Follow layoutMirroring in Layout margins

If a layout is laid out left to right using the layoutDirection
property, we want left Margins on the left, and rightMargin still on the
right

However, if a layout is mirrored, not only should the layout direction
change but also the left margin should now be on the right and vice
versa.

Task-number: QTBUG-62989
Change-Id: Iaae4bc436fd1eb7f1947869563ac325f3d6b79bb
Reviewed-by: Paul Olav Tvete <paul.tvete@qt.io>
(cherry picked from commit 16613f3741af013f7e380c98df6889d73512d0ad)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>

4 files changed, 56 insertions, 1 deletions

diff --git a/src/imports/layouts/qquickgridlayoutengine_p.h b/src/imports/layouts/qquickgridlayoutengine_p.h
index 5529d1049c..ff42fa4d43 100644
--- a/src/imports/layouts/qquickgridlayoutengine_p.h
+++ b/src/imports/layouts/qquickgridlayoutengine_p.h
@@ -107,7 +107,7 @@ public:
     void setGeometry(const QRectF &rect) override
     {
         QQuickLayoutAttached *info = attachedLayoutObject(m_item, false);
-        const QRectF r = info ? rect.marginsRemoved(info->qMargins()) : rect;
+        const QRectF r = info ? rect.marginsRemoved(info->effectiveQMargins()) : rect;
         const QSizeF oldSize(m_item->width(), m_item->height());
         const QSizeF newSize = r.size();
         m_item->setPosition(r.topLeft());
diff --git a/src/imports/layouts/qquicklayout.cpp b/src/imports/layouts/qquicklayout.cpp
index a34b77ca11..e66b00e96f 100644
--- a/src/imports/layouts/qquicklayout.cpp
+++ b/src/imports/layouts/qquicklayout.cpp
@@ -936,6 +936,11 @@ bool QQuickLayout::invalidatedArrangement() const
     return d_func()->m_dirtyArrangement;
 }
 
+bool QQuickLayout::isMirrored() const
+{
+    return d_func()->isMirrored();
+}
+
 void QQuickLayout::itemSiblingOrderChanged(QQuickItem *item)
 {
     Q_UNUSED(item);
diff --git a/src/imports/layouts/qquicklayout_p.h b/src/imports/layouts/qquicklayout_p.h
index fb3b39d65d..8a6ad0397c 100644
--- a/src/imports/layouts/qquicklayout_p.h
+++ b/src/imports/layouts/qquicklayout_p.h
@@ -99,6 +99,7 @@ public:
 
     bool invalidated() const;
     bool invalidatedArrangement() const;
+    bool isMirrored() const;
 
     /* QQuickItemChangeListener */
     void itemSiblingOrderChanged(QQuickItem *item) override;
@@ -256,6 +257,14 @@ public:
         return QMarginsF(leftMargin(), topMargin(), rightMargin(), bottomMargin());
     }
 
+    QMarginsF effectiveQMargins() const {
+        bool mirrored = parentLayout() && parentLayout()->isMirrored();
+        if (mirrored)
+            return QMarginsF(rightMargin(), topMargin(), leftMargin(), bottomMargin());
+        else
+            return qMargins();
+    }
+
     bool setChangesNotificationEnabled(bool enabled)
     {
         const bool old = m_changesNotificationEnabled;
diff --git a/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml b/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
index 0fa84a1617..46d18a4384 100644
--- a/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
+++ b/tests/auto/quick/qquicklayouts/data/tst_gridlayout.qml
@@ -991,6 +991,47 @@ Item {
         }
 
         Component {
+
+            id: layout_RTL_Component
+            GridLayout {
+                LayoutMirroring.enabled: true
+                columns: 2
+                rowSpacing: 0
+                columnSpacing: 0
+                Rectangle {
+                    color: "red"
+                    Layout.preferredWidth: 20
+                    Layout.preferredHeight: 20
+                    Layout.leftMargin: 2
+                    Layout.rightMargin: 1
+                }
+                Rectangle {
+                    color: "blue"
+                    Layout.preferredWidth: 20
+                    Layout.preferredHeight: 20
+                    Layout.leftMargin: 3
+                    Layout.rightMargin: 4
+                }
+            }
+        }
+
+        function test_Rtl()
+        {
+            var layout = layout_RTL_Component.createObject(container)
+
+            compare(layout.implicitWidth, 3 + 20 + 4 + 2 + 20 + 1 )
+            layout.width = layout.implicitWidth
+
+            waitForRendering(layout)
+
+            var c0 = layout.children[0]
+            var c1 = layout.children[1]
+
+            compare(c1.x, 4) // c1 is first, with the right margin on the left
+            compare(c0.x, 20 + 3 + 4 + 1)
+        }
+
+        Component {
             id: layout_invalidateWhileRearranging_Component
 
             GridLayout {