pdfviewer example: PageRenderer owns document and thread. Smooth

PageCache renamed to PageRenderer and minimized to just being a
worker thread.  The UI is finally responsive, biecause the locking in
QPdfDocument is isolated behind PageRenderer.
ATM only renders visible pages though.

1 files changed, 41 insertions, 33 deletions

diff --git a/examples/widgets/pdfviewer/sequentialpagewidget.cpp b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
index da880be..2f4e3fb 100644
--- a/examples/widgets/pdfviewer/sequentialpagewidget.cpp
+++ b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
@@ -1,5 +1,5 @@
 #include "sequentialpagewidget.h"
-#include "pagecache.h"
+#include "pagerenderer.h"
 #include <QPaintEvent>
 #include <QPainter>
 #include <QPdfDocument>
@@ -12,30 +12,27 @@ Q_DECLARE_LOGGING_CATEGORY(lcExample)
 
 SequentialPageWidget::SequentialPageWidget(QWidget *parent)
     : QWidget(parent)
-    , m_doc(Q_NULLPTR)
-    , m_pageCache(Q_NULLPTR)
+    , m_pageRenderer(new PageRenderer())
     , m_background(Qt::darkGray)
-    , m_pageSpacing(3)
     , m_placeholderIcon(":icons/images/busy.png")
     , m_placeholderBackground(Qt::white)
+    , m_pageSpacing(3)
     , m_topPageShowing(0)
     , m_zoom(1.)
     , m_screenResolution(QGuiApplication::primaryScreen()->logicalDotsPerInch() / 72.0)
 {
+    connect(m_pageRenderer, SIGNAL(pageReady(int, qreal, QImage)), this, SLOT(pageLoaded(int, qreal, QImage)), Qt::QueuedConnection);
 }
 
 SequentialPageWidget::~SequentialPageWidget()
 {
+    delete m_pageRenderer;
 }
 
-void SequentialPageWidget::setDocument(QPdfDocument *doc)
+void SequentialPageWidget::openDocument(const QUrl &url)
 {
-    m_doc = doc;
+    m_pageSizes = m_pageRenderer->openDocument(url);
     m_topPageShowing = 0;
-    if (m_pageCache)
-        delete m_pageCache;
-    m_pageCache = new PageCache(doc, m_screenResolution * m_zoom);
-    connect(m_pageCache, SIGNAL(pageReady(int)), this, SLOT(update()));
     invalidate();
 }
 
@@ -48,20 +45,19 @@ void SequentialPageWidget::setZoom(qreal factor)
 
 QSizeF SequentialPageWidget::pageSize(int page)
 {
-    return m_doc->pageSize(page) * m_screenResolution * m_zoom;
+//    if (!m_pageSizes.length() <= page)
+//        return QSizeF();
+    return m_pageSizes[page] * m_screenResolution * m_zoom;
 }
 
 void SequentialPageWidget::invalidate()
 {
-    if (m_pageCache)
-        delete m_pageCache;
-    if (m_doc)
-        m_pageCache = new PageCache(m_doc, m_screenResolution * m_zoom);
-    connect(m_pageCache, SIGNAL(pageReady(int)), this, SLOT(update()));
     QSizeF totalSize(0, m_pageSpacing);
-    for (int page = 0; page < m_doc->pageCount(); ++page) {
+qDebug() << "pageCount" << pageCount();
+
+    for (int page = 0; page < pageCount(); ++page) {
         QSizeF size = pageSize(page);
-        qDebug() << "page" << page << "size" << size;
+        qDebug() << "page" << page << "size" << size << "from" << m_pageSizes[page];
         totalSize.setHeight(totalSize.height() + size.height());
         if (size.width() > totalSize.width())
             totalSize.setWidth(size.width());
@@ -73,20 +69,30 @@ void SequentialPageWidget::invalidate()
     update();
 }
 
+void SequentialPageWidget::pageLoaded(int page, qreal zoom, QImage image)
+{
+    Q_UNUSED(zoom)
+    m_pageCache.insert(page, image);
+    update();
+}
+
+int SequentialPageWidget::pageCount()
+{
+    return m_pageSizes.count();
+}
+
 void SequentialPageWidget::paintEvent(QPaintEvent * event)
 {
     QPainter painter(this);
-    if (!m_doc) {
-        painter.drawText(rect(), Qt::AlignCenter, tr("no document loaded"));
-        return;
-    }
-
     painter.fillRect(event->rect(), m_background);
 
+    if (m_pageSizes.isEmpty())
+        return;
+
     // Find the first page that needs to be rendered
     int page = 0;
     int y = 0;
-    while (page < m_doc->pageCount()) {
+    while (page < pageCount()) {
         QSizeF size = pageSize(page);
         int height = size.toSize().height();
         if (y + height >= event->rect().top())
@@ -96,20 +102,22 @@ void SequentialPageWidget::paintEvent(QPaintEvent * event)
     }
     y += m_pageSpacing;
     m_topPageShowing = page;
-    if (!m_pageCache) return;
+
+qDebug() << y << m_topPageShowing << pageCount();
 
     // Actually render pages
-    while (y < event->rect().bottom() && page < m_doc->pageCount()) {
-        const QPixmap &pm = m_pageCache->get(page);
-        if (pm.isNull()) {
-            QSizeF size = pageSize(page);
+    while (y < event->rect().bottom() && page < pageCount()) {
+        QSizeF size = pageSize(page);
+        if (m_pageCache.contains(page)) {
+            const QImage &img = m_pageCache[page];
+            painter.drawImage((width() - img.width()) / 2, y, img);
+        } else {
             painter.fillRect((width() - size.width()) / 2, y, size.width(), size.height(), m_placeholderBackground);
             painter.drawPixmap((size.width() - m_placeholderIcon.width()) / 2,
                                (size.height() - m_placeholderIcon.height()) / 2, m_placeholderIcon);
-        } else {
-            painter.drawPixmap((width() - pm.width()) / 2, y, pm);
+            m_pageRenderer->requestPage(page, m_screenResolution * m_zoom);
         }
-        y += pm.height() + m_pageSpacing;
+        y += size.height() + m_pageSpacing;
         ++page;
     }
     m_bottomPageShowing = page - 1;
@@ -120,7 +128,7 @@ qreal SequentialPageWidget::yForPage(int endPage)
 {
     // TODO maybe put this loop into a page iterator class
     int y = m_pageSpacing;
-    for (int page = 0; page < m_doc->pageCount() && page < endPage; ++page) {
+    for (int page = 0; page < pageCount() && page < endPage; ++page) {
         QSizeF size = pageSize(page);
         int height = size.toSize().height();
         y += height + m_pageSpacing;