Move the zoomIn/zoomOut functionality into BaseViewer (PR 14038 follow-up)

Given the simplicity of this functionality, we can move it from the default viewer and into the `BaseViewer` class instead. This way, it's possible to support more scripting functionality in the standalone viewer components; please see PR 14038.

Please note that I purposely went with `increaseScale`/`decreaseScale`-method names, rather than using "zoom", to better match the existing `currentScale`/`currentScaleValue` getters/setters that's being used in the `BaseViewer` class.

web/app.js

@@ -26,8 +26,6 @@ import {
   isValidRotation,
   isValidScrollMode,
   isValidSpreadMode,
-  MAX_SCALE,
-  MIN_SCALE,
   noContextMenuHandler,
   normalizeWheelEventDirection,
   parseQueryString,
@@ -81,7 +79,6 @@ import { SecondaryToolbar } from "./secondary_toolbar.js";
 import { Toolbar } from "./toolbar.js";
 import { ViewHistory } from "./view_history.js";
 
-const DEFAULT_SCALE_DELTA = 1.1;
 const DISABLE_AUTO_FETCH_LOADING_BAR_TIMEOUT = 5000; // ms
 const FORCE_PAGES_LOADED_TIMEOUT = 10000; // ms
 const WHEEL_ZOOM_DISABLED_TIMEOUT = 1000; // ms
@@ -637,30 +634,18 @@ const PDFViewerApplication = {
     return this._initializedCapability.promise;
   },
 
-  zoomIn(ticks) {
+  zoomIn(steps) {
     if (this.pdfViewer.isInPresentationMode) {
       return;
     }
-    let newScale = this.pdfViewer.currentScale;
+    this.pdfViewer.increaseScale(steps);
-    do {
-      newScale = (newScale * DEFAULT_SCALE_DELTA).toFixed(2);
-      newScale = Math.ceil(newScale * 10) / 10;
-      newScale = Math.min(MAX_SCALE, newScale);
-    } while (--ticks > 0 && newScale < MAX_SCALE);
-    this.pdfViewer.currentScaleValue = newScale;
   },
 
-  zoomOut(ticks) {
+  zoomOut(steps) {
     if (this.pdfViewer.isInPresentationMode) {
       return;
     }
-    let newScale = this.pdfViewer.currentScale;
+    this.pdfViewer.decreaseScale(steps);
-    do {
-      newScale = (newScale / DEFAULT_SCALE_DELTA).toFixed(2);
-      newScale = Math.floor(newScale * 10) / 10;
-      newScale = Math.max(MIN_SCALE, newScale);
-    } while (--ticks > 0 && newScale > MIN_SCALE);
-    this.pdfViewer.currentScaleValue = newScale;
   },
 
   zoomReset() {

web/base_viewer.js

@@ -17,6 +17,7 @@ import { AnnotationMode, createPromiseCapability, version } from "pdfjs-lib";
 import {
   CSS_UNITS,
   DEFAULT_SCALE,
+  DEFAULT_SCALE_DELTA,
   DEFAULT_SCALE_VALUE,
   getVisibleElements,
   isPortraitOrientation,
@@ -24,6 +25,8 @@ import {
   isValidScrollMode,
   isValidSpreadMode,
   MAX_AUTO_SCALE,
+  MAX_SCALE,
+  MIN_SCALE,
   moveToEndOfArray,
   PresentationModeState,
   RendererType,
@@ -1693,6 +1696,34 @@ class BaseViewer {
     this.currentPageNumber = Math.max(currentPageNumber - advance, 1);
     return true;
   }
+
+  /**
+   * Increase the current zoom level one, or more, times.
+   * @param {number} [steps] - Defaults to zooming once.
+   */
+  increaseScale(steps = 1) {
+    let newScale = this._currentScale;
+    do {
+      newScale = (newScale * DEFAULT_SCALE_DELTA).toFixed(2);
+      newScale = Math.ceil(newScale * 10) / 10;
+      newScale = Math.min(MAX_SCALE, newScale);
+    } while (--steps > 0 && newScale < MAX_SCALE);
+    this.currentScaleValue = newScale;
+  }
+
+  /**
+   * Decrease the current zoom level one, or more, times.
+   * @param {number} [steps] - Defaults to zooming once.
+   */
+  decreaseScale(steps = 1) {
+    let newScale = this._currentScale;
+    do {
+      newScale = (newScale / DEFAULT_SCALE_DELTA).toFixed(2);
+      newScale = Math.floor(newScale * 10) / 10;
+      newScale = Math.max(MIN_SCALE, newScale);
+    } while (--steps > 0 && newScale > MIN_SCALE);
+    this.currentScaleValue = newScale;
+  }
 }
 
 export { BaseViewer };

web/pdf_scripting_manager.js

@@ -324,13 +324,13 @@ class PDFScriptingManager {
           if (isInPresentationMode) {
             return;
           }
-          this._eventBus.dispatch("zoomin", { source: this });
+          this._pdfViewer.increaseScale();
           break;
         case "ZoomViewOut":
           if (isInPresentationMode) {
             return;
           }
-          this._eventBus.dispatch("zoomout", { source: this });
+          this._pdfViewer.decreaseScale();
           break;
       }
       return;

web/ui_utils.js

@@ -18,6 +18,7 @@ import { PixelsPerInch } from "pdfjs-lib";
 const CSS_UNITS = PixelsPerInch.CSS / PixelsPerInch.PDF;
 const DEFAULT_SCALE_VALUE = "auto";
 const DEFAULT_SCALE = 1.0;
+const DEFAULT_SCALE_DELTA = 1.1;
 const MIN_SCALE = 0.1;
 const MAX_SCALE = 10.0;
 const UNKNOWN_SCALE = 0;
@@ -1005,6 +1006,7 @@ export {
   binarySearchFirstItem,
   CSS_UNITS,
   DEFAULT_SCALE,
+  DEFAULT_SCALE_DELTA,
   DEFAULT_SCALE_VALUE,
   EventBus,
   getActiveOrFocusedElement,