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#include "pagecache.h"
#include <QPainter>
#include <QPdfDocument>
#include <QLoggingCategory>
#include <QElapsedTimer>
Q_DECLARE_LOGGING_CATEGORY(lcExample)
PageCache::PageCache(QPdfDocument *doc, qreal zoom)
: QThread(Q_NULLPTR)
, m_doc(doc)
, m_zoom(zoom)
, m_placeholderIcon(":icons/images/busy.png")
, m_placeholderBackground(Qt::white)
, m_minRenderTime(1000000000.)
, m_maxRenderTime(0.)
, m_totalRenderTime(0.)
, m_totalPagesRendered(0)
{
}
PageCache::~PageCache()
{
}
/*!
Get the result from the cache,
or a placeholder pixmap if unavailable.
*/
QPixmap PageCache::get(int page)
{
m_lastPageRequested = page;
if (m_pageCache.contains(page))
return m_pageCache[page];
if (!isRunning())
start(QThread::LowestPriority);
QSizeF sizeF = m_doc->pageSize(page);
if (!sizeF.isValid())
return QPixmap();
QSize size = QSizeF(sizeF * m_zoom).toSize();
QPixmap placeholder(size);
{
QPainter painter(&placeholder);
painter.fillRect(QRect(QPoint(), size), m_placeholderBackground);
painter.drawPixmap((size.width() - m_placeholderIcon.width()) / 2,
(size.height() - m_placeholderIcon.height()) / 2, m_placeholderIcon);
}
return placeholder;
}
void PageCache::run()
{
int lastPageRequested = m_lastPageRequested;
int forward = lastPageRequested;
int backward = lastPageRequested - 1;
while (true) {
bool done = true;
if (lastPageRequested != m_lastPageRequested) {
lastPageRequested = m_lastPageRequested;
forward = lastPageRequested;
backward = lastPageRequested - 1;
}
if (forward < m_doc->pageCount()) {
if (!m_pageCache.contains(forward))
insertPage(forward);
done = false;
}
if (backward >= 0) {
if (!m_pageCache.contains(backward))
insertPage(backward);
done = false;
}
++forward;
--backward;
if (done)
return;
}
}
void PageCache::insertPage(int page)
{
if (!m_pageCache.contains(page)) {
QSizeF size = m_doc->pageSize(page) * m_zoom;
QElapsedTimer timer; timer.start();
const QImage &img = m_doc->render(page, size);
qreal secs = timer.nsecsElapsed() / 1000000000.0;
if (secs < m_minRenderTime)
m_minRenderTime = secs;
if (secs > m_maxRenderTime)
m_maxRenderTime = secs;
m_totalRenderTime += secs;
++m_totalPagesRendered;
m_pageCache.insert(page, QPixmap::fromImage(img));
emit pageReady(page);
qCDebug(lcExample) << "page" << page << "zoom" << m_zoom << "size" << size << "in" << secs <<
"secs; min" << m_minRenderTime <<
"avg" << m_totalRenderTime / m_totalPagesRendered <<
"max" << m_maxRenderTime;
}
}
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