All files / tools/src/eventListeners/wheel normalizeWheel.ts

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
 
428x
428x
428x
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
// Reasonable defaults
const PIXEL_STEP = 10;
const LINE_HEIGHT = 40;
const PAGE_HEIGHT = 800;
 
/**
 * Normalizes wheel events and provides properties that are more
 * consistent and helpful across different browsers
 *
 * @param event - the original mouse event
 * @returns a normalized eventDetail
 */
export default function normalizeWheel(event) {
  let spinX = 0,
    spinY = 0,
    pixelX = 0,
    pixelY = 0;
 
  // Legacy
  if ('detail' in event) {
    spinY = event.detail;
  }
  if ('wheelDelta' in event) {
    spinY = -event.wheelDelta / 120;
  }
  if ('wheelDeltaY' in event) {
    spinY = -event.wheelDeltaY / 120;
  }
  if ('wheelDeltaX' in event) {
    spinX = -event.wheelDeltaX / 120;
  }
 
  pixelX = spinX * PIXEL_STEP;
  pixelY = spinY * PIXEL_STEP;
 
  if ('deltaY' in event) {
    pixelY = event.deltaY;
  }
  if ('deltaX' in event) {
    pixelX = event.deltaX;
  }
 
  if ((pixelX || pixelY) && event.deltaMode) {
    if (event.deltaMode === 1) {
      // Delta in LINE units
      pixelX *= LINE_HEIGHT;
      pixelY *= LINE_HEIGHT;
    } else {
      // Delta in PAGE units
      pixelX *= PAGE_HEIGHT;
      pixelY *= PAGE_HEIGHT;
    }
  }
 
  // Fall-back if spin cannot be determined
  if (pixelX && !spinX) {
    spinX = pixelX < 1 ? -1 : 1;
  }
  if (pixelY && !spinY) {
    spinY = pixelY < 1 ? -1 : 1;
  }
 
  return {
    spinX,
    spinY,
    pixelX,
    pixelY,
  };
}