Remove margins added by the helper to size hints of FlexBoxLayoutItem

QQuickLayout::effectiveSizeHints_helper() adds margins to the size hints,
which are not needed in FlexBoxLayoutItem case as the item is managed
by the Yoga layout library.

Fixes: QTBUG-142153
Pick-to: 6.10
Change-Id: Ibd243a375c0f459770688250606462485666a282
Reviewed-by: SanthoshKumar Selvaraj <santhosh.kumar.selvaraj@qt.io>
(cherry picked from commit 8ea218874eb058f1294c56ed64f705a422aa6562)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

3 files changed, 77 insertions, 9 deletions

diff --git a/src/quicklayouts/qquickflexboxlayoutengine.cpp b/src/quicklayouts/qquickflexboxlayoutengine.cpp
index d6d2451459..3fc29b5eb6 100644
--- a/src/quicklayouts/qquickflexboxlayoutengine.cpp
+++ b/src/quicklayouts/qquickflexboxlayoutengine.cpp
@@ -73,6 +73,15 @@ void QQuickFlexboxLayoutEngine::collectItemSizeHints(QQuickFlexboxLayoutItem *fl
     if (!info)
         return;
 
+    // remove margins from the size added by the helper
+    auto m = info->qMargins();
+    const QSizeF margins{m.left() + m.right(), m.top() + m.bottom()};
+    flexItem->cachedItemSizeHints().margins = margins; // save margins for later use
+
+    QSizeF noMarginsHints[Qt::NSizeHints];
+    for (int i = 0; i < Qt::NSizeHints; ++i)
+        noMarginsHints[i] = sizeHints[i] - margins;
+
     // Set layout margins to the flex item (Layout.margins)
     if (info->isMarginsSet())
         flexItem->setFlexMargin(QQuickFlexboxLayout::EdgeAll, info->margins());
@@ -103,8 +112,8 @@ void QQuickFlexboxLayoutEngine::collectItemSizeHints(QQuickFlexboxLayoutItem *fl
                 // If the Layout.fillHeight not been set, the preferred height
                 // will be set as height
                 if (!info->fillHeight())
-                    flexItem->setHeight(sizeHints[Qt::PreferredSize].height());
-                flexItem->setFlexBasis(sizeHints[Qt::PreferredSize].width(), !info->fillWidth());
+                    flexItem->setHeight(noMarginsHints[Qt::PreferredSize].height());
+                flexItem->setFlexBasis(noMarginsHints[Qt::PreferredSize].width(), !info->fillWidth());
                 // Set child item to grow on main-axis (i.e. the flex
                 // direction)
                 flexItem->setItemGrowAlongMainAxis(info->fillWidth() ? 1.0f : 0.0f);
@@ -116,8 +125,8 @@ void QQuickFlexboxLayoutEngine::collectItemSizeHints(QQuickFlexboxLayoutItem *fl
                 // If the Layout.fillWidth not been set, the preferred width
                 // will be set as width
                 if (!info->fillWidth())
-                    flexItem->setWidth(sizeHints[Qt::PreferredSize].width());
-                flexItem->setFlexBasis(sizeHints[Qt::PreferredSize].height(), !info->fillHeight());
+                    flexItem->setWidth(noMarginsHints[Qt::PreferredSize].width());
+                flexItem->setFlexBasis(noMarginsHints[Qt::PreferredSize].height(), !info->fillHeight());
                 // Set child item to grow on main-axis (i.e. the flex
                 // direction)
                 flexItem->setItemGrowAlongMainAxis(info->fillHeight() ? 1.0f : 0.0f);
@@ -175,8 +184,13 @@ QSizeF QQuickFlexboxLayoutEngine::sizeHint(Qt::SizeHint whichSizeHint) const
         const int count = itemCount();
         for (int i = 0; i < count; ++i) {
             SizeHints &hints = cachedItemSizeHints(i);
+
+            QSizeF noMarginsHints[Qt::NSizeHints];
+            for (int i = 0; i < Qt::NSizeHints; ++i)
+                noMarginsHints[i] = hints.array[i] - hints.margins;
+
             auto &flexLayoutItem = m_flexLayoutItems.at(i);
-            flexLayoutItem->setMinSize(hints.min());
+            flexLayoutItem->setMinSize(noMarginsHints[Qt::MinimumSize]);
             if (flexLayoutItem->isFlexBasisUndefined()) {
                 // If flex basis is undefined and item is still stretched, it
                 // meant the flex child item has a const width or height but
@@ -191,16 +205,16 @@ QSizeF QQuickFlexboxLayoutEngine::sizeHint(Qt::SizeHint whichSizeHint) const
                         flexLayoutItem->resetSize();
                         if (qFlexLayout->direction() == QQuickFlexboxLayout::Row ||
                             qFlexLayout->direction() == QQuickFlexboxLayout::RowReverse) {
-                            flexLayoutItem->setWidth(hints.pref().width());
+                            flexLayoutItem->setWidth(noMarginsHints[Qt::PreferredSize].width());
                         } else {
-                            flexLayoutItem->setHeight(hints.pref().height());
+                            flexLayoutItem->setHeight(noMarginsHints[Qt::PreferredSize].height());
                         }
                     }
                 } else {
-                    flexLayoutItem->setSize(hints.pref());
+                    flexLayoutItem->setSize(noMarginsHints[Qt::PreferredSize]);
                 }
             }
-            flexLayoutItem->setMaxSize(hints.max());
+            flexLayoutItem->setMaxSize(noMarginsHints[Qt::MaximumSize]);
             // The preferred size, minimum and maximum size of the parent item
             // will be calculated as follows
             // If no wrap enabled in the flex layout:
@@ -312,6 +326,7 @@ void QQuickFlexboxLayoutEngine::invalidateItemSizeHint(QQuickItem *item)
         hints.min() = QSizeF();
         hints.pref() = QSizeF();
         hints.max() = QSizeF();
+        hints.margins = {0,0};
     }
 }
 
diff --git a/src/quicklayouts/qquickflexboxlayoutitem_p.h b/src/quicklayouts/qquickflexboxlayoutitem_p.h
index d0b1b7deb9..f1c8530e49 100644
--- a/src/quicklayouts/qquickflexboxlayoutitem_p.h
+++ b/src/quicklayouts/qquickflexboxlayoutitem_p.h
@@ -27,6 +27,7 @@ struct SizeHints {
     inline QSizeF &pref() { return array[Qt::PreferredSize]; }
     inline QSizeF &max() { return array[Qt::MaximumSize]; }
     QSizeF array[Qt::NSizeHints];
+    QSizeF margins{0,0};
 };
 
 class QQuickFlexboxLayoutItem
diff --git a/tests/auto/quick/qquicklayouts/data/tst_flexboxlayout.qml b/tests/auto/quick/qquicklayouts/data/tst_flexboxlayout.qml
index 5334f7a977..e5fdbbfc99 100644
--- a/tests/auto/quick/qquicklayouts/data/tst_flexboxlayout.qml
+++ b/tests/auto/quick/qquicklayouts/data/tst_flexboxlayout.qml
@@ -911,5 +911,57 @@ Item {
             compare(flexboxLayout.Layout.maximumWidth, 300 + 5)
             compare(flexboxLayout.Layout.maximumHeight, 300 + 5)
         }
+
+        function test_margins() {
+            let flexboxLayout = createTemporaryObject(dynamicFlexboxLayoutComponent, container)
+            waitForItemPolished(flexboxLayout)
+
+            compare(flexboxLayout.implicitWidth, 0)
+            compare(flexboxLayout.implicitHeight, 0)
+            compare(flexboxLayout.Layout.minimumWidth, 0)
+            compare(flexboxLayout.Layout.minimumHeight, 0)
+
+            let item1 = flexItem.createObject(flexboxLayout)
+            waitForItemPolished(flexboxLayout)
+            compare(item1.width, 20)
+            compare(item1.height, 20)
+            // item2 has no margins
+            compare(flexboxLayout.implicitWidth, 20)
+            compare(flexboxLayout.implicitHeight, 20)
+            compare(flexboxLayout.Layout.minimumWidth, 0)
+            compare(flexboxLayout.Layout.minimumHeight, 0)
+            // add margins
+            item1.Layout.margins = 7
+            waitForItemPolished(flexboxLayout)
+            compare(item1.width, 20)
+            compare(item1.height, 20)
+            // margins affect the implicit size of the layout itself
+            // item1 (20 + 2 * item1.Layout.margins)
+            compare(flexboxLayout.implicitWidth, 34)
+            compare(flexboxLayout.implicitHeight, 34)
+            compare(flexboxLayout.Layout.minimumWidth, 14)
+            compare(flexboxLayout.Layout.minimumHeight, 14)
+
+
+            let item2 = flexItem.createObject(flexboxLayout)
+            waitForItemPolished(flexboxLayout)
+            compare(item2.width, 20)
+            compare(item2.height, 20)
+            // item2 has no margins
+            compare(flexboxLayout.implicitWidth, 54)
+            compare(flexboxLayout.implicitHeight, 34)
+            compare(flexboxLayout.Layout.minimumWidth, 14)
+            compare(flexboxLayout.Layout.minimumHeight, 14)
+            // add margins
+            item2.Layout.leftMargin = 17
+            waitForItemPolished(flexboxLayout)
+            compare(item2.width, 20)
+            compare(item2.height, 20)
+            // item1 (34) + item2 (17 + 20 = 37)
+            compare(flexboxLayout.implicitWidth, 71)
+            compare(flexboxLayout.implicitHeight, 34)
+            compare(flexboxLayout.Layout.minimumWidth, 31)
+            compare(flexboxLayout.Layout.minimumHeight, 14)
+        }
     }
 }