From 569c9b84cecdef0d7fb7cc3af0a007662a97cece Mon Sep 17 00:00:00 2001
From: Fabio D'Urso <fabiodurso@hotmail.it>
Date: Mon, 2 Jul 2012 08:22:51 +0200
Subject: [PATCH] Before preloading pixmaps check that they fit in cache

---
 core/document.cpp  | 25 ++++++++++++++++++++++++-
 core/generator.cpp | 14 ++++++++++++++
 core/generator_p.h |  1 +
 3 files changed, 39 insertions(+), 1 deletion(-)

diff --git a/core/document.cpp b/core/document.cpp
index 3200ebdb3..f6bf699a7 100644
--- a/core/document.cpp
+++ b/core/document.cpp
@@ -11,6 +11,7 @@
 #include "document.h"
 #include "document_p.h"
 
+#include <limits.h>
 #ifdef Q_OS_WIN
 #define _WIN32_WINNT 0x0500
 #include <windows.h>
@@ -973,6 +974,20 @@ void DocumentPrivate::slotTimedMemoryCheck()
 
 void DocumentPrivate::sendGeneratorRequest()
 {
+    /* If the pixmap cache will have to be cleaned in order to make room for the
+     * next request, get the distance from the current viewport of the page
+     * whose pixmap will be removed. We will ignore preload requests for pages
+     * that are at the same distance or farther */
+    const qulonglong memoryToFree = calculateMemoryToFree();
+    const int currentViewportPage = (*m_viewportIterator).pageNumber;
+    int maxDistance = INT_MAX; // Default: No maximum
+    if ( memoryToFree )
+    {
+        AllocatedPixmap *pixmapToReplace = searchLowestPriorityUnloadablePixmap();
+        if ( pixmapToReplace )
+            maxDistance = qAbs( pixmapToReplace->page - currentViewportPage );
+    }
+
     // find a request
     PixmapRequest * request = 0;
     m_pixmapRequestsMutex.lock();
@@ -1000,8 +1015,16 @@ void DocumentPrivate::sendGeneratorRequest()
             }
             delete r;
         }
+        else if ( !r->d->mForce && r->d->isPreload() && qAbs( r->pageNumber() - currentViewportPage ) >= maxDistance )
+        {
+            m_pixmapRequestsStack.pop_back();
+            //kDebug() << "Ignoring request that doesn't fit in cache";
+            delete r;
+        }
         else
+        {
             request = r;
+        }
     }
 
     // if no request found (or already generated), return
@@ -1014,7 +1037,7 @@ void DocumentPrivate::sendGeneratorRequest()
     // [MEM] preventive memory freeing
     qulonglong pixmapBytes = 4 * request->width() * request->height();
     if ( pixmapBytes > (1024 * 1024) )
-        cleanupPixmapMemory();
+        cleanupPixmapMemory( memoryToFree /* previously calculated value */ );
 
     // submit the request to the generator
     if ( m_generator->canGeneratePixmap() )
diff --git a/core/generator.cpp b/core/generator.cpp
index 17b5e6309..0073943a0 100644
--- a/core/generator.cpp
+++ b/core/generator.cpp
@@ -10,6 +10,7 @@
 
 #include "generator.h"
 #include "generator_p.h"
+#include "observer.h"
 
 #include <qeventloop.h>
 #include <QtGui/QPrinter>
@@ -477,6 +478,19 @@ void PixmapRequestPrivate::swap()
     qSwap( mWidth, mHeight );
 }
 
+bool PixmapRequestPrivate::isPreload() const
+{
+    switch ( mPriority )
+    {
+        case PAGEVIEW_PRELOAD_PRIO:
+        case THUMBNAILS_PRELOAD_PRIO:
+        case PRESENTATION_PRELOAD_PRIO:
+            return true;
+        default:
+            return false;
+    }
+}
+
 class Okular::ExportFormatPrivate : public QSharedData
 {
     public:
diff --git a/core/generator_p.h b/core/generator_p.h
index f2d746a19..775da7f5b 100644
--- a/core/generator_p.h
+++ b/core/generator_p.h
@@ -70,6 +70,7 @@ class PixmapRequestPrivate
 {
     public:
         void swap();
+        bool isPreload() const;
 
         int mId;
         int mPageNumber;