// Copyright 2015 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import {ZoomBehavior} from './browser_api.js';
const MIN_ZOOM_DELTA = 0.01;
/** @return Whether two numbers are approximately equal. */
function floatingPointEquals(a: number, b: number): boolean {
// If the zoom level is close enough to the current zoom level, don't
// change it. This avoids us getting into an infinite loop of zoom changes
// due to floating point error.
return Math.abs(a - b) <= MIN_ZOOM_DELTA;
}
// Abstract parent of classes that manage updating the browser with zoom changes
// and/or updating the viewer's zoom when the browser zoom changes.
export abstract class ZoomManager {
protected browserZoom: number;
protected getViewportZoom: () => number;
private eventTarget_ = new EventTarget();
/**
* @param getViewportZoomCallback Callback to get the viewport's current zoom
* level.
* @param initialZoom The initial browser zoom level.
*/
constructor(getViewportZoomCallback: () => number, initialZoom: number) {
this.browserZoom = initialZoom;
this.getViewportZoom = getViewportZoomCallback;
}
getEventTarget(): EventTarget {
return this.eventTarget_;
}
/**
* Creates the appropriate kind of zoom manager given the zoom behavior.
* @param zoomBehavior How to manage zoom.
* @param getViewportZoom A function that gets the current viewport zoom.
* @param setBrowserZoomFunction A function that sets the browser zoom to the
* provided value.
* @param initialZoom The initial browser zoom level.
*/
static create(
zoomBehavior: ZoomBehavior, getViewportZoom: () => number,
setBrowserZoomFunction: (zoom: number) => Promise<void>,
initialZoom: number): ZoomManager {
switch (zoomBehavior) {
case ZoomBehavior.MANAGE:
return new ActiveZoomManager(
getViewportZoom, setBrowserZoomFunction, initialZoom);
case ZoomBehavior.PROPAGATE_PARENT:
return new EmbeddedZoomManager(getViewportZoom, initialZoom);
default:
return new InactiveZoomManager(getViewportZoom, initialZoom);
}
}
/**
* Invoked when a browser-initiated zoom-level change occurs.
* @param newZoom the zoom level to zoom to.
*/
abstract onBrowserZoomChange(newZoom: number): void;
/** Invoked when an extension-initiated zoom-level change occurs. */
abstract onPdfZoomChange(): void;
/**
* Combines the internal pdf zoom and the browser zoom to
* produce the total zoom level for the viewer.
* @param internalZoom the zoom level internal to the viewer.
* @return the total zoom level.
*/
applyBrowserZoom(internalZoom: number): number {
return this.browserZoom * internalZoom;
}
/**
* Given a zoom level, return the internal zoom level needed to
* produce that zoom level.
* @param totalZoom the total zoom level.
* @return the zoom level internal to the viewer.
*/
internalZoomComponent(totalZoom: number): number {
return totalZoom / this.browserZoom;
}
}
// Has no control over the browser's zoom and does not respond to browser zoom
// changes.
export class InactiveZoomManager extends ZoomManager {
override onBrowserZoomChange(_newZoom: number) {}
override onPdfZoomChange() {}
}
// ActiveZoomManager controls the browser's zoom.
class ActiveZoomManager extends ZoomManager {
private setBrowserZoomFunction_: (zoom: number) => Promise<void>;
private changingBrowserZoom_: Promise<void>|null = null;
/**
* Constructs a ActiveZoomManager.
* @param getViewportZoom A function that gets the current viewport zoom level
* @param setBrowserZoomFunction A function that sets the browser zoom to the
* provided value.
* @param initialZoom The initial browser zoom level.
*/
constructor(
getViewportZoom: () => number,
setBrowserZoomFunction: (zoom: number) => Promise<void>,
initialZoom: number) {
super(getViewportZoom, initialZoom);
this.setBrowserZoomFunction_ = setBrowserZoomFunction;
}
onBrowserZoomChange(newZoom: number) {
// If we are changing the browser zoom level, ignore any browser zoom level
// change events. Either, the change occurred before our update and will be
// overwritten, or the change being reported is the change we are making,
// which we have already handled.
if (this.changingBrowserZoom_) {
return;
}
if (floatingPointEquals(this.browserZoom, newZoom)) {
return;
}
this.browserZoom = newZoom;
this.getEventTarget().dispatchEvent(
new CustomEvent('set-zoom', {detail: newZoom}));
}
override onPdfZoomChange() {
// If we are already changing the browser zoom level in response to a
// previous extension-initiated zoom-level change, ignore this zoom change.
// Once the browser zoom level is changed, we check whether the extension's
// zoom level matches the most recently sent zoom level.
if (this.changingBrowserZoom_) {
return;
}
const viewportZoom = this.getViewportZoom();
if (floatingPointEquals(this.browserZoom, viewportZoom)) {
return;
}
this.changingBrowserZoom_ =
this.setBrowserZoomFunction_(viewportZoom).then(() => {
this.browserZoom = viewportZoom;
this.changingBrowserZoom_ = null;
// The extension's zoom level may have changed while the browser zoom
// change was in progress. We call back into onPdfZoomChange to ensure
// the browser zoom is up to date.
this.onPdfZoomChange();
});
}
/**
* Combines the internal pdf zoom and the browser zoom to
* produce the total zoom level for the viewer.
* @param internalZoom the zoom level internal to the viewer.
* @return the total zoom level.
*/
override applyBrowserZoom(internalZoom: number): number {
// The internal zoom and browser zoom are changed together, so the
// browser zoom is already applied.
return internalZoom;
}
/**
* Given a zoom level, return the internal zoom level needed to
* produce that zoom level.
* @param totalZoom the total zoom level.
* @return the zoom level internal to the viewer.
*/
override internalZoomComponent(totalZoom: number): number {
// The internal zoom and browser zoom are changed together, so the
// internal zoom is the total zoom.
return totalZoom;
}
}
// Responds to changes in the browser zoom, but does not control the browser
// zoom.
class EmbeddedZoomManager extends ZoomManager {
/**
* Invoked when a browser-initiated zoom-level change occurs.
* @param newZoom the new browser zoom level.
*/
override onBrowserZoomChange(newZoom: number) {
const oldZoom = this.browserZoom;
this.browserZoom = newZoom;
this.getEventTarget().dispatchEvent(
new CustomEvent('update-zoom-from-browser', {detail: oldZoom}));
}
override onPdfZoomChange() {}
}
Codebase Browser
chromium