citra-qt: Add a utility spinbox class called CSpinBox.

This class has a few advantages over the regular QSpinBox:
- QSpinBox stores its as signed 32 bit integers, which for instance is unsuitable for representing memory addresses. CSpinBox uses 64 bit integers instead.
- QSpinBox does not provide an easy way to handle number input from bases different than 10.
- QSpinBox is quite inflexible in general and almost any sort of customization requires reimplementing it anyway.

src/citra_qt/util/spinbox.hxx

@@ -0,0 +1,88 @@
+// Licensed under GPLv2+
+// Refer to the license.txt file included.
+
+
+// Copyright 2014 Tony Wasserka
+// All rights reserved.
+//
+// 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 owner 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,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+
+#pragma once
+
+#include <QAbstractSpinBox>
+#include <QtGlobal>
+
+class QVariant;
+
+/**
+ * A custom spin box widget with enhanced functionality over Qt's QSpinBox
+ */
+class CSpinBox : public QAbstractSpinBox {
+    Q_OBJECT
+
+public:
+    CSpinBox(QWidget* parent = nullptr);
+
+    void stepBy(int steps) override;
+    StepEnabled stepEnabled() const override;
+
+    void SetValue(qint64 val);
+
+    void SetRange(qint64 min, qint64 max);
+
+    void SetBase(int base);
+
+    void SetPrefix(const QString& prefix);
+    void SetSuffix(const QString& suffix);
+
+    void SetNumDigits(int num_digits);
+
+    QValidator::State validate(QString& input, int& pos) const override;
+
+signals:
+    void ValueChanged(qint64 val);
+
+private slots:
+    void OnEditingFinished();
+
+private:
+    void UpdateText();
+
+    bool HasSign() const;
+
+    QString TextFromValue();
+    qint64 ValueFromText();
+
+    qint64 min_value, max_value;
+
+    qint64 value;
+
+    QString prefix, suffix;
+
+    int base;
+
+    int num_digits;
+};