Fixed PDF export page size

In some cases, export of a document containing a PDF background to PDF
caused the contents to be truncated.

The "simple" PDF exporter will now set the output page size to be equal
either to the document nominal size or, if the document has a background
PDF item, to the size of this item.

src/adaptors/UBExportPDF.cpp

@@ -32,6 +32,7 @@
 #include <QtCore>
 #include <QtSvg>
 #include <QPrinter>
+#include <QPdfWriter>
 
 #include "core/UBApplication.h"
 #include "core/UBSettings.h"
@@ -40,6 +41,7 @@
 
 #include "domain/UBGraphicsScene.h"
 #include "domain/UBGraphicsSvgItem.h"
+#include "domain/UBGraphicsPDFItem.h"
 
 #include "document/UBDocumentProxy.h"
 
@@ -66,56 +68,67 @@ void UBExportPDF::persist(UBDocumentProxy* pDocumentProxy)
 
 bool UBExportPDF::persistsDocument(UBDocumentProxy* pDocumentProxy, const QString& filename)
 {
-    QPrinter pdfPrinter;
+    QPdfWriter pdfWriter(filename);
 
     qDebug() << "exporting document to PDF" << filename;
 
-    pdfPrinter.setOutputFormat(QPrinter::PdfFormat);
-    pdfPrinter.setResolution(UBSettings::settings()->pdfResolution->get().toInt());
-    pdfPrinter.setOutputFileName(filename);
-    pdfPrinter.setFullPage(true);
+    pdfWriter.setResolution(UBSettings::settings()->pdfResolution->get().toInt());
+    pdfWriter.setPageMargins(QMarginsF());
+    pdfWriter.setTitle(pDocumentProxy->name());
+    pdfWriter.setCreator("OpenBoard PDF export");
 
     //need to calculate screen resolution
     QDesktopWidget* desktop = UBApplication::desktop();
     int dpiCommon = (desktop->physicalDpiX() + desktop->physicalDpiY()) / 2;
     float scaleFactor = 72.0f / dpiCommon;
-    
+
     QPainter pdfPainter;
     bool painterNeedsBegin = true;
 
     int existingPageCount = pDocumentProxy->pageCount();
 
-    for(int pageIndex = 0 ; pageIndex < existingPageCount; pageIndex++)
-    {
+    for(int pageIndex = 0 ; pageIndex < existingPageCount; pageIndex++) {
+
         UBGraphicsScene* scene = UBPersistenceManager::persistenceManager()->loadDocumentScene(pDocumentProxy, pageIndex);
         UBApplication::showMessage(tr("Exporting page %1 of %2").arg(pageIndex + 1).arg(existingPageCount));
+
         // set background to white, no crossing for PDF output
         bool isDark = scene->isDarkBackground();
         bool isCrossed = scene->isCrossedBackground();
         scene->setBackground(false, false);
 
-        QSize pageSize = scene->nominalSize();
+        // pageSize is the output PDF page size; it is set to equal the scene's boundary size; if the contents
+        // of the scene overflow from the boundaries, they will be scaled down.
+        QSize pageSize = scene->sceneSize();
 
         // set high res rendering
         scene->setRenderingQuality(UBItem::RenderingQualityHigh);
         scene->setRenderingContext(UBGraphicsScene::NonScreen);
 
-        //setting page size to appropriate value
-        pdfPrinter.setPaperSize(QSizeF(pageSize.width()*scaleFactor, pageSize.height()*scaleFactor), QPrinter::Point);
-        if(painterNeedsBegin) painterNeedsBegin = !pdfPainter.begin(&pdfPrinter);
-        //render to PDF
-        scene->render(&pdfPainter, QRectF(), scene->normalizedSceneRect());
+        // Setting output page size
+        QPageSize outputPageSize = QPageSize(QSizeF(pageSize.width()*scaleFactor, pageSize.height()*scaleFactor), QPageSize::Point);
+        pdfWriter.setPageSize(outputPageSize);
 
-        if (pageIndex < existingPageCount - 1) pdfPrinter.newPage();
+        // Call begin only once
+        if(painterNeedsBegin)
+            painterNeedsBegin = !pdfPainter.begin(&pdfWriter);
 
-        //restore screen rendering quality
+        else if (pageIndex < existingPageCount)
+            pdfWriter.newPage();
+
+        // Render the scene
+        scene->render(&pdfPainter, QRectF(), scene->normalizedSceneRect());
+
+        // Restore screen rendering quality
         scene->setRenderingContext(UBGraphicsScene::Screen);
         scene->setRenderingQuality(UBItem::RenderingQualityNormal);
 
-        //restore background state
+        // Restore background state
         scene->setBackground(isDark, isCrossed);
     }
-    if(!painterNeedsBegin) pdfPainter.end();
+
+    if(!painterNeedsBegin)
+        pdfPainter.end();
 
     return true;
 }