Plotter and waterfall performance enhancements

README.md

@@ -211,6 +211,7 @@ The following people and organisations have contributed to gqrx:
 * Grigory Shipunov
 * Gwenhael Goavec-Merou
 * Herman Semenov
+* James Yuzawa
 * Jaroslav Škarvada
 * Jeff Long
 * Jiawei Chen

src/applications/gqrx/mainwindow.ui

@@ -21,7 +21,7 @@
  <set>QMainWindow::AllowNestedDocks|QMainWindow::AllowTabbedDocks|QMainWindow::AnimatedDocks</set>
  </property>
  <property name="unifiedTitleAndToolBarOnMac">
- <bool>true</bool>
+ <bool>false</bool>
  </property>
  <widget class="QWidget" name="centralWidget">
  <layout class="QVBoxLayout" name="verticalLayout_2">
@@ -349,9 +349,6 @@
  <verstretch>0</verstretch>
  </sizepolicy>
  </property>
- <property name="autoFillBackground">
- <bool>true</bool>
- </property>
  <property name="frameShape">
  <enum>QFrame::StyledPanel</enum>
  </property>

src/qtgui/meter.cpp

@@ -53,6 +53,7 @@ CMeter::CMeter(QWidget *parent) : QFrame(parent)
 
  m_dBFS = MIN_DB;
  m_Sql = -150.0;
+ m_font = QFont("Arial");
 }
 
 CMeter::~CMeter()
@@ -71,9 +72,14 @@ QSize CMeter::sizeHint() const
 
 void CMeter::setLevel(float dbfs)
 {
+ const float old = m_dBFS;
  float alpha = dbfs < m_dBFS ? ALPHA_DECAY : ALPHA_RISE;
  m_dBFS -= alpha * (m_dBFS - dbfs);
- update();
+ // only redraw when the label needs to change
+ if (qRound(m_dBFS * 10) != qRound(old * 10))
+ {
+ update();
+ }
 }
 
 void CMeter::setSqlLevel(float dbfs)
@@ -116,9 +122,8 @@ void CMeter::draw(QPainter &painter)
  painter.drawLine(QLineF(x, hline, x, hline + 8));
  }
 
- QFont font("Arial");
- font.setPixelSize(height() / 4);
- painter.setFont(font);
+ m_font.setPixelSize(height() / 4);
+ painter.setFont(m_font);
 
  painter.setPen(QColor(0xDA, 0xDA, 0xDA, 0xFF));
  painter.drawText(marg, height() - 2, QString::number((double)m_dBFS, 'f', 1) + " dBFS" );
@@ -148,9 +153,8 @@ void CMeter::drawOverlay(QPainter &painter)
  }
 
  // draw scale text
- QFont font("Arial");
- font.setPixelSize(height() / 4);
- painter.setFont(font);
+ m_font.setPixelSize(height() / 4);
+ painter.setFont(m_font);
  qreal rwidth = (hstop - marg) / 5.0;
  QRectF rect(marg - rwidth / 2, 0, rwidth, majstart);
 

src/qtgui/meter.h

@@ -58,4 +58,5 @@ public slots:
 
  float m_dBFS;
  float m_Sql;
+ QFont m_font;
 };