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<h1 class="title">histogramwidget.cpp Example File</h1>
<span class="subtitle">multimediawidgets/player/histogramwidget.cpp</span>
<!-- $$$multimediawidgets/player/histogramwidget.cpp-description -->
<div class="descr"> <a name="details"></a>
<pre class="cpp">
<span class="comment">/****************************************************************************
**
** 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
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** LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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****************************************************************************/</span>
<span class="preprocessor">#include "histogramwidget.h"</span>
<span class="preprocessor">#include <QPainter></span>
<span class="preprocessor">#include <QHBoxLayout></span>
<span class="keyword">template</span> <span class="operator"><</span><span class="keyword">class</span> T<span class="operator">></span>
<span class="keyword">static</span> <span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> getBufferLevels(<span class="keyword">const</span> T <span class="operator">*</span>buffer<span class="operator">,</span> <span class="type">int</span> frames<span class="operator">,</span> <span class="type">int</span> channels);
<span class="keyword">class</span> <span class="type">QAudioLevel</span> : <span class="keyword">public</span> <span class="type">QWidget</span>
{
Q_OBJECT
<span class="keyword">public</span>:
<span class="keyword">explicit</span> <span class="type">QAudioLevel</span>(<span class="type">QWidget</span> <span class="operator">*</span>parent <span class="operator">=</span> <span class="number">0</span>);
<span class="comment">// Using [0; 1.0] range</span>
<span class="type">void</span> setLevel(<span class="type">qreal</span> level);
<span class="keyword">protected</span>:
<span class="type">void</span> paintEvent(<span class="type">QPaintEvent</span> <span class="operator">*</span>event);
<span class="keyword">private</span>:
<span class="type">qreal</span> m_level;
};
<span class="type">QAudioLevel</span><span class="operator">::</span><span class="type">QAudioLevel</span>(<span class="type">QWidget</span> <span class="operator">*</span>parent)
: <span class="type">QWidget</span>(parent)
<span class="operator">,</span> m_level(<span class="number">0.0</span>)
{
setMinimumHeight(<span class="number">15</span>);
setMaximumHeight(<span class="number">50</span>);
}
<span class="type">void</span> <span class="type">QAudioLevel</span><span class="operator">::</span>setLevel(<span class="type">qreal</span> level)
{
<span class="keyword">if</span> (m_level <span class="operator">!</span><span class="operator">=</span> level) {
m_level <span class="operator">=</span> level;
update();
}
}
<span class="type">void</span> <span class="type">QAudioLevel</span><span class="operator">::</span>paintEvent(<span class="type">QPaintEvent</span> <span class="operator">*</span>event)
{
Q_UNUSED(event);
<span class="type">QPainter</span> painter(<span class="keyword">this</span>);
<span class="comment">// draw level</span>
<span class="type">qreal</span> widthLevel <span class="operator">=</span> m_level <span class="operator">*</span> width();
painter<span class="operator">.</span>fillRect(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> widthLevel<span class="operator">,</span> height()<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>red);
<span class="comment">// clear the rest of the control</span>
painter<span class="operator">.</span>fillRect(widthLevel<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> width()<span class="operator">,</span> height()<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>black);
}
HistogramWidget<span class="operator">::</span>HistogramWidget(<span class="type">QWidget</span> <span class="operator">*</span>parent)
: <span class="type">QWidget</span>(parent)
<span class="operator">,</span> m_levels(<span class="number">128</span>)
<span class="operator">,</span> m_isBusy(<span class="keyword">false</span>)
{
m_processor<span class="operator">.</span>moveToThread(<span class="operator">&</span>m_processorThread);
qRegisterMetaType<span class="operator"><</span><span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> <span class="operator">></span>(<span class="string">"QVector<qreal>"</span>);
connect(<span class="operator">&</span>m_processor<span class="operator">,</span> SIGNAL(histogramReady(<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span>))<span class="operator">,</span> SLOT(setHistogram(<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span>)));
m_processorThread<span class="operator">.</span>start(<span class="type">QThread</span><span class="operator">::</span>LowestPriority);
setLayout(<span class="keyword">new</span> <span class="type">QHBoxLayout</span>);
}
HistogramWidget<span class="operator">::</span><span class="operator">~</span>HistogramWidget()
{
m_processorThread<span class="operator">.</span>quit();
m_processorThread<span class="operator">.</span>wait(<span class="number">10000</span>);
}
<span class="type">void</span> HistogramWidget<span class="operator">::</span>processFrame(<span class="type"><a href="qvideoframe.html">QVideoFrame</a></span> frame)
{
<span class="keyword">if</span> (m_isBusy <span class="operator">&</span><span class="operator">&</span> frame<span class="operator">.</span>isValid())
<span class="keyword">return</span>; <span class="comment">//drop frame</span>
m_isBusy <span class="operator">=</span> <span class="keyword">true</span>;
<span class="type">QMetaObject</span><span class="operator">::</span>invokeMethod(<span class="operator">&</span>m_processor<span class="operator">,</span> <span class="string">"processFrame"</span><span class="operator">,</span>
<span class="type">Qt</span><span class="operator">::</span>QueuedConnection<span class="operator">,</span> Q_ARG(<span class="type"><a href="qvideoframe.html">QVideoFrame</a></span><span class="operator">,</span> frame)<span class="operator">,</span> Q_ARG(<span class="type">int</span><span class="operator">,</span> m_levels));
}
<span class="comment">// This function returns the maximum possible sample value for a given audio format</span>
<span class="type">qreal</span> getPeakValue(<span class="keyword">const</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">&</span> format)
{
<span class="comment">// Note: Only the most common sample formats are supported</span>
<span class="keyword">if</span> (<span class="operator">!</span>format<span class="operator">.</span>isValid())
<span class="keyword">return</span> <span class="type">qreal</span>(<span class="number">0</span>);
<span class="keyword">if</span> (format<span class="operator">.</span>codec() <span class="operator">!</span><span class="operator">=</span> <span class="string">"audio/pcm"</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(<span class="number">0</span>);
<span class="keyword">switch</span> (format<span class="operator">.</span>sampleType()) {
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>Unknown:
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>Float:
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">!</span><span class="operator">=</span> <span class="number">32</span>) <span class="comment">// other sample formats are not supported</span>
<span class="keyword">return</span> <span class="type">qreal</span>(<span class="number">0</span>);
<span class="keyword">return</span> <span class="type">qreal</span>(<span class="number">1.00003</span>);
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>SignedInt:
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">32</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(INT_MAX);
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(SHRT_MAX);
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(CHAR_MAX);
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>UnSignedInt:
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">32</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(UINT_MAX);
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(USHRT_MAX);
<span class="keyword">if</span> (format<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>)
<span class="keyword">return</span> <span class="type">qreal</span>(UCHAR_MAX);
<span class="keyword">break</span>;
}
<span class="keyword">return</span> <span class="type">qreal</span>(<span class="number">0</span>);
}
<span class="comment">// returns the audio level for each channel</span>
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> getBufferLevels(<span class="keyword">const</span> <span class="type"><a href="qaudiobuffer.html">QAudioBuffer</a></span><span class="operator">&</span> buffer)
{
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> values;
<span class="keyword">if</span> (<span class="operator">!</span>buffer<span class="operator">.</span>isValid())
<span class="keyword">return</span> values;
<span class="keyword">if</span> (<span class="operator">!</span>buffer<span class="operator">.</span>format()<span class="operator">.</span>isValid() <span class="operator">|</span><span class="operator">|</span> buffer<span class="operator">.</span>format()<span class="operator">.</span>byteOrder() <span class="operator">!</span><span class="operator">=</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>LittleEndian)
<span class="keyword">return</span> values;
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>codec() <span class="operator">!</span><span class="operator">=</span> <span class="string">"audio/pcm"</span>)
<span class="keyword">return</span> values;
<span class="type">int</span> channelCount <span class="operator">=</span> buffer<span class="operator">.</span>format()<span class="operator">.</span>channelCount();
values<span class="operator">.</span>fill(<span class="number">0</span><span class="operator">,</span> channelCount);
<span class="type">qreal</span> peak_value <span class="operator">=</span> getPeakValue(buffer<span class="operator">.</span>format());
<span class="keyword">if</span> (qFuzzyCompare(peak_value<span class="operator">,</span> <span class="type">qreal</span>(<span class="number">0</span>)))
<span class="keyword">return</span> values;
<span class="keyword">switch</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleType()) {
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>Unknown:
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>UnSignedInt:
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">32</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">quint32</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">quint16</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">quint8</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> values<span class="operator">.</span>size(); <span class="operator">+</span><span class="operator">+</span>i)
values<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">=</span> qAbs(values<span class="operator">.</span>at(i) <span class="operator">-</span> peak_value <span class="operator">/</span> <span class="number">2</span>) <span class="operator">/</span> (peak_value <span class="operator">/</span> <span class="number">2</span>);
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>Float:
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">32</span>) {
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">float</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> values<span class="operator">.</span>size(); <span class="operator">+</span><span class="operator">+</span>i)
values<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">/</span><span class="operator">=</span> peak_value;
}
<span class="keyword">break</span>;
<span class="keyword">case</span> <span class="type"><a href="qaudioformat.html">QAudioFormat</a></span><span class="operator">::</span>SignedInt:
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">32</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">qint32</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">16</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">qint16</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">if</span> (buffer<span class="operator">.</span>format()<span class="operator">.</span>sampleSize() <span class="operator">=</span><span class="operator">=</span> <span class="number">8</span>)
values <span class="operator">=</span> getBufferLevels(buffer<span class="operator">.</span>constData<span class="operator"><</span><span class="type">qint8</span><span class="operator">></span>()<span class="operator">,</span> buffer<span class="operator">.</span>frameCount()<span class="operator">,</span> channelCount);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> values<span class="operator">.</span>size(); <span class="operator">+</span><span class="operator">+</span>i)
values<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">/</span><span class="operator">=</span> peak_value;
<span class="keyword">break</span>;
}
<span class="keyword">return</span> values;
}
<span class="keyword">template</span> <span class="operator"><</span><span class="keyword">class</span> T<span class="operator">></span>
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> getBufferLevels(<span class="keyword">const</span> T <span class="operator">*</span>buffer<span class="operator">,</span> <span class="type">int</span> frames<span class="operator">,</span> <span class="type">int</span> channels)
{
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> max_values;
max_values<span class="operator">.</span>fill(<span class="number">0</span><span class="operator">,</span> channels);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> frames; <span class="operator">+</span><span class="operator">+</span>i) {
<span class="keyword">for</span> (<span class="type">int</span> j <span class="operator">=</span> <span class="number">0</span>; j <span class="operator"><</span> channels; <span class="operator">+</span><span class="operator">+</span>j) {
<span class="type">qreal</span> value <span class="operator">=</span> qAbs(<span class="type">qreal</span>(buffer<span class="operator">[</span>i <span class="operator">*</span> channels <span class="operator">+</span> j<span class="operator">]</span>));
<span class="keyword">if</span> (value <span class="operator">></span> max_values<span class="operator">.</span>at(j))
max_values<span class="operator">.</span>replace(j<span class="operator">,</span> value);
}
}
<span class="keyword">return</span> max_values;
}
<span class="type">void</span> HistogramWidget<span class="operator">::</span>processBuffer(<span class="type"><a href="qaudiobuffer.html">QAudioBuffer</a></span> buffer)
{
<span class="keyword">if</span> (audioLevels<span class="operator">.</span>count() <span class="operator">!</span><span class="operator">=</span> buffer<span class="operator">.</span>format()<span class="operator">.</span>channelCount()) {
qDeleteAll(audioLevels);
audioLevels<span class="operator">.</span>clear();
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> buffer<span class="operator">.</span>format()<span class="operator">.</span>channelCount(); <span class="operator">+</span><span class="operator">+</span>i) {
<span class="type">QAudioLevel</span> <span class="operator">*</span>level <span class="operator">=</span> <span class="keyword">new</span> <span class="type">QAudioLevel</span>(<span class="keyword">this</span>);
audioLevels<span class="operator">.</span>append(level);
layout()<span class="operator">-</span><span class="operator">></span>addWidget(level);
}
}
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> levels <span class="operator">=</span> getBufferLevels(buffer);
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> levels<span class="operator">.</span>count(); <span class="operator">+</span><span class="operator">+</span>i)
audioLevels<span class="operator">.</span>at(i)<span class="operator">-</span><span class="operator">></span>setLevel(levels<span class="operator">.</span>at(i));
}
<span class="type">void</span> HistogramWidget<span class="operator">::</span>setHistogram(<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> histogram)
{
m_isBusy <span class="operator">=</span> <span class="keyword">false</span>;
m_histogram <span class="operator">=</span> histogram;
update();
}
<span class="type">void</span> HistogramWidget<span class="operator">::</span>paintEvent(<span class="type">QPaintEvent</span> <span class="operator">*</span>event)
{
Q_UNUSED(event);
<span class="keyword">if</span> (<span class="operator">!</span>audioLevels<span class="operator">.</span>isEmpty())
<span class="keyword">return</span>;
<span class="type">QPainter</span> painter(<span class="keyword">this</span>);
<span class="keyword">if</span> (m_histogram<span class="operator">.</span>isEmpty()) {
painter<span class="operator">.</span>fillRect(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> width()<span class="operator">,</span> height()<span class="operator">,</span> <span class="type">QColor</span><span class="operator">::</span>fromRgb(<span class="number">0</span><span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> <span class="number">0</span>));
<span class="keyword">return</span>;
}
<span class="type">qreal</span> barWidth <span class="operator">=</span> width() <span class="operator">/</span> (<span class="type">qreal</span>)m_histogram<span class="operator">.</span>size();
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> m_histogram<span class="operator">.</span>size(); i<span class="operator">+</span><span class="operator">+</span>) {
<span class="type">qreal</span> h <span class="operator">=</span> m_histogram<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">*</span> height();
<span class="comment">// draw level</span>
painter<span class="operator">.</span>fillRect(barWidth <span class="operator">*</span> i<span class="operator">,</span> height() <span class="operator">-</span> h<span class="operator">,</span> barWidth <span class="operator">*</span> (i <span class="operator">+</span> <span class="number">1</span>)<span class="operator">,</span> height()<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>red);
<span class="comment">// clear the rest of the control</span>
painter<span class="operator">.</span>fillRect(barWidth <span class="operator">*</span> i<span class="operator">,</span> <span class="number">0</span><span class="operator">,</span> barWidth <span class="operator">*</span> (i <span class="operator">+</span> <span class="number">1</span>)<span class="operator">,</span> height() <span class="operator">-</span> h<span class="operator">,</span> <span class="type">Qt</span><span class="operator">::</span>black);
}
}
<span class="type">void</span> FrameProcessor<span class="operator">::</span>processFrame(<span class="type"><a href="qvideoframe.html">QVideoFrame</a></span> frame<span class="operator">,</span> <span class="type">int</span> levels)
{
<span class="type">QVector</span><span class="operator"><</span><span class="type">qreal</span><span class="operator">></span> histogram(levels);
<span class="keyword">do</span> {
<span class="keyword">if</span> (<span class="operator">!</span>levels)
<span class="keyword">break</span>;
<span class="keyword">if</span> (<span class="operator">!</span>frame<span class="operator">.</span>map(<span class="type"><a href="qabstractvideobuffer.html">QAbstractVideoBuffer</a></span><span class="operator">::</span>ReadOnly))
<span class="keyword">break</span>;
<span class="keyword">if</span> (frame<span class="operator">.</span>pixelFormat() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qvideoframe.html">QVideoFrame</a></span><span class="operator">::</span>Format_YUV420P <span class="operator">|</span><span class="operator">|</span>
frame<span class="operator">.</span>pixelFormat() <span class="operator">=</span><span class="operator">=</span> <span class="type"><a href="qvideoframe.html">QVideoFrame</a></span><span class="operator">::</span>Format_NV12) {
<span class="comment">// Process YUV data</span>
<span class="type">uchar</span> <span class="operator">*</span>b <span class="operator">=</span> frame<span class="operator">.</span>bits();
<span class="keyword">for</span> (<span class="type">int</span> y <span class="operator">=</span> <span class="number">0</span>; y <span class="operator"><</span> frame<span class="operator">.</span>height(); y<span class="operator">+</span><span class="operator">+</span>) {
<span class="type">uchar</span> <span class="operator">*</span>lastPixel <span class="operator">=</span> b <span class="operator">+</span> frame<span class="operator">.</span>width();
<span class="keyword">for</span> (<span class="type">uchar</span> <span class="operator">*</span>curPixel <span class="operator">=</span> b; curPixel <span class="operator"><</span> lastPixel; curPixel<span class="operator">+</span><span class="operator">+</span>)
histogram<span class="operator">[</span>(<span class="operator">*</span>curPixel <span class="operator">*</span> levels) <span class="operator">></span><span class="operator">></span> <span class="number">8</span><span class="operator">]</span> <span class="operator">+</span><span class="operator">=</span> <span class="number">1.0</span>;
b <span class="operator">+</span><span class="operator">=</span> frame<span class="operator">.</span>bytesPerLine();
}
} <span class="keyword">else</span> {
<span class="type">QImage</span><span class="operator">::</span>Format imageFormat <span class="operator">=</span> <span class="type"><a href="qvideoframe.html">QVideoFrame</a></span><span class="operator">::</span>imageFormatFromPixelFormat(frame<span class="operator">.</span>pixelFormat());
<span class="keyword">if</span> (imageFormat <span class="operator">!</span><span class="operator">=</span> <span class="type">QImage</span><span class="operator">::</span>Format_Invalid) {
<span class="comment">// Process RGB data</span>
<span class="type">QImage</span> image(frame<span class="operator">.</span>bits()<span class="operator">,</span> frame<span class="operator">.</span>width()<span class="operator">,</span> frame<span class="operator">.</span>height()<span class="operator">,</span> imageFormat);
image <span class="operator">=</span> image<span class="operator">.</span>convertToFormat(<span class="type">QImage</span><span class="operator">::</span>Format_RGB32);
<span class="keyword">const</span> <span class="type">QRgb</span><span class="operator">*</span> b <span class="operator">=</span> (<span class="keyword">const</span> <span class="type">QRgb</span><span class="operator">*</span>)image<span class="operator">.</span>bits();
<span class="keyword">for</span> (<span class="type">int</span> y <span class="operator">=</span> <span class="number">0</span>; y <span class="operator"><</span> image<span class="operator">.</span>height(); y<span class="operator">+</span><span class="operator">+</span>) {
<span class="keyword">const</span> <span class="type">QRgb</span> <span class="operator">*</span>lastPixel <span class="operator">=</span> b <span class="operator">+</span> frame<span class="operator">.</span>width();
<span class="keyword">for</span> (<span class="keyword">const</span> <span class="type">QRgb</span> <span class="operator">*</span>curPixel <span class="operator">=</span> b; curPixel <span class="operator"><</span> lastPixel; curPixel<span class="operator">+</span><span class="operator">+</span>)
histogram<span class="operator">[</span>(qGray(<span class="operator">*</span>curPixel) <span class="operator">*</span> levels) <span class="operator">></span><span class="operator">></span> <span class="number">8</span><span class="operator">]</span> <span class="operator">+</span><span class="operator">=</span> <span class="number">1.0</span>;
b <span class="operator">=</span> (<span class="keyword">const</span> <span class="type">QRgb</span><span class="operator">*</span>)((<span class="type">uchar</span><span class="operator">*</span>)b <span class="operator">+</span> image<span class="operator">.</span>bytesPerLine());
}
}
}
<span class="comment">// find maximum value</span>
<span class="type">qreal</span> maxValue <span class="operator">=</span> <span class="number">0.0</span>;
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> histogram<span class="operator">.</span>size(); i<span class="operator">+</span><span class="operator">+</span>) {
<span class="keyword">if</span> (histogram<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">></span> maxValue)
maxValue <span class="operator">=</span> histogram<span class="operator">[</span>i<span class="operator">]</span>;
}
<span class="keyword">if</span> (maxValue <span class="operator">></span> <span class="number">0.0</span>) {
<span class="keyword">for</span> (<span class="type">int</span> i <span class="operator">=</span> <span class="number">0</span>; i <span class="operator"><</span> histogram<span class="operator">.</span>size(); i<span class="operator">+</span><span class="operator">+</span>)
histogram<span class="operator">[</span>i<span class="operator">]</span> <span class="operator">/</span><span class="operator">=</span> maxValue;
}
frame<span class="operator">.</span>unmap();
} <span class="keyword">while</span> (<span class="keyword">false</span>);
<span class="keyword">emit</span> histogramReady(histogram);
}
<span class="preprocessor">#include "histogramwidget.moc"</span>
</pre>
</div>
<!-- @@@multimediawidgets/player/histogramwidget.cpp -->
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<acronym title="Copyright">©</acronym> 2017 The Qt Company Ltd.
Documentation contributions included herein are the copyrights of
their respective owners.<br> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property
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