use egui::{Align2, Color32, Painter, Pos2, Rect, Stroke, Ui, Vec2};
use crate::config::KnobConfig;
use crate::style::{KnobStyle, LabelPosition};
pub(crate) struct KnobRenderer<'a> {
config: &'a KnobConfig,
value: f32,
raw: f32,
min: f32,
max: f32,
}
impl<'a> KnobRenderer<'a> {
pub fn new(config: &'a KnobConfig, value: f32, raw: f32, min: f32, max: f32) -> Self {
Self {
config,
value,
raw,
min,
max,
}
}
pub fn compute_angle(&self) -> f32 {
if self.min == self.max || self.raw.is_nan() {
self.config.min_angle
} else {
self.config.min_angle
+ self.raw * (self.config.max_angle - self.config.min_angle)
}
}
pub fn render_knob(&self, painter: &Painter, center: Pos2, radius: f32, hovered: bool) {
let knob_color = if hovered {
self.config.colors.knob_color.linear_multiply(1.15)
} else {
self.config.colors.knob_color
};
painter.circle_filled(
center,
radius - self.config.stroke_width / 2.0,
self.config.colors.knob_color.gamma_multiply(0.15),
);
painter.circle_stroke(
center,
radius,
Stroke::new(self.config.stroke_width, knob_color),
);
if self.config.show_background_arc {
self.render_background_arc(painter, center, radius);
}
let angle = self.compute_angle();
match self.config.style {
KnobStyle::Wiper => {
let pointer = center + Vec2::angled(angle) * (radius * 0.65);
painter.line_segment(
[center, pointer],
Stroke::new(
self.config.stroke_width * 1.2,
self.config.colors.line_color,
),
);
}
KnobStyle::Dot => {
let dot_pos = center + Vec2::angled(angle) * (radius * 0.7);
painter.circle_filled(
dot_pos,
self.config.stroke_width * 1.8,
self.config.colors.line_color,
);
}
}
}
fn render_background_arc(&self, painter: &Painter, center: Pos2, radius: f32) {
let arc_start = self.config.min_angle;
let arc_end = self.config.max_angle;
let segments = 128;
let arc_color = self.config.colors.knob_color.gamma_multiply(0.35);
let arc_radius = radius * 0.85;
let mut points = Vec::with_capacity(segments + 1);
for i in 0..=segments {
let t = i as f32 / segments as f32;
let angle = arc_start + (arc_end - arc_start) * t;
let pos = center + Vec2::angled(angle) * arc_radius;
points.push(pos);
}
painter.add(egui::Shape::line(
points,
Stroke::new(self.config.stroke_width, arc_color),
));
if self.config.show_filled_segments {
let filled_segments = (segments as f32
* self.raw.clamp(0.0, 1.0))
as usize;
if filled_segments > 0 {
let mut fill_points = Vec::with_capacity(filled_segments + 1);
for i in 0..=filled_segments {
let t = i as f32 / segments as f32;
let angle = arc_start + (arc_end - arc_start) * t;
let pos = center + Vec2::angled(angle) * arc_radius;
fill_points.push(pos);
}
painter.add(egui::Shape::line(
fill_points,
Stroke::new(
self.config.stroke_width * 1.2,
self.config.colors.line_color,
),
));
}
}
}
pub fn render_label(&self, ui: &Ui, rect: Rect) {
if let Some(label) = &self.config.label {
let label_text = format!("{}: {}", label, (self.config.label_format)(self.value));
let font_id = egui::FontId::proportional(self.config.font_size);
let label_padding = 4.0;
let (label_pos, alignment) = match self.config.label_position {
LabelPosition::Top => (
Vec2::new(rect.center().x, rect.min.y + label_padding),
Align2::CENTER_TOP,
),
LabelPosition::Bottom => (
Vec2::new(rect.center().x, rect.max.y - label_padding),
Align2::CENTER_BOTTOM,
),
LabelPosition::Left => (
Vec2::new(rect.min.x + label_padding, rect.center().y),
Align2::LEFT_CENTER,
),
LabelPosition::Right => (
Vec2::new(rect.max.x - label_padding, rect.center().y),
Align2::RIGHT_CENTER,
),
};
ui.painter().text(
label_pos.to_pos2(),
alignment,
label_text,
font_id,
self.config.colors.text_color,
);
}
}
pub fn calculate_size(&self, ui: &Ui) -> Vec2 {
let knob_size = Vec2::splat(self.config.size + self.config.stroke_width * 2.0);
let label_size = if let Some(label) = &self.config.label {
let font_id = egui::FontId::proportional(self.config.font_size);
let max_text = format!("{}: {}", label, (self.config.label_format)(self.max));
ui.painter()
.layout(max_text, font_id, Color32::WHITE, f32::INFINITY)
.size()
} else {
Vec2::ZERO
};
let label_padding = 8.0;
match self.config.label_position {
LabelPosition::Top | LabelPosition::Bottom => Vec2::new(
knob_size.x.max(label_size.x + label_padding * 2.0),
knob_size.y + label_size.y + label_padding + self.config.label_offset,
),
LabelPosition::Left | LabelPosition::Right => Vec2::new(
knob_size.x + label_size.x + label_padding + self.config.label_offset,
knob_size.y.max(label_size.y + label_padding),
),
}
}
pub fn calculate_knob_rect(&self, rect: Rect) -> Rect {
let knob_size = Vec2::splat(self.config.size);
match self.config.label_position {
LabelPosition::Left => {
Rect::from_min_size(rect.right_top() + Vec2::new(-knob_size.x, 0.0), knob_size)
}
LabelPosition::Right => Rect::from_min_size(rect.left_top(), knob_size),
LabelPosition::Top => Rect::from_min_size(
rect.left_bottom() + Vec2::new((rect.width() - knob_size.x) / 2.0, -knob_size.y),
knob_size,
),
LabelPosition::Bottom => Rect::from_min_size(
rect.left_top() + Vec2::new((rect.width() - knob_size.x) / 2.0, 0.0),
knob_size,
),
}
}
}