| 1 | //! Grid layout, cursor, scrolling and the visual-mode range. |
| 2 | //! |
| 3 | //! All sizes are physical pixels. Content coordinates start at the top of the first row's |
| 4 | //! gap; the scroll offset is how far the content has moved up. |
| 5 | |
| 6 | use std::ops::Range; |
| 7 | use std::time::{Duration, Instant}; |
| 8 | |
| 9 | use super::view::Dir; |
| 10 | use crate::anim::Tween; |
| 11 | |
| 12 | /// One frame's grid geometry. |
| 13 | #[derive(Clone, Copy, Debug, PartialEq)] |
| 14 | pub struct Layout { |
| 15 | pub count: usize, |
| 16 | pub cols: usize, |
| 17 | /// Side of the square each thumbnail fits in. |
| 18 | pub cell: f32, |
| 19 | pub gap: f32, |
| 20 | /// Room under each cell for its name (0 without names). |
| 21 | pub label: f32, |
| 22 | /// x of the first column; the grid is centred. |
| 23 | pub left: f32, |
| 24 | pub viewport: [f32; 2], |
| 25 | } |
| 26 | |
| 27 | impl Layout { |
| 28 | pub fn new(count: usize, viewport: [f32; 2], cell: f32, gap: f32, label: f32) -> Self { |
| 29 | let cell = cell.max(1.0); |
| 30 | let cols = ((viewport[0] - gap) / (cell + gap)).floor().max(1.0) as usize; |
| 31 | let used = cols as f32 * cell + (cols - 1) as f32 * gap; |
| 32 | Self { |
| 33 | count, |
| 34 | cols, |
| 35 | cell, |
| 36 | gap, |
| 37 | label, |
| 38 | left: ((viewport[0] - used) * 0.5).max(0.0).round(), |
| 39 | viewport, |
| 40 | } |
| 41 | } |
| 42 | |
| 43 | pub fn row_height(&self) -> f32 { |
| 44 | self.cell + self.label + self.gap |
| 45 | } |
| 46 | |
| 47 | pub fn rows(&self) -> usize { |
| 48 | self.count.div_ceil(self.cols) |
| 49 | } |
| 50 | |
| 51 | pub fn row_of(&self, i: usize) -> usize { |
| 52 | i / self.cols |
| 53 | } |
| 54 | |
| 55 | pub fn content_height(&self) -> f32 { |
| 56 | self.gap + self.rows() as f32 * self.row_height() |
| 57 | } |
| 58 | |
| 59 | pub fn max_scroll(&self) -> f32 { |
| 60 | (self.content_height() - self.viewport[1]).max(0.0) |
| 61 | } |
| 62 | |
| 63 | pub fn clamp_scroll(&self, s: f32) -> f32 { |
| 64 | s.clamp(0.0, self.max_scroll()) |
| 65 | } |
| 66 | |
| 67 | /// Top-left of cell `i` in content coordinates. |
| 68 | pub fn origin(&self, i: usize) -> [f32; 2] { |
| 69 | let (row, col) = (i / self.cols, i % self.cols); |
| 70 | [ |
| 71 | self.left + col as f32 * (self.cell + self.gap), |
| 72 | self.gap + row as f32 * self.row_height(), |
| 73 | ] |
| 74 | } |
| 75 | |
| 76 | /// Cells at least partly on screen at `scroll`. |
| 77 | pub fn visible(&self, scroll: f32) -> Range<usize> { |
| 78 | self.rows_between(scroll, scroll + self.viewport[1]) |
| 79 | } |
| 80 | |
| 81 | /// Cells whose rows overlap content `top..bottom`. |
| 82 | pub fn rows_between(&self, top: f32, bottom: f32) -> Range<usize> { |
| 83 | let rh = self.row_height(); |
| 84 | let first = ((top - self.gap - self.cell - self.label) / rh) |
| 85 | .ceil() |
| 86 | .max(0.0) as usize; |
| 87 | let last = ((bottom - self.gap) / rh).ceil().max(0.0) as usize; |
| 88 | let start = (first * self.cols).min(self.count); |
| 89 | let end = (last * self.cols).min(self.count); |
| 90 | start..end.max(start) |
| 91 | } |
| 92 | |
| 93 | /// Whole rows that fit on screen (at least one). |
| 94 | pub fn page_rows(&self) -> usize { |
| 95 | ((self.viewport[1] - self.gap) / self.row_height()) |
| 96 | .floor() |
| 97 | .max(1.0) as usize |
| 98 | } |
| 99 | |
| 100 | /// The cell under a viewport point. |
| 101 | pub fn hit(&self, p: [f32; 2], scroll: f32) -> Option<usize> { |
| 102 | let y = p[1] + scroll - self.gap; |
| 103 | let x = p[0] - self.left; |
| 104 | if x < 0.0 || y < 0.0 { |
| 105 | return None; |
| 106 | } |
| 107 | let (col, row) = ( |
| 108 | (x / (self.cell + self.gap)) as usize, |
| 109 | (y / self.row_height()) as usize, |
| 110 | ); |
| 111 | let in_cell = x - col as f32 * (self.cell + self.gap) <= self.cell |
| 112 | && y - row as f32 * self.row_height() <= self.cell + self.label; |
| 113 | let i = row * self.cols + col; |
| 114 | (col < self.cols && in_cell && i < self.count).then_some(i) |
| 115 | } |
| 116 | |
| 117 | /// The scroll offset nearest to `scroll` that shows cell `i`'s row whole, gaps included. |
| 118 | pub fn follow(&self, i: usize, scroll: f32) -> f32 { |
| 119 | let top = self.row_of(i) as f32 * self.row_height(); |
| 120 | let bottom = top + self.row_height() + self.gap; |
| 121 | let s = if top < scroll { |
| 122 | top |
| 123 | } else if bottom > scroll + self.viewport[1] { |
| 124 | bottom - self.viewport[1] |
| 125 | } else { |
| 126 | scroll |
| 127 | }; |
| 128 | self.clamp_scroll(s) |
| 129 | } |
| 130 | |
| 131 | /// Move the cursor `n` cells (left/right) or rows (up/down). Down onto a short last row |
| 132 | /// lands on the last cell. |
| 133 | pub fn step(&self, i: usize, dir: Dir, n: usize) -> usize { |
| 134 | if self.count == 0 { |
| 135 | return 0; |
| 136 | } |
| 137 | let last = self.count - 1; |
| 138 | match dir { |
| 139 | Dir::Left => i.saturating_sub(n), |
| 140 | Dir::Right => i.saturating_add(n).min(last), |
| 141 | Dir::Up => i - n.min(self.row_of(i)) * self.cols, |
| 142 | Dir::Down => { |
| 143 | let rows = n.min(self.row_of(last) - self.row_of(i)); |
| 144 | (i + rows * self.cols).min(last) |
| 145 | } |
| 146 | } |
| 147 | } |
| 148 | |
| 149 | /// Move by whole rows, clamping into the first or last row instead of stopping. |
| 150 | pub fn step_rows(&self, i: usize, rows: isize) -> usize { |
| 151 | if self.count == 0 { |
| 152 | return 0; |
| 153 | } |
| 154 | let target = i as isize + rows * self.cols as isize; |
| 155 | target.clamp(0, self.count as isize - 1) as usize |
| 156 | } |
| 157 | |
| 158 | pub fn row_start(&self, i: usize) -> usize { |
| 159 | i - i % self.cols |
| 160 | } |
| 161 | |
| 162 | pub fn row_end(&self, i: usize) -> usize { |
| 163 | (self.row_start(i) + self.cols - 1).min(self.count.saturating_sub(1)) |
| 164 | } |
| 165 | |
| 166 | /// Bring the cursor onto the screen at `scroll`, keeping its column. |
| 167 | pub fn pull_into_view(&self, i: usize, scroll: f32) -> usize { |
| 168 | if self.count == 0 { |
| 169 | return 0; |
| 170 | } |
| 171 | let rh = self.row_height(); |
| 172 | let row = self.row_of(i) as f32; |
| 173 | // First and last rows fully on screen. |
| 174 | let first = (scroll / rh).ceil(); |
| 175 | let last = ((scroll + self.viewport[1] - self.gap) / rh).floor() - 1.0; |
| 176 | let target = if row < first { |
| 177 | first |
| 178 | } else if row > last && last >= first { |
| 179 | last |
| 180 | } else { |
| 181 | return i; |
| 182 | }; |
| 183 | let j = target as usize * self.cols + i % self.cols; |
| 184 | j.min(self.count - 1) |
| 185 | } |
| 186 | } |
| 187 | |
| 188 | /// Grid view state that outlives a frame: size, scroll and the visual anchor. |
| 189 | #[derive(Clone, Debug)] |
| 190 | pub struct Grid { |
| 191 | /// Logical thumbnail size, one of `grid.sizes`. |
| 192 | pub size: u32, |
| 193 | scroll: Tween<f32>, |
| 194 | /// Visual mode's fixed end. |
| 195 | pub anchor: Option<usize>, |
| 196 | } |
| 197 | |
| 198 | impl Grid { |
| 199 | pub fn new(size: u32, now: Instant) -> Self { |
| 200 | Self { |
| 201 | size, |
| 202 | scroll: Tween::new(0.0, now), |
| 203 | anchor: None, |
| 204 | } |
| 205 | } |
| 206 | |
| 207 | /// The scroll offset to draw at `now`. |
| 208 | pub fn scroll(&self, layout: &Layout, now: Instant) -> f32 { |
| 209 | layout.clamp_scroll(self.scroll.value(now)) |
| 210 | } |
| 211 | |
| 212 | /// Where scrolling is heading. |
| 213 | pub fn target(&self, layout: &Layout) -> f32 { |
| 214 | layout.clamp_scroll(self.scroll.target()) |
| 215 | } |
| 216 | |
| 217 | pub fn scroll_to(&mut self, to: f32, now: Instant, dur: Duration) { |
| 218 | if (self.scroll.target() - to).abs() > 0.01 { |
| 219 | self.scroll.retarget(to, now, dur); |
| 220 | } |
| 221 | } |
| 222 | |
| 223 | pub fn jump_to(&mut self, to: f32) { |
| 224 | self.scroll.set(to); |
| 225 | } |
| 226 | |
| 227 | pub fn is_animating(&self, now: Instant) -> bool { |
| 228 | self.scroll.is_active(now) |
| 229 | } |
| 230 | |
| 231 | /// The visual range, inclusive, given the cursor. |
| 232 | pub fn range(&self, cursor: usize) -> Option<Range<usize>> { |
| 233 | self.anchor.map(|a| a.min(cursor)..a.max(cursor) + 1) |
| 234 | } |
| 235 | } |
| 236 | |
| 237 | /// Step through `sizes` from the entry nearest `current`. |
| 238 | pub fn next_size(sizes: &[u32], current: u32, delta: i32) -> u32 { |
| 239 | if sizes.is_empty() { |
| 240 | return current; |
| 241 | } |
| 242 | let i = sizes |
| 243 | .iter() |
| 244 | .enumerate() |
| 245 | .min_by_key(|(_, s)| s.abs_diff(current)) |
| 246 | .map_or(0, |(i, _)| i); |
| 247 | let j = (i as i64 + delta as i64).clamp(0, sizes.len() as i64 - 1) as usize; |
| 248 | sizes[j] |
| 249 | } |
| 250 | |
| 251 | #[cfg(test)] |
| 252 | mod tests { |
| 253 | use super::*; |
| 254 | |
| 255 | /// 10 cells of 100 with gap 10 in 450×300: 4 columns, 3 rows. |
| 256 | fn layout(count: usize) -> Layout { |
| 257 | Layout::new(count, [450.0, 300.0], 100.0, 10.0, 0.0) |
| 258 | } |
| 259 | |
| 260 | #[test] |
| 261 | fn columns_are_centred() { |
| 262 | let l = layout(10); |
| 263 | assert_eq!(l.cols, 4); |
| 264 | assert_eq!(l.left, 10.0); |
| 265 | assert_eq!(l.rows(), 3); |
| 266 | assert_eq!(l.origin(5), [120.0, 120.0]); |
| 267 | assert_eq!(l.content_height(), 340.0); |
| 268 | assert_eq!(l.max_scroll(), 40.0); |
| 269 | // Never fewer than one column. |
| 270 | assert_eq!(Layout::new(3, [50.0, 50.0], 100.0, 10.0, 0.0).cols, 1); |
| 271 | } |
| 272 | |
| 273 | #[test] |
| 274 | fn cursor_moves_like_nsxiv() { |
| 275 | let l = layout(10); |
| 276 | assert_eq!(l.step(0, Dir::Left, 1), 0); |
| 277 | assert_eq!(l.step(4, Dir::Left, 1), 3); |
| 278 | assert_eq!(l.step(3, Dir::Right, 1), 4); |
| 279 | assert_eq!(l.step(9, Dir::Right, 5), 9); |
| 280 | assert_eq!(l.step(5, Dir::Up, 1), 1); |
| 281 | assert_eq!(l.step(1, Dir::Up, 1), 1); |
| 282 | assert_eq!(l.step(5, Dir::Up, 9), 1); |
| 283 | assert_eq!(l.step(1, Dir::Down, 1), 5); |
| 284 | // Onto the short last row: the last cell. |
| 285 | assert_eq!(l.step(7, Dir::Down, 1), 9); |
| 286 | assert_eq!(l.step(9, Dir::Down, 1), 9); |
| 287 | assert_eq!(l.step(2, Dir::Down, 5), 9); |
| 288 | assert_eq!(l.row_start(6), 4); |
| 289 | assert_eq!(l.row_end(6), 7); |
| 290 | assert_eq!(l.row_end(8), 9); |
| 291 | assert_eq!(l.step_rows(2, 5), 9); |
| 292 | assert_eq!(l.step_rows(6, -5), 0); |
| 293 | assert_eq!(layout(0).step(0, Dir::Down, 1), 0); |
| 294 | } |
| 295 | |
| 296 | #[test] |
| 297 | fn visibility_and_following() { |
| 298 | let l = layout(40); // 10 rows, content 1110 high |
| 299 | assert_eq!(l.visible(0.0), 0..12); |
| 300 | assert_eq!(l.visible(110.0), 0..16); |
| 301 | assert_eq!(l.visible(115.0), 4..16); |
| 302 | // Row 5 spans 550..670 including the gaps; a 300 viewport must scroll to 370. |
| 303 | assert_eq!(l.follow(20, 0.0), 370.0); |
| 304 | assert_eq!(l.follow(20, 400.0), 400.0); |
| 305 | assert_eq!(l.follow(0, 400.0), 0.0); |
| 306 | assert_eq!(l.page_rows(), 2); |
| 307 | } |
| 308 | |
| 309 | #[test] |
| 310 | fn hit_testing() { |
| 311 | let l = layout(10); |
| 312 | assert_eq!(l.hit([15.0, 15.0], 0.0), Some(0)); |
| 313 | assert_eq!(l.hit([125.0, 125.0], 0.0), Some(5)); |
| 314 | // In a gap. |
| 315 | assert_eq!(l.hit([115.0, 15.0], 0.0), None); |
| 316 | // Past the last cell. |
| 317 | assert_eq!(l.hit([345.0, 235.0], 0.0), None); |
| 318 | assert_eq!(l.hit([15.0, 15.0], 110.0), Some(4)); |
| 319 | } |
| 320 | |
| 321 | #[test] |
| 322 | fn pulling_the_cursor_into_view() { |
| 323 | let l = layout(40); |
| 324 | assert_eq!(l.pull_into_view(1, 0.0), 1); |
| 325 | // Scrolled so rows 2 and 3 are whole: row 0 comes down to row 2. |
| 326 | assert_eq!(l.pull_into_view(1, 220.0), 9); |
| 327 | assert_eq!(l.pull_into_view(37, 220.0), 13); |
| 328 | } |
| 329 | |
| 330 | #[test] |
| 331 | fn sizes_step_and_clamp() { |
| 332 | let s = [96, 128, 160, 224, 320]; |
| 333 | assert_eq!(next_size(&s, 160, 1), 224); |
| 334 | assert_eq!(next_size(&s, 160, -2), 96); |
| 335 | assert_eq!(next_size(&s, 320, 1), 320); |
| 336 | assert_eq!(next_size(&s, 150, 0), 160); |
| 337 | } |
| 338 | |
| 339 | #[test] |
| 340 | fn visual_range_is_inclusive() { |
| 341 | let mut g = Grid::new(160, Instant::now()); |
| 342 | assert_eq!(g.range(3), None); |
| 343 | g.anchor = Some(5); |
| 344 | assert_eq!(g.range(2), Some(2..6)); |
| 345 | assert_eq!(g.range(7), Some(5..8)); |
| 346 | } |
| 347 | } |