From 3051ab71b2547956a7fab76b8a1ff27f860262ed Mon Sep 17 00:00:00 2001
From: Pierre Kancir <pierre.kancir.emn@gmail.com>
Date: Tue, 23 May 2017 17:44:05 +0200
Subject: [PATCH] Joystick: add a button to support negative thrust

---
 src/Joystick/Joystick.cc            | 21 ++++++++++++++++++++-
 src/Joystick/Joystick.h             |  8 ++++++++
 src/VehicleSetup/JoystickConfig.qml |  8 ++++++++
 3 files changed, 36 insertions(+), 1 deletion(-)

diff --git a/src/Joystick/Joystick.cc b/src/Joystick/Joystick.cc
index b1c00e2d8..356ed2fa1 100644
--- a/src/Joystick/Joystick.cc
+++ b/src/Joystick/Joystick.cc
@@ -55,6 +55,7 @@ Joystick::Joystick(const QString& name, int axisCount, int buttonCount, int hatC
     , _rgButtonValues(NULL)
     , _lastButtonBits(0)
     , _throttleMode(ThrottleModeCenterZero)
+    , _negativeThrust(false)
     , _exponential(0)
     , _accumulator(false)
     , _deadband(false)
@@ -462,7 +463,9 @@ void Joystick::run(void)
 
             // Adjust throttle to 0:1 range
             if (_throttleMode == ThrottleModeCenterZero && _activeVehicle->supportsThrottleModeCenterZero()) {
-                throttle = std::max(0.0f, throttle);
+                if (!_negativeThrust) {
+                    throttle = std::max(0.0f, throttle);
+                }
             } else {
                 throttle = (throttle + 1.0f) / 2.0f;
             }
@@ -687,6 +690,22 @@ void Joystick::setThrottleMode(int mode)
     emit throttleModeChanged(_throttleMode);
 }
 
+bool Joystick::negativeThrust(void)
+{
+    return _negativeThrust;
+}
+
+void Joystick::setNegativeThrust(bool allowNegative)
+{
+    if (_negativeThrust == allowNegative) {
+        return;
+    }
+    _negativeThrust = allowNegative;
+
+    _saveSettings();
+    emit negativeThrustChanged(_negativeThrust);
+}
+
 float Joystick::exponential(void)
 {
     return _exponential;
diff --git a/src/Joystick/Joystick.h b/src/Joystick/Joystick.h
index 2e98c3f8f..89717f715 100644
--- a/src/Joystick/Joystick.h
+++ b/src/Joystick/Joystick.h
@@ -72,6 +72,7 @@ public:
     Q_INVOKABLE QString getButtonAction(int button);
 
     Q_PROPERTY(int throttleMode READ throttleMode WRITE setThrottleMode NOTIFY throttleModeChanged)
+    Q_PROPERTY(bool negativeThrust READ negativeThrust WRITE setNegativeThrust NOTIFY negativeThrustChanged)
     Q_PROPERTY(float exponential READ exponential WRITE setExponential NOTIFY exponentialChanged)
     Q_PROPERTY(bool accumulator READ accumulator WRITE setAccumulator NOTIFY accumulatorChanged)
 	Q_PROPERTY(bool requiresCalibration READ requiresCalibration CONSTANT)
@@ -106,6 +107,9 @@ public:
     int throttleMode(void);
     void setThrottleMode(int mode);
 
+    bool negativeThrust(void);
+    void setNegativeThrust(bool allowNegative);
+
     float exponential(void);
     void setExponential(float expo);
 
@@ -141,6 +145,8 @@ signals:
 
     void throttleModeChanged(int mode);
 
+    void negativeThrustChanged(bool allowNegative);
+
     void exponentialChanged(float exponential);
 
     void accumulatorChanged(bool accumulator);
@@ -206,6 +212,8 @@ protected:
 
     ThrottleMode_t      _throttleMode;
 
+    bool                _negativeThrust;
+
     float                _exponential;
     bool                _accumulator;
     bool                _deadband;
diff --git a/src/VehicleSetup/JoystickConfig.qml b/src/VehicleSetup/JoystickConfig.qml
index 75c9c58f0..d893ec027 100644
--- a/src/VehicleSetup/JoystickConfig.qml
+++ b/src/VehicleSetup/JoystickConfig.qml
@@ -453,6 +453,14 @@ SetupPage {
 
                                     onClicked: _activeJoystick.throttleMode = 1
                                 }
+
+                                QGCCheckBox {
+                                    id:             negativeThrust
+                                    text:           qsTr("Allow negative Thrust")
+                                    checked:        _activeJoystick ? _activeJoystick.negativeThrust : false
+
+                                    onClicked: _activeJoystick.negativeThrust = checked
+                                }
                             }
 
                             Column {
-- 
2.22.0