IQ Tool GUI improvements

Fix jumpy scrollbar of IQ player

When file list grows long and the user tries to scroll the list to a new
postion, the list continues to return it's scroll to the last selected item.
That's really annoying.
Return the list to last seen position after refreshing it's contents.

IQ recorder: disable harmful buttons while recording is in progress.

Changing IO devices and loading/saving settings does not look like good thing
to do while recording an IQ file.

IQ tool: Always choose correct sampling rate

Reselect file before starting playback. Fixes incorrect sample rate
when playback is started, stopped, devices switched, dsp started,
stopped and then started playback of the same IQ file.

IQ tool: disable/enable controls properly

Disable directory selector, file list while playing/recording  IQ
file.
Disable slider while recording IQ file.

src/applications/gqrx/mainwindow.cpp

@@ -1581,6 +1581,8 @@ void MainWindow::startIqRecording(const QString& recdir)
             toString("%1/gqrx_yyyyMMdd_hhmmss_%2_%3_fc.'raw'")
             .arg(recdir).arg(freq).arg(sr/dec);
 
+    ui->actionIoConfig->setDisabled(true);
+    ui->actionLoadSettings->setDisabled(true);
     // start recorder; fails if recording already in progress
     if (rx->start_iq_recording(lastRec.toStdString()))
     {
@@ -1611,6 +1613,8 @@ void MainWindow::stopIqRecording()
         ui->statusBar->showMessage(tr("Error stopping I/Q recoder"));
     else
         ui->statusBar->showMessage(tr("I/Q data recoding stopped"), 5000);
+    ui->actionIoConfig->setDisabled(false);
+    ui->actionLoadSettings->setDisabled(false);
 }
 
 void MainWindow::startIqPlayback(const QString& filename, float samprate, qint64 center_freq)
@@ -1622,6 +1626,8 @@ void MainWindow::startIqPlayback(const QString& filename, float samprate, qint64
     }
 
     storeSession();
+    backupFreq = ui->freqCtrl->getFrequency();
+    backupOffset = (qint64) rx->get_filter_offset();
 
     auto sri = (int)samprate;
     auto cf  = center_freq;
@@ -1653,6 +1659,9 @@ void MainWindow::startIqPlayback(const QString& filename, float samprate, qint64
 
     // FIXME: would be nice with good/bad status
     ui->statusBar->showMessage(tr("Playing %1").arg(filename));
+    ui->actionIoConfig->setDisabled(true);
+    ui->actionLoadSettings->setDisabled(true);
+    ui->actionSaveSettings->setDisabled(true);
 
     on_actionDSP_triggered(true);
 }
@@ -1666,6 +1675,9 @@ void MainWindow::stopIqPlayback()
     }
 
     ui->statusBar->showMessage(tr("I/Q playback stopped"), 5000);
+    ui->actionIoConfig->setDisabled(false);
+    ui->actionLoadSettings->setDisabled(false);
+    ui->actionSaveSettings->setDisabled(false);
 
     // restore original input device
     auto indev = m_settings->value("input/device", "").toString();

src/applications/gqrx/mainwindow.h

@@ -80,6 +80,8 @@ public slots:
     qint64 d_hw_freq;
     qint64 d_hw_freq_start{};
     qint64 d_hw_freq_stop{};
+    qint64 backupFreq; /* for IQ player */
+    qint64 backupOffset; /* for IQ player */
 
     bool d_ignore_limits;
 

src/qtgui/iq_tool.cpp

@@ -29,6 +29,7 @@
 #include <QString>
 #include <QStringList>
 #include <QTime>
+#include <QScrollBar>
 
 #include <math.h>
 
@@ -100,6 +101,20 @@ void CIqTool::on_listWidget_currentTextChanged(const QString &currentText)
 
 }
 
+/*! \brief Show/hide/enable/disable GUI controls */
+
+void CIqTool::switchControlsState(bool recording, bool playback)
+{
+    ui->recButton->setEnabled(!playback);
+
+    ui->playButton->setEnabled(!recording);
+    ui->slider->setEnabled(!recording);
+
+    ui->listWidget->setEnabled(!(recording || playback));
+    ui->recDirEdit->setEnabled(!(recording || playback));
+    ui->recDirButton->setEnabled(!(recording || playback));
+}
+
 /*! \brief Start/stop playback */
 void CIqTool::on_playButton_clicked(bool checked)
 {
@@ -125,17 +140,17 @@ void CIqTool::on_playButton_clicked(bool checked)
         }
         else
         {
-            ui->listWidget->setEnabled(false);
-            ui->recButton->setEnabled(false);
+            on_listWidget_currentTextChanged(current_file);
+            switchControlsState(false, true);
+
             emit startPlayback(recdir->absoluteFilePath(current_file),
                                (float)sample_rate, center_freq);
         }
     }
     else
     {
         emit stopPlayback();
-        ui->listWidget->setEnabled(true);
-        ui->recButton->setEnabled(true);
+        switchControlsState(false, false);
         ui->slider->setValue(0);
     }
 }
@@ -148,9 +163,7 @@ void CIqTool::on_playButton_clicked(bool checked)
  */
 void CIqTool::cancelPlayback()
 {
-    ui->playButton->setChecked(false);
-    ui->listWidget->setEnabled(true);
-    ui->recButton->setEnabled(true);
+    switchControlsState(false, false);
     is_playing = false;
 }
 
@@ -172,15 +185,15 @@ void CIqTool::on_recButton_clicked(bool checked)
 
     if (checked)
     {
-        ui->playButton->setEnabled(false);
+        switchControlsState(true, false);
         emit startRecording(recdir->path());
 
         refreshDir();
         ui->listWidget->setCurrentRow(ui->listWidget->count()-1);
     }
     else
     {
-        ui->playButton->setEnabled(true);
+        switchControlsState(false, false);
         emit stopRecording();
     }
 }
@@ -303,13 +316,16 @@ void CIqTool::refreshDir()
 {
     int selection = ui->listWidget->currentRow();
 
+    QScrollBar * sc = ui->listWidget->verticalScrollBar();
+    int lastScroll = sc->sliderPosition();
     recdir->refresh();
     QStringList files = recdir->entryList();
 
     ui->listWidget->blockSignals(true);
     ui->listWidget->clear();
     ui->listWidget->insertItems(0, files);
     ui->listWidget->setCurrentRow(selection);
+    sc->setSliderPosition(lastScroll);
     ui->listWidget->blockSignals(false);
 
     if (is_recording)

src/qtgui/iq_tool.h

@@ -85,6 +85,8 @@ private slots:
     void refreshDir(void);
     void refreshTimeWidgets(void);
     void parseFileName(const QString &filename);
+    void switchControlsState(bool recording, bool playback);
+
 
 private:
     Ui::CIqTool *ui;