Hokusai

https://docs.rs/hokusai
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Hokusai is a pure Rust brush engine inspired by libmypaint for stroke rendering, pixel blending, and...
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### pub fn get(&self, s: BrushSetting) -> &SettingValue

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=u32+-%3E+bool

Returns a reference to the value of the specified brush setting.

```APIDOC
## pub fn get(&self, s: BrushSetting) -> &SettingValue

### Description
Returns a reference to the value of the specified brush setting.

### Method
get

### Parameters
- **s** (BrushSetting) - The setting to retrieve.

### Returns
- **&SettingValue** - A reference to the setting value.

```

--------------------------------

### BrushInput Enum

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushInput.html?search=std%3A%3Avec

The BrushInput enum represents different brush input types. It has 19 variants, each with a numeric value, and provides methods to get the canonical name, find a variant from a name, and get the numeric index.

```APIDOC
## Enum BrushInput

### Description
The `BrushInput` enum defines various input types for brush behavior, such as pressure, speed, tilt, and direction. It is used to specify which input drives a brush parameter.

### Variants
- `Pressure = 0`
- `Speed1 = 1`
- `Speed2 = 2`
- `Random = 3`
- `Stroke = 4`
- `Direction = 5`
- `Tilt = 6`
- `TiltDeclination = 7`
- `TiltAscension = 8`
- `DirectionAngle = 9`
- `AttackAngle = 10`
- `GridmapX = 11`
- `GridmapY = 12`
- `Custom = 13`
- `TiltDeclinationX = 14`
- `TiltDeclinationY = 15`
- `Viewzoom = 16`
- `BarrelRotation = 17`
- `BrushRadius = 18`

### Implementations

#### `pub const ALL: &'static [BrushInput]`
A slice containing all variants of `BrushInput`.

#### `pub const fn cname(self) -> &'static str`
Returns the canonical name of the variant as a string.

#### `pub fn from_cname(s: &str) -> Option<BrushInput>`
Attempts to find a `BrushInput` variant from its canonical name. Returns `Some(variant)` if found, otherwise `None`.

#### `pub const fn index(self) -> usize`
Returns the numeric index of the variant.

### Trait Implementations
The enum implements the following traits: `Clone`, `Copy`, `Debug`, `Default`, `Eq`, `Hash`, `PartialEq`, and `StructuralPartialEq`.

```

--------------------------------

### Brush::new

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=std%3A%3Avec

Creates a new Brush instance with default settings.

```APIDOC
## Brush::new

### Description
Creates a new Brush instance with default settings.

### Method
`pub fn new() -> Brush`

### Parameters
None.

### Returns
- `Brush` - A new Brush instance.
```

--------------------------------

### pub const ALL: &'static [BrushSetting]

Source: https://docs.rs/hokusai/latest/hokusai/setting/enum.BrushSetting.html?search=std%3A%3Avec

A constant array of all BrushSetting variants.

```APIDOC
## pub const ALL: &'static [BrushSetting]

### Description
A constant array containing all variants of the BrushSetting enum.

### Type
&'static [BrushSetting]

### Usage
Access all brush settings as a slice.

### Example
```rust
let all_settings = BrushSetting::ALL;
```

```

--------------------------------

### Rust Enum BrushInput

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushInput.html?search=u32+-%3E+bool

Definition of the BrushInput enum with variants and their discriminant values, plus associated methods for converting to/from names and getting indices.

```APIDOC
## Rust Doc: BrushInput Enum

### Description
The `BrushInput` enum represents different types of brush input parameters. Each variant corresponds to a specific input type and has an associated numeric value.

### Variants
- `Pressure = 0`
- `Speed1 = 1`
- `Speed2 = 2`
- `Random = 3`
- `Stroke = 4`
- `Direction = 5`
- `Tilt = 6`
- `TiltDeclination = 7`
- `TiltAscension = 8`
- `DirectionAngle = 9`
- `AttackAngle = 10`
- `GridmapX = 11`
- `GridmapY = 12`
- `Custom = 13`
- `TiltDeclinationX = 14`
- `TiltDeclinationY = 15`
- `Viewzoom = 16`
- `BarrelRotation = 17`
- `BrushRadius = 18`

### Implementations

#### `pub const ALL: &'static [BrushInput]`
A constant slice containing all variants of `BrushInput`.

#### `pub const fn cname(self) -> &'static str`
Returns the canonical name of the variant as a string literal.

#### `pub fn from_cname(s: &str) -> Option<BrushInput>`
Converts a string name to the corresponding `BrushInput` variant. Returns `None` if the name is not recognized.

#### `pub const fn index(self) -> usize`
Returns the numeric index/discriminant of the variant.

### Trait Implementations
- `Clone`, `Copy`, `Debug`, `Default`, `Eq`, `Hash`, `PartialEq`, `StructuralPartialEq` are implemented.
- Also implements auto traits like `Send`, `Sync`, `Unpin`, etc., and blanket implementations from `Any`, `Borrow`, `BorrowMut`, etc.

### Example Usage
```rust
use brush::BrushInput;

let input = BrushInput::Pressure;
let index = input.index(); // returns 0
let name = input.cname();  // returns "Pressure"
\nlet from_name = BrushInput::from_cname("Speed1"); // Some(BrushInput::Speed1)
```
```

--------------------------------

### pub fn new() -> Brush

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=u32+-%3E+bool

Creates a new Brush instance with default settings.

```APIDOC
## pub fn new() -> Brush

### Description
Creates a new Brush instance with default settings.

### Method
new

### Parameters
None

### Returns
- **Brush** - A new Brush instance.

```

--------------------------------

### MemSurface::new

Source: https://docs.rs/hokusai/latest/hokusai/tile_mem/struct.MemSurface.html?search=std%3A%3Avec

Creates a new, empty MemSurface instance.

```APIDOC
## [mem_surface_new]

### Description
Creates a new in-memory surface instance.

### Method
`pub fn new() -> MemSurface`

### Parameters
None.

### Returns
- `MemSurface` - A new, empty surface.
```

--------------------------------

### pub fn from_cname(s: &str) -> Option<BrushSetting>

Source: https://docs.rs/hokusai/latest/hokusai/setting/enum.BrushSetting.html?search=std%3A%3Avec

Attempts to convert a canonical string name back into a BrushSetting.

```APIDOC
## pub fn from_cname(s: &str) -> Option<BrushSetting>

### Description
Attempts to convert a canonical string name back into a BrushSetting.

### Parameters
- **s** (&str) - The canonical string name.

### Returns
- **Option<BrushSetting>** - The corresponding BrushSetting, or None if not found.

### Example
```rust
if let Some(setting) = BrushSetting::from_cname("opacity") {
    // use setting
}
```

```

--------------------------------

### tile_request_start

Source: https://docs.rs/hokusai/latest/hokusai/surface/trait.TiledSurface.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Requests a mutable reference to a 64x64 tile at the given coordinates, used for tile-based modification.

```APIDOC
## tile_request_start(tx: i32, ty: i32)

### Description
Requests a mutable reference to a 64x64 tile at the given coordinates.

### Method
Required method of `TiledSurface` trait.

### Parameters
- `tx` (i32) - Required - X coordinate of the tile.
- `ty` (i32) - Required - Y coordinate of the tile.

### Returns
`&mut [[[u16; 4]; 64]; 64]` - Mutable reference to the tile data.

```

--------------------------------

### BrushSetting::cname

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushSetting.html

Returns the libmypaint canonical string name for the brush setting, matching .myb JSON keys.

```APIDOC
## BrushSetting::cname

### Description
Returns the libmypaint canonical string name for the brush setting, matching `.myb` JSON keys.

### Method
pub const fn cname(self) -> &'static str

### Parameters
- **self** (BrushSetting) - The brush setting enum value.

### Returns
- **&'static str** - The canonical string name.

### Example
```rust
let name = setting.cname();
```
```

--------------------------------

### pub fn settings(&self) -> &[SettingValue]

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=u32+-%3E+bool

Returns a slice of all setting values in the brush.

```APIDOC
## pub fn settings(&self) -> &[SettingValue]

### Description
Returns a slice of all setting values in the brush.

### Method
settings

### Parameters
None

### Returns
- **&[SettingValue]** - A slice of setting values.

```

--------------------------------

### Flatten a MemSurface to a Pixmap with flatten_over_white

Source: https://docs.rs/hokusai-tiny-skia/%5E0.3.0

Creates a MemSurface, renders to it, then flattens over white and saves as PNG. Requires tiny-skia's png-format feature for save_png.

```rust
use hokusai_core::TiledSurface;
use hokusai_tile_mem::MemSurface;
let mut surf = MemSurface::new();
render(&mut surf);
let pixmap = hokusai_tiny_skia::flatten_over_white(&surf, 320, 120);
pixmap.save_png("out.png").unwrap(); // requires tiny-skia's png-format feature
```

--------------------------------

### SettingValues::new

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/struct.SettingValues.html?search=

Creates a new SettingValues instance.

```APIDOC
## SettingValues::new

### Description
Creates a new SettingValues instance.

### Method
new

### Signature
pub fn new() -> SettingValues

### Parameters
None

### Returns
- **SettingValues** - A new SettingValues instance.
```

--------------------------------

### BrushSetting::from_cname

Source: https://docs.rs/hokusai/latest/hokusai/setting/enum.BrushSetting.html

Converts a string name to a BrushSetting, returning None if the name does not match any setting.

```APIDOC
## BrushSetting::from_cname

### Description
Converts a string name to a BrushSetting, returning None if the name does not match any setting.

### Signature
```rust
pub fn from_cname(s: &str) -> Option<BrushSetting>
```

### Parameters
- `s` (&str) - The string name to convert.

### Returns
- `Option<BrushSetting>` - The corresponding BrushSetting, or None if not found.
```

--------------------------------

### InputMapping

Source: https://docs.rs/hokusai/latest/hokusai/mapping/struct.InputMapping.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Documentation for the InputMapping struct, its fields, and its methods.

```APIDOC
## Struct InputMapping

### Description
Represents a mapping from brush input to output offsets using piecewise-linear knots.

### Fields
- **input** (`BrushInput`) - The brush input type.
- **points** (`Vec<(f32, f32)>`) - `(input_value, output_offset)` knots. libmypaint requires `x` strictly ascending. Output is added to `base_value` after summing all inputs.

### Methods

#### `new`

##### Signature
`pub fn new(input: BrushInput) -> InputMapping`

##### Description
Creates a new `InputMapping` with the given brush input.

#### `eval`

##### Signature
`pub fn eval(&self, x: f32) -> f32`

##### Description
Evaluates the piecewise-linear curve at `x`. Mirrors libmypaint’s `mypaint_mapping_calculate` (mypaint-mapping.c): starts with the first two knots, walks forward while `x > x1`, and if the resulting bracket has `x0 == x1` or `y0 == y1` returns `y0` directly to dodge division by zero on duplicate-x knots (Dieterle/Posterizer’s opaque_multiply curve has `[(0,0),(0,1),(1,1)]` exactly).

### Trait Implementations
- `Clone`
- `Debug`
- `Default`
- `PartialEq`
- `StructuralPartialEq`
```

--------------------------------

### SettingValues::new

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/struct.SettingValues.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Creates a new SettingValues instance with default values.

```APIDOC
## SettingValues::new

### Description
Creates a new SettingValues instance with default values.

### Method
new

### Signature
pub fn new() -> SettingValues

### Returns
- **SettingValues** - A new SettingValues instance.
```

--------------------------------

### BrushSetting::ALL

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushSetting.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Returns a static slice containing all BrushSetting variants.

```APIDOC
## BrushSetting::ALL

### Description
Returns a static slice containing all BrushSetting variants.

### Method
Associated constant

### Signature
`pub const ALL: &'static [BrushSetting]`

### Returns
- `&'static [BrushSetting]` - A slice of all BrushSetting variants.
```

--------------------------------

### InputMapping::new

Source: https://docs.rs/hokusai/latest/hokusai/mapping/struct.InputMapping.html?search=u32+-%3E+bool

Creates a new InputMapping instance with the specified brush input. This is the constructor for the InputMapping struct.

```APIDOC
## InputMapping::new

### Description
Creates a new `InputMapping` instance with the given brush input.

### Method
`pub fn new(input: BrushInput) -> InputMapping`

### Parameters
- **input** (BrushInput) - Required - The brush input for the mapping.

### Returns
- **InputMapping** - The newly created InputMapping struct.
```

--------------------------------

### InputMapping::new

Source: https://docs.rs/hokusai/latest/hokusai/mapping/struct.InputMapping.html?search=std%3A%3Avec

Creates a new InputMapping instance for the given brush input.

```APIDOC
## Rust

### Description
Creates a new `InputMapping` instance with the provided `BrushInput` and an empty points vector.

### Method
`pub fn new(input: BrushInput) -> InputMapping`

### Parameters
- `input` (BrushInput) - Required - The brush input associated with this mapping.

### Returns
A new `InputMapping` struct.

```

--------------------------------

### pub const fn cname(self) -> &'static str

Source: https://docs.rs/hokusai/latest/hokusai/setting/enum.BrushSetting.html?search=std%3A%3Avec

Returns the libmypaint canonical string name for the brush setting, matching .myb JSON keys.

```APIDOC
## pub const fn cname(self) -> &'static str

### Description
Returns the libmypaint canonical string name for the brush setting, matching `.myb` JSON keys.

### Parameters
- **self** (BrushSetting) - The brush setting.

### Returns
- **&'static str** - The canonical string name.

### Example
```rust
let name = setting.cname();
```

```

--------------------------------

### RgbaF32::new

Source: https://docs.rs/hokusai/latest/hokusai/color/struct.RgbaF32.html

Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

```APIDOC
## RgbaF32::new

### Description
Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

### Method
`pub const fn new(r: f32, g: f32, b: f32, a: f32) -> RgbaF32`

### Parameters
- **r** (f32) - Required - Red component.
- **g** (f32) - Required - Green component.
- **b** (f32) - Required - Blue component.
- **a** (f32) - Required - Alpha component.

### Returns
- **RgbaF32** - The constructed color.

### Example
```rust
let color = RgbaF32::new(1.0, 0.5, 0.0, 1.0);
```
```

--------------------------------

### RgbaF32::new

Source: https://docs.rs/hokusai/latest/hokusai/color/struct.RgbaF32.html?search=u32+-%3E+bool

Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

```APIDOC
## RgbaF32::new

### Description
Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

### Signature
```rust
pub const fn new(r: f32, g: f32, b: f32, a: f32) -> RgbaF32
```

### Parameters
- **r** (f32) - Required - Red component.
- **g** (f32) - Required - Green component.
- **b** (f32) - Required - Blue component.
- **a** (f32) - Required - Alpha component.

### Returns
- **RgbaF32** - The constructed color.

```

--------------------------------

### RgbaF32::new

Source: https://docs.rs/hokusai/latest/hokusai/color/struct.RgbaF32.html?search=

Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

```APIDOC
## RgbaF32::new

### Description
Creates a new RgbaF32 instance with the given red, green, blue, and alpha components.

### Method
new

### Signature
pub const fn new(r: f32, g: f32, b: f32, a: f32) -> RgbaF32

### Parameters
- **r** (f32) - Required - Red component.
- **g** (f32) - Required - Green component.
- **b** (f32) - Required - Blue component.
- **a** (f32) - Required - Alpha component.

### Returns
- **RgbaF32** - The constructed color value.
```

--------------------------------

### pub const fn index(self) -> usize

Source: https://docs.rs/hokusai/latest/hokusai/setting/enum.BrushSetting.html?search=std%3A%3Avec

Returns the index of the brush setting.

```APIDOC
## pub const fn index(self) -> usize

### Description
Returns the index of the brush setting.

### Parameters
- **self** (BrushSetting) - The brush setting.

### Returns
- **usize** - The index.

### Example
```rust
let idx = setting.index();
```

```

--------------------------------

### pub fn empty_tile() -> Box<[[[u16; 4]; 64]; 64]>

Source: https://docs.rs/hokusai/latest/hokusai/tile/fn.empty_tile.html?search=

Creates a new empty tile represented as a boxed 64x64 grid of RGBA color values, each component being a u16.

```APIDOC
## pub fn empty_tile() -> Box<[[[u16; 4]; 64]; 64]>

### Description
Creates a new empty tile represented as a boxed 64x64 grid of RGBA color values, each component being a u16.

### Signature
```rust
pub fn empty_tile() -> Box<[[[u16; 4]; 64]; 64]>
```

### Parameters
None

### Return Value
- **Box<[[[u16; 4]; 64]; 64]>** - A boxed 64x64 tile where each cell is an RGBA color with u16 components.
```

--------------------------------

### InputMapping::new

Source: https://docs.rs/hokusai/latest/hokusai/mapping/struct.InputMapping.html

Creates a new InputMapping instance with the given BrushInput.

```APIDOC
## InputMapping::new

### Description
Creates a new InputMapping instance with the given BrushInput.

### Method
new

### Signature
pub fn new(input: BrushInput) -> InputMapping

### Parameters
- **input** (BrushInput) - Required - The brush input to associate with this mapping.

### Returns
- **InputMapping** - A new InputMapping instance.
```

--------------------------------

### InputValues::new

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/struct.InputValues.html?search=u32+-%3E+bool

Creates a new InputValues instance with default values.

```APIDOC
## InputValues::new

### Description
Creates a new InputValues instance.

### Method
`pub const fn new() -> InputValues`

### Parameters
None.

### Returns
- **InputValues** - A new InputValues instance.
```

--------------------------------

### TiledSurface::tile_request_start

Source: https://docs.rs/hokusai/latest/hokusai/tile_mem/struct.MemSurface.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Requests a mutable reference to the tile at the given coordinates, creating it if necessary.

```APIDOC
## TiledSurface::tile_request_start

### Description
Requests a mutable reference to the tile at the given coordinates, creating it if necessary.

### Method
`fn tile_request_start(&mut self, tx: i32, ty: i32) -> &mut [[[u16; 4]; 64]; 64]`

### Parameters
- **tx** (i32) - Required - The x-coordinate of the tile.
- **ty** (i32) - Required - The y-coordinate of the tile.

### Returns
- **&mut [[[u16; 4]; 64]; 64]** - A mutable reference to the tile.

```

--------------------------------

### TiledSurface::begin_atomic

Source: https://docs.rs/hokusai/latest/hokusai/tile_mem/struct.MemSurface.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Begins an atomic operation, tracking tile modifications.

```APIDOC
## TiledSurface::begin_atomic

### Description
Begins an atomic operation, tracking tile modifications.

### Method
`fn begin_atomic(&mut self)`

### Parameters
None.

### Returns
None.

```

--------------------------------

### begin_atomic

Source: https://docs.rs/hokusai/latest/hokusai/surface/trait.TiledSurface.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Begins an atomic operation, grouping modifications for batch processing.

```APIDOC
## begin_atomic()

### Description
Begins an atomic operation, grouping modifications for batch processing.

### Method
Provided method of `TiledSurface` trait.

### Parameters
None

### Returns
None

```

--------------------------------

### SettingValues::new()

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/struct.SettingValues.html?search=u32+-%3E+bool

Creates a new SettingValues instance with default values.

```APIDOC
## SettingValues::new()

### Description
Creates a new SettingValues instance.

### Method
new

### Signature
pub fn new() -> SettingValues

### Parameters
None

### Returns
- **SettingValues** - A new SettingValues instance.
```

--------------------------------

### from_str

Source: https://docs.rs/hokusai/latest/hokusai/myb/index.html?search=std%3A%3Avec

Parses a `.myb` JSON document into a `Brush`.

```APIDOC
## from_str

### Description
Parses a `.myb` JSON document into a `Brush`.

### Method
N/A (Rust function)

### Endpoint
N/A

### Parameters
#### Input
- **input** (string) - Required - The `.myb` JSON document as a string.

### Request Example
```rust
let brush = myb::from_str(json_str)?;
```

### Response
#### Success Response
- **brush** (Brush) - The parsed brush object.

#### Response Example
```rust
let brush: Brush = myb::from_str(json_str)?;
```
```

--------------------------------

### BrushState::new

Source: https://docs.rs/hokusai/latest/hokusai/struct.BrushState.html?search=u32+-%3E+bool

Creates a new BrushState with a given seed for the PRNG. This initializes the stroke state.

```APIDOC
## `pub fn new(seed: u32) -> BrushState`

### Description
Constructs a new `BrushState` initialized with the given PRNG seed.

### Parameters
- `seed` (u32) - Required - Seed value for the random number generator.

### Returns
- `BrushState` - A new `BrushState` instance.

```

--------------------------------

### mix_colors

Source: https://docs.rs/hokusai/latest/hokusai/spectral/index.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Port of libmypaint's mix_colors (helpers.c). Blends two RGBA straight-alpha colours `a` and `b` (the 'current smudge state' and the 'sampled / brush' colour) with weight `fac` for `a`. When `paint_mode > 0` the colour channels mix in spectral space via WGM; when `paint_mode < 1` a linear mix is layered in proportionally so a fractional setting fades smoothly between the two.

```APIDOC
## mix_colors

### Description
Port of libmypaint's `mix_colors` (helpers.c). Blends two RGBA straight-alpha colours `a` and `b` (the 'current smudge state' and the 'sampled / brush' colour) with weight `fac` for `a`. When `paint_mode > 0` the colour channels mix in spectral space via WGM; when `paint_mode < 1` a linear mix is layered in proportionally so a fractional setting fades smoothly between the two.

### Method
Function

### Signature
`mix_colors(a: RGBA, b: RGBA, fac: f32, paint_mode: f32) -> RGBA`

### Parameters
- `a` (RGBA) - Required - The 'current smudge state' colour.
- `b` (RGBA) - Required - The 'sampled / brush' colour.
- `fac` (f32) - Required - The weight for `a`.
- `paint_mode` (f32) - Required - When > 0, mix in spectral space via WGM; when < 1, linear mix is layered in proportionally.

### Returns
- (RGBA) - The blended colour.
```

--------------------------------

### pub fn new(seed: u32) -> BrushState

Source: https://docs.rs/hokusai/latest/hokusai/struct.BrushState.html?search=

Creates a new BrushState with the given seed for the random number generator.

```APIDOC
## pub fn new(seed: u32) -> BrushState

### Description
Creates a new `BrushState` instance, initializing the internal random number generator with the provided `seed`.

### Method
`new`

### Parameters
- **seed** (u32) - Required - The seed value for the random number generator.

### Returns
- **BrushState** - A new `BrushState` instance.
```

--------------------------------

### rgb_to_hsv

Source: https://docs.rs/hokusai/latest/hokusai/color/fn.rgb_to_hsv.html?search=std%3A%3Avec

Documentation for the rgb_to_hsv function in the hokusai crate.

```APIDOC
## Function rgb_to_hsv

### Description
Converts RGB color components to HSV color space.

### Signature
```rust
pub fn rgb_to_hsv(r: f32, g: f32, b: f32) -> Hsv
```

### Parameters
- **r** (f32) - Required - Red component (0.0 to 1.0)
- **g** (f32) - Required - Green component (0.0 to 1.0)
- **b** (f32) - Required - Blue component (0.0 to 1.0)

### Returns
- **Hsv** - The HSV representation of the input color.
```

--------------------------------

### Brush::settings

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=std%3A%3Avec

Returns a slice of all setting values in the brush.

```APIDOC
## Brush::settings

### Description
Returns a slice of all setting values in the brush.

### Method
`pub fn settings(&self) -> &[SettingValue]`

### Parameters
None.

### Returns
- `&[SettingValue]` - A slice of all setting values.
```

--------------------------------

### pub const fn constant(v: f32) -> SettingValue

Source: https://docs.rs/hokusai/latest/hokusai/struct.SettingValue.html

Creates a new SettingValue with a constant base value and no input mappings.

```APIDOC
## pub const fn constant(v: f32) -> SettingValue

### Description
Creates a new SettingValue with the given constant base value and no input mappings.

### Method
Associated function (constructor)

### Signature
```rust
pub const fn constant(v: f32) -> SettingValue
```

### Parameters
- **v** (f32) - The constant base value for the setting.

### Returns
- **SettingValue** - A new SettingValue instance with `base_value` set to `v`, `inputs` empty, and `unknown_inputs` empty.

### Example
```rust
let value = SettingValue::constant(0.5);
```
```

--------------------------------

### InputValues

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/struct.InputValues.html?search=

Documentation for the InputValues struct, including its fields and methods.

```APIDOC
## Struct InputValues

### Description
Normalized input values, indexed by `BrushInput`. The stroke engine fills this each event before calling `evaluate`.

### Fields
- **values** (`[f32; 19]`) - The normalized input values.

### Implementations

#### `pub const fn new() -> InputValues`
Creates a new `InputValues` instance.

#### `pub fn get(&self, input: BrushInput) -> f32`
Gets the value for the given `BrushInput`.

#### `pub fn set(&mut self, input: BrushInput, v: f32)`
Sets the value for the given `BrushInput`.

### Trait Implementations
- `Clone`
- `Copy`
- `Debug`
- `Default`
```

--------------------------------

### Brush::get

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=std%3A%3Avec

Returns a reference to the value of a brush setting.

```APIDOC
## Brush::get

### Description
Returns a reference to the value of a brush setting.

### Method
`pub fn get(&self, s: BrushSetting) -> &SettingValue`

### Parameters
- `s` (BrushSetting) - The brush setting to retrieve.

### Returns
- `&SettingValue` - A reference to the setting value.
```

--------------------------------

### fastpow

Source: https://docs.rs/hokusai/latest/hokusai/spectral/index.html?search=u32+-%3E+bool

Approximates x.powf(p) matching libmypaint's fastpow. Relative error is about 2% per call, but it uses the same arithmetic as libmypaint's mix_colors and get_color_pixels_accumulate, ensuring bit-identical output.

```APIDOC
## fastpow

### Description
Approximates `x.powf(p)` matching libmypaint's `fastpow`. Relative error is about 2% per call, but it uses the same arithmetic as libmypaint's `mix_colors` and `get_color_pixels_accumulate`, ensuring bit-identical output.

### Parameters
- **x** (float) - The base value.
- **p** (float) - The exponent.

### Returns
- **float** - Approximation of `x.powf(p)`.
```

--------------------------------

### evaluate

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/index.html?search=

Evaluates every setting on a brush at the given normalized inputs.

```APIDOC
## evaluate

### Description
Evaluates every setting on `brush` at the given normalized inputs.

### Function Signature
`evaluate(brush: &Brush, inputs: &InputValues) -> SettingValues`

### Parameters
- **brush** (`&Brush`) - The brush whose settings are to be evaluated.
- **inputs** (`&InputValues`) - Normalized input values indexed by `BrushInput`.

### Returns
- **SettingValues** - Evaluated setting values indexed by `crate::BrushSetting`.

### Notes
- This function is the pure `(base_value + Σ mapping.eval(input_value))` step.
- Input normalization (pressure, speed, tilt, etc.) is handled by the stroke engine before calling this function.
```

--------------------------------

### pub fn rgb_to_hsv(r: f32, g: f32, b: f32) -> Hsv

Source: https://docs.rs/hokusai/latest/hokusai/color/fn.rgb_to_hsv.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Converts RGB color values to HSV color space. Takes red, green, and blue components as f32 values and returns an Hsv struct.

```APIDOC
## pub fn rgb_to_hsv(r: f32, g: f32, b: f32) -> Hsv

### Description
Converts RGB color values to HSV color space. Takes red, green, and blue components as f32 values and returns an Hsv struct.

### Function Signature
```rust
pub fn rgb_to_hsv(r: f32, g: f32, b: f32) -> Hsv
```

### Parameters
- **r** (f32) - Required - Red component of the color.
- **g** (f32) - Required - Green component of the color.
- **b** (f32) - Required - Blue component of the color.

### Return Value
- **Hsv** - The HSV representation of the input color.
```

--------------------------------

### world_to_tile

Source: https://docs.rs/hokusai/latest/hokusai/tile/fn.world_to_tile.html

Documentation for the `world_to_tile` function in the `hokusai::tile` module.

```APIDOC
## world_to_tile

### Description
Convert a world pixel coordinate to `(tile_x, tile_y, in_tile_x, in_tile_y)`.

### Function Signature
```rust
pub fn world_to_tile(x: i32, y: i32) -> (i32, i32, usize, usize)
```

### Parameters
- **x** (i32) - Required - The world pixel x-coordinate.
- **y** (i32) - Required - The world pixel y-coordinate.

### Returns
- **(i32, i32, usize, usize)** - A tuple containing the tile coordinates `(tile_x, tile_y)` and the in-tile pixel coordinates `(in_tile_x, in_tile_y)`.
```

--------------------------------

### spectral_to_rgb

Source: https://docs.rs/hokusai/latest/hokusai/spectral/fn.spectral_to_rgb.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Documentation for the `spectral_to_rgb` function in the `hokusai::spectral` module.

```APIDOC
## Function `spectral_to_rgb`

### Description
Downsamples 10 spectral channels back to straight-alpha linear sRGB. Negative `T_MATRIX` rows can push the result below `WGM_EPSILON`; the `(tmp - WGM_EPSILON) / offset` step undoes the upsample epsilon and clamps the result into `[0, 1]`.

### Signature
```rust
pub fn spectral_to_rgb(spec: &[f32; 10]) -> (f32, f32, f32)
```

### Parameters
- `spec` (`&[f32; 10]`) - Required - The 10 spectral channel values to convert.

### Returns
- `(f32, f32, f32)` - The resulting RGB values in straight-alpha linear sRGB.
```

--------------------------------

### BrushSetting::index

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushSetting.html

Returns the index of the brush setting.

```APIDOC
## BrushSetting::index

### Description
Returns the index of the brush setting.

### Method
pub const fn index(self) -> usize

### Parameters
- **self** (BrushSetting) - The brush setting enum value.

### Returns
- **usize** - The index.

### Example
```rust
let idx = setting.index();
```
```

--------------------------------

### lib.rs: Re-export backends based on cargo features

Source: https://docs.rs/hokusai/latest/src/hokusai/lib.rs.html?search=

The lib.rs source for the hokusai crate. It re-exports hokusai_core by default and conditionally exposes modules for the myb, tile_mem, and tiny_skia backends based on the corresponding cargo features.

```rust
1//! Hokusai — pure Rust brush engine inspired by libmypaint.
2//!
3//! Umbrella crate that re-exports the active backends based on cargo features.
4
5pub use hokusai_core::*;
6
7#[cfg(feature = "myb-json")]
8pub mod myb {
9    pub use hokusai_brush::*;
10}
11
12#[cfg(feature = "tile-mem")]
13pub mod tile_mem {
14    pub use hokusai_tile_mem::*;
15}
16
#[cfg(feature = "tiny-skia")]
17pub mod tiny_skia {
18    pub use hokusai_tiny_skia::*;
19}

```

--------------------------------

### Brush::get

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Retrieves the value of a specified brush setting.

```APIDOC
## Brush::get

### Description
Retrieves the value of a specified brush setting.

### Method
get

### Signature
pub fn get(&self, s: BrushSetting) -> &SettingValue

### Parameters
- **s** (BrushSetting) - Required - The brush setting to retrieve.

### Returns
- **&SettingValue** - A reference to the setting value.
```

--------------------------------

### BrushSetting::from_cname

Source: https://docs.rs/hokusai/latest/hokusai/enum.BrushSetting.html

Attempts to convert a canonical string name to a BrushSetting enum value.

```APIDOC
## BrushSetting::from_cname

### Description
Attempts to convert a canonical string name to a BrushSetting enum value.

### Method
pub fn from_cname(s: &str) -> Option<BrushSetting>

### Parameters
- **s** (&str) - The canonical string name.

### Returns
- **Option<BrushSetting>** - The corresponding BrushSetting, or None if not found.

### Example
```rust
if let Some(setting) = BrushSetting::from_cname("opaque_multiplier") { ... }
```
```

--------------------------------

### from_f32

Source: https://docs.rs/hokusai/latest/hokusai/fix15/fn.from_f32.html?search=Option%3CT%3E%2C+%28T+-%3E+U%29+-%3E+Option%3CU%3E

Documentation for the from_f32 function in the hokusai::fix15 module.

```APIDOC
## from_f32

### Description
Converts a 32-bit floating-point value to a 16-bit unsigned integer representation used by the fix15 fixed-point format.

### Signature
```rust
pub fn from_f32(v: f32) -> u16
```

### Parameters
- **v** (f32) - The floating-point value to convert.

### Returns
- **u16** - The fixed-point representation of the input value.
```

--------------------------------

### to_string_pretty

Source: https://docs.rs/hokusai/latest/hokusai/myb/fn.to_string_pretty.html?search=u32+-%3E+bool

Serializes a Brush to libmypaint-style JSON. This function takes a reference to a Brush and returns a Result containing a String on success or an Error on failure.

```APIDOC
## to_string_pretty

### Description
Serializes a `Brush` back to libmypaint-style JSON.

### Function Signature
```rust
pub fn to_string_pretty(brush: &Brush) -> Result<String, Error>
```

### Parameters
- **brush** (`&Brush`) - Required - A reference to the Brush to serialize.

### Returns
- `Result<String, Error>` - On success, returns a JSON string representation of the Brush. On failure, returns an Error.
```

--------------------------------

### pub fn set(&mut self, s: BrushSetting, v: SettingValue)

Source: https://docs.rs/hokusai/latest/hokusai/brush/struct.Brush.html?search=u32+-%3E+bool

Sets the value of the specified brush setting.

```APIDOC
## pub fn set(&mut self, s: BrushSetting, v: SettingValue)

### Description
Sets the value of the specified brush setting.

### Method
set

### Parameters
- **s** (BrushSetting) - The setting to set.
- **v** (SettingValue) - The value to assign.

### Returns
None

```

--------------------------------

### empty_tile()

Source: https://docs.rs/hokusai/latest/hokusai/tile/fn.empty_tile.html?search=std%3A%3Avec

Creates and returns an empty tile as a boxed three-dimensional array. The tile has dimensions 64 by 64 cells, and each cell holds an array of four u16 values.

```APIDOC
## empty_tile

### Description
Creates and returns an empty tile as a boxed three-dimensional array. The tile has dimensions 64 by 64 cells, and each cell holds an array of four u16 values.

### Function Signature
```rust
pub fn empty_tile() -> Box<[[[u16; 4]; 64]; 64]>
```

### Parameters
None

### Return Type
- **Box<[[[u16; 4]; 64]; 64]>** - A boxed three-dimensional array representing the tile.

### Example Usage
```rust
let tile = hokusai::tile::empty_tile();
```
```

--------------------------------

### pub fn evaluate(brush: &Brush, inputs: &InputValues) -> SettingValues

Source: https://docs.rs/hokusai/latest/hokusai/evaluator/fn.evaluate.html?search=std%3A%3Avec

Evaluates every setting on the provided brush at the given normalized inputs. For each setting, the value is computed as base_value plus the sum of mapping evaluations. Clamping is intentionally not applied.

```APIDOC
## Function: evaluate

### Description
Evaluates every setting on the given brush at the provided normalized inputs. For each setting, the value is computed as `base_value + Σ mapping.eval(inputs[mapping.input])`. Clamping is intentionally not performed.

### Signature
```rust
pub fn evaluate(brush: &Brush, inputs: &InputValues) -> SettingValues
```

### Parameters
- **brush** (`&Brush`) - The brush whose settings are to be evaluated.
- **inputs** (`&InputValues`) - The normalized input values used for evaluation.

### Return Value
- **SettingValues** - The evaluated setting values for the brush.

### Notes
- Clamping of certain settings (e.g., `opaque` into `[0, 2]`) is intentionally not done here; the stroke engine applies setting-specific post-processing.
```

--------------------------------

### pub fn fastpow(x: f32, p: f32) -> f32

Source: https://docs.rs/hokusai/latest/hokusai/spectral/fn.fastpow.html?search=

Approximates `x.powf(p)` with a relative error of about 2% per call, but uses the same arithmetic as libmypaint to produce bit-identical output in spectral operations.

```APIDOC
## Function: fastpow

### Description
Approximates `x.powf(p)` with a relative error of about 2% per call. It uses the same arithmetic as libmypaint's `fastpow`, ensuring bit-identical output in `mix_colors` and `get_color_pixels_accumulate`.

### Signature
```rust
pub fn fastpow(x: f32, p: f32) -> f32
```

### Parameters
- **x** (f32) - The base value.
- **p** (f32) - The exponent.

### Return Value
- **f32** - The approximate result of `x.powf(p)`.

### Example
```rust
let result = hokusai::spectral::fastpow(2.0, 3.0);
```

### Notes
- Relative error is approximately 2% per call.
- Produces bit-identical output to libmypaint's `fastpow`.
```
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