Fix delegate loading issue when valid size is specified

The patchset ebefb583c8 is made to avoid
loading delegate when view port size is zero. But this affects the
scenario when any of its size is valid in delegates.

This patchset fixes delegate loading issue when valid size is specified
in it.

Fixes: QTBUG-113852
Pick-to: 6.5
Change-Id: Ib8b527175b91fefb8062f7ea5abc0c9b7860a0e7
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

src/quick/items/qquicktableview.cpp

@@ -2072,7 +2072,10 @@ void QQuickTableViewPrivate::updateContentWidth()
 
     if (loadedItems.isEmpty()) {
         QBoolBlocker fixupGuard(inUpdateContentSize, true);
-        q->QQuickFlickable::setContentWidth(0);
+        if (model && model->count() > 0 && tableModel && tableModel->delegate())
+            q->QQuickFlickable::setContentWidth(kDefaultColumnWidth);
+        else
+            q->QQuickFlickable::setContentWidth(0);
         return;
     }
 
@@ -2105,7 +2108,10 @@ void QQuickTableViewPrivate::updateContentHeight()
 
     if (loadedItems.isEmpty()) {
         QBoolBlocker fixupGuard(inUpdateContentSize, true);
-        q->QQuickFlickable::setContentHeight(0);
+        if (model && model->count() > 0 && tableModel && tableModel->delegate())
+            q->QQuickFlickable::setContentHeight(kDefaultRowHeight);
+        else
+            q->QQuickFlickable::setContentHeight(0);
         return;
     }
 

tests/auto/quick/qquicktableview/data/zerosizedviewport.qml

@@ -0,0 +1,31 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only WITH Qt-GPL-exception-1.0
+
+import QtQuick
+import QtQuick.Window
+
+Item {
+    width: 640
+    height: 450
+
+    property alias tableView: tableView
+
+    TableView {
+        id: tableView
+        anchors.top: parent.top
+        anchors.left: parent.left
+        anchors.bottom: parent.bottom
+        width: contentWidth
+        delegate: tableViewDelegate
+    }
+
+    Component {
+        id: tableViewDelegate
+        Rectangle {
+            objectName: "tableViewDelegate"
+            implicitWidth: tableView.width
+            implicitHeight: 50
+        }
+    }
+
+}

tests/auto/quick/qquicktableview/tst_qquicktableview.cpp

@@ -87,6 +87,7 @@ private slots:
     void checkZeroSizedDelegate();
     void checkImplicitSizeDelegate();
     void checkZeroSizedTableView();
+    void checkZeroSizedViewPort();
     void checkColumnWidthWithoutProvider();
     void checkColumnWidthAndRowHeightFunctions();
     void checkDelegateWithAnchors();
@@ -460,6 +461,17 @@ void tst_QQuickTableView::checkZeroSizedTableView()
     QCOMPARE(tableViewPrivate->loadedItems.size(), 1);
 }
 
+void tst_QQuickTableView::checkZeroSizedViewPort()
+{
+    LOAD_TABLEVIEW("zerosizedviewport.qml");
+
+    auto model = TestModelAsVariant(20, 20);
+    tableView->setModel(model);
+
+    WAIT_UNTIL_POLISHED;
+
+    QVERIFY(!tableViewPrivate->loadedItems.isEmpty());
+}
 
 void tst_QQuickTableView::checkColumnWidthWithoutProvider()
 {