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/*
* screen.js
* Part of Pointless Viewer, a Beamer presentation viewer
* Copyright 2018 Pacien TRAN-GIRARD
* License: GNU GPL v3
*/
"use strict";
class Screen {
constructor(window, secondary=false, withTimer=false) {
this.window = window;
this.secondary = secondary;
this.canvasId = "screen";
this.page = null;
this.timer = withTimer ? new Timer(window) : null;
this.pageTurnCount = 0;
this._registerListeners();
this._hideWelcomeScreen();
}
setPage(page) {
if (this.pageTurnCount++ === 1 && this.timer != null)
this.timer.start();
this.page = page;
this._repaint();
}
_registerListeners() {
const self = this;
this.window.addEventListener("resize", function() {
self._repaint();
});
}
_hideWelcomeScreen() {
const welcomeScreen = this.window.document.getElementById("welcomeScreen");
welcomeScreen.style.display = "none";
}
_getScreenSize(ratio) {
const windowRatio = this.window.innerWidth / this.window.innerHeight;
const horizontalScaleFactor = ratio / windowRatio;
return {
width: this.window.innerWidth * Math.min(horizontalScaleFactor, 1),
height: this.window.innerHeight / Math.max(horizontalScaleFactor, 1)
};
}
_getSlideSizeRatio() {
const viewport = this.page.getViewport(1);
return (viewport.width / 2) / viewport.height;
}
_newCanvas(width, height, xOffset, yOffset) {
const canvas = document.createElement("canvas");
canvas.width = width;
canvas.height = height;
const context = canvas.getContext("2d");
context.transform(1, 0, 0, 1, xOffset, yOffset);
return { canvas: canvas, context: context };
}
_showCanvas(canvas) {
const oldCanvas = this.window.document.getElementById(this.canvasId);
canvas.id = oldCanvas.id;
canvas.classList = oldCanvas.classList;
oldCanvas.replaceWith(canvas);
}
_render(canvas, context, scaleFactor) {
const renderContext = {
canvasContext: context,
viewport: this.page.getViewport(scaleFactor)
};
const self = this;
this.page.render(renderContext).then(function() {
self._showCanvas(canvas);
});
}
_repaint() {
if (this.page == null) return;
const screenRatio = this._getSlideSizeRatio();
const { width, height } = this._getScreenSize(screenRatio);
const scaleFactor = height / this.page.getViewport(1).height;
const xOffset = this.secondary ? -width : 0;
const { canvas, context } = this._newCanvas(width, height, xOffset, 0);
this._render(canvas, context, scaleFactor);
}
}
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