From 4747467103d65a0c53454fc186cd24c6322d4343 Mon Sep 17 00:00:00 2001
From: Kalervo Kujala <kkujala@com>
Date: Thu, 13 Sep 2012 23:23:44 +0300
Subject: [PATCH] Add firefox mouse scrolling support in presentation mode.

Convert ticks to mouse delta values and use that to determine
when to flip the page.

Also use cooldown time for presentation mode page scrolling.
This way hi res mouses do not scroll multiple pages at once.
http://www.codeproject.com/Articles/155717/Handling-Enhanced-Mouse-Wheels-in-your-Application
---
 web/viewer.js | 72 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/web/viewer.js b/web/viewer.js
index e9de32196..52179a914 100644
--- a/web/viewer.js
+++ b/web/viewer.js
@@ -227,6 +227,8 @@ var PDFView = {
   isFullscreen: false,
   previousScale: null,
   pageRotation: 0,
+  mouseScrollTimeStamp: 0,
+  mouseScrollDelta: 0,
   lastScroll: 0,
 
   // called once when the document is loaded
@@ -1187,6 +1189,7 @@ var PDFView = {
     this.isFullscreen = false;
     this.parseScale(this.previousScale);
     this.page = this.page;
+    this.clearMouseScrollState();
   },
 
   rotatePages: function pdfViewPageRotation(delta) {
@@ -1213,6 +1216,71 @@ var PDFView = {
     setTimeout(function() {
       currentPage.scrollIntoView();
     }, 0);
+  },
+
+  /**
+   * This function flips the page in presentation mode if the user scrolls up
+   * or down with large enough motion and prevents page flipping too often.
+   *
+   * @this {PDFView}
+   * @param {number} mouseScrollDelta The delta value from the mouse event.
+   */
+  mouseScroll: function pdfViewMouseScroll(mouseScrollDelta) {
+    var MOUSE_SCROLL_COOLDOWN_TIME = 50;
+
+    var currentTime = (new Date()).getTime();
+    var storedTime = this.mouseScrollTimeStamp;
+
+    // In case one page has already been flipped there is a cooldown time
+    // which has to expire before next page can be scrolled on to.
+    if (currentTime > storedTime &&
+        currentTime - storedTime < MOUSE_SCROLL_COOLDOWN_TIME)
+      return;
+
+    // In case the user decides to scroll to the opposite direction than before
+    // clear the accumulated delta.
+    if ((this.mouseScrollDelta > 0 && mouseScrollDelta < 0) ||
+        (this.mouseScrollDelta < 0 && mouseScrollDelta > 0))
+      this.clearMouseScrollState();
+
+    this.mouseScrollDelta += mouseScrollDelta;
+
+    var PAGE_FLIP_THRESHOLD = 120;
+    if (Math.abs(this.mouseScrollDelta) >= PAGE_FLIP_THRESHOLD) {
+
+      var PageFlipDirection = {
+        UP: -1,
+        DOWN: 1
+      };
+
+      // In fullscreen mode scroll one page at a time.
+      var pageFlipDirection = (this.mouseScrollDelta > 0) ?
+                                PageFlipDirection.UP :
+                                PageFlipDirection.DOWN;
+      this.clearMouseScrollState();
+      var currentPage = this.page;
+
+      // In case we are already on the first or the last page there is no need
+      // to do anything.
+      if ((currentPage == 1 && pageFlipDirection == PageFlipDirection.UP) ||
+          (currentPage == this.pages.length &&
+           pageFlipDirection == PageFlipDirection.DOWN))
+        return;
+
+      this.page += pageFlipDirection;
+      this.mouseScrollTimeStamp = currentTime;
+    }
+  },
+
+  /**
+   * This function clears the member attributes used with mouse scrolling in
+   * presentation mode.
+   *
+   * @this {PDFView}
+   */
+  clearMouseScrollState: function pdfViewClearMouseScrollState() {
+    this.mouseScrollTimeStamp = 0;
+    this.mouseScrollDelta = 0;
   }
 };
 
@@ -2317,6 +2385,9 @@ window.addEventListener('DOMMouseScroll', function(evt) {
     var direction = (ticks > 0) ? 'zoomOut' : 'zoomIn';
     for (var i = 0, length = Math.abs(ticks); i < length; i++)
       PDFView[direction]();
+  } else if (PDFView.isFullscreen) {
+    var FIREFOX_DELTA_FACTOR = -40;
+    PDFView.mouseScroll(evt.detail * FIREFOX_DELTA_FACTOR);
   }
 }, false);
 
@@ -2407,6 +2478,7 @@ window.addEventListener('keydown', function keydown(evt) {
 
   if (handled) {
     evt.preventDefault();
+    PDFView.clearMouseScrollState();
   }
 });