Enum Brush

pub enum Brush {
    SolidColor(Color),
    Gradient(Gradient),
}

A Brush defines the fill pattern of shapes. The syntax allows to express fill patterns in several ways:

• solid colors
• colors with alpha channel
• gradients of colors
• gradients with directions
• gradients with angles

The string declaration of a Brush is composed combining the following syntax elements:

1. The color name
2. The gradient string
   • the gradient type (linear, repeating-linear)
   • gradient attributes (direction-identifier, angles, color names )

Examples

Here are some implementations with declarations of colors, degrees, orientations and directions.

.foreground("white")
.background("black")
.background("linear-gradient(0deg, #4b6cb7, #182848)")
.background("repeating-linear-gradient(0.25turn, rgba(255, 255, 0, 0.6), dodgerblue, deepskyblue)")
.background("linear-gradient(-90deg, hsv(201, 94%, 80.5%), steelblue)")
.background("linear-gradient(to top right, white, skyblue 60%, lightskyblue 80%, yellow 83%, yellow)")

Read on to see how the syntax is composed.

Definition of a color name

With the given implementation you can choose between three methods to define a color.

A. color codes

You can define the value of a color with a symbol “#” followed by letters or numbers. These numbers are in hexadecimal numeral system. The short variant will use 3 numbers , the long variant will use 6 numbers. For example #f00 will give you red. If you write #0000ff, you will get blue. To include an alpha channel, the short variant takes 4 numbers. If you need a yellow with 50.2% opaque, you use #ff08. In the long form you need 8 numbers. #0000ff80 represents 50.2% opaque (non-premultiplied) blue.

B. color function

Currently the unique available functions that interpret a color are distincted with the keywords rgb, hsv, hsb, hsl. There are alpha variants as well. hsb is an alias to hsv. Alpha variants are coded with the keywords rgba, abgr or argb. Here is an example to define a color via the function method: hsl(197, 71%, 73%) will provide you a pretty skyblue color. For rgb and rgba the range of the values are 0-255. Any other keyword will use floating point integers to define the color value. hsva(0.0-360.0, 0.0-1.0, 0.0-1.0, 0.0-1.0) is such an example. In addition you can choose to use percent values (% sign) for the given parameters. When appending the % sign to the range parameters of the rgb function call, the values are mapped to 0.0-100.0 (percent) or 0.0-1.0 (min/max). For all other keywords (hsv, hsb, hsl) you are not allowed to append the percent sign to the first parameter. If you append % to the following parameters, OrbTk will interpret the values in a range between 0.0-100.0.

C. color name

WIP: The given implementation is using (utils/colors.txt). This has to be adopted!!!

OrbTk maintains a list of color names as constants. You may directly choose their string value inside the code.

Example color names are:

• COLOR_WHITE
• COLOR_RED
• COLOR_OLIVE
• COLOR_LINK_WATER
• COLOR_SLATE_GRAY

Definition of a gradient

The syntax of a gradient definition is structured as follows:

• Optional parameters are inside brackets ([]).
• Within braces ({}) you define the appropriate parameter value.
• The pipe (|) is offering mutual exclusive variants e.g: degrees(deg), radians(rad) or turns(turn).
• Three points (...) refer to multiple stops. They are respected when a gradient is rendered.

To understand gradient directions, imagine a line or vector that starts at a given point inside the entity and points to an imaginary target point within the same entity. Gradients will be rendered along the choosen direction to reach its target poing. Supported directions are:

• “to bottom”
• “to bottom left”
• “to bottom right”
• “to left”
• “to right”
• “to top
• “to top left”
• “to top right”

Displacement points tell the gradient algorithm to add (positive) or or substract (negative) the given pixel numbers from the original starting point.

Lets look at some examples. The first one shows the structure of an angled gradient

[repeating-]linear-gradient({Gradient-angle}{deg|rad|turn}, ...) [{X Displacement}px {Y Displacement}px], {Color} [{Stop  position}{%|px}]

The next example shows the structure of a gradient that will be rendered in a given direction

[repeating-]linear-gradient({direction-identifier}, {initial color-name}, {terminating color-name}

Variants

SolidColor(Color)

Paints an area with a solid color.

Gradient(Gradient)

Paints an area with a gradient.

Implementations

impl Brush

pub fn is_transparent(&self) -> bool

Trait Implementations

impl Clone for Brush

fn clone(&self) -> Brush

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Brush

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Default for Brush

fn default() -> Self

Returns the “default value” for a type.

impl From<&str> for Brush

fn from(s: &str) -> Brush

Converts to this type from the input type.

impl From<Brush> for Color

fn from(b: Brush) -> Color

Converts to this type from the input type.

impl From<Brush> for Gradient

fn from(b: Brush) -> Gradient

Converts to this type from the input type.

impl From<Color> for Brush

fn from(c: Color) -> Brush

Converts to this type from the input type.

impl From<Gradient> for Brush

fn from(g: Gradient) -> Brush

Converts to this type from the input type.

impl From<String> for Brush

fn from(s: String) -> Brush

Converts to this type from the input type.

impl From<Value> for Brush

fn from(v: Value) -> Self

Converts to this type from the input type.

impl PartialEq for Brush

fn eq(&self, other: &Brush) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for Brush