Type Mappings

The types used for properties in .slint design markup each translate to specific types in C++. The follow table summarizes the entire mapping:

.slint Type	C++ Type	Note
int	int
float	float
bool	bool
string	slint::SharedString	A reference-counted string type that uses UTF-8 encoding and can be easily converted to a std::string_view or a const char *.
color	slint::Color
brush	slint::Brush
image	slint::Image
physical_length	float	The unit are physical pixels.
length	float	At run-time, logical lengths are automatically translated to physical pixels using the device pixel ratio.
duration	std::int64_t	At run-time, durations are always represented as signed 64-bit integers with millisecond precision.
angle	float	The angle in degrees.
relative-font-size	float	Relative font size factor that is multiplied with the Window.default-font-size and can be converted to a length.
structure	A class of the same name	The order of the data member are in the same as in the slint declaration
anonymous object	A std::tuple	The fields are in alphabetical order.
enum	An enum class	The values are always converted to CamelCase. The order of the values is the same as in the declaration.
Point	slint::LogicalPosition	A struct with x and y fields, representing logical coordinates.

Structures

The Slint compiler generates a class with all data members in the same order for any user-defined, exported struct in the .slint code.

For example, this struct in a .slint file

export struct MyStruct {
    foo: int,
    bar: string,
}

will generate the following type in C++:

class MyStruct {
public:
    int foo;
    slint::SharedString bar;
};

Enums

The Slint compiler generates an enum class with all values in the same order and converted to camel case for any user-defined, exported enum in the .slint code.

For example, this enum in a .slint file

export enum MyEnum { alpha, beta-gamma, omicron }

will generate the following type in C++:

enum class MyEnum { Alpha, BetaGamma, Omicron };