Add QPdfDocument::pageLabel(int) and pageModel property

This API is available for both C++ and QML.

The pageModel makes it easier to populate item-views with per-page
information, such as thumbnails labeled with page labels.

Fixes: QTBUG-102271
Change-Id: I70df481b378efed0327e7bb89a63c7669daecc70
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

11 files changed, 168 insertions, 24 deletions

diff --git a/examples/pdf/multipage/viewer.qml b/examples/pdf/multipage/viewer.qml
index cf94c099b..3a12d9700 100644
--- a/examples/pdf/multipage/viewer.qml
+++ b/examples/pdf/multipage/viewer.qml
@@ -371,11 +371,13 @@ ApplicationWindow {
                     id: thumbnailsView
                     implicitWidth: parent.width
                     implicitHeight: parent.height
-                    model: doc.pageCount
+                    model: doc.pageModel
                     cellWidth: width / 2
                     cellHeight: cellWidth + 10
                     delegate: Item {
                         required property int index
+                        required property string label
+                        required property size pointSize
                         width: thumbnailsView.cellWidth
                         height: thumbnailsView.cellHeight
                         Rectangle {
@@ -390,11 +392,10 @@ ApplicationWindow {
                                 currentFrame: index
                                 asynchronous: true
                                 fillMode: Image.PreserveAspectFit
-                                property size naturalSize: doc.pagePointSize(index)
-                                property bool landscape: naturalSize.width > naturalSize.height
+                                property bool landscape: pointSize.width > pointSize.height
                                 width: landscape ? thumbnailsView.cellWidth - 6
-                                                 : height * naturalSize.width / naturalSize.height
-                                height: landscape ? width * naturalSize.height / naturalSize.width
+                                                 : height * pointSize.width / pointSize.height
+                                height: landscape ? width * pointSize.height / pointSize.width
                                                   : thumbnailsView.cellHeight - 14
                                 sourceSize.width: width
                                 sourceSize.height: height
@@ -404,7 +405,7 @@ ApplicationWindow {
                             id: pageNumber
                             anchors.bottom: parent.bottom
                             anchors.horizontalCenter: parent.horizontalCenter
-                            text: "Page " + (image.currentFrame + 1)
+                            text: label
                         }
                         TapHandler {
                             onTapped: view.goToPage(index)
diff --git a/src/pdf/qpdfdocument.cpp b/src/pdf/qpdfdocument.cpp
index 8e3cea2da..ee589d0e7 100644
--- a/src/pdf/qpdfdocument.cpp
+++ b/src/pdf/qpdfdocument.cpp
@@ -65,6 +65,52 @@ QPdfMutexLocker::QPdfMutexLocker()
 {
 }
 
+class Q_PDF_EXPORT QPdfPageModel : public QAbstractListModel
+{
+    Q_OBJECT
+public:
+    QPdfPageModel(QPdfDocument *doc) : QAbstractListModel(doc)
+    {
+        m_roleNames = QAbstractItemModel::roleNames();
+        QMetaEnum rolesMetaEnum = doc->metaObject()->enumerator(doc->metaObject()->indexOfEnumerator("PageModelRole"));
+        for (int r = Qt::UserRole; r < int(QPdfDocument::PageModelRole::_Count); ++r) {
+            auto name = QByteArray(rolesMetaEnum.valueToKey(r));
+            name[0] = tolower(name[0]);
+            m_roleNames.insert(r, name);
+        }
+        connect(doc, &QPdfDocument::statusChanged, this, [this](QPdfDocument::Status s) {
+            if (s == QPdfDocument::Status::Loading)
+                beginResetModel();
+            else if (s == QPdfDocument::Status::Ready)
+                endResetModel();
+        });
+    }
+
+    QVariant data(const QModelIndex &index, int role) const override
+    {
+        if (!index.isValid())
+            return QVariant();
+        switch (QPdfDocument::PageModelRole(role)) {
+        case QPdfDocument::PageModelRole::Label:
+            return document()->pageLabel(index.row());
+        case QPdfDocument::PageModelRole::PointSize:
+            return document()->pagePointSize(index.row());
+        case QPdfDocument::PageModelRole::_Count:
+            break;
+        }
+        return QVariant();
+    }
+
+    int rowCount(const QModelIndex & = QModelIndex()) const override { return document()->pageCount(); }
+
+    QHash<int, QByteArray> roleNames() const override { return m_roleNames; }
+
+private:
+    QPdfDocument *document() const { return static_cast<QPdfDocument *>(parent()); }
+
+    QHash<int, QByteArray> m_roleNames;
+};
+
 QPdfDocumentPrivate::QPdfDocumentPrivate()
     : avail(nullptr)
     , doc(nullptr)
@@ -127,6 +173,7 @@ void QPdfDocumentPrivate::clear()
     if (pageCount != 0) {
         pageCount = 0;
         emit q->pageCountChanged(pageCount);
+        emit q->pageModelChanged();
     }
 
     loadComplete = false;
@@ -220,6 +267,7 @@ void QPdfDocumentPrivate::load(QIODevice *newDevice, bool transferDeviceOwnershi
         if (newPageCount != pageCount) {
             pageCount = newPageCount;
             emit q->pageCountChanged(pageCount);
+            emit q->pageModelChanged();
         }
 
         // If it's a local file, and the first couple of pages are available,
@@ -349,6 +397,7 @@ void QPdfDocumentPrivate::checkComplete()
         if (newPageCount != pageCount) {
             pageCount = newPageCount;
             emit q->pageCountChanged(pageCount);
+            emit q->pageModelChanged();
         }
 
         setStatus(QPdfDocument::Status::Ready);
@@ -731,6 +780,57 @@ QSizeF QPdfDocument::pagePointSize(int page) const
 }
 
 /*!
+    \enum QPdfDocument::PageModelRole
+
+    Roles in pageModel().
+
+    \value Label The page number to be used for display purposes (QString).
+    \value PointSize The page size in points (1/72 of an inch) (QSizeF).
+    \omitvalue _Count
+*/
+
+/*!
+    \property QPdfDocument::pageModel
+
+    This property holds an instance of QAbstractListModel to provide
+    page-specific metadata, containing one row for each page in the document.
+
+    \sa QPdfDocument::PageModelRole
+*/
+QAbstractListModel *QPdfDocument::pageModel()
+{
+    if (!d->pageModel)
+        d->pageModel = new QPdfPageModel(this);
+    return d->pageModel;
+}
+
+/*!
+    Returns the \a page number to be used for display purposes.
+
+    For example, a document may have multiple sections with different numbering.
+    Perhaps the preface uses roman numerals, the body starts on page 1, and the
+    appendix starts at A1. Whenever a PDF viewer shows a page number, to avoid
+    confusing the user it should be the same "number" as is printed on the
+    corner of the page, rather than the zero-based page index that we use in
+    APIs (assuming the document author has made the page labels match the
+    printed numbers).
+
+    If the document does not have custom page numbering, this function returns
+    \c {page + 1}.
+*/
+QString QPdfDocument::pageLabel(int page)
+{
+    const unsigned long len = FPDF_GetPageLabel(d->doc, page, nullptr, 0);
+    if (len == 0)
+        return QString::number(page + 1);
+    QList<char16_t> buf(len);
+    QPdfMutexLocker lock;
+    FPDF_GetPageLabel(d->doc, page, buf.data(), len);
+    lock.unlock();
+    return QString::fromUtf16(buf.constData());
+}
+
+/*!
     Renders the \a page into a QImage of size \a imageSize according to the
     provided \a renderOptions.
 
@@ -964,4 +1064,5 @@ QPdfSelection QPdfDocument::getAllText(int page)
 
 QT_END_NAMESPACE
 
+#include "qpdfdocument.moc"
 #include "moc_qpdfdocument.cpp"
diff --git a/src/pdf/qpdfdocument.h b/src/pdf/qpdfdocument.h
index 02d8294ac..398b8e365 100644
--- a/src/pdf/qpdfdocument.h
+++ b/src/pdf/qpdfdocument.h
@@ -43,6 +43,7 @@
 #include <QtPdf/qtpdfglobal.h>
 
 #include <QtCore/qobject.h>
+#include <QtCore/QAbstractListModel>
 #include <QtGui/qimage.h>
 #include <QtPdf/qpdfdocumentrenderoptions.h>
 #include <QtPdf/qpdfselection.h>
@@ -59,6 +60,7 @@ class Q_PDF_EXPORT QPdfDocument : public QObject
     Q_PROPERTY(int pageCount READ pageCount NOTIFY pageCountChanged FINAL)
     Q_PROPERTY(QString password READ password WRITE setPassword NOTIFY passwordChanged FINAL)
     Q_PROPERTY(Status status READ status NOTIFY statusChanged FINAL)
+    Q_PROPERTY(QAbstractListModel* pageModel READ pageModel NOTIFY pageModelChanged FINAL)
 
 public:
     enum class Status {
@@ -93,6 +95,13 @@ public:
     };
     Q_ENUM(MetaDataField)
 
+    enum class PageModelRole {
+        Label = Qt::UserRole,
+        PointSize,
+        _Count
+    };
+    Q_ENUM(PageModelRole)
+
     QPdfDocument() : QPdfDocument(nullptr) {}
     explicit QPdfDocument(QObject *parent);
     ~QPdfDocument() override;
@@ -115,6 +124,10 @@ public:
 
     Q_INVOKABLE QSizeF pagePointSize(int page) const;
 
+    Q_INVOKABLE QString pageLabel(int page);
+
+    QAbstractListModel *pageModel();
+
     QImage render(int page, QSize imageSize, QPdfDocumentRenderOptions options = QPdfDocumentRenderOptions());
 
     Q_INVOKABLE QPdfSelection getSelection(int page, QPointF start, QPointF end);
@@ -126,11 +139,13 @@ Q_SIGNALS:
     void passwordRequired();
     void statusChanged(QPdfDocument::Status status);
     void pageCountChanged(int pageCount);
+    void pageModelChanged();
 
 private:
     friend struct QPdfBookmarkModelPrivate;
     friend class QPdfFile;
     friend class QPdfLinkModelPrivate;
+    friend class QPdfPageModel;
     friend class QPdfSearchModel;
     friend class QPdfSearchModelPrivate;
     friend class QQuickPdfSelection;
diff --git a/src/pdf/qpdfdocument_p.h b/src/pdf/qpdfdocument_p.h
index 4f8fc5993..3fc4c9926 100644
--- a/src/pdf/qpdfdocument_p.h
+++ b/src/pdf/qpdfdocument_p.h
@@ -71,6 +71,8 @@ public:
     QPdfMutexLocker();
 };
 
+class QPdfPageModel;
+
 class Q_PDF_PRIVATE_EXPORT QPdfDocumentPrivate: public FPDF_FILEACCESS, public FX_FILEAVAIL, public FX_DOWNLOADHINTS
 {
 public:
@@ -78,6 +80,7 @@ public:
     ~QPdfDocumentPrivate();
 
     QPdfDocument *q;
+    QPdfPageModel *pageModel = nullptr;
 
     FPDF_AVAIL avail;
     FPDF_DOCUMENT doc;
diff --git a/tests/auto/pdf/qpdfdocument/test.pdf b/tests/auto/pdf/qpdfdocument/test.pdf
new file mode 100644
index 000000000..0832dfbed
--- /dev/null
+++ b/tests/auto/pdf/qpdfdocument/test.pdf
diff --git a/tests/auto/pdf/qpdfdocument/tst_qpdfdocument.cpp b/tests/auto/pdf/qpdfdocument/tst_qpdfdocument.cpp
index b44edc703..df437349e 100644
--- a/tests/auto/pdf/qpdfdocument/tst_qpdfdocument.cpp
+++ b/tests/auto/pdf/qpdfdocument/tst_qpdfdocument.cpp
@@ -69,6 +69,7 @@ private slots:
     void status();
     void passwordClearedOnClose();
     void metaData();
+    void pageLabels();
 
 private:
     void consistencyCheck(QPdfDocument &doc) const;
@@ -415,6 +416,16 @@ void tst_QPdfDocument::metaData()
     QCOMPARE(doc.metaData(QPdfDocument::MetaDataField::ModificationDate).toDateTime(), QDateTime(QDate(2016, 8, 8), QTime(8, 3, 6), Qt::UTC));
 }
 
+void tst_QPdfDocument::pageLabels()
+{
+    QPdfDocument doc;
+    QCOMPARE(doc.load(QFINDTESTDATA("test.pdf")), QPdfDocument::Error::None);
+    QCOMPARE(doc.pageCount(), 3);
+    QCOMPARE(doc.pageLabel(0), "Qt");
+    QCOMPARE(doc.pageLabel(1), "1");
+    QCOMPARE(doc.pageLabel(2), "i"); // i of the tiger!
+}
+
 QTEST_MAIN(tst_QPdfDocument)
 
 #include "tst_qpdfdocument.moc"
diff --git a/tests/manual/quick/pdf/bookmarks-list.qml b/tests/manual/quick/pdf/bookmarks-list.qml
index a4c030ea5..fd6c38b54 100644
--- a/tests/manual/quick/pdf/bookmarks-list.qml
+++ b/tests/manual/quick/pdf/bookmarks-list.qml
@@ -87,11 +87,10 @@ ApplicationWindow {
                     width: parent.width
                     text: model.title
                     background: Item { }
-                    onClicked: image.currentFrame = pageNumber
+                    onClicked: image.currentFrame = page
                 }
                 model: PdfBookmarkModel {
                     document: root.doc
-                    structureMode: PdfBookmarkModel.ListMode
                 }
             }
         }
@@ -179,6 +178,6 @@ ApplicationWindow {
     }
     Text {
         anchors { bottom: parent.bottom; right: parent.right; margins: 6 }
-        text: "page " + (image.currentFrame + 1) + " of " + doc.pageCount
+        text: "page " + doc.pageLabel(image.currentFrame) + " of " + doc.pageCount
     }
 }
diff --git a/tests/manual/quick/pdf/bookmarks.qml b/tests/manual/quick/pdf/bookmarks.qml
index 0d7a84dee..230e3daf4 100644
--- a/tests/manual/quick/pdf/bookmarks.qml
+++ b/tests/manual/quick/pdf/bookmarks.qml
@@ -88,7 +88,7 @@ ApplicationWindow {
                 clip: true
                 delegate: TreeViewDelegate {
                     width: parent.width
-                    onClicked: image.currentFrame = pageNumber
+                    onClicked: image.currentFrame = page
                 }
                 model: PdfBookmarkModel {
                     document: root.doc
@@ -189,6 +189,6 @@ ApplicationWindow {
     }
     Label {
         anchors { bottom: parent.bottom; right: parent.right; margins: 6 }
-        text: "page " + (image.currentFrame + 1) + " of " + doc.pageCount
+        text: "page " + doc.pageLabel(image.currentFrame) + " of " + doc.pageCount
     }
 }
diff --git a/tests/manual/quick/pdf/gridview.qml b/tests/manual/quick/pdf/gridview.qml
index 48e34732a..4ad9e4676 100644
--- a/tests/manual/quick/pdf/gridview.qml
+++ b/tests/manual/quick/pdf/gridview.qml
@@ -68,10 +68,13 @@ Window {
         id: view
         anchors.fill: parent
         anchors.margins: 10
-        model: doc.pageCount
+        model: doc.pageModel
         cellWidth: cellSize
         cellHeight: cellSize
         delegate: Item {
+            required property int index
+            required property string label
+            required property size pointSize
             width: view.cellWidth
             height: view.cellHeight
             Rectangle {
@@ -86,10 +89,11 @@ Window {
                     currentFrame: index
                     asynchronous: true
                     fillMode: Image.PreserveAspectFit
-                    property size naturalSize: doc.pagePointSize(index)
-                    property bool landscape: naturalSize.width > naturalSize.height
-                    width: landscape ? Math.min(view.cellWidth, naturalSize.width) : height * naturalSize.width / naturalSize.height
-                    height: landscape ? width * naturalSize.height / naturalSize.width : Math.min(view.cellHeight - pageNumber.height, naturalSize.height)
+                    property bool landscape: pointSize.width > pointSize.height
+                    width: landscape ? Math.min(view.cellWidth, pointSize.width)
+                                     : height * pointSize.width / pointSize.height
+                    height: landscape ? width * pointSize.height / pointSize.width
+                                      : Math.min(view.cellHeight - pageNumber.height, pointSize.height)
                     sourceSize.width: width
                     sourceSize.height: height
                 }
@@ -98,7 +102,7 @@ Window {
                 id: pageNumber
                 anchors.bottom: parent.bottom
                 anchors.horizontalCenter: parent.horizontalCenter
-                text: "Page " + (image.currentFrame + 1)
+                text: "Page " + label
             }
         }
     }
diff --git a/tests/manual/quick/pdf/listview.qml b/tests/manual/quick/pdf/listview.qml
index 65da5d483..3201908ac 100644
--- a/tests/manual/quick/pdf/listview.qml
+++ b/tests/manual/quick/pdf/listview.qml
@@ -81,7 +81,7 @@ Window {
                 }
             }
             Text {
-                text: "Page " + (image.currentFrame + 1)
+                text: "Page " + doc.pageLabel(image.currentFrame)
             }
         }
     }
diff --git a/tests/manual/quick/pdf/pdfPageView.qml b/tests/manual/quick/pdf/pdfPageView.qml
index 393d1f774..7038e61d0 100644
--- a/tests/manual/quick/pdf/pdfPageView.qml
+++ b/tests/manual/quick/pdf/pdfPageView.qml
@@ -136,18 +136,28 @@ ApplicationWindow {
             }
             SpinBox {
                 id: currentPageSB
-                from: 1
+                from: 0
                 to: document.pageCount
                 editable: true
-                value: pageView.currentPage + 1
-                onValueModified: pageView.goToPage(value - 1)
+                value: pageView.currentPage
+                onValueModified: pageView.goToPage(value)
+
+                textFromValue: function(value) { return document.pageLabel(value) }
+                valueFromText: function(text) {
+                    for (var i = 0; i < document.pageCount; ++i) {
+                        if (document.pageLabel(i).toLowerCase().indexOf(text.toLowerCase()) === 0)
+                            return i
+                    }
+                    return spinBox.value
+                }
+
                 Shortcut {
                     sequence: StandardKey.MoveToPreviousPage
-                    onActivated: pageView.goToPage(currentPageSB.value - 2)
+                    onActivated: pageView.goToPage(currentPageSB.value - 1)
                 }
                 Shortcut {
                     sequence: StandardKey.MoveToNextPage
-                    onActivated: pageView.goToPage(currentPageSB.value)
+                    onActivated: pageView.goToPage(currentPageSB.value + 1)
                 }
             }
             ToolButton {
@@ -331,7 +341,7 @@ ApplicationWindow {
                 ScrollBar.vertical: ScrollBar { }
                 delegate: ItemDelegate {
                     width: parent ? parent.width : 0
-                    text: "page " + (page + 1) + ": " + contextBefore + pageView.searchString + contextAfter
+                    text: "page " + document.pageLabel(page) + ": " + contextBefore + pageView.searchString + contextAfter
                     highlighted: ListView.isCurrentItem
                     onClicked: {
                         searchResultsList.currentIndex = index