aboutsummaryrefslogtreecommitdiff
path: root/beamer/viewer/screen/screen.js
diff options
context:
space:
mode:
Diffstat (limited to 'beamer/viewer/screen/screen.js')
-rw-r--r--beamer/viewer/screen/screen.js110
1 files changed, 110 insertions, 0 deletions
diff --git a/beamer/viewer/screen/screen.js b/beamer/viewer/screen/screen.js
new file mode 100644
index 0000000..c65ebc3
--- /dev/null
+++ b/beamer/viewer/screen/screen.js
@@ -0,0 +1,110 @@
1/*
2 * Beamer Viewer, a web-based PDF presentation viewer
3 * Copyright (C) 2018 Pacien TRAN-GIRARD
4 *
5 * This program is free software: you can redistribute it and/or modify
6 * it under the terms of the GNU Affero General Public License as
7 * published by the Free Software Foundation, either version 3 of the
8 * License, or (at your option) any later version.
9 *
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU Affero General Public License for more details.
14 *
15 * You should have received a copy of the GNU Affero General Public License
16 * along with this program. If not, see <https://www.gnu.org/licenses/>.
17 */
18
19"use strict";
20
21class Screen {
22 constructor(window, secondary=false, withTimer=false) {
23 this.window = window;
24 this.secondary = secondary;
25
26 this.canvasId = "screen";
27 this.page = null;
28
29 this.timer = withTimer ? new Timer(window) : null;
30 this.pageTurnCount = 0;
31
32 this._registerListeners();
33 this._hideWelcomeScreen();
34 }
35
36 setPage(page) {
37 if (this.pageTurnCount++ === 1 && this.timer != null)
38 this.timer.start();
39
40 this.page = page;
41 this._repaint();
42 }
43
44 _registerListeners() {
45 const self = this;
46 this.window.addEventListener("resize", function() {
47 self._repaint();
48 });
49 }
50
51 _hideWelcomeScreen() {
52 const welcomeScreen = this.window.document.getElementById("welcomeScreen");
53 welcomeScreen.style.display = "none";
54 }
55
56 _getScreenSize(ratio) {
57 const windowRatio = this.window.innerWidth / this.window.innerHeight;
58 const horizontalScaleFactor = ratio / windowRatio;
59 return {
60 width: this.window.innerWidth * Math.min(horizontalScaleFactor, 1),
61 height: this.window.innerHeight / Math.max(horizontalScaleFactor, 1)
62 };
63 }
64
65 _getSlideSizeRatio() {
66 const viewport = this.page.getViewport(1);
67 return (viewport.width / 2) / viewport.height;
68 }
69
70 _newCanvas(width, height, xOffset, yOffset) {
71 const canvas = document.createElement("canvas");
72 canvas.width = width;
73 canvas.height = height;
74
75 const context = canvas.getContext("2d");
76 context.transform(1, 0, 0, 1, xOffset, yOffset);
77
78 return { canvas: canvas, context: context };
79 }
80
81 _showCanvas(canvas) {
82 const oldCanvas = this.window.document.getElementById(this.canvasId);
83 canvas.id = oldCanvas.id;
84 canvas.classList = oldCanvas.classList;
85 oldCanvas.replaceWith(canvas);
86 }
87
88 _render(canvas, context, scaleFactor) {
89 const renderContext = {
90 canvasContext: context,
91 viewport: this.page.getViewport(scaleFactor)
92 };
93
94 const self = this;
95 this.page.render(renderContext).then(function() {
96 self._showCanvas(canvas);
97 });
98 }
99
100 _repaint() {
101 if (this.page == null) return;
102
103 const screenRatio = this._getSlideSizeRatio();
104 const { width, height } = this._getScreenSize(screenRatio);
105 const scaleFactor = height / this.page.getViewport(1).height;
106 const xOffset = this.secondary ? -width : 0;
107 const { canvas, context } = this._newCanvas(width, height, xOffset, 0);
108 this._render(canvas, context, scaleFactor);
109 }
110}