[Commit-gnuradio] [gnuradio] 11/23: qtgui: for sink_x, waterfall_sink_x, and freq_sink_x, when the display is double-clicked, the center frequency is adjusted to the clicked frequency and a message is posted containing the new center frequency.

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trondeau pushed a commit to branch master
in repository gnuradio.

commit 8cf4334a96288f4f24b3369d44146da21b9e0375
Author: Tom Rondeau <address@hidden>
Date:   Wed Jun 25 18:18:08 2014 -0400

    qtgui: for sink_x, waterfall_sink_x, and freq_sink_x, when the display is 
double-clicked, the center frequency is adjusted to the clicked frequency and a 
message is posted containing the new center frequency.
    
    Should be able to connect this to a radio message port input that will 
adjust the frequency of the device itself.
---
 gr-qtgui/grc/qtgui_freq_sink_x.xml                 |  7 ++++
 gr-qtgui/grc/qtgui_sink_x.xml                      | 12 +++++--
 gr-qtgui/grc/qtgui_waterfall_sink_x.xml            |  7 ++++
 gr-qtgui/include/gnuradio/qtgui/SpectrumGUIClass.h |  3 ++
 gr-qtgui/include/gnuradio/qtgui/displayform.h      |  2 +-
 gr-qtgui/include/gnuradio/qtgui/freqdisplayform.h  | 11 ++++++
 .../include/gnuradio/qtgui/spectrumdisplayform.h   | 10 ++++++
 .../include/gnuradio/qtgui/waterfalldisplayform.h  | 11 ++++++
 gr-qtgui/lib/SpectrumGUIClass.cc                   | 13 +++++++
 gr-qtgui/lib/freq_sink_c_impl.cc                   | 14 ++++++++
 gr-qtgui/lib/freq_sink_c_impl.h                    |  1 +
 gr-qtgui/lib/freq_sink_f_impl.cc                   | 14 ++++++++
 gr-qtgui/lib/freq_sink_f_impl.h                    |  1 +
 gr-qtgui/lib/freqdisplayform.cc                    | 33 ++++++++++++++++--
 gr-qtgui/lib/sink_c_impl.cc                        | 15 +++++++-
 gr-qtgui/lib/sink_c_impl.h                         |  1 +
 gr-qtgui/lib/sink_f_impl.cc                        | 14 ++++++++
 gr-qtgui/lib/sink_f_impl.h                         |  1 +
 gr-qtgui/lib/spectrumdisplayform.cc                | 40 +++++++++++++++++-----
 gr-qtgui/lib/waterfall_sink_c_impl.cc              | 14 ++++++++
 gr-qtgui/lib/waterfall_sink_c_impl.h               |  1 +
 gr-qtgui/lib/waterfall_sink_f_impl.cc              | 14 ++++++++
 gr-qtgui/lib/waterfall_sink_f_impl.h               |  1 +
 gr-qtgui/lib/waterfalldisplayform.cc               | 31 +++++++++++++++--
 24 files changed, 255 insertions(+), 16 deletions(-)

diff --git a/gr-qtgui/grc/qtgui_freq_sink_x.xml 
b/gr-qtgui/grc/qtgui_freq_sink_x.xml
index 761943e..b8bbbe1 100644
--- a/gr-qtgui/grc/qtgui_freq_sink_x.xml
+++ b/gr-qtgui/grc/qtgui_freq_sink_x.xml
@@ -550,6 +550,13 @@ $(gui_hint()($win))</make>
     <type>$type</type>
     <nports>$nconnections</nports>
   </sink>
+
+  <source>
+    <name>freq</name>
+    <type>message</type>
+    <optional>1</optional>
+  </source>
+
   <doc>
 The GUI hint can be used to position the widget within the application. \
 The hint is of the form address@hidden: [row, col, row_span, col_span]. \
diff --git a/gr-qtgui/grc/qtgui_sink_x.xml b/gr-qtgui/grc/qtgui_sink_x.xml
index ea14947..c41468d 100644
--- a/gr-qtgui/grc/qtgui_sink_x.xml
+++ b/gr-qtgui/grc/qtgui_sink_x.xml
@@ -179,9 +179,17 @@ Qt.QObject.connect(self._$(id)_win, 
Qt.SIGNAL("plotPointSelected(QPointF, int)")
                <type>$type</type>
                <nports>$num_inputs</nports>
        </sink>
-       <doc>
+
+
+  <source>
+    <name>freq</name>
+    <type>message</type>
+    <optional>1</optional>
+  </source>
+
+  <doc>
 The GUI hint can be used to position the widget within the application. \
 The hint is of the form address@hidden: [row, col, row_span, col_span]. \
 Both the tab specification and the grid position are optional.
-       </doc>
+  </doc>
 </block>
diff --git a/gr-qtgui/grc/qtgui_waterfall_sink_x.xml 
b/gr-qtgui/grc/qtgui_waterfall_sink_x.xml
index fcd8d97..c340313 100644
--- a/gr-qtgui/grc/qtgui_waterfall_sink_x.xml
+++ b/gr-qtgui/grc/qtgui_waterfall_sink_x.xml
@@ -392,6 +392,13 @@ $(gui_hint()($win))</make>
     <type>$type</type>
     <nports>$nconnections</nports>
   </sink>
+
+  <source>
+    <name>freq</name>
+    <type>message</type>
+    <optional>1</optional>
+  </source>
+
   <doc>
 The GUI hint can be used to position the widget within the application. \
 The hint is of the form address@hidden: [row, col, row_span, col_span]. \
diff --git a/gr-qtgui/include/gnuradio/qtgui/SpectrumGUIClass.h 
b/gr-qtgui/include/gnuradio/qtgui/SpectrumGUIClass.h
index 68a7201..2fb7044 100644
--- a/gr-qtgui/include/gnuradio/qtgui/SpectrumGUIClass.h
+++ b/gr-qtgui/include/gnuradio/qtgui/SpectrumGUIClass.h
@@ -105,6 +105,9 @@ public:
 
   void enableRFFreq(bool en);
 
+  bool checkClicked();
+  float getClickedFreq();
+
 protected:
 
 private:
diff --git a/gr-qtgui/include/gnuradio/qtgui/displayform.h 
b/gr-qtgui/include/gnuradio/qtgui/displayform.h
index c4a9cf7..42c8e40 100644
--- a/gr-qtgui/include/gnuradio/qtgui/displayform.h
+++ b/gr-qtgui/include/gnuradio/qtgui/displayform.h
@@ -91,7 +91,7 @@ private slots:
   virtual void autoScale(bool) = 0;
   void updateGuiTimer();
 
-  void onPlotPointSelected(const QPointF p);
+  virtual void onPlotPointSelected(const QPointF p);
 
 signals:
   void plotPointSelected(const QPointF p, int type);
diff --git a/gr-qtgui/include/gnuradio/qtgui/freqdisplayform.h 
b/gr-qtgui/include/gnuradio/qtgui/freqdisplayform.h
index 95e6337..1fa57c1 100644
--- a/gr-qtgui/include/gnuradio/qtgui/freqdisplayform.h
+++ b/gr-qtgui/include/gnuradio/qtgui/freqdisplayform.h
@@ -49,6 +49,12 @@ class FreqDisplayForm : public DisplayForm
   float getFFTAverage() const;
   gr::filter::firdes::win_type getFFTWindowType() const;
 
+  // returns the frequency that was last double-clicked on by the user
+  float getClickedFreq() const;
+
+  // checks if there was a double-click event; reset if there was
+  bool checkClicked();
+
 public slots:
   void customEvent(QEvent *e);
 
@@ -64,6 +70,7 @@ public slots:
 
 private slots:
   void newData(const QEvent *updateEvent);
+  void onPlotPointSelected(const QPointF p);
 
 private:
   uint64_t d_num_real_data_points;
@@ -73,6 +80,10 @@ private:
   int d_fftsize;
   float d_fftavg;
   gr::filter::firdes::win_type d_fftwintype;
+  double d_units;
+
+  bool d_clicked;
+  double d_clicked_freq;
 
   FFTSizeMenu *d_sizemenu;
   FFTAverageMenu *d_avgmenu;
diff --git a/gr-qtgui/include/gnuradio/qtgui/spectrumdisplayform.h 
b/gr-qtgui/include/gnuradio/qtgui/spectrumdisplayform.h
index 50cbc58..7c71254 100644
--- a/gr-qtgui/include/gnuradio/qtgui/spectrumdisplayform.h
+++ b/gr-qtgui/include/gnuradio/qtgui/spectrumdisplayform.h
@@ -55,6 +55,12 @@ class SpectrumDisplayForm : public QWidget, public 
Ui::SpectrumDisplayForm
   void resizeBuffers(const uint64_t numFFTDataPoints,
                     const uint64_t numTimeDomainDataPoints);
 
+  // returns the frequency that was last double-clicked on by the user
+  float getClickedFreq() const;
+
+  // checks if there was a double-click event; reset if there was
+  bool checkClicked();
+
 public slots:
   void resizeEvent(QResizeEvent * e);
   void customEvent(QEvent * e);
@@ -125,6 +131,10 @@ private:
   double _peakAmplitude;
   double _stopFrequency;
 
+  double d_units;
+  bool d_clicked;
+  double d_clicked_freq;
+
   //SpectrumUpdateEvent _lastSpectrumEvent;
 
   // whether or not to use a particular display
diff --git a/gr-qtgui/include/gnuradio/qtgui/waterfalldisplayform.h 
b/gr-qtgui/include/gnuradio/qtgui/waterfalldisplayform.h
index 1ac1cf4..5af2680 100644
--- a/gr-qtgui/include/gnuradio/qtgui/waterfalldisplayform.h
+++ b/gr-qtgui/include/gnuradio/qtgui/waterfalldisplayform.h
@@ -56,6 +56,12 @@ class WaterfallDisplayForm : public DisplayForm
 
   void clearData();
 
+  // returns the frequency that was last double-clicked on by the user
+  float getClickedFreq() const;
+
+  // checks if there was a double-click event; reset if there was
+  bool checkClicked();
+
 public slots:
   void customEvent(QEvent *e);
 
@@ -81,6 +87,7 @@ public slots:
 
 private slots:
   void newData(const QEvent *updateEvent);
+  void onPlotPointSelected(const QPointF p);
 
 private:
   QIntValidator* d_int_validator;
@@ -89,6 +96,10 @@ private:
   int d_fftsize;
   float d_fftavg;
   gr::filter::firdes::win_type d_fftwintype;
+  double d_units;
+
+  bool d_clicked;
+  double d_clicked_freq;
 
   double d_min_val;
   double d_max_val;
diff --git a/gr-qtgui/lib/SpectrumGUIClass.cc b/gr-qtgui/lib/SpectrumGUIClass.cc
index b7c5883..98feec5 100644
--- a/gr-qtgui/lib/SpectrumGUIClass.cc
+++ b/gr-qtgui/lib/SpectrumGUIClass.cc
@@ -477,5 +477,18 @@ SpectrumGUIClass::enableRFFreq(bool en)
   _spectrumDisplayForm->toggleRFFrequencies(en);
 }
 
+bool
+SpectrumGUIClass::checkClicked()
+{
+  gr::thread::scoped_lock lock(d_mutex);
+  return _spectrumDisplayForm->checkClicked();
+}
+
+float
+SpectrumGUIClass::getClickedFreq()
+{
+  gr::thread::scoped_lock lock(d_mutex);
+  return _spectrumDisplayForm->getClickedFreq();
+}
 
 #endif /* SPECTRUM_GUI_CLASS_CPP */
diff --git a/gr-qtgui/lib/freq_sink_c_impl.cc b/gr-qtgui/lib/freq_sink_c_impl.cc
index ff40ff3..da8a750 100644
--- a/gr-qtgui/lib/freq_sink_c_impl.cc
+++ b/gr-qtgui/lib/freq_sink_c_impl.cc
@@ -69,6 +69,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -444,6 +448,15 @@ namespace gr {
       }
     }
 
+    void
+    freq_sink_c_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     freq_sink_c_impl::work(int noutput_items,
                           gr_vector_const_void_star &input_items,
@@ -455,6 +468,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/freq_sink_c_impl.h b/gr-qtgui/lib/freq_sink_c_impl.h
index 15b5137..8cc5438 100644
--- a/gr-qtgui/lib/freq_sink_c_impl.h
+++ b/gr-qtgui/lib/freq_sink_c_impl.h
@@ -70,6 +70,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const gr_complex *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/freq_sink_f_impl.cc b/gr-qtgui/lib/freq_sink_f_impl.cc
index b661f7b..0b564d5 100644
--- a/gr-qtgui/lib/freq_sink_f_impl.cc
+++ b/gr-qtgui/lib/freq_sink_f_impl.cc
@@ -69,6 +69,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -447,6 +451,15 @@ namespace gr {
       }
     }
 
+    void
+    freq_sink_f_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     freq_sink_f_impl::work(int noutput_items,
                           gr_vector_const_void_star &input_items,
@@ -458,6 +471,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/freq_sink_f_impl.h b/gr-qtgui/lib/freq_sink_f_impl.h
index 68cb8c6..e0fdcf9 100644
--- a/gr-qtgui/lib/freq_sink_f_impl.h
+++ b/gr-qtgui/lib/freq_sink_f_impl.h
@@ -70,6 +70,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const float *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/freqdisplayform.cc b/gr-qtgui/lib/freqdisplayform.cc
index 16576b3..6d2f9b9 100644
--- a/gr-qtgui/lib/freqdisplayform.cc
+++ b/gr-qtgui/lib/freqdisplayform.cc
@@ -39,6 +39,8 @@ FreqDisplayForm::FreqDisplayForm(int nplots, QWidget* parent)
   d_num_real_data_points = 1024;
   d_fftsize = 1024;
   d_fftavg = 1.0;
+  d_clicked = false;
+  d_clicked_freq = 0;
 
   d_sizemenu = new FFTSizeMenu(this);
   d_avgmenu = new FFTAverageMenu(this);
@@ -147,14 +149,14 @@ FreqDisplayForm::setFrequencyRange(const double 
centerfreq,
   std::string strunits[4] = {"Hz", "kHz", "MHz", "GHz"};
   double units10 = floor(log10(bandwidth));
   double units3  = std::max(floor(units10 / 3.0), 0.0);
-  double units = pow(10, (units10-fmod(units10, 3.0)));
+  d_units = pow(10, (units10-fmod(units10, 3.0)));
   int iunit = static_cast<int>(units3);
 
   d_center_freq = centerfreq;
   d_samp_rate = bandwidth;
 
   getPlot()->setFrequencyRange(centerfreq, bandwidth,
-                              units, strunits[iunit]);
+                              d_units, strunits[iunit]);
 }
 
 void
@@ -177,3 +179,30 @@ FreqDisplayForm::autoScale(bool en)
   getPlot()->setAutoScale(d_autoscale_state);
   getPlot()->replot();
 }
+
+void
+FreqDisplayForm::onPlotPointSelected(const QPointF p)
+{
+  d_clicked = true;
+  d_clicked_freq = d_units*p.x();
+
+  setFrequencyRange(d_clicked_freq, d_samp_rate);
+}
+
+bool
+FreqDisplayForm::checkClicked()
+{
+  if(d_clicked) {
+    d_clicked = false;
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+float
+FreqDisplayForm::getClickedFreq() const
+{
+  return d_clicked_freq;
+}
diff --git a/gr-qtgui/lib/sink_c_impl.cc b/gr-qtgui/lib/sink_c_impl.cc
index 5d1c33e..b73ab47 100644
--- a/gr-qtgui/lib/sink_c_impl.cc
+++ b/gr-qtgui/lib/sink_c_impl.cc
@@ -73,6 +73,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -221,7 +225,6 @@ namespace gr {
     void
     sink_c_impl::enable_rf_freq(bool en)
     {
-      std::cerr << "ENABLE RF: " << en << std::endl;
       d_main_gui->enableRFFreq(en);
     }
 
@@ -319,6 +322,15 @@ namespace gr {
       }
     }
 
+    void
+    sink_c_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     sink_c_impl::general_work(int noutput_items,
                              gr_vector_int &ninput_items,
@@ -331,6 +343,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/sink_c_impl.h b/gr-qtgui/lib/sink_c_impl.h
index d303c05..22b8b21 100644
--- a/gr-qtgui/lib/sink_c_impl.h
+++ b/gr-qtgui/lib/sink_c_impl.h
@@ -67,6 +67,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const gr_complex *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/sink_f_impl.cc b/gr-qtgui/lib/sink_f_impl.cc
index 0a0e119..960acb3 100644
--- a/gr-qtgui/lib/sink_f_impl.cc
+++ b/gr-qtgui/lib/sink_f_impl.cc
@@ -73,6 +73,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -307,6 +311,15 @@ namespace gr {
       }
     }
 
+    void
+    sink_f_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     sink_f_impl::general_work(int noutput_items,
                              gr_vector_int &ninput_items,
@@ -319,6 +332,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/sink_f_impl.h b/gr-qtgui/lib/sink_f_impl.h
index 68331cc..a547da3 100644
--- a/gr-qtgui/lib/sink_f_impl.h
+++ b/gr-qtgui/lib/sink_f_impl.h
@@ -65,6 +65,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const float *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/spectrumdisplayform.cc 
b/gr-qtgui/lib/spectrumdisplayform.cc
index aaaae63..6dc38a2 100644
--- a/gr-qtgui/lib/spectrumdisplayform.cc
+++ b/gr-qtgui/lib/spectrumdisplayform.cc
@@ -426,7 +426,7 @@ SpectrumDisplayForm::setFrequencyRange(const double 
newCenterFrequency,
     std::string strtime[4] = {"sec", "ms", "us", "ns"};
     double units10 = floor(log10(fdiff));
     double units3  = std::max(floor(units10 / 3.0), 0.0);
-    double units = pow(10, (units10-fmod(units10, 3.0)));
+    d_units = pow(10, (units10-fmod(units10, 3.0)));
     int iunit = static_cast<int>(units3);
 
     _startFrequency = newStartFrequency;
@@ -434,11 +434,11 @@ SpectrumDisplayForm::setFrequencyRange(const double 
newCenterFrequency,
     _centerFrequency = newCenterFrequency;
 
     _frequencyDisplayPlot->setFrequencyRange(fcenter, fdiff,
-                                            units, strunits[iunit]);
+                                            d_units, strunits[iunit]);
     _waterfallDisplayPlot->setFrequencyRange(fcenter, fdiff,
-                                            units, strunits[iunit]);
+                                            d_units, strunits[iunit]);
     _timeDomainDisplayPlot->setSampleRate((_stopFrequency - 
_startFrequency)/2.0,
-                                         units, strtime[iunit]);
+                                         d_units, strtime[iunit]);
   }
 }
 
@@ -768,23 +768,47 @@ SpectrumDisplayForm::setUpdateTime(double t)
 void
 SpectrumDisplayForm::onFFTPlotPointSelected(const QPointF p)
 {
-  emit plotPointSelected(p, 1);
+  d_clicked = true;
+  d_clicked_freq = d_units*p.x();
+
+  setFrequencyRange(d_clicked_freq, _startFrequency, _stopFrequency);
 }
 
 void
 SpectrumDisplayForm::onWFallPlotPointSelected(const QPointF p)
 {
-  emit plotPointSelected(p, 2);
+  d_clicked = true;
+  d_clicked_freq = d_units*p.x();
+
+  setFrequencyRange(d_clicked_freq, _startFrequency, _stopFrequency);
 }
 
 void
 SpectrumDisplayForm::onTimePlotPointSelected(const QPointF p)
 {
-  emit plotPointSelected(p, 3);
+  //emit plotPointSelected(p, 3);
 }
 
 void
 SpectrumDisplayForm::onConstPlotPointSelected(const QPointF p)
 {
-  emit plotPointSelected(p, 4);
+  //emit plotPointSelected(p, 4);
+}
+
+bool
+SpectrumDisplayForm::checkClicked()
+{
+  if(d_clicked) {
+    d_clicked = false;
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+float
+SpectrumDisplayForm::getClickedFreq() const
+{
+  return d_clicked_freq;
 }
diff --git a/gr-qtgui/lib/waterfall_sink_c_impl.cc 
b/gr-qtgui/lib/waterfall_sink_c_impl.cc
index 2c436db..6147b31 100644
--- a/gr-qtgui/lib/waterfall_sink_c_impl.cc
+++ b/gr-qtgui/lib/waterfall_sink_c_impl.cc
@@ -69,6 +69,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -418,6 +422,15 @@ namespace gr {
       }
     }
 
+    void
+    waterfall_sink_c_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     waterfall_sink_c_impl::work(int noutput_items,
                                gr_vector_const_void_star &input_items,
@@ -429,6 +442,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/waterfall_sink_c_impl.h 
b/gr-qtgui/lib/waterfall_sink_c_impl.h
index aad4a4d..1e5ee17 100644
--- a/gr-qtgui/lib/waterfall_sink_c_impl.h
+++ b/gr-qtgui/lib/waterfall_sink_c_impl.h
@@ -68,6 +68,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const gr_complex *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/waterfall_sink_f_impl.cc 
b/gr-qtgui/lib/waterfall_sink_f_impl.cc
index fc6d9fa..27de72e 100644
--- a/gr-qtgui/lib/waterfall_sink_f_impl.cc
+++ b/gr-qtgui/lib/waterfall_sink_f_impl.cc
@@ -68,6 +68,10 @@ namespace gr {
       d_argv = new char;
       d_argv[0] = '\0';
 
+      // setup output message port to post frequency when display is
+      // double-clicked
+      message_port_register_out(pmt::mp("freq"));
+
       d_main_gui = NULL;
 
       // Perform fftshift operation;
@@ -419,6 +423,15 @@ namespace gr {
       }
     }
 
+    void
+    waterfall_sink_f_impl::check_clicked()
+    {
+      if(d_main_gui->checkClicked()) {
+        d_center_freq = d_main_gui->getClickedFreq();
+        message_port_pub(pmt::mp("freq"), pmt::from_double(d_center_freq));
+      }
+    }
+
     int
     waterfall_sink_f_impl::work(int noutput_items,
                                gr_vector_const_void_star &input_items,
@@ -430,6 +443,7 @@ namespace gr {
       // Update the FFT size from the application
       fftresize();
       windowreset();
+      check_clicked();
 
       for(int i=0; i < noutput_items; i+=d_fftsize) {
        unsigned int datasize = noutput_items - i;
diff --git a/gr-qtgui/lib/waterfall_sink_f_impl.h 
b/gr-qtgui/lib/waterfall_sink_f_impl.h
index 172f873..db86b6a 100644
--- a/gr-qtgui/lib/waterfall_sink_f_impl.h
+++ b/gr-qtgui/lib/waterfall_sink_f_impl.h
@@ -68,6 +68,7 @@ namespace gr {
       void windowreset();
       void buildwindow();
       void fftresize();
+      void check_clicked();
       void fft(float *data_out, const float *data_in, int size);
 
     public:
diff --git a/gr-qtgui/lib/waterfalldisplayform.cc 
b/gr-qtgui/lib/waterfalldisplayform.cc
index f4dd2fd..3f7cf79 100644
--- a/gr-qtgui/lib/waterfalldisplayform.cc
+++ b/gr-qtgui/lib/waterfalldisplayform.cc
@@ -217,14 +217,14 @@ WaterfallDisplayForm::setFrequencyRange(const double 
centerfreq,
   std::string strunits[4] = {"Hz", "kHz", "MHz", "GHz"};
   double units10 = floor(log10(bandwidth));
   double units3  = std::max(floor(units10 / 3.0), 0.0);
-  double units = pow(10, (units10-fmod(units10, 3.0)));
+  d_units = pow(10, (units10-fmod(units10, 3.0)));
   int iunit = static_cast<int>(units3);
 
   d_center_freq = centerfreq;
   d_samp_rate = bandwidth;
 
   getPlot()->setFrequencyRange(centerfreq, bandwidth,
-                              units, strunits[iunit]);
+                              d_units, strunits[iunit]);
   getPlot()->replot();
 }
 
@@ -269,3 +269,30 @@ WaterfallDisplayForm::clearData()
 {
   getPlot()->clearData();
 }
+
+void
+WaterfallDisplayForm::onPlotPointSelected(const QPointF p)
+{
+  d_clicked = true;
+  d_clicked_freq = d_units*p.x();
+
+  setFrequencyRange(d_clicked_freq, d_samp_rate);
+}
+
+bool
+WaterfallDisplayForm::checkClicked()
+{
+  if(d_clicked) {
+    d_clicked = false;
+    return true;
+  }
+  else {
+    return false;
+  }
+}
+
+float
+WaterfallDisplayForm::getClickedFreq() const
+{
+  return d_clicked_freq;
+}