Make sure z-hop won't change retract when not supposed to

CURA-11978

Author: wawanbreton

include/gcodeExport.h

@@ -531,9 +531,9 @@ class GCodeExport : public NoCopy
      * Start or end a z hop
      * \param speed The speed used for moving, or 0 to take the default speed
      * \param height The actual height to be reached, relative to the current layer height
-     * \param retract_distance The absolute retraction distance to be reached while doing the z-hop move
+     * \param retract_distance The absolute retraction distance to be reached while doing the z-hop move, or nullopt to leave it unchanged
      */
-    void writeZhop(Velocity speed = 0.0, const coord_t height = 0, const double retract_distance = 0.0);
+    void writeZhop(Velocity speed = 0.0, const coord_t height = 0, const std::optional<double> retract_distance = std::nullopt);
 
 public:
     /*!
@@ -560,21 +560,21 @@ class GCodeExport : public NoCopy
      *
      * \param hop_height The height to move above the current layer.
      * \param speed The speed used for moving.
-     * \param retract_distance The absolute retract distance to be reached during the z-hop move
+     * \param retract_distance The absolute retract distance to be reached during the z-hop move, or nullopt to leave it unchanged
      * \param retract_ratio This is the ratio of the complete z-hop move that should be used to process the retraction. If >0 and <1 then the z-hop move
      *                      will actually be split in two part, one with retraction and one without.
      */
-    void writeZhopStart(const coord_t hop_height, Velocity speed = 0.0, double retract_distance = 0.0, const Ratio& retract_ratio = 0.0_r);
+    void writeZhopStart(const coord_t hop_height, Velocity speed = 0.0, std::optional<double> retract_distance = std::nullopt, const Ratio& retract_ratio = 0.0_r);
 
     /*!
      * End a z hop: go back to the layer height
      *
      * \param speed The speed used for moving.
-     * \param prime_distance The absolute prime distance to be reached during the z-hop move
+     * \param prime_distance The absolute prime distance to be reached during the z-hop move, or nullopt to leave it unchanged
      * \param prime_ratio This is the ratio of the complete z-hop move that should be used to process the priming. If >0 and <1 then the z-hop move
      *                    will actually be split in two part, one without priming and one with.
      */
-    void writeZhopEnd(Velocity speed = 0.0, const coord_t height = 0, const double prime_distance = 0.0, const Ratio& prime_ratio = 0.0_r);
+    void writeZhopEnd(Velocity speed = 0.0, const coord_t height = 0, const std::optional<double> prime_distance = std::nullopt, const Ratio& prime_ratio = 0.0_r);
 
     /*!
      * Start the new_extruder:

src/gcodeExport.cpp

@@ -1298,9 +1298,9 @@ void GCodeExport::writeRetraction(const RetractionConfig& config, bool force, bo
     extr_attr.prime_volume_ += config.prime_volume;
 }
 
-void GCodeExport::writeZhopStart(const coord_t hop_height, Velocity speed /*= 0*/, const double retract_distance, const Ratio& retract_ratio)
+void GCodeExport::writeZhopStart(const coord_t hop_height, Velocity speed /*= 0*/, const std::optional<double> retract_distance, const Ratio& retract_ratio)
 {
-    if (retract_ratio > 0.0 && retract_ratio < 1.0)
+    if (retract_distance.has_value() && retract_ratio > 0.0 && retract_ratio < 1.0)
     {
         // We have to split the z-hop move in two sub-moves, one with retraction and one without
         writeZhopStart(hop_height * retract_ratio, speed, retract_distance, 0.0);
@@ -1314,7 +1314,7 @@ void GCodeExport::writeZhopStart(const coord_t hop_height, Velocity speed /*= 0*
     }
 }
 
-void GCodeExport::writeZhopEnd(Velocity speed /*= 0*/, const coord_t height, const double prime_distance, const Ratio& prime_ratio)
+void GCodeExport::writeZhopEnd(Velocity speed /*= 0*/, const coord_t height, const std::optional<double> prime_distance, const Ratio& prime_ratio)
 {
     if (z_hop_prime_leftover_.has_value())
     {
@@ -1325,7 +1325,7 @@ void GCodeExport::writeZhopEnd(Velocity speed /*= 0*/, const coord_t height, con
 
     if (is_z_hopped_)
     {
-        if (prime_ratio > 0.0 && prime_ratio < 1.0)
+        if (prime_distance.has_value() && prime_ratio > 0.0 && prime_ratio < 1.0)
         {
             // We have to split the z-hop move in two sub-moves, one without prime and one with
             writeZhopEnd(speed, is_z_hopped_ * prime_ratio, extruder_attr_[current_extruder_].retraction_e_amount_current_, 0.0);
@@ -1338,15 +1338,19 @@ void GCodeExport::writeZhopEnd(Velocity speed /*= 0*/, const coord_t height, con
     }
 }
 
-void GCodeExport::writeZhop(Velocity speed /*= 0*/, const coord_t height, const double retract_distance)
+void GCodeExport::writeZhop(Velocity speed /*= 0*/, const coord_t height, const std::optional<double> retract_distance)
 {
     if (speed == 0)
     {
         const ExtruderTrain& extruder = Application::getInstance().current_slice_->scene.extruders[current_extruder_];
         speed = extruder.settings_.get<Velocity>("speed_z_hop");
     }
 
-    RetractionAmounts retraction_amounts = computeRetractionAmounts(extruder_attr_[current_extruder_], retract_distance);
+    RetractionAmounts retraction_amounts;
+    if (retract_distance.has_value())
+    {
+        retraction_amounts = computeRetractionAmounts(extruder_attr_[current_extruder_], *retract_distance);
+    }
 
     is_z_hopped_ = height;
     const coord_t target_z = current_layer_z_ + is_z_hopped_;