Fix MenuItem width not matching Menu's available width

Short version:

There are currently two problems with MenuItems:
- Mirrored MenuItems don't fill the Menu's available width.
- MenuItem does not fill the Menu's available width when changed
after Component completion.

This patch fixes both of them by listening to geometry changes in both
the contentItem and individual menu items, and setting the explicit
width of those menu items when either changes.

Longer version:

The first problem can be seen whenever the MenuItem's implicitWidth
changes:
- QQmlEngine::retranslate() is called, causing all bindings to be
  re-evaluated
- The MenuItem's font size changes
- The MenuItem's icon size changes
- etc.

We fix this by making Menu listen to the width of each of its MenuItems
and call resizeItem() if it doesn't have an explicit width.

The second problem can be seen when e.g. resizing a Menu to account
for new items that are wider and hence require more space.
This can be fixed by listening to width changes in Menu's contentItem,
which was actually done in earlier versions but (probably accidentally)
removed in 482ecb0f.

I had tried to solve both issues by setting the explicit width of
MenuItem to the width of its Menu, or undefined if it has none
(which means it reverts to its implicit width). However, this does
not account for e.g. MenuSeparator and custom items that can be added
to Menu - they should also have their width fill the Menu automatically
if they don't have an explicit width set.

Change-Id: I95dd0da0919a1e297f2e2030da746ff1f1a17644
Fixes: QTBUG-75051
Fixes: QTBUG-75142
Reviewed-by: Richard Moe Gustavsen <richard.gustavsen@qt.io>

1 files changed, 103 insertions, 0 deletions

diff --git a/tests/auto/qquickmenu/data/menuItemWidths.qml b/tests/auto/qquickmenu/data/menuItemWidths.qml
new file mode 100644
index 00000000..6d2baa32
--- /dev/null
+++ b/tests/auto/qquickmenu/data/menuItemWidths.qml
@@ -0,0 +1,103 @@
+/****************************************************************************
+**
+** Copyright (C) 2019 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the test suite of the Qt Toolkit.
+**
+** $QT_BEGIN_LICENSE:BSD$
+** Commercial License Usage
+** Licensees holding valid commercial Qt licenses may use this file in
+** accordance with the commercial license agreement provided with the
+** Software or, alternatively, in accordance with the terms contained in
+** a written agreement between you and The Qt Company. For licensing terms
+** and conditions see https://www.qt.io/terms-conditions. For further
+** information use the contact form at https://www.qt.io/contact-us.
+**
+** BSD License Usage
+** Alternatively, you may use this file under the terms of the BSD license
+** as follows:
+**
+** "Redistribution and use in source and binary forms, with or without
+** modification, are permitted provided that the following conditions are
+** met:
+**   * Redistributions of source code must retain the above copyright
+**     notice, this list of conditions and the following disclaimer.
+**   * Redistributions in binary form must reproduce the above copyright
+**     notice, this list of conditions and the following disclaimer in
+**     the documentation and/or other materials provided with the
+**     distribution.
+**   * Neither the name of The Qt Company Ltd nor the names of its
+**     contributors may be used to endorse or promote products derived
+**     from this software without specific prior written permission.
+**
+**
+** THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+** "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+** A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+** OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+** SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+** LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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+** THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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+** OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+import QtQuick 2.12
+import QtQuick.Controls 2.12
+
+ApplicationWindow {
+    width: 600
+    height: 600
+
+    property alias menu: menu
+
+    Menu {
+        id: menu
+        MenuItem {
+            objectName: "MenuItem"
+            text: "MenuItem"
+        }
+        MenuSeparator {
+            objectName: "MenuSeparator"
+        }
+        Menu {
+            title: "Sub-menu"
+            objectName: "Sub-menu"
+
+            MenuItem {
+                objectName: "SubMenuItem"
+                text: "SubMenuItem"
+            }
+        }
+        Rectangle {
+            objectName: "CustomSeparator"
+            height: 2
+            color: "salmon"
+        }
+        Rectangle {
+            // Use a binding to test retranslate(), which re-evaluates all bindings.
+            implicitWidth: someValue
+            objectName: "CustomRectangleSeparator"
+            height: 2
+            color: "salmon"
+
+            property int someValue: 120
+        }
+        Control {
+            objectName: "CustomControlSeparator"
+            implicitWidth: someOtherValue
+            height: 2
+            background: Rectangle {
+                color: "navajowhite"
+            }
+
+            property int someOtherValue: 180
+        }
+    }
+}