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1 | /** | |
2 | * @license MIT | |
3 | */ | |
4 | ||
5 | import { ITerminal } from './Interfaces'; | |
6 | import { CharMeasure } from './utils/CharMeasure'; | |
7 | ||
8 | /** | |
9 | * Represents the viewport of a terminal, the visible area within the larger buffer of output. | |
10 | * Logic for the virtual scroll bar is included in this object. | |
11 | */ | |
12 | export class Viewport { | |
13 | private currentRowHeight: number; | |
14 | private lastRecordedBufferLength: number; | |
15 | private lastRecordedViewportHeight: number; | |
16 | ||
17 | /** | |
18 | * Creates a new Viewport. | |
19 | * @param terminal The terminal this viewport belongs to. | |
20 | * @param viewportElement The DOM element acting as the viewport. | |
21 | * @param scrollArea The DOM element acting as the scroll area. | |
22 | * @param charMeasureElement A DOM element used to measure the character size of. the terminal. | |
23 | */ | |
24 | constructor( | |
25 | private terminal: ITerminal, | |
26 | private viewportElement: HTMLElement, | |
27 | private scrollArea: HTMLElement, | |
28 | private charMeasure: CharMeasure | |
29 | ) { | |
30 | this.currentRowHeight = 0; | |
31 | this.lastRecordedBufferLength = 0; | |
32 | this.lastRecordedViewportHeight = 0; | |
33 | ||
34 | this.terminal.on('scroll', this.syncScrollArea.bind(this)); | |
35 | this.terminal.on('resize', this.syncScrollArea.bind(this)); | |
36 | this.viewportElement.addEventListener('scroll', this.onScroll.bind(this)); | |
37 | ||
38 | // Perform this async to ensure the CharMeasure is ready. | |
39 | setTimeout(() => this.syncScrollArea(), 0); | |
40 | } | |
41 | ||
42 | /** | |
43 | * Refreshes row height, setting line-height, viewport height and scroll area height if | |
44 | * necessary. | |
45 | * @param charSize A character size measurement bounding rect object, if it doesn't exist it will | |
46 | * be created. | |
47 | */ | |
48 | private refresh(): void { | |
49 | if (this.charMeasure.height > 0) { | |
50 | const rowHeightChanged = this.charMeasure.height !== this.currentRowHeight; | |
51 | if (rowHeightChanged) { | |
52 | this.currentRowHeight = this.charMeasure.height; | |
53 | this.viewportElement.style.lineHeight = this.charMeasure.height + 'px'; | |
54 | this.terminal.rowContainer.style.lineHeight = this.charMeasure.height + 'px'; | |
55 | } | |
56 | const viewportHeightChanged = this.lastRecordedViewportHeight !== this.terminal.rows; | |
57 | if (rowHeightChanged || viewportHeightChanged) { | |
58 | this.lastRecordedViewportHeight = this.terminal.rows; | |
59 | this.viewportElement.style.height = this.charMeasure.height * this.terminal.rows + 'px'; | |
60 | this.terminal.selectionContainer.style.height = this.viewportElement.style.height; | |
61 | } | |
62 | this.scrollArea.style.height = (this.charMeasure.height * this.lastRecordedBufferLength) + 'px'; | |
63 | } | |
64 | } | |
65 | ||
66 | /** | |
67 | * Updates dimensions and synchronizes the scroll area if necessary. | |
68 | */ | |
69 | public syncScrollArea(): void { | |
70 | if (this.lastRecordedBufferLength !== this.terminal.lines.length) { | |
71 | // If buffer height changed | |
72 | this.lastRecordedBufferLength = this.terminal.lines.length; | |
73 | this.refresh(); | |
74 | } else if (this.lastRecordedViewportHeight !== this.terminal.rows) { | |
75 | // If viewport height changed | |
76 | this.refresh(); | |
77 | } else { | |
78 | // If size has changed, refresh viewport | |
79 | if (this.charMeasure.height !== this.currentRowHeight) { | |
80 | this.refresh(); | |
81 | } | |
82 | } | |
83 | ||
84 | // Sync scrollTop | |
85 | const scrollTop = this.terminal.ydisp * this.currentRowHeight; | |
86 | if (this.viewportElement.scrollTop !== scrollTop) { | |
87 | this.viewportElement.scrollTop = scrollTop; | |
88 | } | |
89 | } | |
90 | ||
91 | /** | |
92 | * Handles scroll events on the viewport, calculating the new viewport and requesting the | |
93 | * terminal to scroll to it. | |
94 | * @param ev The scroll event. | |
95 | */ | |
96 | private onScroll(ev: Event) { | |
97 | const newRow = Math.round(this.viewportElement.scrollTop / this.currentRowHeight); | |
98 | const diff = newRow - this.terminal.ydisp; | |
99 | this.terminal.scrollDisp(diff, true); | |
100 | } | |
101 | ||
102 | /** | |
103 | * Handles mouse wheel events by adjusting the viewport's scrollTop and delegating the actual | |
104 | * scrolling to `onScroll`, this event needs to be attached manually by the consumer of | |
105 | * `Viewport`. | |
106 | * @param ev The mouse wheel event. | |
107 | */ | |
108 | public onWheel(ev: WheelEvent) { | |
109 | if (ev.deltaY === 0) { | |
110 | // Do nothing if it's not a vertical scroll event | |
111 | return; | |
112 | } | |
113 | // Fallback to WheelEvent.DOM_DELTA_PIXEL | |
114 | let multiplier = 1; | |
115 | if (ev.deltaMode === WheelEvent.DOM_DELTA_LINE) { | |
116 | multiplier = this.currentRowHeight; | |
117 | } else if (ev.deltaMode === WheelEvent.DOM_DELTA_PAGE) { | |
118 | multiplier = this.currentRowHeight * this.terminal.rows; | |
119 | } | |
120 | this.viewportElement.scrollTop += ev.deltaY * multiplier; | |
121 | // Prevent the page from scrolling when the terminal scrolls | |
122 | ev.preventDefault(); | |
123 | }; | |
124 | } |