crabshell-render 0.3.0

Draws Crabshell windows into pixmaps: shapes, gradients, shadows, text, icons, images and damage tracking
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194

//! Turning logical damage into buffer pixels, and planning what each frame
//! repaints and reports.

use crabshell_ui::Rect;

use crate::damage::{Plan, merge, to_pixels};
use crate::{BufferAge, DamageHistory, PixelRect};

#[test]
fn logical_damage_rounds_outward_with_a_margin() {
  // 1..3 logical is 1.5..4.5 at scale 1.5: pixels 1 to 4, plus one around.
  let rect = to_pixels(Rect::new(1.0, 1.0, 2.0, 2.0), 1.5, 100, 100);
  assert_eq!(rect, Some(PixelRect::new(0, 0, 6, 6)));
  let rect = to_pixels(Rect::new(10.0, 4.0, 5.0, 2.0), 1.0, 100, 100);
  assert_eq!(rect, Some(PixelRect::new(9, 3, 7, 4)));
}

#[test]
fn logical_damage_is_clipped_to_the_buffer() {
  // -10..30 by 80..120 in pixels, plus the margin, cut to 0..100.
  let rect = to_pixels(Rect::new(-5.0, 40.0, 20.0, 20.0), 2.0, 100, 100);
  assert_eq!(rect, Some(PixelRect::new(0, 79, 31, 21)));
  assert_eq!(
    to_pixels(Rect::new(-5.0, 90.0, 20.0, 50.0), 2.0, 100, 100),
    None
  );
  assert_eq!(
    to_pixels(Rect::new(0.0, 0.0, 0.0, 5.0), 1.0, 100, 100),
    None
  );
  assert_eq!(
    to_pixels(Rect::new(200.0, 0.0, 5.0, 5.0), 1.0, 100, 100),
    None
  );
  assert_eq!(
    to_pixels(Rect::new(0.0, 0.0, f32::NAN, 5.0), 1.0, 100, 100),
    None
  );
}

#[test]
fn overlapping_rectangles_merge_and_touching_ones_stay_apart() {
  let merged = merge(vec![
    PixelRect::new(0, 0, 10, 10),
    PixelRect::new(5, 5, 10, 10),
    PixelRect::new(15, 0, 5, 5),
    PixelRect::new(40, 0, 5, 5),
    PixelRect::new(0, 0, 0, 5),
  ]);
  // The first two merge into 0..15, which then overlaps nothing: 15..20
  // only touches it.
  assert_eq!(
    merged,
    vec![
      PixelRect::new(0, 0, 15, 15),
      PixelRect::new(40, 0, 5, 5),
      PixelRect::new(15, 0, 5, 5),
    ]
  );
  // A merge can make a rectangle overlap one it missed before.
  let merged = merge(vec![
    PixelRect::new(20, 0, 5, 5),
    PixelRect::new(0, 0, 5, 5),
    PixelRect::new(3, 0, 20, 2),
  ]);
  assert_eq!(merged, vec![PixelRect::new(0, 0, 25, 5)]);
}

/// Plans a frame of `damage` in a 100 by 20 buffer at scale 1.
fn plan(history: &mut DamageHistory, damage: &[Rect], age: &mut BufferAge) -> Plan {
  history.plan(damage, 1.0, 100, 20, age)
}

const FULL: PixelRect = PixelRect::new(0, 0, 100, 20);

#[test]
fn a_new_buffer_and_the_first_frame_repaint_everything() {
  let mut history = DamageHistory::new();
  let mut age = BufferAge::default();
  let small = [Rect::new(10.0, 5.0, 4.0, 4.0)];
  let first = plan(&mut history, &small, &mut age);
  assert_eq!(first.repaint, vec![FULL]);
  assert_eq!(first.report, vec![FULL]);

  // The same buffer next frame repaints only the damage.
  let second = plan(&mut history, &small, &mut age);
  assert_eq!(second.repaint, vec![PixelRect::new(9, 4, 6, 6)]);
  assert_eq!(second.report, second.repaint);

  // Another, new buffer repaints everything but reports only the damage.
  let third = plan(&mut history, &small, &mut BufferAge::default());
  assert_eq!(third.repaint, vec![FULL]);
  assert_eq!(third.report, vec![PixelRect::new(9, 4, 6, 6)]);
}

#[test]
fn a_buffer_that_skipped_frames_repaints_what_changed_in_them() {
  let mut history = DamageHistory::new();
  let (mut a, mut b) = (BufferAge::default(), BufferAge::default());
  plan(&mut history, &[], &mut a);
  plan(&mut history, &[Rect::new(10.0, 0.0, 4.0, 4.0)], &mut b);
  plan(&mut history, &[Rect::new(30.0, 0.0, 4.0, 4.0)], &mut b);
  // `a` missed the last two frames.
  let frame = plan(&mut history, &[Rect::new(60.0, 0.0, 4.0, 4.0)], &mut a);
  let mut repaint = frame.repaint.clone();
  repaint.sort_by_key(|rect| rect.x);
  assert_eq!(
    repaint,
    vec![
      PixelRect::new(9, 0, 6, 5),
      PixelRect::new(29, 0, 6, 5),
      PixelRect::new(59, 0, 6, 5),
    ]
  );
  assert_eq!(frame.report, vec![PixelRect::new(59, 0, 6, 5)]);
}

#[test]
fn a_buffer_older_than_the_history_repaints_everything() {
  let mut history = DamageHistory::new();
  let mut old = BufferAge::default();
  plan(&mut history, &[], &mut old);
  let mut other = BufferAge::default();
  for _ in 0..6 {
    plan(&mut history, &[Rect::new(10.0, 0.0, 4.0, 4.0)], &mut other);
  }
  let frame = plan(&mut history, &[Rect::new(10.0, 0.0, 4.0, 4.0)], &mut old);
  assert_eq!(frame.repaint, vec![FULL]);
}

#[test]
fn more_than_half_dirty_repaints_the_whole_buffer() {
  let mut history = DamageHistory::new();
  let mut age = BufferAge::default();
  plan(&mut history, &[], &mut age);
  // 48 of 100 columns, plus the margin: 50 columns, exactly half.
  let half = plan(&mut history, &[Rect::new(1.0, 0.0, 48.0, 20.0)], &mut age);
  assert_eq!(half.repaint, vec![PixelRect::new(0, 0, 50, 20)]);
  // One more column tips it over.
  let more = plan(&mut history, &[Rect::new(1.0, 0.0, 49.0, 20.0)], &mut age);
  assert_eq!(more.repaint, vec![FULL]);
  assert_eq!(more.report, vec![FULL]);
}

#[test]
fn missed_frames_can_tip_a_repaint_over_half() {
  let mut history = DamageHistory::new();
  let (mut a, mut b) = (BufferAge::default(), BufferAge::default());
  plan(&mut history, &[], &mut a);
  plan(&mut history, &[Rect::new(0.0, 0.0, 30.0, 20.0)], &mut b);
  let frame = plan(&mut history, &[Rect::new(60.0, 0.0, 30.0, 20.0)], &mut a);
  assert_eq!(frame.repaint, vec![FULL]);
  // Only this frame's change is reported.
  assert_eq!(frame.report, vec![PixelRect::new(59, 0, 32, 20)]);
}

#[test]
fn a_new_size_or_scale_repaints_everything_and_forgets_earlier_frames() {
  let mut history = DamageHistory::new();
  let (mut a, mut b) = (BufferAge::default(), BufferAge::default());
  plan(&mut history, &[], &mut a);
  plan(&mut history, &[], &mut b);
  let bigger = history.plan(&[], 1.0, 120, 20, &mut a);
  assert_eq!(bigger.repaint, vec![PixelRect::new(0, 0, 120, 20)]);
  assert_eq!(bigger.report, bigger.repaint);
  let scaled = history.plan(&[], 2.0, 120, 20, &mut b);
  assert_eq!(scaled.report, vec![PixelRect::new(0, 0, 120, 20)]);
  // `a` last held a frame at scale 1, which the history forgot.
  let next = history.plan(&[], 2.0, 120, 20, &mut a);
  assert_eq!(next.repaint, vec![PixelRect::new(0, 0, 120, 20)]);
  // `b` holds the latest frame, so nothing needs repainting.
  let quiet = history.plan(&[], 2.0, 120, 20, &mut b);
  assert!(
    quiet.repaint.is_empty() && quiet.report.is_empty(),
    "{quiet:?}"
  );
}

#[test]
fn a_buffer_from_another_history_is_repainted_whole() {
  let mut first = DamageHistory::new();
  let mut age = BufferAge::default();
  for _ in 0..10 {
    plan(&mut first, &[], &mut age);
  }
  // The buffer moves to another window, whose history is at frame 3.
  let mut second = DamageHistory::new();
  let mut other = BufferAge::default();
  for _ in 0..3 {
    plan(&mut second, &[], &mut other);
  }
  let frame = plan(&mut second, &[Rect::new(10.0, 0.0, 4.0, 4.0)], &mut age);
  assert_eq!(frame.repaint, vec![FULL]);
}