Layout items had the wrong size if the layout was resized to maximum.

The problem was that if targetSize was the layouts maximum size,
then sumAvailable could be reduced to exactly 0 in the "while
(keepGoing)" loop. That would mean that we would not enter the block
that actually copied the new sizes from the temporary "newSizes" array
to the output "sizes" array due to the "if (sumAvailable > 0)"
condition.

Task-number: none, discovered while fixing QT-3570
Reviewed-by: Frederik Gladhorn

2 files changed, 20 insertions, 19 deletions

diff --git a/src/gui/graphicsview/qgridlayoutengine.cpp b/src/gui/graphicsview/qgridlayoutengine.cpp
index a084647..4fba5ff 100644
--- a/src/gui/graphicsview/qgridlayoutengine.cpp
+++ b/src/gui/graphicsview/qgridlayoutengine.cpp
@@ -250,6 +250,7 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
 
         sumAvailable = targetSize - totalBox.q_preferredSize;
         if (sumAvailable > 0.0) {
+            qreal sumCurrentAvailable = sumAvailable;
             bool somethingHasAMaximumSize = false;
 
             qreal sumPreferredSizes = 0.0;
@@ -308,12 +309,12 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
                         qreal ultimateFactor = (stretch * ultimateSumPreferredSizes
                                                 / sumStretches)
                                                - (box.q_preferredSize);
-                        qreal transitionalFactor = sumAvailable
+                        qreal transitionalFactor = sumCurrentAvailable
                                                    * (ultimatePreferredSize - box.q_preferredSize)
                                                    / (ultimateSumPreferredSizes
                                                       - sumPreferredSizes);
 
-                        qreal alpha = qMin(sumAvailable,
+                        qreal alpha = qMin(sumCurrentAvailable,
                                            ultimateSumPreferredSizes - sumPreferredSizes);
                         qreal beta = ultimateSumPreferredSizes - sumPreferredSizes;
 
@@ -321,7 +322,7 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
                                       + ((beta - alpha) * transitionalFactor)) / beta;
                     }
                     sumFactors += factors[i];
-                    if (desired < sumAvailable)
+                    if (desired < sumCurrentAvailable)
                         somethingHasAMaximumSize = true;
 
                     newSizes[i] = -1.0;
@@ -337,12 +338,12 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
                         continue;
 
                     const QGridLayoutBox &box = boxes.at(start + i);
-                    qreal avail = sumAvailable * factors[i] / sumFactors;
+                    qreal avail = sumCurrentAvailable * factors[i] / sumFactors;
                     if (sizes[i] + avail >= box.q_maximumSize) {
                         newSizes[i] = box.q_maximumSize;
-                        sumAvailable -= box.q_maximumSize - sizes[i];
+                        sumCurrentAvailable -= box.q_maximumSize - sizes[i];
                         sumFactors -= factors[i];
-                        keepGoing = (sumAvailable > 0.0);
+                        keepGoing = (sumCurrentAvailable > 0.0);
                         if (!keepGoing)
                             break;
                     }
@@ -352,7 +353,7 @@ void QGridLayoutRowData::calculateGeometries(int start, int end, qreal targetSiz
             for (int i = 0; i < n; ++i) {
                 if (newSizes[i] < 0.0) {
                     qreal delta = (sumFactors == 0.0) ? 0.0
-                                                      : sumAvailable * factors[i] / sumFactors;
+                                                      : sumCurrentAvailable * factors[i] / sumFactors;
                     newSizes[i] = sizes[i] + delta;
                 }
             }
diff --git a/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp b/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
index d1d6860..5b03767 100644
--- a/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
+++ b/tests/auto/qgraphicsgridlayout/tst_qgraphicsgridlayout.cpp
@@ -485,12 +485,12 @@ void tst_QGraphicsGridLayout::alignment()
     widget->resize(widget->effectiveSizeHint(Qt::MaximumSize));
     QApplication::processEvents();
 
-    QCOMPARE(layout->itemAt(0,0)->geometry(), QRectF(0,    0,  50,  25));
-    QCOMPARE(layout->itemAt(1,0)->geometry(), QRectF(0,   25,  50,  25));
-    QCOMPARE(layout->itemAt(0,1)->geometry(), QRectF(125,  0,  50,  25));
-    QCOMPARE(layout->itemAt(1,1)->geometry(), QRectF(125, 25,  50,  25));
-    QCOMPARE(layout->itemAt(0,2)->geometry(), QRectF(250,  0,  50,  25));
-    QCOMPARE(layout->itemAt(1,2)->geometry(), QRectF(250, 25,  50,  25));
+    QCOMPARE(layout->itemAt(0,0)->geometry(), QRectF(0,    0,  50,  50));
+    QCOMPARE(layout->itemAt(1,0)->geometry(), QRectF(0,   50,  50,  50));
+    QCOMPARE(layout->itemAt(0,1)->geometry(), QRectF(125,  0,  50,  50));
+    QCOMPARE(layout->itemAt(1,1)->geometry(), QRectF(125, 50,  50,  50));
+    QCOMPARE(layout->itemAt(0,2)->geometry(), QRectF(250,  0,  50,  50));
+    QCOMPARE(layout->itemAt(1,2)->geometry(), QRectF(250, 50,  50,  50));
 
     delete widget;
 }
@@ -544,12 +544,12 @@ void tst_QGraphicsGridLayout::columnAlignment()
       | HCenter  |   Right    |   Left  |
       +---------------------------------+
     */
-    QCOMPARE(layout->itemAt(0,0)->geometry(), QRectF(0,   0,   50,  25));
-    QCOMPARE(layout->itemAt(1,0)->geometry(), QRectF(25,  26,  50,  25));   // item is king
-    QCOMPARE(layout->itemAt(0,1)->geometry(), QRectF(126,  0,  50,  25));
-    QCOMPARE(layout->itemAt(1,1)->geometry(), QRectF(151, 26,  50,  25));   // item is king
-    QCOMPARE(layout->itemAt(0,2)->geometry(), QRectF(252,  0,  50,  25));
-    QCOMPARE(layout->itemAt(1,2)->geometry(), QRectF(202, 26,  50,  25));   // item is king
+    QCOMPARE(layout->itemAt(0,0)->geometry(), QRectF(0,   0,   50,  50));
+    QCOMPARE(layout->itemAt(1,0)->geometry(), QRectF(25,  51,  50,  50));   // item is king
+    QCOMPARE(layout->itemAt(0,1)->geometry(), QRectF(126,  0,  50,  50));
+    QCOMPARE(layout->itemAt(1,1)->geometry(), QRectF(151, 51,  50,  50));   // item is king
+    QCOMPARE(layout->itemAt(0,2)->geometry(), QRectF(252,  0,  50,  50));
+    QCOMPARE(layout->itemAt(1,2)->geometry(), QRectF(202, 51,  50,  50));   // item is king
 
     delete widget;
 }