Integrated a patch from D Pavet. This patch keep the angular position

of the leader in sync when changing the leader position with -labeldx
and -labeldy.

1 files changed, 18 insertions, 2 deletions

diff --git a/generic/Track.c b/generic/Track.c
index 232089e..0b25256 100644
--- a/generic/Track.c
+++ b/generic/Track.c
@@ -95,7 +95,7 @@ typedef struct _TrackItemStruct {
   unsigned short flags;
   ZnImage       symbol;                 /* item symbol                  */
   ZnGradient    *symbol_color;
-  int           label_angle;            /* Label angle from track. */
+  int           label_angle;            /* Label angle from track (degree). */
   ZnDim         label_distance;         /* Label distance from track. */
   ZnDim         label_dx;               /* Label dx/dy from track.      */
   ZnDim         label_dy;
@@ -823,7 +823,7 @@ ComputeCoordinates(ZnItem       item,
   /* Compute the new label bounding box. */
   if (field_set->label_format && field_set->num_fields) {
     ZnDim       bb_width, bb_height;
-    ZnReal      rho, dist;
+    ZnReal      rho, theta, dist;
     ZnPoint     leader_end;
     int it;
 
@@ -832,6 +832,9 @@ ComputeCoordinates(ZnItem       item,
      * Compute the label position.
      */
     if (ISSET(track->flags, POLAR_BIT)) {
+      /*
+       * Update label_dx, label_dy from label_distance, label_angle
+       */
       rho = track->label_distance;
       /*
        * Compute heading after applying the transform.
@@ -841,6 +844,10 @@ ComputeCoordinates(ZnItem       item,
         ZnProjectionToAngle(track->speed_vector.x, track->speed_vector.y),
         track->label_angle);*/
       rotation = ZnProjectionToAngle(track->speed_vector.x, track->speed_vector.y)-rotation;
+      /*
+       * Adjust the distance to match the requested label_distance
+       * whatever the label_angle.
+       */
       it = 0;
       while (1) {
         ZnPointPolarToCartesian(rotation, rho, (ZnReal) track->label_angle,
@@ -862,6 +869,15 @@ ComputeCoordinates(ZnItem       item,
       }
     }
     else {
+      /*
+       * Update label_angle following the change in label_dx, label_dy.
+       * label_distance is not updated.
+       */
+      ZnTransfoDecompose(wi->current_transfo, NULL, NULL, &rotation, NULL);
+      rotation = ZnProjectionToAngle(track->speed_vector.x, track->speed_vector.y) - rotation;
+      ZnPointCartesianToPolar(rotation, &dist, &theta, track->label_dx, track->label_dy); 
+      track->label_angle = (int) theta;  
+    
       field_set->label_pos.x = track->dev.x + track->label_dx;
       field_set->label_pos.y = track->dev.y - track->label_dy;
       ZnAnchor2Origin(&field_set->label_pos, bb_width, bb_height,