[gnome-control-center] wacom: Fix x/y ranges' swapping when calibrating on rotated screens

[Carlos Garnacho <carlosg src gnome org>]

commit b1ae5c734a5d387ea9ff99ec69cd22c9fdebe103
Author: Carlos Garnacho <carlosg gnome org>
Date:   Tue Jul 1 17:06:11 2014 +0200

    wacom: Fix x/y ranges' swapping when calibrating on rotated screens
    
    The previous axis swapping code would oddly rely on the input coordinates
    remaining on untransformed device coordinates, while those are gotten on
    screen coordinates (hence rotated), this would cause swapping not to kick
    in, and result in swapped X/Y scaling to be applied to X/Y ranges.
    
    So make the axis swapping code be calculated upon screen coordinates, as
    the collected points already are, and swap the applied scalings if
    necessary.
    
    Also, the code that swapped coordinates before returning to the caller
    would scramble min/max values when swapping x/y. Fix that too, minimum
    and maximum should stay like that when swapping axes.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=732442

 panels/wacom/calibrator/calibrator.c |   26 +++++++++++++++++---------
 1 files changed, 17 insertions(+), 9 deletions(-)
---
diff --git a/panels/wacom/calibrator/calibrator.c b/panels/wacom/calibrator/calibrator.c
index baa45b6..b78f328 100644
--- a/panels/wacom/calibrator/calibrator.c
+++ b/panels/wacom/calibrator/calibrator.c
@@ -141,20 +141,28 @@ finish (struct Calib *c,
     if (c->num_clicks != 4)
         return FALSE;
 
-    /* Should x and y be swapped? */
-    swap_xy = (abs (c->clicked_x [UL] - c->clicked_x [UR]) < abs (c->clicked_y [UL] - c->clicked_y [UR]));
+    /* Should x and y be swapped? If the device and output are wider
+     * towards different axes, swapping must be performed
+     */
+    swap_xy = (c->geometry.width > c->geometry.height) !=
+        ((c->old_axis.x_max - c->old_axis.x_min) > (c->old_axis.y_max - c->old_axis.y_min));
+
     if (swap_xy)
-    {
-        SWAP(int, c->clicked_x[LL], c->clicked_x[UR]);
-        SWAP(int, c->clicked_y[LL], c->clicked_y[UR]);
-    }
+        SWAP (int, c->geometry.width, c->geometry.height);
 
     /* Compute min/max coordinates. */
     /* These are scaled using the values of old_axis */
     scale_x = (c->old_axis.x_max - c->old_axis.x_min)/(float)c->geometry.width;
+    scale_y = (c->old_axis.y_max - c->old_axis.y_min)/(float)c->geometry.height;
+
+    /* Swap back for usage with the collected click points, which are in screen
+     * coordinates, hence possibly rotated.
+     */
+    if (swap_xy)
+        SWAP(gdouble, scale_x, scale_y);
+
     axis.x_min = ((((c->clicked_x[UL] + c->clicked_x[LL]) / 2)) * scale_x) + c->old_axis.x_min;
     axis.x_max = ((((c->clicked_x[UR] + c->clicked_x[LR]) / 2)) * scale_x) + c->old_axis.x_min;
-    scale_y = (c->old_axis.y_max - c->old_axis.y_min)/(float)c->geometry.height;
     axis.y_min = ((((c->clicked_y[UL] + c->clicked_y[UR]) / 2)) * scale_y) + c->old_axis.y_min;
     axis.y_max = ((((c->clicked_y[LL] + c->clicked_y[LR]) / 2)) * scale_y) + c->old_axis.y_min;
 
@@ -171,8 +179,8 @@ finish (struct Calib *c,
     /* If x and y has to be swapped we also have to swap the parameters */
     if (swap_xy)
     {
-        SWAP(int, axis.x_min, axis.y_max);
-        SWAP(int, axis.y_min, axis.x_max);
+        SWAP (int, axis.x_min, axis.y_min);
+        SWAP (int, axis.x_max, axis.y_max);
     }
 
     *new_axis = axis;