Utils: Add push button with menu and default click action

QPushButton has the functionality of setting a menu, but that replaces
the normal "click" functionality, and always opens the menu on click.

QToolButton can have a menu and the user can still click on it to just
click. But, QToolButton looks very different, and in combination with
other, normal push buttons very alien.

Create a push button that only shows the menu when clicking on/near the
menu indicator, and otherwise just sends the clicked() signal like a
non-menu push button.

Change-Id: Id6ba367e40c370275f67f0fbf77521c2e974b3b8
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Marcus Tillmanns <marcus.tillmanns@qt.io>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/libs/utils/CMakeLists.txt

@@ -106,6 +106,8 @@ add_qtc_library(Utils
     namevaluevalidator.cpp namevaluevalidator.h
     navigationtreeview.cpp navigationtreeview.h
     networkaccessmanager.cpp networkaccessmanager.h
+    optionpushbutton.h
+    optionpushbutton.cpp
     osspecificaspects.h
     outputformat.h
     outputformatter.cpp outputformatter.h

src/libs/utils/optionpushbutton.cpp

@@ -0,0 +1,87 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#include "optionpushbutton.h"
+
+#include <QMouseEvent>
+#include <QPushButton>
+#include <QStyleOptionButton>
+
+namespace Utils {
+
+/*!
+    \class Utils::OptionPushButton
+
+    \brief The OptionPushButton class implements a QPushButton for which the menu is only opened
+    if the user presses the menu indicator.
+
+    Use OptionPushButton::setOptionalMenu() to set the menu and its actions.
+    If the users clicks on the menu indicator of the push button, this menu is opened, and
+    its actions are triggered when the user selects them.
+
+    If the user clicks anywhere else on the button, the QAbstractButton::clicked() signal is
+    sent, as if the button didn't have a menu.
+
+    Note: You may not call QPushButton::setMenu(). Use OptionPushButton::setOptionalMenu() instead.
+*/
+
+/*!
+    Constructs an option push button with parent \a parent.
+*/
+OptionPushButton::OptionPushButton(QWidget *parent)
+    : QPushButton(parent)
+{}
+
+/*!
+    Constructs an option push button with text \a text and parent \a parent.
+*/
+OptionPushButton::OptionPushButton(const QString &text, QWidget *parent)
+    : QPushButton(text, parent)
+{}
+
+/*!
+    Associates the popup menu \a menu with this push button.
+    This menu is shown if the user clicks on the menu indicator that is shown.
+    If the user clicks anywhere else on the button, QAbstractButton::clicked() is sent instead.
+
+    Ownership of the menu is not transferred to the push button.
+*/
+void OptionPushButton::setOptionalMenu(QMenu *menu)
+{
+    setMenu(menu);
+    // hack away that QPushButton opens the menu on "pressed"
+    disconnect(this, SIGNAL(pressed()), this, SLOT(_q_popupPressed()));
+}
+
+/*!
+    \internal
+*/
+void OptionPushButton::mouseReleaseEvent(QMouseEvent *event)
+{
+    if (!menu() || event->button() != Qt::LeftButton)
+        return QPushButton::mouseReleaseEvent(event);
+    setDown(false);
+    const QRect r = rect();
+    if (!r.contains(event->position().toPoint()))
+        return;
+    QStyleOptionButton option;
+    initStyleOption(&option);
+    // for Mac style
+    const QRect contentRect = style()->subElementRect(QStyle::SE_PushButtonContents, &option, this);
+    // for Common style
+    const int menuButtonSize = style()->pixelMetric(QStyle::PM_MenuButtonIndicator, &option, this);
+    // see: newBtn.rect = QRect(ir.right() - mbi - 2, ir.height()/2 - mbi/2 + 3, mbi - 6, mbi - 6);
+    // in QCommonStyle::drawControl, CE_PushButtonBevel, QStyleOptionButton::HasMenu
+    static const int magicBorder = 4;
+    const int clickX = event->position().toPoint().x();
+    if ((option.direction == Qt::LeftToRight
+         && clickX <= std::min(contentRect.right(), r.right() - menuButtonSize - magicBorder))
+        || (option.direction == Qt::RightToLeft
+            && clickX >= std::max(contentRect.left(), r.left() + menuButtonSize + magicBorder))) {
+        click();
+    } else {
+        showMenu();
+    }
+}
+
+} // namespace Utils

src/libs/utils/optionpushbutton.h

@@ -0,0 +1,31 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0 WITH Qt-GPL-exception-1.0
+
+#pragma once
+
+#include "utils_global.h"
+
+#include <QPushButton>
+
+QT_BEGIN_NAMESPACE
+class QMenu;
+class QMouseEvent;
+QT_END_NAMESPACE
+
+namespace Utils {
+
+class QTCREATOR_UTILS_EXPORT OptionPushButton : public QPushButton
+{
+    Q_OBJECT
+
+public:
+    OptionPushButton(QWidget *parent = nullptr);
+    OptionPushButton(const QString &text, QWidget *parent = nullptr);
+
+    void setOptionalMenu(QMenu *menu);
+
+protected:
+    void mouseReleaseEvent(QMouseEvent *event) override;
+};
+
+} // namespace Utils

src/libs/utils/utils.qbs

@@ -208,6 +208,8 @@ Project {
             "navigationtreeview.h",
             "networkaccessmanager.cpp",
             "networkaccessmanager.h",
+            "optionpushbutton.h",
+            "optionpushbutton.cpp",
             "osspecificaspects.h",
             "outputformat.h",
             "outputformatter.cpp",