QtMessageLogView: Optimize performance

Performance is hit when rendering a large number of messages.
Show text contents that fits a line and expands to show the
complete text when clicked.

Change-Id: I803a8b2da12830172f9e75f86546adf121799a67
Reviewed-by: Kai Koehne <[email protected]>

5 files changed, 63 insertions, 34 deletions

diff --git a/src/plugins/debugger/qml/qmlengine.cpp b/src/plugins/debugger/qml/qmlengine.cpp
index 7b8557621b8..251fc4bb08d 100644
--- a/src/plugins/debugger/qml/qmlengine.cpp
+++ b/src/plugins/debugger/qml/qmlengine.cpp
@@ -1314,9 +1314,9 @@ QtMessageLogItem *QmlEngine::constructLogItemTree(
     QtMessageLogItem *item = new QtMessageLogItem(parent);
     if (result.type() == QVariant::Map) {
         if (key.isEmpty())
-            item->text = _("Object");
+            item->setText(_("Object"));
         else
-            item->text = QString(_("%1: Object")).arg(key);
+            item->setText(key + _(" : Object"));
 
         QMapIterator<QString, QVariant> i(result.toMap());
         while (i.hasNext()) {
@@ -1328,9 +1328,9 @@ QtMessageLogItem *QmlEngine::constructLogItemTree(
         }
     } else if (result.type() == QVariant::List) {
         if (key.isEmpty())
-            item->text = _("List");
+            item->setText(_("List"));
         else
-            item->text = QString(_("[%1] : List")).arg(key);
+            item->setText(QString(_("[%1] : List")).arg(key));
         QVariantList resultList = result.toList();
         for (int i = 0; i < resultList.count(); i++) {
             QtMessageLogItem *child = constructLogItemTree(item, resultList.at(i),
@@ -1339,9 +1339,9 @@ QtMessageLogItem *QmlEngine::constructLogItemTree(
                 item->insertChild(child);
         }
     } else if (result.canConvert(QVariant::String)) {
-        item->text = result.toString();
+        item->setText(result.toString());
     } else {
-        item->text = _("Unknown Value");
+        item->setText(_("Unknown Value"));
     }
 
     return item;
diff --git a/src/plugins/debugger/qtmessageloghandler.cpp b/src/plugins/debugger/qtmessageloghandler.cpp
index 3ca2d33bfa0..bd9874232e6 100644
--- a/src/plugins/debugger/qtmessageloghandler.cpp
+++ b/src/plugins/debugger/qtmessageloghandler.cpp
@@ -50,11 +50,11 @@ namespace Internal {
 QtMessageLogItem::QtMessageLogItem(QtMessageLogItem *parent,
                              QtMessageLogHandler::ItemType itemType, const QString &text)
     : m_parentItem(parent),
-      text(text),
       itemType(itemType),
       line(-1)
 
 {
+    setText(text);
 }
 
 QtMessageLogItem::~QtMessageLogItem()
@@ -105,7 +105,7 @@ void QtMessageLogItem::insertChild(QtMessageLogItem *item)
 
     int i = 0;
     for (; i < m_childItems.count(); i++) {
-        if (item->text < m_childItems[i]->text) {
+        if (item->m_text < m_childItems[i]->m_text) {
             break;
         }
     }
@@ -148,6 +148,20 @@ bool QtMessageLogItem::detachChild(int position)
     return true;
 }
 
+void QtMessageLogItem::setText(const QString &text)
+{
+    m_text = text;
+    for (int i = 0; i < m_text.length(); ++i) {
+        if (m_text.at(i).isPunct())
+            m_text.insert(++i, QChar(0x200b)); // ZERO WIDTH SPACE
+    }
+}
+
+const QString &QtMessageLogItem::text() const
+{
+    return m_text;
+}
+
 ///////////////////////////////////////////////////////////////////////
 //
 // QtMessageLogHandler
@@ -171,8 +185,8 @@ void QtMessageLogHandler::clear()
 {
     beginResetModel();
     reset();
-    qDeleteAll(m_rootItem->m_childItems);
-    m_rootItem->m_childItems.clear();
+    delete m_rootItem;
+    m_rootItem = new QtMessageLogItem(0);
     endResetModel();
 
     if (m_hasEditableRow)
@@ -262,7 +276,7 @@ QVariant QtMessageLogHandler::data(const QModelIndex &index, int role) const
     QtMessageLogItem *item = getItem(index);
 
     if (role == Qt::DisplayRole )
-        return item->text;
+        return item->text();
     else if (role == QtMessageLogHandler::TypeRole)
         return int(item->itemType);
     else if (role == QtMessageLogHandler::FileRole)
@@ -338,7 +352,7 @@ bool QtMessageLogHandler::setData(const QModelIndex &index, const QVariant &valu
     QtMessageLogItem *item = getItem(index);
     bool result = false;
     if (role == Qt::DisplayRole) {
-        item->text = value.toString();
+        item->setText(value.toString());
         result = true;
     } else if (role == QtMessageLogHandler::TypeRole) {
         item->itemType = (QtMessageLogHandler::ItemType)value.toInt();
diff --git a/src/plugins/debugger/qtmessageloghandler.h b/src/plugins/debugger/qtmessageloghandler.h
index 6e84f67a189..671dcd7aa45 100644
--- a/src/plugins/debugger/qtmessageloghandler.h
+++ b/src/plugins/debugger/qtmessageloghandler.h
@@ -132,19 +132,18 @@ public:
     bool removeChildren(int position, int count);
     bool detachChild(int position);
     int childNumber() const;
+    void setText(const QString &text);
+    const QString &text() const;
 
 private:
     QtMessageLogItem *m_parentItem;
     QList<QtMessageLogItem *> m_childItems;
+    QString m_text;
 
 public:
-    QString text;
     QtMessageLogHandler::ItemType itemType;
     QString file;
     int line;
-
-private:
-    friend class QtMessageLogHandler;
 };
 
 } //Internal
diff --git a/src/plugins/debugger/qtmessagelogitemdelegate.cpp b/src/plugins/debugger/qtmessagelogitemdelegate.cpp
index 48f3ad6c26d..ab51c9db6e3 100644
--- a/src/plugins/debugger/qtmessagelogitemdelegate.cpp
+++ b/src/plugins/debugger/qtmessagelogitemdelegate.cpp
@@ -73,7 +73,8 @@ QtMessageLogItemDelegate::QtMessageLogItemDelegate(QObject *parent) :
     m_expandIcon(QLatin1String(":/debugger/images/expand.png")),
     m_collapseIcon(QLatin1String(":/debugger/images/collapse.png")),
     m_prompt(QLatin1String(":/debugger/images/prompt.png")),
-    m_itemModel(0)
+    m_itemModel(0),
+    m_cachedHeight(0)
 {
 }
 
@@ -189,12 +190,18 @@ void QtMessageLogItemDelegate::paint(QPainter *painter, const QStyleOptionViewIt
     // Paint TextArea:
     // Layout the description
     QString str = index.data(Qt::DisplayRole).toString();
-    formatTextForWidth(str);
-    QTextLayout tl(str, opt.font);
     bool showFileLineInfo = true;
-    layoutText(tl, positions.textAreaWidth(), &showFileLineInfo);
-    tl.draw(painter, QPoint(positions.textAreaLeft(), positions.adjustedTop()));
-
+    // show complete text if selected
+    if (view->selectionModel()->currentIndex() == index) {
+        QTextLayout tl(str, opt.font);
+        layoutText(tl, positions.textAreaWidth(), &showFileLineInfo);
+        tl.draw(painter, QPoint(positions.textAreaLeft(), positions.adjustedTop()));
+    } else {
+        QFontMetrics fm(opt.font);
+        painter->drawText(positions.textArea(),
+                          fm.elidedText(str, Qt::ElideRight,
+                                        positions.textAreaWidth()));
+    }
     //skip if area is editable
     if (showExpandableIcon) {
         // Paint ExpandableIconArea:
@@ -267,6 +274,10 @@ QSize QtMessageLogItemDelegate::sizeHint(const QStyleOptionViewItem &option,
     if (index.flags() & Qt::ItemIsEditable)
         return QSize(width, view->height() * 1/2);
 
+    const bool selected = (view->selectionModel()->currentIndex() == index);
+    if (!selected && option.font == m_cachedFont && m_cachedHeight > 0)
+        return QSize(width, m_cachedHeight);
+
     QtMessageLogHandler::ItemType type = (QtMessageLogHandler::ItemType)index.data(
                 QtMessageLogHandler::TypeRole).toInt();
     bool showTypeIcon = index.parent() == QModelIndex();
@@ -277,14 +288,25 @@ QSize QtMessageLogItemDelegate::sizeHint(const QStyleOptionViewItem &option,
                         showTypeIcon, showExpandableIcon, m_itemModel);
 
     QFontMetrics fm(option.font);
-    QString str = index.data(Qt::DisplayRole).toString();
-    formatTextForWidth(str);
-    QTextLayout tl(str, option.font);
-    qreal height = layoutText(tl, positions.textAreaWidth());
+    qreal height = fm.height();
+
+    if (selected) {
+        QString str = index.data(Qt::DisplayRole).toString();
+
+        QTextLayout tl(str, option.font);
+        height = layoutText(tl, positions.textAreaWidth());
+    }
+
     height += 2 * ConsoleItemPositions::ITEM_PADDING;
+
     if (height < positions.minimumHeight())
         height = positions.minimumHeight();
 
+    if (!selected) {
+        m_cachedHeight = height;
+        m_cachedFont = option.font;
+    }
+
     return QSize(width, height);
 }
 
@@ -359,13 +381,6 @@ qreal QtMessageLogItemDelegate::layoutText(QTextLayout &tl, int width,
     return height;
 }
 
-void QtMessageLogItemDelegate::formatTextForWidth(QString &text) const
-{
-    for (int i = 0; i < text.length(); ++i) {
-        if (text.at(i).isPunct())
-            text.insert(++i, QChar(0x200b)); // ZERO WIDTH SPACE
-    }
-}
 void QtMessageLogItemDelegate::setItemModel(QtMessageLogHandler *model)
 {
     m_itemModel = model;
diff --git a/src/plugins/debugger/qtmessagelogitemdelegate.h b/src/plugins/debugger/qtmessagelogitemdelegate.h
index 3bca324f225..6050c038a6f 100644
--- a/src/plugins/debugger/qtmessagelogitemdelegate.h
+++ b/src/plugins/debugger/qtmessagelogitemdelegate.h
@@ -76,7 +76,6 @@ private slots:
 
 private:
     qreal layoutText(QTextLayout &tl, int width, bool *success = 0) const;
-    void formatTextForWidth(QString &text) const;
 
 private:
     const QIcon m_logIcon;
@@ -86,6 +85,8 @@ private:
     const QIcon m_collapseIcon;
     const QIcon m_prompt;
     QtMessageLogHandler *m_itemModel;
+    mutable int m_cachedHeight;
+    mutable QFont m_cachedFont;
 };
 
 /*