pdfviewer example: direct inheritance from QThread

But either way, the UI is not as responsive as one could wish for
during background rendering.

2 files changed, 8 insertions, 11 deletions

diff --git a/examples/widgets/pdfviewer/pagecache.cpp b/examples/widgets/pdfviewer/pagecache.cpp
index 5943b90..589a7b0 100644
--- a/examples/widgets/pdfviewer/pagecache.cpp
+++ b/examples/widgets/pdfviewer/pagecache.cpp
@@ -3,13 +3,11 @@
 #include <QPdfDocument>
 #include <QLoggingCategory>
 #include <QElapsedTimer>
-#include <QThread>
 
 Q_DECLARE_LOGGING_CATEGORY(lcExample)
 
 PageCache::PageCache(QPdfDocument *doc, qreal zoom)
-    : QObject(Q_NULLPTR)
-    , m_thread(new QThread(this))
+    : QThread(Q_NULLPTR)
     , m_doc(doc)
     , m_zoom(zoom)
     , m_placeholderIcon(":icons/images/busy.png")
@@ -19,8 +17,6 @@ PageCache::PageCache(QPdfDocument *doc, qreal zoom)
     , m_totalRenderTime(0.)
     , m_totalPagesRendered(0)
 {
-    moveToThread(m_thread);
-    connect(this, &PageCache::pagesNeeded, this, &PageCache::run, Qt::QueuedConnection);
 }
 
 PageCache::~PageCache()
@@ -36,9 +32,8 @@ QPixmap PageCache::get(int page)
     m_lastPageRequested = page;
     if (m_pageCache.contains(page))
         return m_pageCache[page];
-    if (!m_thread->isRunning())
-        m_thread->start(QThread::LowestPriority);
-    emit pagesNeeded();
+    if (!isRunning())
+        start(QThread::LowestPriority);
     QSizeF sizeF = m_doc->pageSize(page);
     if (!sizeF.isValid())
         return QPixmap();
diff --git a/examples/widgets/pdfviewer/pagecache.h b/examples/widgets/pdfviewer/pagecache.h
index 49d8bf8..6d93211 100644
--- a/examples/widgets/pdfviewer/pagecache.h
+++ b/examples/widgets/pdfviewer/pagecache.h
@@ -5,10 +5,11 @@
 #include <QHash>
 #include <QPixmap>
 #include <QRunnable>
+#include <QThread>
 
 class QPdfDocument;
 
-class PageCache : public QObject
+class PageCache : public QThread
 {
     Q_OBJECT
 public:
@@ -21,14 +22,15 @@ public slots:
     void run();
 
 signals:
-    void pagesNeeded();
     void pageReady(int page);
 
+protected:
+    Q_DECL_OVERRIDE void run();
+
 private:
     void insertPage(int page);
 
 private:
-    QThread *m_thread;
     QPdfDocument *m_doc;
     QHash<int, QPixmap> m_pageCache;
     qreal m_zoom;