pdfviewer example: page cache has a page count limit

to limit memory usage

2 files changed, 6 insertions, 0 deletions

diff --git a/examples/widgets/pdfviewer/sequentialpagewidget.cpp b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
index c85f784..c5ba650 100644
--- a/examples/widgets/pdfviewer/sequentialpagewidget.cpp
+++ b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
@@ -12,6 +12,7 @@ Q_DECLARE_LOGGING_CATEGORY(lcExample)
 
 SequentialPageWidget::SequentialPageWidget(QWidget *parent)
     : QWidget(parent)
+    , m_pageCacheLimit(20)
     , m_pageRenderer(new PageRenderer())
     , m_background(Qt::darkGray)
     , m_placeholderIcon(":icons/images/busy.png")
@@ -69,7 +70,10 @@ void SequentialPageWidget::invalidate()
 void SequentialPageWidget::pageLoaded(int page, qreal zoom, QImage image)
 {
     Q_UNUSED(zoom)
+    if (m_cachedPagesLRU.length() > m_pageCacheLimit)
+        m_pageCache.remove(m_cachedPagesLRU.takeFirst());
     m_pageCache.insert(page, image);
+    m_cachedPagesLRU.append(page);
     update();
 }
 
diff --git a/examples/widgets/pdfviewer/sequentialpagewidget.h b/examples/widgets/pdfviewer/sequentialpagewidget.h
index 2a3025d..d612e9a 100644
--- a/examples/widgets/pdfviewer/sequentialpagewidget.h
+++ b/examples/widgets/pdfviewer/sequentialpagewidget.h
@@ -38,6 +38,8 @@ private:
 
 private:
     QHash<int, QImage> m_pageCache;
+    QList<int> m_cachedPagesLRU;
+    int m_pageCacheLimit;
     QVector<QSizeF> m_pageSizes;
     PageRenderer *m_pageRenderer;
     QBrush m_background;