diff --git a/src/core/GridMesh.cpp b/src/core/GridMesh.cpp
index 068eadf7..08faae1f 100644
--- a/src/core/GridMesh.cpp
+++ b/src/core/GridMesh.cpp
@@ -624,7 +624,10 @@ bool GridMesh::deserialize(Deserializer& aIn)
     {
         // note: the bug on version 0.4 or lower. mVertexRect doesn't be serialized.
         auto positions = mPositions.data();
-        float l, t, r, b = 0.0f;
+        float l = 0.0f;
+        float t = 0.0f;
+        float r = 0.0f;
+        float b = 0.0f;
         for (int i = 0; i < mVertexCount; ++i)
         {
             auto pos = positions[i];
diff --git a/src/core/TimeFormat.cpp b/src/core/TimeFormat.cpp
index f07dada9..0a6c48db 100644
--- a/src/core/TimeFormat.cpp
+++ b/src/core/TimeFormat.cpp
@@ -17,8 +17,9 @@ const QString TimeFormat::frameToString(const int aFrame, const TimeFormatType a
         return QString::number(aFrame+1);
 
     case TimeFormatType_Relative_FPS: {
-        QString number;
-        return number.sprintf("%.1f", static_cast<double>(aFrame) / mFps);
+        QString number = QString("%1")
+            .arg(static_cast<double>(aFrame) / mFps, 0, 'f');
+        return number;
     }
 
     case TimeFormatType_Seconds_Frames: { // (SS:FF)
@@ -31,10 +32,9 @@ const QString TimeFormat::frameToString(const int aFrame, const TimeFormatType a
         int rangeMaxSeconds = static_cast<int>(util::MathUtil::remap(mRange.max(),min,max,nMin,nMax));
         double seconds = util::MathUtil::remap(aFrame,min,max,nMin,nMax);
 
-        QString n;
-        n.sprintf("%0*d:%02d",
-                  QString::number(rangeMaxSeconds).length(), static_cast<int>(seconds),
-                  static_cast<int>(util::MathUtil::cycle(aFrame, 0.0, 60.0)));
+        QString n = QString("%1:%2")
+            .arg(static_cast<int>(seconds), rangeMaxSeconds, 10, QLatin1Char('0'))
+            .arg(static_cast<int>(util::MathUtil::cycle(aFrame, 0.0, 60.0)), 2, 10, QLatin1Char('0'));
 
         return n;
     }
@@ -50,10 +50,11 @@ const QString TimeFormat::frameToString(const int aFrame, const TimeFormatType a
 
         DDHHMMSSmmm timeStruct = msToDDHHMMSSmmm(ms);
 
-        QString n;
-        n.sprintf("%02d:%02d:%02d:%02d",
-                  timeStruct.hours, timeStruct.minutes,timeStruct.seconds,
-                  static_cast<int>(util::MathUtil::cycle(aFrame, 0.0, 60.0)));
+        QString n = QString("%1:%2:%3:%4")
+            .arg(timeStruct.hours, 2, 10, QLatin1Char('0'))
+            .arg(timeStruct.minutes, 2, 10, QLatin1Char('0'))
+            .arg(timeStruct.seconds, 2, 10, QLatin1Char('0'))
+            .arg(static_cast<int>(util::MathUtil::cycle(aFrame, 0.0, 60.0)), 2, 10, QLatin1Char('0'));
 
         return n;
     }
@@ -69,8 +70,11 @@ const QString TimeFormat::frameToString(const int aFrame, const TimeFormatType a
 
         DDHHMMSSmmm timeStruct = msToDDHHMMSSmmm(ms);
 
-        QString n;
-        n.sprintf("%02d:%02d:%02d:%03d", timeStruct.hours, timeStruct.minutes,timeStruct.seconds,timeStruct.milliseconds);
+        QString n = QString("%1:%2:%3:%4")
+            .arg(timeStruct.hours, 2, 10, QLatin1Char('0'))
+            .arg(timeStruct.minutes, 2, 10, QLatin1Char('0'))
+            .arg(timeStruct.seconds, 2, 10, QLatin1Char('0'))
+            .arg(timeStruct.milliseconds, 3, 10, QLatin1Char('0'));
 
         return n;
     }
diff --git a/src/ctrl/Exporter.cpp b/src/ctrl/Exporter.cpp
index db09f5b0..2bf7eba7 100644
--- a/src/ctrl/Exporter.cpp
+++ b/src/ctrl/Exporter.cpp
@@ -125,7 +125,11 @@ bool Exporter::FFMpeg::start(const QString& aArgments)
         this->mFinished = true;
     });
 
-    mProcess->start(program + " " + aArgments, QIODevice::ReadWrite);
+    // TODO improve the arguments build process
+    QStringList arguments;
+    arguments = aArgments.split(' ');
+
+    mProcess->start(program, arguments, QIODevice::ReadWrite);
 
     return !mErrorOccurred;
 }
diff --git a/src/ctrl/Painter.cpp b/src/ctrl/Painter.cpp
index c146648b..231293d1 100644
--- a/src/ctrl/Painter.cpp
+++ b/src/ctrl/Painter.cpp
@@ -184,7 +184,7 @@ void GLCorePaintEngine::drawImage(
         auto cache = new TextureCaches::Cache();
         cache->obj.reset(new QOpenGLTexture(ptr->mirrored()));
         cache->key = key;
-        cache->size = (size_t)ptr->byteCount();
+        cache->size = (size_t)ptr->sizeInBytes();
 
         cache->obj->setMinificationFilter(QOpenGLTexture::LinearMipMapLinear);
         cache->obj->setMagnificationFilter(QOpenGLTexture::Linear);
@@ -207,7 +207,7 @@ void GLCorePaintEngine::drawPixmap(const QRectF& aRect, const QPixmap& aPixmap,
             auto image = ptr->toImage();
             cache->obj.reset(new QOpenGLTexture(image.mirrored()));
             cache->key = key;
-            cache->size = (size_t)image.byteCount();
+            cache->size = (size_t)image.sizeInBytes();
 
             cache->obj->setMinificationFilter(QOpenGLTexture::LinearMipMapLinear);
             cache->obj->setMagnificationFilter(QOpenGLTexture::Linear);
diff --git a/src/ctrl/TimeLineUtil.cpp b/src/ctrl/TimeLineUtil.cpp
index cad79d5f..f35e604a 100644
--- a/src/ctrl/TimeLineUtil.cpp
+++ b/src/ctrl/TimeLineUtil.cpp
@@ -30,7 +30,7 @@ MoveFrameOfKey::MoveFrameOfKey(const TimeLineEvent& aCommandEvent)
         mSortedTargets.push_back(target);
     }
     // sort targets for the purpose of the move with no conflict.
-    qSort(mSortedTargets.begin(), mSortedTargets.end(), lessThan);
+    std::sort(mSortedTargets.begin(), mSortedTargets.end(), lessThan);
 }
 
 bool MoveFrameOfKey::lessThan(const TimeLineEvent::Target& aLhs, const TimeLineEvent::Target& aRhs)
diff --git a/src/gl/FontDrawer.cpp b/src/gl/FontDrawer.cpp
index 30599193..6713845a 100644
--- a/src/gl/FontDrawer.cpp
+++ b/src/gl/FontDrawer.cpp
@@ -2,6 +2,8 @@
 #include "gl/Global.h"
 #include "gl/Util.h"
 
+#include <QPainterPath>
+
 namespace
 {
 static const int kAttachmentId = 0;
diff --git a/src/gui/MainDisplayWidget.cpp b/src/gui/MainDisplayWidget.cpp
index bb974e4c..b3cff8cb 100644
--- a/src/gui/MainDisplayWidget.cpp
+++ b/src/gui/MainDisplayWidget.cpp
@@ -461,7 +461,7 @@ void MainDisplayWidget::mouseReleaseEvent(QMouseEvent* aEvent)
 
 void MainDisplayWidget::wheelEvent(QWheelEvent* aEvent)
 {
-    if (mCanvasMover.updateByWheel(QVector2D(aEvent->pos()), aEvent->delta(),
+    if (mCanvasMover.updateByWheel(QVector2D(aEvent->position()), aEvent->angleDelta().y(),
                                    mViaPoint.mouseSetting().invertMainViewScaling))
     {
         updateRender();
diff --git a/src/gui/ObjectTreeWidget.cpp b/src/gui/ObjectTreeWidget.cpp
index d411f1b2..4969d048 100644
--- a/src/gui/ObjectTreeWidget.cpp
+++ b/src/gui/ObjectTreeWidget.cpp
@@ -849,7 +849,7 @@ void ObjectTreeWidget::rowsAboutToBeRemoved(const QModelIndex& aParent, int aSta
     if (mStoreInsert)
     {
         XC_ASSERT(aStart == aEnd);
-        QTreeWidgetItem* item = this->itemFromIndex(aParent.child(aStart, kItemColumn));
+        QTreeWidgetItem* item = this->itemFromIndex(aParent.model()->index(aStart, kItemColumn, aParent));
         util::TreePos removePos(this->indexFromItem(item));
         XC_ASSERT(removePos.isValid());
         //qDebug() << "remove"; removePos.dump();
@@ -885,7 +885,7 @@ void ObjectTreeWidget::rowsInserted(const QModelIndex& aParent, int aStart, int
     if (mStoreInsert)
     {
         XC_ASSERT(aStart == aEnd);
-        QTreeWidgetItem* item = this->itemFromIndex(aParent.child(aStart, kItemColumn));
+        QTreeWidgetItem* item = this->itemFromIndex(aParent.model()->index(aStart, kItemColumn, aParent));
         util::TreePos insertPos(this->indexFromItem(item));
         XC_ASSERT(insertPos.isValid());
         //qDebug() << "insert"; insertPos.dump();
diff --git a/src/gui/TimeLineEditorWidget.cpp b/src/gui/TimeLineEditorWidget.cpp
index 3566e51c..d8c7fca7 100644
--- a/src/gui/TimeLineEditorWidget.cpp
+++ b/src/gui/TimeLineEditorWidget.cpp
@@ -230,7 +230,7 @@ bool TimeLineEditorWidget::updateCursor(const core::AbstractCursor& aCursor)
 
 void TimeLineEditorWidget::updateWheel(QWheelEvent* aEvent)
 {
-    mEditor->updateWheel(aEvent->delta(), mViaPoint.mouseSetting().invertTimeLineScaling);
+    mEditor->updateWheel(aEvent->angleDelta().y(), mViaPoint.mouseSetting().invertTimeLineScaling);
     updateSize();
 }
 
diff --git a/src/gui/TimeLineWidget.cpp b/src/gui/TimeLineWidget.cpp
index 0d393119..0db4b32b 100644
--- a/src/gui/TimeLineWidget.cpp
+++ b/src/gui/TimeLineWidget.cpp
@@ -245,7 +245,7 @@ void TimeLineWidget::mouseDoubleClickEvent(QMouseEvent* aEvent)
 void TimeLineWidget::wheelEvent(QWheelEvent* aEvent)
 {
     QPoint viewTrans = viewportTransform();
-    const QPoint cursor = aEvent->pos();
+    const QPoint cursor = aEvent->position().toPoint();
     const QRect rectPrev = mInner->rect();
 
     mInner->updateWheel(aEvent);
diff --git a/src/gui/TimeLineWidget.h b/src/gui/TimeLineWidget.h
index 9f4762c7..b46b75c3 100644
--- a/src/gui/TimeLineWidget.h
+++ b/src/gui/TimeLineWidget.h
@@ -78,7 +78,7 @@ class TimeLineWidget : public QScrollArea
 
     // for animation
     QTimer mTimer;
-    QTime mElapsed;
+    QElapsedTimer mElapsed;
     core::Frame mBeginFrame;
     core::Frame mLastFrame;
     bool mDoesLoop;
diff --git a/src/gui/tool/tool_FlowLayout.cpp b/src/gui/tool/tool_FlowLayout.cpp
index 7943f700..3c7192d6 100644
--- a/src/gui/tool/tool_FlowLayout.cpp
+++ b/src/gui/tool/tool_FlowLayout.cpp
@@ -62,11 +62,6 @@ QLayoutItem* FlowLayout::takeAt(int aIndex)
     return mItemList.takeAt(aIndex);
 }
 
-Qt::Orientations FlowLayout::expandingDirections() const
-{
-    return 0;
-}
-
 bool FlowLayout::hasHeightForWidth() const
 {
     return true;
diff --git a/src/gui/tool/tool_FlowLayout.h b/src/gui/tool/tool_FlowLayout.h
index f7cd1f58..3ea00928 100644
--- a/src/gui/tool/tool_FlowLayout.h
+++ b/src/gui/tool/tool_FlowLayout.h
@@ -20,7 +20,6 @@ class FlowLayout : public QLayout
     void addItem(QLayoutItem* aItem);
     int horizontalSpacing() const;
     int verticalSpacing() const;
-    Qt::Orientations expandingDirections() const;
     bool hasHeightForWidth() const;
     int heightForWidth(int) const;
     int count() const;
diff --git a/src/gui/tool/tool_ModePanel.cpp b/src/gui/tool/tool_ModePanel.cpp
index 7925a5e4..69c7bd42 100644
--- a/src/gui/tool/tool_ModePanel.cpp
+++ b/src/gui/tool/tool_ModePanel.cpp
@@ -63,9 +63,11 @@ void ModePanel::pushButton(ctrl::ToolType aId)
 
 int ModePanel::updateGeometry(const QPoint& aPos, int aWidth)
 {
-    int l, t, r, b;
-    this->getContentsMargins(&l, &t, &r, &b);
-
+    QMargins margins = this->contentsMargins();
+    int l = margins.left();
+    int r = margins.right();
+    int b = margins.bottom();
+ 
     auto height = mLayout.heightForWidth(aWidth - l - r);
     this->setGeometry(aPos.x(), aPos.y(), aWidth, height + b);
 
diff --git a/src/gui/tool/tool_ViewPanel.cpp b/src/gui/tool/tool_ViewPanel.cpp
index 403c978a..5fbd3ed9 100644
--- a/src/gui/tool/tool_ViewPanel.cpp
+++ b/src/gui/tool/tool_ViewPanel.cpp
@@ -33,8 +33,10 @@ void ViewPanel::addButton(const QString& aIconName, bool aCheckable,
 
 int ViewPanel::updateGeometry(const QPoint& aPos, int aWidth)
 {
-    int l, t, r, b;
-    this->getContentsMargins(&l, &t, &r, &b);
+    QMargins margins = this->contentsMargins();
+    int l = margins.left();
+    int r = margins.right();
+    int b = margins.bottom();
 
     auto height = mLayout.heightForWidth(aWidth - l - r);
     this->setGeometry(aPos.x(), aPos.y(), aWidth, height + b);
diff --git a/src/img/Util.cpp b/src/img/Util.cpp
index b6b90250..41d59a2a 100644
--- a/src/img/Util.cpp
+++ b/src/img/Util.cpp
@@ -261,7 +261,7 @@ std::pair<XCMemBlock, QRect> Util::createTextureImage(const QImage& aImage)
         return std::pair<XCMemBlock, QRect>(block, QRect(0, 0, 1, 1));
     }
 
-    const size_t length = (size_t)aImage.byteCount();
+    const size_t length = (size_t)aImage.sizeInBytes();
 
     XCMemBlock workImage;
     workImage.size = length;
diff --git a/src/util/MathUtil.cpp b/src/util/MathUtil.cpp
index e5a1e5b1..8f73484e 100644
--- a/src/util/MathUtil.cpp
+++ b/src/util/MathUtil.cpp
@@ -34,7 +34,7 @@ float MathUtil::getClockwiseRotationRad(const QVector2D& aFrom, const QVector2D&
 
     const float from = getAngleRad(aFrom);
     const float to = getAngleRad(aTo);
-    const double rotate = static_cast<const double>(to - from);
+    const double rotate = static_cast<double>(to - from);
     return static_cast<float>(rotate < 0 ? rotate : (rotate - 2.0 * M_PI));
 }
 
diff --git a/src/util/TreePos.cpp b/src/util/TreePos.cpp
index f455815c..0c930e00 100644
--- a/src/util/TreePos.cpp
+++ b/src/util/TreePos.cpp
@@ -123,8 +123,8 @@ void TreePos::dump() const
     QString text;
     for (size_t i = 0; i < mRows.size(); ++i)
     {
-        QString row;
-        row.sprintf("%d,", mRows[i]);
+        QString row = QString("%1,")
+            .arg(mRows[i]);
         text += row;
     }
     qDebug() << text;