Fix: Presentation preloading scales without max (#487)

This now matches the behavior of the presentation viewer, which doesn't have a max zoom scale.

src/lib/constants.js

@@ -82,6 +82,11 @@ export const X_REP_HINT_IMAGE = '[jpg?dimensions=2048x2048,png?dimensions=2048x2
 export const X_REP_HINT_VIDEO_DASH = '[dash,mp4][filmstrip]';
 export const X_REP_HINT_VIDEO_MP4 = '[mp4]';
 
+export const PDFJS_CSS_UNITS = 96.0 / 72.0; // Should match CSS_UNITS in pdf_viewer.js
+export const PDFJS_MAX_AUTO_SCALE = 1.25; // Should match MAX_AUTO_SCALE in pdf_viewer.js
+export const PDFJS_WIDTH_PADDING_PX = 40; // Should match SCROLLBAR_PADDING in pdf_viewer.js
+export const PDFJS_HEIGHT_PADDING_PX = 5; // Should match VERTICAL_PADDING in pdf_viewer.js
+
 // These should be updated to match the Preview version in package.json whenever a file in that third party directory
 // is updated. Also, update the matching configuration in karma.conf.js, which is needed for tests
 export const DOC_STATIC_ASSETS_VERSION = '1.17.0';

src/lib/viewers/doc/DocPreloader.js

@@ -7,18 +7,17 @@ import {
     CLASS_INVISIBLE,
     CLASS_IS_TRANSPARENT,
     CLASS_PREVIEW_LOADED,
-    CLASS_SPINNER
+    CLASS_SPINNER,
+    PDFJS_CSS_UNITS,
+    PDFJS_MAX_AUTO_SCALE,
+    PDFJS_WIDTH_PADDING_PX,
+    PDFJS_HEIGHT_PADDING_PX
 } from '../../constants';
 import { get, setDimensions } from '../../util';
 
 const EXIF_COMMENT_TAG_NAME = 'UserComment'; // Read EXIF data from 'UserComment' tag
 const EXIF_COMMENT_REGEX = /pdfWidth:([0-9.]+)pts,pdfHeight:([0-9.]+)pts,numPages:([0-9]+)/;
 
-const PDFJS_CSS_UNITS = 96.0 / 72.0; // Should match CSS_UNITS in pdf_viewer.js
-const PDFJS_MAX_AUTO_SCALE = 1.25; // Should match MAX_AUTO_SCALE in pdf_viewer.js
-const PDFJS_WIDTH_PADDING_PX = 40; // Should match SCROLLBAR_PADDING in pdf_viewer.js
-const PDFJS_HEIGHT_PADDING_PX = 5; // Should match VERTICAL_PADDING in pdf_viewer.js
-
 const NUM_PAGES_DEFAULT = 2; // Default to 2 pages for preload if true number of pages cannot be read
 const NUM_PAGES_MAX = 500; // Don't show more than 500 placeholder pages
 
@@ -33,6 +32,9 @@ class DocPreloader extends EventEmitter {
     /** @property {HTMLElement} - Preload image element */
     imageEl;
 
+    /** @property {HTMLElement} - Maximum auto-zoom scale */
+    maxZoomScale = PDFJS_MAX_AUTO_SCALE;
+
     /** @property {HTMLElement} - Preload overlay element */
     overlayEl;
 
@@ -59,7 +61,6 @@ class DocPreloader extends EventEmitter {
      */
     constructor(previewUI) {
         super();
-
         this.previewUI = previewUI;
         this.wrapperClassName = CLASS_BOX_PREVIEW_PRELOAD_WRAPPER_DOCUMENT;
     }
@@ -242,6 +243,33 @@ class DocPreloader extends EventEmitter {
             });
     };
 
+    /**
+     * Returns scaled PDF dimensions using same algorithm as pdf.js up to a maximum of 1.25x zoom.
+     *
+     * @private
+     * @param {number} pdfWidth - Width of PDF in pixels
+     * @param {number} pdfHeight - Height of PDF in pixels
+     * @return {Object} Scaled width and height in pixels
+     */
+    getScaledDimensions(pdfWidth, pdfHeight) {
+        const { clientWidth, clientHeight } = this.wrapperEl;
+        const widthScale = (clientWidth - PDFJS_WIDTH_PADDING_PX) / pdfWidth;
+        const heightScale = (clientHeight - PDFJS_HEIGHT_PADDING_PX) / pdfHeight;
+
+        const isLandscape = pdfWidth > pdfHeight;
+        let scale = isLandscape ? Math.min(heightScale, widthScale) : widthScale;
+
+        // Optionally limit to maximum zoom scale if defined
+        if (this.maxZoomScale) {
+            scale = Math.min(this.maxZoomScale, scale);
+        }
+
+        return {
+            scaledWidth: Math.floor(scale * pdfWidth),
+            scaledHeight: Math.floor(scale * pdfHeight)
+        };
+    }
+
     /**
      * Reads EXIF from preload JPG for PDF width, height, and numPages. This is currently encoded
      * by Box Conversion into the preload JPG itself, but eventually this information will be
@@ -309,29 +337,6 @@ class DocPreloader extends EventEmitter {
         });
     }
 
-    /**
-     * Returns scaled PDF dimensions using same algorithm as pdf.js up to a maximum of 1.25x zoom.
-     *
-     * @private
-     * @param {number} pdfWidth - Width of PDF in pixels
-     * @param {number} pdfHeight - Height of PDF in pixels
-     * @return {Object} Scaled width and height in pixels
-     */
-    getScaledDimensions(pdfWidth, pdfHeight) {
-        const { clientWidth, clientHeight } = this.wrapperEl;
-        const widthScale = (clientWidth - PDFJS_WIDTH_PADDING_PX) / pdfWidth;
-        const heightScale = (clientHeight - PDFJS_HEIGHT_PADDING_PX) / pdfHeight;
-        const isLandscape = pdfWidth > pdfHeight;
-
-        let scale = isLandscape ? Math.min(heightScale, widthScale) : widthScale;
-        scale = Math.min(PDFJS_MAX_AUTO_SCALE, scale);
-
-        return {
-            scaledWidth: Math.floor(scale * pdfWidth),
-            scaledHeight: Math.floor(scale * pdfHeight)
-        };
-    }
-
     /**
      * Check if full document is already loaded - if so, hide the preload.
      *

src/lib/viewers/doc/PresentationPreloader.js

@@ -3,6 +3,12 @@ import { CLASS_INVISIBLE, CLASS_BOX_PREVIEW_PRELOAD_WRAPPER_PRESENTATION } from
 import { setDimensions } from '../../util';
 
 class PresentationPreloader extends DocPreloader {
+    /**
+     * @property {HTMLELement} - Maximum auto-zoom scale, set to 0 for no limit since presentation viewer doesn't
+     * have a maximum zoom scale and scales up to available viewport
+     */
+    maxZoomScale = 0;
+
     /** @property {HTMLElement} - Preload container element */
     preloadEl;
 
@@ -20,6 +26,7 @@ class PresentationPreloader extends DocPreloader {
      */
     constructor(previewUI) {
         super(previewUI);
+
         this.wrapperClassName = CLASS_BOX_PREVIEW_PRELOAD_WRAPPER_PRESENTATION;
     }