Simplify and fix spectrum build structure

It is not obvious why the example did go to quite a length to
make ffpeg a separate dynamic library. Just build it always
as a static library. The code is LGPLv2.1, but that is compatible
with the BSD-3-Clause license of the example.

Also move the actual application out of the sub-app directory
into the top level directory. This is much more intuitive to use.

Pick-to: 6.2
Change-Id: Ib6173ce21dab78d02190fb0b38c90629b41d26cd
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Lars Knoll <lars.knoll@qt.io>

1 files changed, 108 insertions, 0 deletions

diff --git a/examples/multimedia/spectrum/spectrograph.h b/examples/multimedia/spectrum/spectrograph.h
new file mode 100644
index 000000000..0e7b11717
--- /dev/null
+++ b/examples/multimedia/spectrum/spectrograph.h
@@ -0,0 +1,108 @@
+/****************************************************************************
+**
+** Copyright (C) 2017 The Qt Company Ltd.
+** Contact: https://www.qt.io/licensing/
+**
+** This file is part of the examples 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,
+** 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."
+**
+** $QT_END_LICENSE$
+**
+****************************************************************************/
+
+#ifndef SPECTROGRAPH_H
+#define SPECTROGRAPH_H
+
+#include "frequencyspectrum.h"
+
+#include <QWidget>
+
+/**
+ * Widget which displays a spectrograph showing the frequency spectrum
+ * of the window of audio samples most recently analyzed by the Engine.
+ */
+class Spectrograph : public QWidget
+{
+    Q_OBJECT
+
+public:
+    explicit Spectrograph(QWidget *parent = 0);
+    ~Spectrograph();
+
+    void setParams(int numBars, qreal lowFreq, qreal highFreq);
+
+    // QObject
+    void timerEvent(QTimerEvent *event) override;
+
+    // QWidget
+    void paintEvent(QPaintEvent *event) override;
+    void mousePressEvent(QMouseEvent *event) override;
+
+signals:
+    void infoMessage(const QString &message, int intervalMs);
+
+public slots:
+    void reset();
+    void spectrumChanged(const FrequencySpectrum &spectrum);
+
+private:
+    int barIndex(qreal frequency) const;
+    QPair<qreal, qreal> barRange(int barIndex) const;
+    void updateBars();
+
+    void selectBar(int index);
+
+private:
+    struct Bar {
+        Bar() : value(0.0), clipped(false) { }
+        qreal   value;
+        bool    clipped;
+    };
+
+    QList<Bar>          m_bars;
+    int                 m_barSelected;
+    int                 m_timerId;
+    qreal               m_lowFreq;
+    qreal               m_highFreq;
+    FrequencySpectrum   m_spectrum;
+};
+
+#endif // SPECTROGRAPH_H