Axis formatter customization example

Also refactored the formatter api somewhat:

- Removed virtual from allowNegatives and allowZero and added a
setter function for those. This will make it cleaner if we need to
add similar properties to the axis formatter in the future, as
no new virtual methods can be added without breaking BC.

- Changed the labelValues array to labelStrings list, as it makes
more sense to directly format the strings in recalculate.

Change-Id: I3ea005afa984bb756845ca356b999762e0807415
Reviewed-by: Tomi Korpipää <tomi.korpipaa@digia.com>

1 files changed, 48 insertions, 39 deletions

diff --git a/src/datavisualization/axis/qvalue3daxisformatter.cpp b/src/datavisualization/axis/qvalue3daxisformatter.cpp
index 92940a1b..4cd84d88 100644
--- a/src/datavisualization/axis/qvalue3daxisformatter.cpp
+++ b/src/datavisualization/axis/qvalue3daxisformatter.cpp
@@ -75,12 +75,28 @@ QValue3DAxisFormatter::~QValue3DAxisFormatter()
 }
 
 /*!
+ * Allow the parent axis to have negative values if \a allow is true.
+ */
+void QValue3DAxisFormatter::setAllowNegatives(bool allow)
+{
+    d_ptr->m_allowNegatives = allow;
+}
+
+/*!
  * \return \c true if negative values are valid values for parent axis.
  * The default implementation always returns true.
  */
 bool QValue3DAxisFormatter::allowNegatives() const
 {
-    return true;
+    return d_ptr->m_allowNegatives;
+}
+
+/*!
+ * Allow the parent axis to have zero value if \a allow is true.
+ */
+void QValue3DAxisFormatter::setAllowZero(bool allow)
+{
+    d_ptr->m_allowZero = allow;
 }
 
 /*!
@@ -89,7 +105,7 @@ bool QValue3DAxisFormatter::allowNegatives() const
  */
 bool QValue3DAxisFormatter::allowZero() const
 {
-    return true;
+    return d_ptr->m_allowZero;
 }
 
 /*!
@@ -104,16 +120,16 @@ QValue3DAxisFormatter *QValue3DAxisFormatter::createNewInstance() const
 }
 
 /*!
- * This method resizes and populates the label and grid line position arrays and the label value
+ * This method resizes and populates the label and grid line position arrays and the label strings
  * array, as well as calculates any values needed for mapping between value and position.
  * It is allowed to access the parent axis from inside this function.
  *
- * This method must be reimplemented in a subclass.
+ * This method must be reimplemented in a subclass if the default array contents are not suitable.
  *
- * See gridPositions(), subGridPositions(), labelPositions(), and labelValues() methods for
+ * See gridPositions(), subGridPositions(), labelPositions(), and labelStrings() methods for
  * documentation about the arrays that need to be resized and populated.
  *
- * \sa gridPositions(), subGridPositions(), labelPositions(), labelValues(), axis()
+ * \sa gridPositions(), subGridPositions(), labelPositions(), labelStrings(), axis()
  */
 void QValue3DAxisFormatter::recalculate()
 {
@@ -121,28 +137,14 @@ void QValue3DAxisFormatter::recalculate()
 }
 
 /*!
- * The parent axis uses this method to request axis label strings for label \a index,
- * using the value stored in label values array and QValue3DAxis::labelFormat property.
- * Reimplement this method in a subclass if the default labeling is not sufficient.
- * If an empty string is returned, the label is not shown.
- *
- * \return A string formatted using axis label formatter.
- *
- * \sa stringForValue(), labelValues(), QValue3DAxis::labelFormat
- */
-QString QValue3DAxisFormatter::labelForIndex(int index) const
-{
-    return d_ptr->labelForIndex(index);
-}
-
-/*!
+ * This method is used to format a string using the specified value and the specified format.
  * Reimplement this method in a subclass to resolve the formatted string for a given \a value
  * if the default formatting rules specified for QValue3DAxis::labelFormat property are not
  * sufficient.
  *
- * \return the formatted label string using \a value and \a format.
+ * \return the formatted label string using a \a value and a \a format.
  *
- * \sa recalculate(), labelForIndex(), QValue3DAxis::labelFormat
+ * \sa recalculate(), labelStrings(), QValue3DAxis::labelFormat
  */
 QString QValue3DAxisFormatter::stringForValue(qreal value, const QString &format) const
 {
@@ -257,15 +259,15 @@ QVector<float> &QValue3DAxisFormatter::labelPositions() const
 }
 
 /*!
- * \return a reference to the array of values used to generate label strings.
+ * \return a reference to the string list containing formatter label strings.
  * The array size must be equal to the size of the label positions array and
  * the indexes correspond to that array as well.
  *
  * \sa labelPositions()
  */
-QVector<qreal> &QValue3DAxisFormatter::labelValues() const
+QStringList &QValue3DAxisFormatter::labelStrings() const
 {
-    return d_ptr->m_labelValues;
+    return d_ptr->m_labelStrings;
 }
 
 // QValue3DAxisFormatterPrivate
@@ -277,7 +279,9 @@ QValue3DAxisFormatterPrivate::QValue3DAxisFormatterPrivate(QValue3DAxisFormatter
       m_max(0.0f),
       m_rangeNormalizer(0.0f),
       m_axis(0),
-      m_preparsedParamType(Utils::ParamTypeUnknown)
+      m_preparsedParamType(Utils::ParamTypeUnknown),
+      m_allowNegatives(true),
+      m_allowZero(true)
 {
 }
 
@@ -303,12 +307,14 @@ void QValue3DAxisFormatterPrivate::doRecalculate()
 {
     int segmentCount = m_axis->segmentCount();
     int subGridCount = m_axis->subSegmentCount() - 1;
+    QString labelFormat =  m_axis->labelFormat();
 
     m_gridPositions.resize(segmentCount + 1);
     m_subGridPositions.resize(segmentCount * subGridCount);
 
     m_labelPositions.resize(segmentCount + 1);
-    m_labelValues.resize(segmentCount + 1);
+    m_labelStrings.clear();
+    m_labelStrings.reserve(segmentCount + 1);
 
     // Use qreals for intermediate calculations for better accuracy on label values
     qreal segmentStep = 1.0 / qreal(segmentCount);
@@ -322,7 +328,8 @@ void QValue3DAxisFormatterPrivate::doRecalculate()
         qreal gridValue = segmentStep * qreal(i);
         m_gridPositions[i] = float(gridValue);
         m_labelPositions[i] = float(gridValue);
-        m_labelValues[i] = gridValue * rangeNormalizer + qreal(m_min);
+        m_labelStrings << q_ptr->stringForValue(gridValue * rangeNormalizer + qreal(m_min),
+                                                labelFormat);
         if (m_subGridPositions.size()) {
             for (int j = 0; j < subGridCount; j++)
                 m_subGridPositions[i * subGridCount + j] = gridValue + subSegmentStep * (j + 1);
@@ -332,6 +339,7 @@ void QValue3DAxisFormatterPrivate::doRecalculate()
     // Ensure max value doesn't suffer from any rounding errors
     m_gridPositions[segmentCount] = 1.0f;
     m_labelPositions[segmentCount] = 1.0f;
+    m_labelStrings << q_ptr->stringForValue(qreal(m_max), labelFormat);
 }
 
 void QValue3DAxisFormatterPrivate::populateCopy(QValue3DAxisFormatter &copy)
@@ -351,12 +359,6 @@ void QValue3DAxisFormatterPrivate::doPopulateCopy(QValue3DAxisFormatterPrivate &
     copy.m_subGridPositions = m_subGridPositions;
 }
 
-QString QValue3DAxisFormatterPrivate::labelForIndex(int index) const
-{
-    Q_ASSERT(index < m_labelValues.size());
-    return q_ptr->stringForValue(m_labelValues.at(index), m_axis->labelFormat());
-}
-
 QString QValue3DAxisFormatterPrivate::stringForValue(qreal value, const QString &format)
 {
     if (m_previousLabelFormat.compare(format)) {
@@ -383,10 +385,15 @@ void QValue3DAxisFormatterPrivate::setAxis(QValue3DAxis *axis)
 {
     Q_ASSERT(axis);
 
+    // These signals are all connected to markDirtyNoLabelChange slot, even though most of them
+    // do require labels to be regenerated. This is because the label regeneration is triggered
+    // elsewhere in these cases.
     connect(axis, &QValue3DAxis::segmentCountChanged,
             this, &QValue3DAxisFormatterPrivate::markDirtyNoLabelChange);
     connect(axis, &QValue3DAxis::subSegmentCountChanged,
             this, &QValue3DAxisFormatterPrivate::markDirtyNoLabelChange);
+    connect(axis, &QValue3DAxis::labelFormatChanged,
+            this, &QValue3DAxisFormatterPrivate::markDirtyNoLabelChange);
     connect(axis, &QAbstract3DAxis::rangeChanged,
             this, &QValue3DAxisFormatterPrivate::markDirtyNoLabelChange);
 
@@ -396,10 +403,12 @@ void QValue3DAxisFormatterPrivate::setAxis(QValue3DAxis *axis)
 void QValue3DAxisFormatterPrivate::markDirty(bool labelsChange)
 {
     m_needsRecalculate = true;
-    if (labelsChange)
-        m_axis->dptr()->emitLabelsChanged();
-    if (m_axis && m_axis->orientation() != QAbstract3DAxis::AxisOrientationNone)
-        emit m_axis->dptr()->formatterDirty();
+    if (m_axis) {
+        if (labelsChange)
+            m_axis->dptr()->emitLabelsChanged();
+        if (m_axis && m_axis->orientation() != QAbstract3DAxis::AxisOrientationNone)
+            emit m_axis->dptr()->formatterDirty();
+    }
 }
 
 void QValue3DAxisFormatterPrivate::markDirtyNoLabelChange()