StratoSDK is a framework with a declarative approach similar to Flutter/React, written and designed entirely for Rust.
| 1 | mod config; |
| 2 | mod glyph_index; |
| 3 | |
| 4 | use std::borrow::Cow; |
| 5 | use std::collections::HashMap; |
| 6 | use std::f32::consts::PI; |
| 7 | use std::sync::{Arc, Mutex, MutexGuard}; |
| 8 | use std::time::Duration; |
| 9 | |
| 10 | use crate::color::ColorU; |
| 11 | pub use crate::elements::shimmering_text::config::ShimmerConfig; |
| 12 | use crate::elements::shimmering_text::glyph_index::GlyphIndex; |
| 13 | use crate::elements::{Axis, Point, DEFAULT_UI_LINE_HEIGHT_RATIO}; |
| 14 | use crate::fonts::{FamilyId, Properties}; |
| 15 | use crate::geometry::rect::RectF; |
| 16 | use crate::geometry::vector::{vec2f, Vector2F}; |
| 17 | use crate::platform::LineStyle; |
| 18 | use crate::text_layout::{ |
| 19 | ClipConfig, Line, PaintStyleOverride, StyleAndFont, TextStyle, DEFAULT_TOP_BOTTOM_RATIO, |
| 20 | }; |
| 21 | use crate::text_offsets::CharOffset; |
| 22 | use crate::{AppContext, Element, PaintContext, SizeConstraint}; |
| 23 | use instant::Instant; |
| 24 | use rangemap::RangeMap; |
| 25 | |
| 26 | /// A key to determine whether we need to re-layout text to a given invocation of #layout to this |
| 27 | /// element. |
| 28 | #[derive(PartialEq, Clone, Debug)] |
| 29 | struct LayoutKey { |
| 30 | text: Cow<'static, str>, |
| 31 | font_family: FamilyId, |
| 32 | font_size: f32, |
| 33 | max_width: f32, |
| 34 | } |
| 35 | |
| 36 | struct StateInternal { |
| 37 | laid_out_key: Option<LayoutKey>, |
| 38 | laid_out_line: Option<Arc<Line>>, |
| 39 | /// A list of the character index of every glyph in the line. In other words, index 0 contains |
| 40 | /// A mapping from glyph index in the line to the character index for that glyph. |
| 41 | /// In other words, key 0 contains the character index of the first glyph. We store this as a map |
| 42 | /// to be resilient to ligatures: the ligature 'fi' is two characters but should only have one fade. |
| 43 | /// to ligatures: the ligature "fi" is two characters but should only have one fade. |
| 44 | glyph_indices_in_order: HashMap<GlyphIndex<usize>, CharOffset>, |
| 45 | animation_start_time: Instant, |
| 46 | } |
| 47 | |
| 48 | #[derive(Clone)] |
| 49 | pub struct ShimmeringTextStateHandle(Arc<Mutex<StateInternal>>); |
| 50 | |
| 51 | impl Default for ShimmeringTextStateHandle { |
| 52 | fn default() -> Self { |
| 53 | Self::new() |
| 54 | } |
| 55 | } |
| 56 | |
| 57 | impl ShimmeringTextStateHandle { |
| 58 | pub fn new() -> Self { |
| 59 | Self(Arc::new(Mutex::new(StateInternal { |
| 60 | laid_out_key: None, |
| 61 | laid_out_line: None, |
| 62 | glyph_indices_in_order: HashMap::default(), |
| 63 | animation_start_time: Instant::now(), |
| 64 | }))) |
| 65 | } |
| 66 | |
| 67 | fn get(&self) -> MutexGuard<'_, StateInternal> { |
| 68 | self.0.lock().expect("Mutex should not be poisoned") |
| 69 | } |
| 70 | } |
| 71 | |
| 72 | /// An element that displays the given text using given `base_color` with a shimmer that animates |
| 73 | /// from left to right with the given `shimmer_color`. |
| 74 | /// |
| 75 | /// See [`ShimmerConfig`] for adjusting configuration options, such as the duration, size, and |
| 76 | /// frequency of the shimmer. |
| 77 | pub struct ShimmeringTextElement { |
| 78 | text: Cow<'static, str>, |
| 79 | |
| 80 | font_family: FamilyId, |
| 81 | font_size: f32, |
| 82 | |
| 83 | base_color: ColorU, |
| 84 | shimmer_color: ColorU, |
| 85 | |
| 86 | config: ShimmerConfig, |
| 87 | |
| 88 | size: Option<Vector2F>, |
| 89 | origin: Option<Point>, |
| 90 | |
| 91 | handle: ShimmeringTextStateHandle, |
| 92 | } |
| 93 | |
| 94 | impl ShimmeringTextElement { |
| 95 | pub fn new( |
| 96 | text: impl Into<Cow<'static, str>>, |
| 97 | font_family: FamilyId, |
| 98 | font_size: f32, |
| 99 | base_color: ColorU, |
| 100 | shimmer_color: ColorU, |
| 101 | config: ShimmerConfig, |
| 102 | state_handle: ShimmeringTextStateHandle, |
| 103 | ) -> Self { |
| 104 | Self { |
| 105 | text: text.into(), |
| 106 | font_family, |
| 107 | font_size, |
| 108 | base_color, |
| 109 | shimmer_color, |
| 110 | config, |
| 111 | size: None, |
| 112 | origin: None, |
| 113 | handle: state_handle, |
| 114 | } |
| 115 | } |
| 116 | |
| 117 | /// Returns the center of the shimmer as a fractional glyph index along the "track". |
| 118 | fn shimmer_center(&self, number_of_glyphs: usize, state: &StateInternal) -> GlyphIndex<f32> { |
| 119 | if number_of_glyphs <= 1 { |
| 120 | return GlyphIndex(0.0); |
| 121 | } |
| 122 | |
| 123 | let period_s = self.config.period.as_secs_f32(); |
| 124 | let elapsed_s = state.animation_start_time.elapsed().as_secs_f32(); |
| 125 | // Get the percent of the way through we are of the current loop. |
| 126 | let progress = (elapsed_s / period_s).fract(); |
| 127 | |
| 128 | // Compute the total number of glyphs the band needs to travel. |
| 129 | let span = (number_of_glyphs as f32 - 1.0) + (2.0 * self.config.padding as f32); |
| 130 | // Get the fractional glyph index for the center of the band, factoring in that the center |
| 131 | // can be negative (before any of the text) |
| 132 | GlyphIndex((progress * span) - self.config.padding as f32) |
| 133 | } |
| 134 | |
| 135 | /// Returns how strong the shimmer effect should be for a given glyph based on how far it is |
| 136 | /// from the center of the shimmer. |
| 137 | fn intensity_at(&self, glyph_index: GlyphIndex<usize>, center: GlyphIndex<f32>) -> f32 { |
| 138 | let dist = (glyph_index.as_f32().0 - center.0).abs(); |
| 139 | // If the distance is greater than the size of the band, there's no intensity. |
| 140 | if dist >= self.config.shimmer_radius as f32 { |
| 141 | return 0.0; |
| 142 | } |
| 143 | // Use a cosine wave to generate the intensity otherwise and normalize it to [0,1]. |
| 144 | let theta = (dist / self.config.shimmer_radius as f32) * PI; |
| 145 | (theta.cos() + 1.0) * 0.5 |
| 146 | } |
| 147 | |
| 148 | fn glyph_index_to_character_index_map(line: &Line) -> HashMap<GlyphIndex<usize>, CharOffset> { |
| 149 | line.runs |
| 150 | .iter() |
| 151 | .flat_map(|run| run.glyphs.iter()) |
| 152 | .enumerate() |
| 153 | .map(|(glyph_index, glyph)| (GlyphIndex(glyph_index), CharOffset::from(glyph.index))) |
| 154 | .collect() |
| 155 | } |
| 156 | |
| 157 | fn build_color_overrides(&self) -> PaintStyleOverride { |
| 158 | let state = self.handle.get(); |
| 159 | |
| 160 | let glyph_indices_in_order = &state.glyph_indices_in_order; |
| 161 | |
| 162 | let n = glyph_indices_in_order.len(); |
| 163 | if n == 0 { |
| 164 | return PaintStyleOverride::default(); |
| 165 | } |
| 166 | |
| 167 | let center = self.shimmer_center(n, &state); |
| 168 | |
| 169 | let mut overrides = RangeMap::new(); |
| 170 | for (glyph_index, char_index) in glyph_indices_in_order.iter() { |
| 171 | let intensity = self.intensity_at(*glyph_index, center); |
| 172 | let color = self |
| 173 | .base_color |
| 174 | .to_f32() |
| 175 | .lerp(self.shimmer_color.to_f32(), intensity) |
| 176 | .to_u8(); |
| 177 | overrides.insert(char_index.as_usize()..char_index.as_usize() + 1, color); |
| 178 | } |
| 179 | |
| 180 | PaintStyleOverride::default().with_color(overrides) |
| 181 | } |
| 182 | } |
| 183 | |
| 184 | impl Element for ShimmeringTextElement { |
| 185 | fn layout( |
| 186 | &mut self, |
| 187 | constraint: SizeConstraint, |
| 188 | ctx: &mut crate::LayoutContext, |
| 189 | app: &AppContext, |
| 190 | ) -> Vector2F { |
| 191 | let mut state = self.handle.get(); |
| 192 | |
| 193 | let text_len = self.text.chars().count(); |
| 194 | let styles = [( |
| 195 | 0..text_len, |
| 196 | StyleAndFont::new(self.font_family, Properties::default(), TextStyle::new()), |
| 197 | )]; |
| 198 | |
| 199 | let max_width = constraint.max_along(Axis::Horizontal); |
| 200 | |
| 201 | let layout_key = LayoutKey { |
| 202 | text: self.text.clone(), |
| 203 | font_family: self.font_family, |
| 204 | font_size: self.font_size, |
| 205 | max_width, |
| 206 | }; |
| 207 | |
| 208 | // Determine whether we need to relayout the text. |
| 209 | let line = match state.laid_out_line.clone() { |
| 210 | Some(line) if Some(&layout_key) == state.laid_out_key.as_ref() => line, |
| 211 | _ => { |
| 212 | let line = ctx.text_layout_cache.layout_line( |
| 213 | self.text.as_ref(), |
| 214 | LineStyle { |
| 215 | font_size: self.font_size, |
| 216 | line_height_ratio: DEFAULT_UI_LINE_HEIGHT_RATIO, |
| 217 | baseline_ratio: DEFAULT_TOP_BOTTOM_RATIO, |
| 218 | fixed_width_tab_size: None, |
| 219 | }, |
| 220 | &styles, |
| 221 | max_width, |
| 222 | ClipConfig::default(), |
| 223 | &app.font_cache().text_layout_system(), |
| 224 | ); |
| 225 | |
| 226 | // Restart the animation if the font or font size has changed. |
| 227 | let should_restart_animation = match (&layout_key, state.laid_out_key.as_ref()) { |
| 228 | (new_layout_key, Some(old_layout_key)) => { |
| 229 | new_layout_key.font_family != old_layout_key.font_family |
| 230 | || new_layout_key.font_size != old_layout_key.font_size |
| 231 | || new_layout_key.text != old_layout_key.text |
| 232 | } |
| 233 | _ => true, |
| 234 | }; |
| 235 | |
| 236 | if should_restart_animation { |
| 237 | state.animation_start_time = Instant::now(); |
| 238 | } |
| 239 | |
| 240 | state.glyph_indices_in_order = Self::glyph_index_to_character_index_map(&line); |
| 241 | state.laid_out_line = Some(line.clone()); |
| 242 | state.laid_out_key = Some(layout_key); |
| 243 | |
| 244 | line |
| 245 | } |
| 246 | }; |
| 247 | |
| 248 | let size = vec2f( |
| 249 | line.width.max(constraint.min.x()).min(constraint.max.x()), |
| 250 | line.height(), |
| 251 | ); |
| 252 | |
| 253 | self.size = Some(size); |
| 254 | size |
| 255 | } |
| 256 | |
| 257 | fn after_layout(&mut self, _: &mut crate::AfterLayoutContext, _: &AppContext) {} |
| 258 | |
| 259 | fn paint(&mut self, origin: Vector2F, ctx: &mut PaintContext, app: &AppContext) { |
| 260 | /// Duration, in ms, for which to repaint. Approximately 30fps. |
| 261 | const REPAINT_DURATION: u64 = 32; |
| 262 | |
| 263 | self.origin = Some(Point::from_vec2f(origin, ctx.scene.z_index())); |
| 264 | |
| 265 | let Some(size) = self.size else { |
| 266 | return; |
| 267 | }; |
| 268 | |
| 269 | let Some(line) = self.handle.get().laid_out_line.clone() else { |
| 270 | return; |
| 271 | }; |
| 272 | |
| 273 | ctx.repaint_after(Duration::from_millis(REPAINT_DURATION)); |
| 274 | |
| 275 | let bounds = RectF::from_points(origin, origin + size); |
| 276 | let style_overrides = self.build_color_overrides(); |
| 277 | |
| 278 | line.paint( |
| 279 | bounds, |
| 280 | &style_overrides, |
| 281 | self.base_color, |
| 282 | app.font_cache(), |
| 283 | ctx.scene, |
| 284 | ); |
| 285 | } |
| 286 | |
| 287 | fn size(&self) -> Option<Vector2F> { |
| 288 | self.size |
| 289 | } |
| 290 | |
| 291 | fn origin(&self) -> Option<Point> { |
| 292 | self.origin |
| 293 | } |
| 294 | |
| 295 | fn dispatch_event( |
| 296 | &mut self, |
| 297 | _: &crate::event::DispatchedEvent, |
| 298 | _: &mut crate::EventContext, |
| 299 | _: &AppContext, |
| 300 | ) -> bool { |
| 301 | false |
| 302 | } |
| 303 | } |
| 304 |