() and set_foo_bar().[sls.gen.prop.names]

get_foo()

pub fn get_foo(&self) -> T

rust

Returns the value of the property foo. It is generated for in, out, and in-out properties, but not for private ones.[sls.gen.prop.get]

set_foo()

pub fn set_foo(&mut self, value: T)

rust

Sets the value of the property foo. It is generated for in and in-out properties, but not for out and private ones.[sls.gen.prop.set]

Property Types

The Rust type T of a property maps from its Slint type:[sls.gen.prop.types]

Slint type	Rust type
int	i32
color	slint_sc::Color
length	i32
bool	bool
image	slint_sc::Image
a declared struct	the generated struct of the same name
a declared enum	the generated enum of the same name

An slint_sc::Image is either Image::None, no image, or Image::StaticArgb, a reference to 'static packed pixel bytes in row-major order together with the image’s width, four bytes per pixel: alpha, red, green, and blue. The default is Image::None.[sls.gen.prop.types.image]

The image of an @image-url() literal is decoded when the code is generated and embedded in it as a static holding an Image::StaticArgb; the literals of one .slint file that name the same image file share one embedded copy.[sls.gen.image.static]

Callbacks

The application reacts to the callbacks declared on the root element by implementing a generated trait.[sls.gen.callback.meta]

The Callbacks Trait

pub trait FooCallbacks {
    fn on_bar(&mut self, component: &mut Foo);
}

rust

The trait is named after the component with Callbacks appended, and is generated whether or not the component declares a callback.[sls.gen.callback.trait]

It has one method per declared callback, named after the callback with on_ prepended and - replaced by _: the method of a callback alarm-raised is on_alarm_raised.[sls.gen.callback.names]

No method has a default body, so an application that leaves a callback of the component unimplemented doesn’t compile.[sls.gen.callback.required]

A method takes the implementing value and the component, both by mutable reference, so a handler reads and writes the state of the application and sets properties of the component.[sls.gen.callback.args]

dispatch_touch_event()

pub fn dispatch_touch_event(
    &mut self,
    event: slint_sc::TouchEvent,
    callbacks: &mut impl FooCallbacks,
)

rust

Delivers event, a slint_sc::TouchEvent carrying a press or a release at a position, to the component as described in Touch Input, calling the methods of callbacks for the callbacks that the event invokes.[sls.gen.dispatch-touch-event]

Types

Each struct or enum declared in the .slint file generates a public Rust type of the same name.[sls.gen.types]

Structs

A struct generates a Rust struct whose fields are public and of the mapped Rust type, each named after the Slint field with - replaced by _ (so line-width becomes line_width); it derives Default, Clone, PartialEq, and Debug.[sls.gen.types.struct]

Enums

An enum generates a Rust enum deriving Default, Clone, Copy, PartialEq, and Debug.[sls.gen.types.enum]

Its Default returns the variant of the enum’s first value.[sls.gen.types.enum.default]

A variant name is formed from the Slint value by removing every - and _ and capitalizing the first letter of the name and the first letter after each removed separator; every other letter keeps its case, so a value already in this form is unchanged and FOO_BAR and Foo_Bar yield different variants.[sls.gen.types.enum.names]

Slint value	Rust variant
up	Up
hello-world	HelloWorld
FooBar	FooBar
Foo_Bar	FooBar
FOO_BAR	FOOBAR
FooBar-x	FooBarX

Names become Rust identifiers

A component, struct, enum, or struct field whose name is a Rust keyword, or an enum value whose variant name is one (a value self becomes Self), generates code that does not compile; rename it. Property names are unaffected: their accessors are always prefixed with get_ or set_.