From b1ae5c734a5d387ea9ff99ec69cd22c9fdebe103 Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Tue, 1 Jul 2014 17:06:11 +0200
Subject: [PATCH] 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 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/panels/wacom/calibrator/calibrator.c b/panels/wacom/calibrator/calibrator.c
index baa45b6c6..b78f328df 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;