Vastly improved the joystick documentation, removed some redundant/unnecessary code, and fixed a couple of small bugs. This code should be ready for live testing.

src/input/JoystickInput.cc

@@ -505,7 +505,6 @@ void JoystickInput::setActiveJoystick(int id)
     joystick = SDL_JoystickOpen(joystickID);
     if (joystick && SDL_JoystickOpened(joystickID))
     {
-        SDL_JoystickUpdate();
         // Update joystick configuration.
         joystickName = QString(SDL_JoystickName(joystickID));
         joystickNumButtons = SDL_JoystickNumButtons(joystick);
@@ -532,6 +531,9 @@ void JoystickInput::setActiveJoystick(int id)
         joystickNumAxes = 0;
     }
 
+    // Specify that a new joystick has been selected, so that any UI elements can update.
+    emit newJoystickSelected();
+    // And then trigger an update of this new UI.
     emit joystickSettingsChanged();
 }
 

src/input/JoystickInput.h

@@ -23,11 +23,20 @@ This file is part of the PIXHAWK project
 
 /**
  * @file
- *   @brief Definition of joystick interface
+ * @brief Definition of joystick interface
  *
- *   @author Lorenz Meier <mavteam@student.ethz.ch>
- *   @author Andreas Romer <mavteam@student.ethz.ch>
+ * This class defines a new thread to operate the reading of any joystick/controllers
+ * via the Simple Directmedia Library (libsdl.org). This relies on polling of the SDL,
+ * which is not their recommended method, instead they suggest use event checking. That
+ * does not seem to support switching joysticks after their internal event loop has started,
+ * so it was abandoned.
  *
+ * All joystick-related functionality is done in this class, though the JoystickWidget provides
+ * a UI around modifying its settings. Additionally controller buttons can be mapped to
+ * actions defined by any UASInterface object through the `UASInterface::getActions()` function.
+ *
+ * @author Lorenz Meier <mavteam@student.ethz.ch>
+ * @author Andreas Romer <mavteam@student.ethz.ch>
  */
 
 #ifndef _JOYSTICKINPUT_H_
@@ -198,6 +207,9 @@ protected:
     quint16 joystickButtons;   ///< The state of every button. Bitfield supporting 16 buttons with 1s indicating that the button is down.
     int xHat, yHat;            ///< The horizontal/vertical hat directions. Values are -1, 0, 1, with (-1,-1) indicating bottom-left.
 
+    /**
+     * @brief Called before main run() event loop starts. Waits for joysticks to be connected.
+     */
     void init();
 
 signals:
@@ -265,6 +277,9 @@ signals:
     /** @brief Signals that new joystick-specific settings were changed. Useful for triggering updates that at dependent on the current joystick. */
     void joystickSettingsChanged();
 
+    /** @brief The JoystickInput has switched to a different joystick. UI should be adjusted accordingly. */
+    void newJoystickSelected();
+
 public slots:
     /** @brief Enable or disable emitting the high-level control signals from the joystick. */
     void setEnabled(bool enable);

src/uas/UAS.cc

@@ -284,7 +284,7 @@ int UAS::getUASID() const
 
 void UAS::triggerAction(int action)
 {
-    if (action > 0 && action < actions.size())
+    if (action >= 0 && action < actions.size())
     {
         qDebug() << "Triggering action: '" << actions[action]->text() << "'";
         actions[action]->trigger();
@@ -2790,27 +2790,6 @@ int UAS::getSystemType()
 }
 
 /**
-* @param buttonIndex
-*/
-void UAS::receiveButton(int buttonIndex)
-{
-    switch (buttonIndex)
-    {
-    case 0:
-
-        break;
-    case 1:
-
-        break;
-    default:
-
-        break;
-    }
-    //    qDebug() << __FILE__ << __LINE__ << ": Received button clicked signal (button # is: " << buttonIndex << "), UNIMPLEMENTED IN MAVLINK!";
-
-}
-
-/**
 * Halt the uas.
 */
 void UAS::halt()

src/uas/UAS.h

@@ -799,8 +799,6 @@ public slots:
 
     /** @brief Set the values for the manual control of the vehicle */
     void setManualControlCommands(double roll, double pitch, double yaw, double thrust, int xHat, int yHat, int buttons);
-    /** @brief Receive a button pressed event from an input device, e.g. joystick */
-    void receiveButton(int buttonIndex);
 
     /** @brief Set the values for the 6dof manual control of the vehicle */
     void setManual6DOFControlCommands(double x, double y, double z, double roll, double pitch, double yaw);

src/uas/UASInterface.h

@@ -261,7 +261,9 @@ public:
     }
 
     /** @brief Returns a list of actions/commands that this vehicle can perform.
-     *  Used for creating UI elements for built-in functionality for this vehicle.
+     * Used for creating UI elements for built-in functionality for this vehicle.
+     * Actions should be mappings to `void f(void);` functions that simply issue
+     * a command to the vehicle.
      */
     virtual QList<QAction*> getActions() const = 0;
 

src/ui/JoystickAxis.h

@@ -1,3 +1,30 @@
+/*=====================================================================
+
+QGroundControl Open Source Ground Control Station
+
+This file is part of the QGROUNDCONTROL project
+
+    QGROUNDCONTROL is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    QGROUNDCONTROL is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+
+======================================================================*/
+
+/**
+ * @file
+ * This class defines a UI element to represent a single controller axis.
+ * It is used by the JoystickWidget to simplify some of the logic in that class.
+ */
+
 #ifndef JOYSTICKAXIS_H
 #define JOYSTICKAXIS_H
 

src/ui/JoystickButton.h

@@ -1,3 +1,30 @@
+/*=====================================================================
+
+QGroundControl Open Source Ground Control Station
+
+This file is part of the QGROUNDCONTROL project
+
+    QGROUNDCONTROL is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    QGROUNDCONTROL is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with QGROUNDCONTROL. If not, see <http://www.gnu.org/licenses/>.
+
+======================================================================*/
+
+/**
+ * @file
+ * This class defines a UI element to represent a single controller axis.
+ * It is used by the JoystickWidget to simplify some of the logic in that class.
+ */
+
 #ifndef JOYSTICKBUTTON_H
 #define JOYSTICKBUTTON_H
 

src/ui/JoystickWidget.cc

@@ -30,8 +30,10 @@ JoystickWidget::JoystickWidget(JoystickInput* joystick, QWidget *parent) :
     // Also watch for when new settings were loaded for the current joystick to do a mass UI refresh.
     connect(this->joystick, SIGNAL(joystickSettingsChanged()), this, SLOT(updateUI()));
 
-    // If the selected joystick is changed, update the joystick.
+    // If the selected joystick is changed, update the JoystickInput.
     connect(m_ui->joystickNameComboBox, SIGNAL(currentIndexChanged(int)), this->joystick, SLOT(setActiveJoystick(int)));
+    // Also wait for the JoystickInput to switch, then update our UI.
+    connect(this->joystick, SIGNAL(newJoystickSelected()), this, SLOT(createUIForJoystick()));
 
     // Initialize the UI to the current JoystickInput state. Also make sure to listen for future changes
     // so that the UI can be updated.
@@ -124,8 +126,6 @@ void JoystickWidget::updateUI()
     for (int i = 0; i < axes.size(); i++)
     {
         JoystickAxis* axis = axes[i];
-        float value = joystick->getCurrentValueForAxis(i);
-        axis->setValue(value);
         JoystickInput::JOYSTICK_INPUT_MAPPING mapping = JoystickInput::JOYSTICK_INPUT_MAPPING_NONE;
         if (i == rollAxis)
         {

src/ui/JoystickWidget.h

@@ -23,7 +23,7 @@ This file is part of the PIXHAWK project
 
 /**
  * @file
- *   @brief Definition of joystick widget
+ *   @brief Definition of joystick widget. Provides a UI for configuring the joystick settings.
  *   @author Lorenz Meier <mavteam@student.ethz.ch>
  *
  */
@@ -76,8 +76,6 @@ public slots:
     void updateUI();
 
 protected:
-    /** @brief Update the proper number of buttons for the current joystick. */
-    void updateButtons();
     /** @brief UI change event */
     virtual void changeEvent(QEvent *e);
     JoystickInput* joystick;  ///< Reference to the joystick
@@ -90,7 +88,9 @@ protected:
 
 private:
     Ui::JoystickWidget *m_ui;
-    /** @brief Initialize all dynamic UI elements (button list, joystick names, etc.) */
+    /** @brief Initialize all dynamic UI elements (button list, joystick names, etc.).
+     * Only done once at startup.
+     */
     void initUI();
 };