Add the beginnings of a very simple VU meter, based on libebur128.

[nageru] / vumeter.cpp

diff --git a/vumeter.cpp b/vumeter.cpp
new file mode 100644 (file)
index 0000000..03a93e7
--- /dev/null
+++ b/vumeter.cpp
@@ -0,0 +1,33 @@
+#include <QPainter>
+
+#include "vumeter.h"
+
+using namespace std;
+
+VUMeter *global_vu_meter = nullptr;
+
+VUMeter::VUMeter(QWidget *parent)
+       : QWidget(parent)
+{
+}
+
+void VUMeter::paintEvent(QPaintEvent *event)
+{
+       QPainter painter(this);
+
+       painter.fillRect(0, 0, width(), height(), Qt::black);
+
+       float level;
+       {
+               unique_lock<mutex> lock(level_mutex);
+               level = this->level;
+       }
+
+       const float min_level = 0.0f;    // y=0 is top of screen, so “min” is the loudest level.
+       const float max_level = -60.0f; 
+       int y = lrintf(height() * (level - min_level) / (max_level - min_level));
+       if (y >= 0 && y < height()) {
+               painter.setPen(Qt::white);
+               painter.drawLine(0, y, width(), y);
+       }
+}