From bdb2df773d774c15cf0a17fcae198d3f2452cdfa Mon Sep 17 00:00:00 2001
From: Kezi Olio <keziolio123@gmail.com>
Date: Sun, 16 Aug 2020 16:21:35 +0200
Subject: [PATCH] Fix forms when inertially scrolling

`setViewport` automatically adds an item to the history if it finds that it
moved for more than a page, which we don't want to do when automatically
scrolling, as with inertial scrolling.

This commit adds a new function `setViewportWithHistory()` which takes an
argument to optionally avoid preserving history. This avoids breaking ABI.
The new history-less functionality is used when inertially scrolling.

BUG: 421354
FIXED-IN: 1.11.2
---
 core/document.cpp | 33 ++++++++++++++++++++-------------
 core/document.h   | 11 +++++++++++
 ui/pageview.cpp   |  5 +++--
 3 files changed, 34 insertions(+), 15 deletions(-)

diff --git a/core/document.cpp b/core/document.cpp
index f31345d5c..baa48a3fd 100644
--- a/core/document.cpp
+++ b/core/document.cpp
@@ -3445,19 +3445,8 @@ void Document::setPrevPage()
         setViewport( DocumentViewport( (*d->m_viewportIterator).pageNumber - 1 ) );
 }
 */
-void Document::setViewportPage(int page, DocumentObserver *excludeObserver, bool smoothMove)
-{
-    // clamp page in range [0 ... numPages-1]
-    if (page < 0)
-        page = 0;
-    else if (page > (int)d->m_pagesVector.count())
-        page = d->m_pagesVector.count() - 1;
 
-    // make a viewport from the page and broadcast it
-    setViewport(DocumentViewport(page), excludeObserver, smoothMove);
-}
-
-void Document::setViewport(const DocumentViewport &viewport, DocumentObserver *excludeObserver, bool smoothMove)
+void Document::setViewportWithHistory(const DocumentViewport &viewport, DocumentObserver *excludeObserver, bool smoothMove, bool updateHistory)
 {
     if (!viewport.isValid()) {
         qCDebug(OkularCoreDebug) << "invalid viewport:" << viewport.toString();
@@ -3477,7 +3466,7 @@ void Document::setViewport(const DocumentViewport &viewport, DocumentObserver *e
     const int oldPageNumber = oldViewport.pageNumber;
 
     // set internal viewport taking care of history
-    if (oldViewport.pageNumber == viewport.pageNumber || !oldViewport.isValid()) {
+    if (oldViewport.pageNumber == viewport.pageNumber || !oldViewport.isValid() || !updateHistory) {
         // if page is unchanged save the viewport at current position in queue
         oldViewport = viewport;
     } else {
@@ -3506,6 +3495,24 @@ void Document::setViewport(const DocumentViewport &viewport, DocumentObserver *e
     }
 }
 
+void Document::setViewportPage(int page, DocumentObserver *excludeObserver, bool smoothMove)
+{
+    // clamp page in range [0 ... numPages-1]
+    if (page < 0)
+        page = 0;
+    else if (page > (int)d->m_pagesVector.count())
+        page = d->m_pagesVector.count() - 1;
+
+    // make a viewport from the page and broadcast it
+    setViewport(DocumentViewport(page), excludeObserver, smoothMove);
+}
+
+void Document::setViewport(const DocumentViewport &viewport, DocumentObserver *excludeObserver, bool smoothMove)
+{
+    // set viewport, updating history
+    setViewportWithHistory(viewport, excludeObserver, smoothMove, true);
+}
+
 void Document::setZoom(int factor, DocumentObserver *excludeObserver)
 {
     // notify change to all other (different from id) observers
diff --git a/core/document.h b/core/document.h
index 9b7f6df14..d2bfa2b29 100644
--- a/core/document.h
+++ b/core/document.h
@@ -431,6 +431,17 @@ public:
      */
     void setViewport(const DocumentViewport &viewport, DocumentObserver *excludeObserver = nullptr, bool smoothMove = false);
 
+    /**
+     * Sets the current document viewport to the given @p viewport.
+     * BCI TODO: merge with setViewport, adding a parameter "bool updateHistory = true"
+     *
+     * @param viewport The document viewport.
+     * @param excludeObserver The observer which shouldn't be effected by this change.
+     * @param smoothMove Whether the move shall be animated smoothly.
+     * @param updateHistory Whether to consider the change of viewport for the history navigation
+     */
+    void setViewportWithHistory(const DocumentViewport &viewport, DocumentObserver *excludeObserver = nullptr, bool smoothMove = false, bool updateHistory = true);
+
     /**
      * Sets the current document viewport to the next viewport in the
      * viewport history.
diff --git a/ui/pageview.cpp b/ui/pageview.cpp
index fb8883257..89daf92f3 100644
--- a/ui/pageview.cpp
+++ b/ui/pageview.cpp
@@ -4360,7 +4360,7 @@ static void slotRequestPreloadPixmap(Okular::DocumentObserver *observer, const P
 void PageView::slotRequestVisiblePixmaps(int newValue)
 {
     // if requests are blocked (because raised by an unwanted event), exit
-    if (d->blockPixmapsRequest || d->scroller->state() == QScroller::Scrolling)
+    if (d->blockPixmapsRequest)
         return;
 
     // precalc view limits for intersecting with page coords inside the loop
@@ -4503,7 +4503,8 @@ void PageView::slotRequestVisiblePixmaps(int newValue)
         newViewport.rePos.normalizedX = focusedX;
         newViewport.rePos.normalizedY = focusedY;
         // set the viewport to other observers
-        d->document->setViewport(newViewport, this);
+        // do not update history if the viewport is autoscrolling
+        d->document->setViewportWithHistory(newViewport, this, false, d->scroller->state() == QScroller::Scrolling);
     }
     d->document->setVisiblePageRects(visibleRects, this);
 }