QGAL: Remove support for QSizePolicy::Expanding

After meeting with Jan-Arve, we are removing the support for
the expanding size hint flag.

The reason for that is that such feature adds too much complexity
to the existing code and makes it harder for us to implement
planned changes, like the support for out-of-order simplification.

As these changes are consireded more important than the support
for the expanding sizeHint, we are dropping expanding support
for now. Once the QGAL is more stable and we have more time
available, we can consider bringing it back.

Signed-off-by: Eduardo M. Fleury <eduardo.fleury@openbossa.org>
Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira@openbossa.org>

2 files changed, 20 insertions, 202 deletions

diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
index baff206..7ad994c 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.cpp
@@ -105,7 +105,7 @@ qreal QGraphicsAnchorPrivate::spacing() const
 static void internalSizeHints(QSizePolicy::Policy policy,
                               qreal minSizeHint, qreal prefSizeHint, qreal maxSizeHint,
                               qreal *minSize, qreal *prefSize,
-                              qreal *expSize, qreal *maxSize)
+                              qreal *maxSize)
 {
     // minSize, prefSize and maxSize are initialized
     // with item's preferred Size: this is QSizePolicy::Fixed.
@@ -135,11 +135,6 @@ static void internalSizeHints(QSizePolicy::Policy policy,
         *prefSize = *minSize;
     else
         *prefSize = prefSizeHint;
-
-    if (policy & QSizePolicy::ExpandFlag)
-        *expSize = *maxSize;
-    else
-        *expSize = *prefSize;
 }
 
 bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
@@ -154,7 +149,6 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
         if (isLayoutAnchor) {
             minSize = 0;
             prefSize = 0;
-            expSize = 0;
             maxSize = QWIDGETSIZE_MAX;
             if (isCenterAnchor)
                 maxSize /= 2;
@@ -205,8 +199,8 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
         }
         maxSizeHint = QWIDGETSIZE_MAX;
     }
-    internalSizeHints(policy, minSizeHint, prefSizeHint, maxSizeHint, 
-                      &minSize, &prefSize, &expSize, &maxSize);
+    internalSizeHints(policy, minSizeHint, prefSizeHint, maxSizeHint,
+                      &minSize, &prefSize, &maxSize);
 
     // Set the anchor effective sizes to preferred.
     //
@@ -217,7 +211,6 @@ bool AnchorData::refreshSizeHints(const QLayoutStyleInfo *styleInfo)
     // recalculate and override the values we set here.
     sizeAtMinimum = prefSize;
     sizeAtPreferred = prefSize;
-    sizeAtExpanding = prefSize;
     sizeAtMaximum = prefSize;
 
     return true;
@@ -227,7 +220,6 @@ void ParallelAnchorData::updateChildrenSizes()
 {
     firstEdge->sizeAtMinimum = secondEdge->sizeAtMinimum = sizeAtMinimum;
     firstEdge->sizeAtPreferred = secondEdge->sizeAtPreferred = sizeAtPreferred;
-    firstEdge->sizeAtExpanding = secondEdge->sizeAtExpanding = sizeAtExpanding;
     firstEdge->sizeAtMaximum = secondEdge->sizeAtMaximum = sizeAtMaximum;
 
     firstEdge->updateChildrenSizes();
@@ -257,16 +249,12 @@ bool ParallelAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *styleIn
         return false;
     }
 
-    expSize = qMax(firstEdge->expSize, secondEdge->expSize);
-    expSize = qMin(expSize, maxSize);
-
     prefSize = qMax(firstEdge->prefSize, secondEdge->prefSize);
-    prefSize = qMin(prefSize, expSize);
+    prefSize = qMin(prefSize, maxSize);
 
     // See comment in AnchorData::refreshSizeHints() about sizeAt* values
     sizeAtMinimum = prefSize;
     sizeAtPreferred = prefSize;
-    sizeAtExpanding = prefSize;
     sizeAtMaximum = prefSize;
 
     return true;
@@ -280,8 +268,7 @@ bool ParallelAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *styleIn
      1 is at Maximum
 */
 static QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> getFactor(qreal value, qreal min,
-                                                                      qreal pref, qreal exp,
-                                                                      qreal max)
+                                                                      qreal pref, qreal max)
 {
     QGraphicsAnchorLayoutPrivate::Interval interval;
     qreal lower;
@@ -291,13 +278,9 @@ static QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> getFactor(qreal valu
         interval = QGraphicsAnchorLayoutPrivate::MinToPreferred;
         lower = min;
         upper = pref;
-    } else if (value < exp) {
-        interval = QGraphicsAnchorLayoutPrivate::PreferredToExpanding;
-        lower = pref;
-        upper = exp;
     } else {
-        interval = QGraphicsAnchorLayoutPrivate::ExpandingToMax;
-        lower = exp;
+        interval = QGraphicsAnchorLayoutPrivate::PreferredToMax;
+        lower = pref;
         upper = max;
     }
 
@@ -313,7 +296,7 @@ static QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> getFactor(qreal valu
 
 static qreal interpolate(const QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> &factor,
                          qreal min, qreal pref,
-                         qreal exp, qreal max)
+                         qreal max)
 {
     qreal lower;
     qreal upper;
@@ -323,12 +306,8 @@ static qreal interpolate(const QPair<QGraphicsAnchorLayoutPrivate::Interval, qre
         lower = min;
         upper = pref;
         break;
-    case QGraphicsAnchorLayoutPrivate::PreferredToExpanding:
+    case QGraphicsAnchorLayoutPrivate::PreferredToMax:
         lower = pref;
-        upper = exp;
-        break;
-    case QGraphicsAnchorLayoutPrivate::ExpandingToMax:
-        lower = exp;
         upper = max;
         break;
     }
@@ -343,34 +322,29 @@ void SequentialAnchorData::updateChildrenSizes()
     // point.
     Q_ASSERT(sizeAtMinimum > minSize || qAbs(sizeAtMinimum - minSize) < 0.00000001);
     Q_ASSERT(sizeAtPreferred > minSize || qAbs(sizeAtPreferred - minSize) < 0.00000001);
-    Q_ASSERT(sizeAtExpanding > minSize || qAbs(sizeAtExpanding - minSize) < 0.00000001);
     Q_ASSERT(sizeAtMaximum > minSize || qAbs(sizeAtMaximum - minSize) < 0.00000001);
 
     // These may be false if this anchor was in parallel with the layout stucture
     // Q_ASSERT(sizeAtMinimum < maxSize || qAbs(sizeAtMinimum - maxSize) < 0.00000001);
     // Q_ASSERT(sizeAtPreferred < maxSize || qAbs(sizeAtPreferred - maxSize) < 0.00000001);
-    // Q_ASSERT(sizeAtExpanding < maxSize || qAbs(sizeAtExpanding - maxSize) < 0.00000001);
     // Q_ASSERT(sizeAtMaximum < maxSize || qAbs(sizeAtMaximum - maxSize) < 0.00000001);
 
     // Band here refers if the value is in the Minimum To Preferred
     // band (the lower band) or the Preferred To Maximum (the upper band).
 
     const QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> minFactor =
-        getFactor(sizeAtMinimum, minSize, prefSize, expSize, maxSize);
+        getFactor(sizeAtMinimum, minSize, prefSize, maxSize);
     const QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> prefFactor =
-        getFactor(sizeAtPreferred, minSize, prefSize, expSize, maxSize);
-    const QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> expFactor =
-        getFactor(sizeAtExpanding, minSize, prefSize, expSize, maxSize);
+        getFactor(sizeAtPreferred, minSize, prefSize, maxSize);
     const QPair<QGraphicsAnchorLayoutPrivate::Interval, qreal> maxFactor =
-        getFactor(sizeAtMaximum, minSize, prefSize, expSize, maxSize);
+        getFactor(sizeAtMaximum, minSize, prefSize, maxSize);
 
     for (int i = 0; i < m_edges.count(); ++i) {
         AnchorData *e = m_edges.at(i);
 
-        e->sizeAtMinimum = interpolate(minFactor, e->minSize, e->prefSize, e->expSize, e->maxSize);
-        e->sizeAtPreferred = interpolate(prefFactor, e->minSize, e->prefSize, e->expSize, e->maxSize);
-        e->sizeAtExpanding = interpolate(expFactor, e->minSize, e->prefSize, e->expSize, e->maxSize);
-        e->sizeAtMaximum = interpolate(maxFactor, e->minSize, e->prefSize, e->expSize, e->maxSize);
+        e->sizeAtMinimum = interpolate(minFactor, e->minSize, e->prefSize, e->maxSize);
+        e->sizeAtPreferred = interpolate(prefFactor, e->minSize, e->prefSize, e->maxSize);
+        e->sizeAtMaximum = interpolate(maxFactor, e->minSize, e->prefSize, e->maxSize);
 
         e->updateChildrenSizes();
     }
@@ -386,7 +360,6 @@ bool SequentialAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *style
 {
     minSize = 0;
     prefSize = 0;
-    expSize = 0;
     maxSize = 0;
 
     for (int i = 0; i < m_edges.count(); ++i) {
@@ -398,14 +371,12 @@ bool SequentialAnchorData::refreshSizeHints_helper(const QLayoutStyleInfo *style
 
         minSize += edge->minSize;
         prefSize += edge->prefSize;
-        expSize += edge->expSize;
         maxSize += edge->maxSize;
     }
 
     // See comment in AnchorData::refreshSizeHints() about sizeAt* values
     sizeAtMinimum = prefSize;
     sizeAtPreferred = prefSize;
-    sizeAtExpanding = prefSize;
     sizeAtMaximum = prefSize;
 
     return true;
@@ -480,7 +451,6 @@ QGraphicsAnchorLayoutPrivate::QGraphicsAnchorLayoutPrivate()
         for (int j = 0; j < 3; ++j) {
             sizeHints[i][j] = -1;
         }
-        sizeAtExpanding[i] = -1;
         interpolationProgress[i] = -1;
 
         spacings[i] = -1;
@@ -1866,27 +1836,19 @@ bool QGraphicsAnchorLayoutPrivate::calculateTrunk(Orientation orientation, const
         if (feasible) {
             solvePreferred(allConstraints, variables);
 
-            // Note that we don't include the sizeHintConstraints, since they
-            // have a different logic for solveExpanding().
-            solveExpanding(constraints, variables);
-
-            // Calculate and set the preferred and expanding sizes for the layout,
+            // Calculate and set the preferred size for the layout,
             // from the edge sizes that were calculated above.
             qreal pref(0.0);
-            qreal expanding(0.0);
             foreach (const AnchorData *ad, path.positives) {
                 pref += ad->sizeAtPreferred;
-                expanding += ad->sizeAtExpanding;
             }
             foreach (const AnchorData *ad, path.negatives) {
                 pref -= ad->sizeAtPreferred;
-                expanding -= ad->sizeAtExpanding;
             }
 
             sizeHints[orientation][Qt::MinimumSize] = min;
             sizeHints[orientation][Qt::PreferredSize] = pref;
             sizeHints[orientation][Qt::MaximumSize] = max;
-            sizeAtExpanding[orientation] = expanding;
         }
 
         qDeleteAll(sizeHintConstraints);
@@ -1900,13 +1862,11 @@ bool QGraphicsAnchorLayoutPrivate::calculateTrunk(Orientation orientation, const
         AnchorData *ad = path.positives.toList()[0];
         ad->sizeAtMinimum = ad->minSize;
         ad->sizeAtPreferred = ad->prefSize;
-        ad->sizeAtExpanding = ad->expSize;
         ad->sizeAtMaximum = ad->maxSize;
 
         sizeHints[orientation][Qt::MinimumSize] = ad->sizeAtMinimum;
         sizeHints[orientation][Qt::PreferredSize] = ad->sizeAtPreferred;
         sizeHints[orientation][Qt::MaximumSize] = ad->sizeAtMaximum;
-        sizeAtExpanding[orientation] = ad->sizeAtExpanding;
     }
 
 #if defined(QT_DEBUG) || defined(Q_AUTOTEST_EXPORT)
@@ -1932,7 +1892,6 @@ bool QGraphicsAnchorLayoutPrivate::calculateNonTrunk(const QList<QSimplexConstra
             AnchorData *ad = variables[j];
             Q_ASSERT(ad);
             ad->sizeAtMinimum = ad->sizeAtPreferred;
-            ad->sizeAtExpanding = ad->sizeAtPreferred;
             ad->sizeAtMaximum = ad->sizeAtPreferred;
         }
     }
@@ -2406,7 +2365,6 @@ void QGraphicsAnchorLayoutPrivate::setupEdgesInterpolation(
     result = getFactor(current,
                        sizeHints[orientation][Qt::MinimumSize],
                        sizeHints[orientation][Qt::PreferredSize],
-                       sizeAtExpanding[orientation],
                        sizeHints[orientation][Qt::MaximumSize]);
 
     interpolationInterval[orientation] = result.first;
@@ -2421,7 +2379,6 @@ void QGraphicsAnchorLayoutPrivate::setupEdgesInterpolation(
 
    - minimum size,
    - preferred size,
-   - size when all expanding anchors are expanded,
    - maximum size.
 
    These three key values are calculated in advance using linear
@@ -2441,7 +2398,7 @@ void QGraphicsAnchorLayoutPrivate::interpolateEdge(AnchorVertex *base,
                                         interpolationProgress[orientation]);
 
     qreal edgeDistance = interpolate(factor, edge->sizeAtMinimum, edge->sizeAtPreferred,
-                                     edge->sizeAtExpanding, edge->sizeAtMaximum);
+                                     edge->sizeAtMaximum);
 
     Q_ASSERT(edge->from == base || edge->to == base);
 
@@ -2628,139 +2585,6 @@ bool QGraphicsAnchorLayoutPrivate::solvePreferred(const QList<QSimplexConstraint
 
 /*!
     \internal
-    Calculate the "expanding" keyframe
-
-    This new keyframe sits between the already existing sizeAtPreferred and
-    sizeAtMaximum keyframes. Its goal is to modify the interpolation between
-    the latter as to respect the "expanding" size policy of some anchors.
-
-    Previously all items would be subject to a linear interpolation between
-    sizeAtPreferred and sizeAtMaximum values. This will change now, the
-    expanding anchors will change their size before the others. To calculate
-    this keyframe we use the following logic:
-
-    1) Ask each anchor for their desired expanding size (ad->expSize), this
-    value depends on the anchor expanding property in the following way:
-
-    - Expanding normal anchors want to grow towards their maximum size
-    - Non-expanding normal anchors want to remain at their preferred size.
-    - Sequential anchors wants to grow towards a size that is calculated by:
-        summarizing it's child anchors, where it will use preferred size for non-expanding anchors
-        and maximum size for expanding anchors.
-    - Parallel anchors want to grow towards the smallest maximum size of all the expanding anchors.
-
-    2) Clamp their desired values to the value they assume in the neighbour
-    keyframes (sizeAtPreferred and sizeAtExpanding)
-
-    3) Run simplex with a setup that ensures the following:
-
-      a. Anchors will change their value from their sizeAtPreferred towards
-         their sizeAtMaximum as much as required to ensure that ALL anchors
-         reach their respective "desired" expanding sizes.
-
-      b. No anchors will change their value beyond what is NEEDED to satisfy
-         the requirement above.
-
-    The final result is that, at the "expanding" keyframe expanding anchors
-    will grow and take with them all anchors that are parallel to them.
-    However, non-expanding anchors will remain at their preferred size unless
-    they are forced to grow by a parallel expanding anchor.
-
-    Note: For anchors where the sizeAtPreferred is bigger than sizeAtMaximum,
-          the visual effect when the layout grows from its preferred size is
-          the following: Expanding anchors will keep their size while non
-          expanding ones will shrink. Only after non-expanding anchors have
-          shrinked all the way, the expanding anchors will start to shrink too.
-*/
-void QGraphicsAnchorLayoutPrivate::solveExpanding(const QList<QSimplexConstraint *> &constraints,
-                                                  const QList<AnchorData *> &variables)
-{
-    QList<QSimplexConstraint *> itemConstraints;
-    QSimplexConstraint *objective = new QSimplexConstraint;
-    bool hasExpanding = false;
-
-    // Construct the simplex constraints and objective
-    for (int i = 0; i < variables.size(); ++i) {
-        // For each anchor
-        AnchorData *ad = variables[i];
-
-        // Clamp the desired expanding size
-        qreal upperBoundary = qMax(ad->sizeAtPreferred, ad->sizeAtMaximum);
-        qreal lowerBoundary = qMin(ad->sizeAtPreferred, ad->sizeAtMaximum);
-        qreal boundedExpSize = qBound(lowerBoundary, ad->expSize, upperBoundary);
-
-        // Expanding anchors are those that want to move from their preferred size
-        if (boundedExpSize != ad->sizeAtPreferred)
-            hasExpanding = true;
-
-        // Lock anchor between boundedExpSize and sizeAtMaximum (ensure 3.a)
-        if (boundedExpSize == ad->sizeAtMaximum || qFuzzyCompare(boundedExpSize, ad->sizeAtMaximum)) {
-            // The interval has only one possible value, we can use an "Equal"
-            // constraint and don't need to add this variable to the objective.
-            QSimplexConstraint *itemC = new QSimplexConstraint;
-            itemC->ratio = QSimplexConstraint::Equal;
-            itemC->variables.insert(ad, 1.0);
-            itemC->constant = boundedExpSize;
-            itemConstraints << itemC;
-        } else {
-            // Add MoreOrEqual and LessOrEqual constraints.
-            QSimplexConstraint *itemC = new QSimplexConstraint;
-            itemC->ratio = QSimplexConstraint::MoreOrEqual;
-            itemC->variables.insert(ad, 1.0);
-            itemC->constant = qMin(boundedExpSize, ad->sizeAtMaximum);
-            itemConstraints << itemC;
-
-            itemC = new QSimplexConstraint;
-            itemC->ratio = QSimplexConstraint::LessOrEqual;
-            itemC->variables.insert(ad, 1.0);
-            itemC->constant = qMax(boundedExpSize, ad->sizeAtMaximum);
-            itemConstraints << itemC;
-
-            // Create objective to avoid the anchors from moving away from
-            // the preferred size more than the needed amount. (ensure 3.b)
-            // The objective function is the distance between sizeAtPreferred
-            // and sizeAtExpanding, it will be minimized.
-            if (ad->sizeAtExpanding < ad->sizeAtMaximum) {
-                // Try to shrink this variable towards its sizeAtPreferred value
-                objective->variables.insert(ad, 1.0);
-            } else {
-                // Try to grow this variable towards its sizeAtPreferred value
-                objective->variables.insert(ad, -1.0);
-            }
-        }
-    }
-
-    // Solve
-    if (hasExpanding == false) {
-        // If no anchors are expanding, we don't need to run the simplex
-        // Set all variables to their preferred size
-        for (int i = 0; i < variables.size(); ++i) {
-            variables[i]->sizeAtExpanding = variables[i]->sizeAtPreferred;
-        }
-    } else {
-        // Run simplex
-        QSimplex simplex;
-
-        // Satisfy expanding (3.a)
-        bool feasible = simplex.setConstraints(constraints + itemConstraints);
-        Q_ASSERT(feasible);
-
-        // Reduce damage (3.b)
-        simplex.setObjective(objective);
-        simplex.solveMin();
-
-        // Collect results
-        for (int i = 0; i < variables.size(); ++i) {
-            variables[i]->sizeAtExpanding = variables[i]->result;
-        }
-    }
-
-    delete objective;
-    qDeleteAll(itemConstraints);
-}
-
-/*!
-    \internal
     Returns true if there are no arrangement that satisfies all constraints.
     Otherwise returns false.
 
diff --git a/src/gui/graphicsview/qgraphicsanchorlayout_p.h b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
index 2f0237c..1e11ee2 100644
--- a/src/gui/graphicsview/qgraphicsanchorlayout_p.h
+++ b/src/gui/graphicsview/qgraphicsanchorlayout_p.h
@@ -158,9 +158,9 @@ struct AnchorData : public QSimplexVariable {
 
     AnchorData()
         : QSimplexVariable(), item(0), from(0), to(0),
-          minSize(0), prefSize(0), expSize(0), maxSize(0),
+          minSize(0), prefSize(0), maxSize(0),
           sizeAtMinimum(0), sizeAtPreferred(0),
-          sizeAtExpanding(0), sizeAtMaximum(0),
+          sizeAtMaximum(0),
           graphicsAnchor(0), skipInPreferred(0),
           type(Normal), hasSize(true), isLayoutAnchor(false),
           isCenterAnchor(false), orientation(0),
@@ -201,7 +201,6 @@ struct AnchorData : public QSimplexVariable {
     // size.
     qreal minSize;
     qreal prefSize;
-    qreal expSize;
     qreal maxSize;
 
     // These attributes define which sizes should that anchor be in when the
@@ -209,7 +208,6 @@ struct AnchorData : public QSimplexVariable {
     // calculated by the Simplex solver based on the current layout setup.
     qreal sizeAtMinimum;
     qreal sizeAtPreferred;
-    qreal sizeAtExpanding;
     qreal sizeAtMaximum;
     QGraphicsAnchor *graphicsAnchor;
 
@@ -345,8 +343,7 @@ public:
     // Interval represents which interpolation interval are we operating in.
     enum Interval {
         MinToPreferred = 0,
-        PreferredToExpanding,
-        ExpandingToMax
+        PreferredToMax
     };
 
     // Several structures internal to the layout are duplicated to handle
@@ -487,8 +484,6 @@ public:
                      GraphPath path, qreal *min, qreal *max);
     bool solvePreferred(const QList<QSimplexConstraint *> &constraints,
                         const QList<AnchorData *> &variables);
-    void solveExpanding(const QList<QSimplexConstraint *> &constraints,
-                        const QList<AnchorData *> &variables);
     bool hasConflicts() const;
 
 #ifdef QT_DEBUG
@@ -499,7 +494,6 @@ public:
     qreal spacings[NOrientations];
     // Size hints from simplex engine
     qreal sizeHints[2][3];
-    qreal sizeAtExpanding[2];
 
     // Items
     QVector<QGraphicsLayoutItem *> items;