From 157b3e8e0aed03e2131c2900cffbb16e3ea34663 Mon Sep 17 00:00:00 2001
From: Shawn Rutledge <shawn.rutledge@theqtcompany.com>
Date: Mon, 15 Dec 2014 16:39:28 +0100
Subject: pdfviewer example: can scroll through pages and render on demand

---
 examples/widgets/pdfviewer/mainwindow.cpp          | 22 +++++++++-
 examples/widgets/pdfviewer/mainwindow.h            |  3 ++
 examples/widgets/pdfviewer/mainwindow.ui           | 25 +++++++----
 .../widgets/pdfviewer/sequentialpagewidget.cpp     | 48 ++++++++++++++++++----
 examples/widgets/pdfviewer/sequentialpagewidget.h  |  8 +++-
 5 files changed, 87 insertions(+), 19 deletions(-)

(limited to 'examples')

diff --git a/examples/widgets/pdfviewer/mainwindow.cpp b/examples/widgets/pdfviewer/mainwindow.cpp
index 1316dede1..e5b29edfd 100644
--- a/examples/widgets/pdfviewer/mainwindow.cpp
+++ b/examples/widgets/pdfviewer/mainwindow.cpp
@@ -4,6 +4,7 @@
 #include <QFileDialog>
 #include <QMessageBox>
 #include <QPdfDocument>
+#include "sequentialpagewidget.h"
 
 Q_LOGGING_CATEGORY(lcExample, "qt.examples.pdfviewer")
 
@@ -11,9 +12,13 @@ MainWindow::MainWindow(QWidget *parent)
     : QMainWindow(parent)
     , ui(new Ui::MainWindow)
     , m_doc(new QPdfDocument(this))
+    , m_pageWidget(new SequentialPageWidget(this))
 {
     ui->setupUi(this);
-    ui->pageWidget->setDocument(m_doc);
+    m_pageWidget->setDocument(m_doc);
+    ui->scrollArea->setWidget(m_pageWidget);
+    connect(m_pageWidget, SIGNAL(showingPageRange(int,int)),
+            this, SLOT(showingPageRange(int,int)), Qt::QueuedConnection);
 }
 
 MainWindow::~MainWindow()
@@ -29,11 +34,24 @@ void MainWindow::open(const QUrl &docLocation)
         qCDebug(lcExample) << docLocation << "is not a valid local file";
         QMessageBox::critical(this, tr("Failed to open"), tr("%1 is not a valid local file").arg(docLocation.toString()));
     }
+    // TODO: connect to signal from document
+    m_pageWidget->invalidate();
+    qCDebug(lcExample) << docLocation;
+    ui->scrollArea->ensureVisible(0, 0, 0, 0);
+}
+
+void MainWindow::showingPageRange(int start, int end)
+{
+    ui->statusBar->clearMessage();
+    if (start == end)
+        ui->statusBar->showMessage(tr("showing page %1").arg(start));
+    else
+        ui->statusBar->showMessage(tr("showing pages %1 to %2").arg(start).arg(end));
 }
 
 void MainWindow::on_actionOpen_triggered()
 {
-    QUrl toOpen = QFileDialog::getOpenFileUrl(this);
+    QUrl toOpen = QFileDialog::getOpenFileUrl(this, tr("Choose a PDF"), QUrl(), "Portable Documents (*.pdf)");
     if (toOpen.isValid())
         open(toOpen);
 }
diff --git a/examples/widgets/pdfviewer/mainwindow.h b/examples/widgets/pdfviewer/mainwindow.h
index e31f0b970..bcad93ebb 100644
--- a/examples/widgets/pdfviewer/mainwindow.h
+++ b/examples/widgets/pdfviewer/mainwindow.h
@@ -11,6 +11,7 @@ class MainWindow;
 }
 
 class QPdfDocument;
+class SequentialPageWidget;
 
 class MainWindow : public QMainWindow
 {
@@ -24,11 +25,13 @@ public slots:
     void open(const QUrl &docLocation);
 
 private slots:
+    void showingPageRange(int start, int end);
     void on_actionOpen_triggered();
 
 private:
     Ui::MainWindow *ui;
     QPdfDocument *m_doc;
+    SequentialPageWidget *m_pageWidget;
 };
 
 #endif // MAINWINDOW_H
diff --git a/examples/widgets/pdfviewer/mainwindow.ui b/examples/widgets/pdfviewer/mainwindow.ui
index 16994fa57..f1f90b307 100644
--- a/examples/widgets/pdfviewer/mainwindow.ui
+++ b/examples/widgets/pdfviewer/mainwindow.ui
@@ -16,7 +16,22 @@
   <widget class="QWidget" name="centralWidget">
    <layout class="QVBoxLayout" name="verticalLayout">
     <item>
-     <widget class="SequentialPageWidget" name="pageWidget" native="true"/>
+     <widget class="QScrollArea" name="scrollArea">
+      <property name="widgetResizable">
+       <bool>true</bool>
+      </property>
+      <widget class="QWidget" name="scrollAreaWidgetContents">
+       <property name="geometry">
+        <rect>
+         <x>0</x>
+         <y>0</y>
+         <width>380</width>
+         <height>210</height>
+        </rect>
+       </property>
+       <layout class="QVBoxLayout" name="verticalLayout_2"/>
+      </widget>
+     </widget>
     </item>
    </layout>
   </widget>
@@ -54,14 +69,6 @@
   </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
- <customwidgets>
-  <customwidget>
-   <class>SequentialPageWidget</class>
-   <extends>QWidget</extends>
-   <header>sequentialpagewidget.h</header>
-   <container>1</container>
-  </customwidget>
- </customwidgets>
  <resources/>
  <connections/>
 </ui>
diff --git a/examples/widgets/pdfviewer/sequentialpagewidget.cpp b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
index 5de4f2ee8..e7dd08746 100644
--- a/examples/widgets/pdfviewer/sequentialpagewidget.cpp
+++ b/examples/widgets/pdfviewer/sequentialpagewidget.cpp
@@ -14,25 +14,45 @@ SequentialPageWidget::SequentialPageWidget(QWidget *parent)
     , m_background(Qt::darkGray)
     , m_pageSpacing(3)
     , m_zoom(1.)
-    , m_top(0.)
     , m_screenResolution(QGuiApplication::primaryScreen()->logicalDotsPerInch() / 72.0)
 {
 }
 
 SequentialPageWidget::~SequentialPageWidget()
 {
-
 }
 
 void SequentialPageWidget::setDocument(QPdfDocument *doc)
 {
     m_doc = doc;
+    invalidate();
 }
 
 void SequentialPageWidget::setZoom(qreal factor)
 {
     m_zoom = factor;
+    invalidate();
+}
+
+QSizeF SequentialPageWidget::pageSize(int page)
+{
+    return m_doc->pageSize(page) * m_screenResolution * m_zoom;
+}
+
+void SequentialPageWidget::invalidate()
+{
     m_pageCache.clear();
+    QSizeF totalSize(0, m_pageSpacing);
+    for (int page = 0; page < m_doc->pageCount(); ++page) {
+        QSizeF size = pageSize(page);
+        qDebug() << "page" << page << "size" << size;
+        totalSize.setHeight(totalSize.height() + size.height());
+        if (size.width() > totalSize.width())
+            totalSize.setWidth(size.width());
+    }
+    m_totalSize = totalSize.toSize();
+    setMinimumSize(m_totalSize);
+    qCDebug(lcExample) << "total size" << m_totalSize;
     update();
 }
 
@@ -45,19 +65,33 @@ void SequentialPageWidget::paintEvent(QPaintEvent * event)
     }
 
     painter.fillRect(event->rect(), m_background);
-    qCDebug(lcExample) << event->rect() << m_doc->pageCount();
 
-    int page = 0; // qFloor(m_top);
-    int y = 0; // TODO event->rect().top();
+    // Find the first page that needs to be rendered
+    int page = 0;
+    int y = 0;
+    while (page < m_doc->pageCount()) {
+        QSizeF size = pageSize(page);
+        int height = size.toSize().height();
+        if (y + height >= event->rect().top())
+            break;
+        y += height;
+        ++page;
+    }
+    y += m_pageSpacing;
+    int startPage = page;
+
+    // Actually render pages
     while (y < event->rect().bottom() && page < m_doc->pageCount()) {
-        QSizeF size = m_doc->pageSize(page) * m_screenResolution * m_zoom;
         if (!m_pageCache.contains(page)) {
+            QSizeF size = pageSize(page);
             qCDebug(lcExample) << "rendering page" << page << "to size" << size;
             m_pageCache.insert(page, QPixmap::fromImage(m_doc->render(page, size)));
         }
         const QPixmap &pm = m_pageCache[page];
-        painter.drawPixmap(0, y, pm);
+        painter.drawPixmap((width() - pm.width()) / 2, y, pm);
         y += pm.height() + m_pageSpacing;
         ++page;
     }
+
+    emit showingPageRange(startPage, page - 1);
 }
diff --git a/examples/widgets/pdfviewer/sequentialpagewidget.h b/examples/widgets/pdfviewer/sequentialpagewidget.h
index 6741fe37e..44b27faad 100644
--- a/examples/widgets/pdfviewer/sequentialpagewidget.h
+++ b/examples/widgets/pdfviewer/sequentialpagewidget.h
@@ -2,6 +2,7 @@
 #define SEQUENTIALPAGEWIDGET_H
 
 #include <QWidget>
+#include <QDebug>
 
 class QPdfDocument;
 
@@ -17,8 +18,13 @@ public:
 public slots:
     void setDocument(QPdfDocument *doc);
     void setZoom(qreal factor);
+    void invalidate();
+
+signals:
+    void showingPageRange(int start, int end);
 
 private:
+    QSizeF pageSize(int page);
     void render(int page);
 
 private:
@@ -26,8 +32,8 @@ private:
     QHash<int, QPixmap> m_pageCache;
     QBrush m_background;
     int m_pageSpacing;
+    QSize m_totalSize;
     qreal m_zoom;
-    qreal m_top; // 1.5 means start from the bottom half of page 1
     qreal m_screenResolution; // pixels per point
 };
 
-- 
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