Fix a behaviour change of sizeHint() introduced by 6d4d265e7e67dde58

Commit 6d4d265e7e67dde58e45d7d89f4974d0bd8b70e4 added a behaviour change
in the cases if there was an item with height-for-width and sizeHint()
was called with no constraint.  The commit tried to return the height
needed for the preferred width, but it still did not satisfy the
constraints, since the width used as the constraint could be less than
the preferred width.  This also meant that the sizeHint(Qt::MinimumSize)
could actually be larger than the smallest possible size.

The behaviour should be that it should return the smallest width
possible regardless of height. For instance, for a label it could return
the size of the longest word (to avoid hyphenation issues).

The same logic applies for the height: It should return the smallest
height possible regardless of width. For instance, for a label it could
then return the height of the font.

I also had to fix some stuff in the heightForWidthWithSpanning()
autotest since it wrongly expected the maximum size to be
QWIDGETSIZE_MAX in several of the cases.  However, that is the current
behaviour (and it is a bug), but it is unrelated to the problem with
spans so I simply fix the test and mark them with QEXPECT_FAIL.

Reviewed-by: John Tapsell

1 files changed, 45 insertions, 50 deletions

diff --git a/src/gui/graphicsview/qgridlayoutengine.cpp b/src/gui/graphicsview/qgridlayoutengine.cpp
index e486b4d..9785b15 100644
--- a/src/gui/graphicsview/qgridlayoutengine.cpp
+++ b/src/gui/graphicsview/qgridlayoutengine.cpp
@@ -1107,7 +1107,50 @@ QSizeF QGridLayoutEngine::sizeHint(const QLayoutStyleInfo &styleInfo, Qt::SizeHi
 {
     QGridLayoutBox sizehint_totalBoxes[NOrientations];
 
-    if(rowCount() < 1 || columnCount() < 1 || !hasDynamicConstraint()) {
+    bool sizeHintCalculated = false;
+
+    if (hasDynamicConstraint() && rowCount() > 0 && columnCount() > 0) {
+        if (constraintOrientation() == Qt::Vertical) {
+            //We have items whose height depends on their width
+            if (constraint.width() >= 0) {
+                if(q_cachedDataForStyleInfo != styleInfo)
+                    ensureColumnAndRowData(&q_columnData, &sizehint_totalBoxes[Hor], styleInfo, NULL, NULL, Qt::Horizontal);
+                else
+                    sizehint_totalBoxes[Hor] = q_totalBoxes[Hor];
+                QVector<qreal> sizehint_xx;
+                QVector<qreal> sizehint_widths;
+
+                sizehint_xx.resize(columnCount());
+                sizehint_widths.resize(columnCount());
+                qreal width = constraint.width();
+                //Calculate column widths and positions, and put results in q_xx.data() and q_widths.data() so that we can use this information as
+                //constraints to find the row heights
+                q_columnData.calculateGeometries(0, columnCount(), width, sizehint_xx.data(), sizehint_widths.data(),
+                        0, sizehint_totalBoxes[Hor]);
+                ensureColumnAndRowData(&q_rowData, &sizehint_totalBoxes[Ver], styleInfo, sizehint_xx.data(), sizehint_widths.data(), Qt::Vertical);
+                sizeHintCalculated = true;
+            }
+        } else {
+            if (constraint.height() >= 0) {
+                //We have items whose width depends on their height
+                ensureColumnAndRowData(&q_rowData, &sizehint_totalBoxes[Ver], styleInfo, NULL, NULL, Qt::Vertical);
+                QVector<qreal> sizehint_yy;
+                QVector<qreal> sizehint_heights;
+
+                sizehint_yy.resize(rowCount());
+                sizehint_heights.resize(rowCount());
+                qreal height = constraint.height();
+                //Calculate row heights and positions, and put results in q_yy.data() and q_heights.data() so that we can use this information as
+                //constraints to find the column widths
+                q_rowData.calculateGeometries(0, rowCount(), height, sizehint_yy.data(), sizehint_heights.data(),
+                        0, sizehint_totalBoxes[Ver]);
+                ensureColumnAndRowData(&q_columnData, &sizehint_totalBoxes[Hor], styleInfo, sizehint_yy.data(), sizehint_heights.data(), Qt::Vertical);
+                sizeHintCalculated = true;
+            }
+        }
+    }
+
+    if (!sizeHintCalculated) {
         //No items with height for width, so it doesn't matter which order we do these in
         if(q_cachedDataForStyleInfo != styleInfo) {
             ensureColumnAndRowData(&q_columnData, &sizehint_totalBoxes[Hor], styleInfo, NULL, NULL, Qt::Horizontal);
@@ -1116,55 +1159,7 @@ QSizeF QGridLayoutEngine::sizeHint(const QLayoutStyleInfo &styleInfo, Qt::SizeHi
             sizehint_totalBoxes[Hor] = q_totalBoxes[Hor];
             sizehint_totalBoxes[Ver] = q_totalBoxes[Ver];
         }
-    } else if(constraintOrientation() == Qt::Vertical) {
-        //We have items whose width depends on their height
-        if(q_cachedDataForStyleInfo != styleInfo)
-            ensureColumnAndRowData(&q_columnData, &sizehint_totalBoxes[Hor], styleInfo, NULL, NULL, Qt::Horizontal);
-        else
-            sizehint_totalBoxes[Hor] = q_totalBoxes[Hor];
-        QVector<qreal> sizehint_xx;
-        QVector<qreal> sizehint_widths;
-
-        sizehint_xx.resize(columnCount());
-        sizehint_widths.resize(columnCount());
-        qreal width = constraint.width();
-        if(width < 0) {
-            /* It's not obvious what the behaviour should be. */
-/*            if(which == Qt::MaximumSize)
-                width = sizehint_totalBoxes[Hor].q_maximumSize;
-            else if(which == Qt::MinimumSize)
-                width = sizehint_totalBoxes[Hor].q_minimumSize;
-            else*/
-                width = sizehint_totalBoxes[Hor].q_preferredSize;
-        }
-        //Calculate column widths and positions, and put results in q_xx.data() and q_widths.data() so that we can use this information as
-        //constraints to find the row heights
-        q_columnData.calculateGeometries(0, columnCount(), width, sizehint_xx.data(), sizehint_widths.data(),
-                0, sizehint_totalBoxes[Hor]);
-        ensureColumnAndRowData(&q_rowData, &sizehint_totalBoxes[Ver], styleInfo, sizehint_xx.data(), sizehint_widths.data(), Qt::Vertical);
-    } else {
-        //We have items whose height depends on their width
-        ensureColumnAndRowData(&q_rowData, &sizehint_totalBoxes[Ver], styleInfo, NULL, NULL, Qt::Vertical);
-        QVector<qreal> sizehint_yy;
-        QVector<qreal> sizehint_heights;
-
-        sizehint_yy.resize(rowCount());
-        sizehint_heights.resize(rowCount());
-        qreal height = constraint.height();
-        if(height < 0) {
-/*            if(which == Qt::MaximumSize)
-                height = sizehint_totalBoxes[Ver].q_maximumSize;
-            else if(which == Qt::MinimumSize)
-                height = sizehint_totalBoxes[Ver].q_minimumSize;
-            else*/
-                height = sizehint_totalBoxes[Ver].q_preferredSize;
-        }
-        //Calculate row heights and positions, and put results in q_yy.data() and q_heights.data() so that we can use this information as
-        //constraints to find the column widths
-        q_rowData.calculateGeometries(0, rowCount(), height, sizehint_yy.data(), sizehint_heights.data(),
-                0, sizehint_totalBoxes[Ver]);
-        ensureColumnAndRowData(&q_columnData, &sizehint_totalBoxes[Hor], styleInfo, sizehint_yy.data(), sizehint_heights.data(), Qt::Vertical);
-    }
+     }
 
     switch (which) {
     case Qt::MinimumSize: