[gimp] app: Make pressure at stroke ends nicer

[Alexia Death <alexiade src gnome org>]

commit ede02a68b992483c11e59b28659f37bfe83c7827
Author: Alexia Death <alexiadeath gmail com>
Date:   Wed Feb 24 02:09:43 2010 +0200

    app: Make pressure at stroke ends nicer

 app/display/gimpdisplayshell-callbacks.c |    2 +-
 app/display/gimpdisplayshell-coords.c    |   19 ++++++++++++++++---
 2 files changed, 17 insertions(+), 4 deletions(-)
---
diff --git a/app/display/gimpdisplayshell-callbacks.c b/app/display/gimpdisplayshell-callbacks.c
index b91396c..74289f8 100644
--- a/app/display/gimpdisplayshell-callbacks.c
+++ b/app/display/gimpdisplayshell-callbacks.c
@@ -1083,7 +1083,7 @@ gimp_display_shell_canvas_tool_events (GtkWidget        *canvas,
               {
                 if (gimp_tool_control_is_active (active_tool->control))
                   {
-                    g_array_append_val (shell->event_queue, image_coords);
+
                     if (shell->event_queue->len > 0)
                       gimp_display_shell_flush_event_queue (shell);
 
diff --git a/app/display/gimpdisplayshell-coords.c b/app/display/gimpdisplayshell-coords.c
index 30dd9fc..a5fa0e5 100644
--- a/app/display/gimpdisplayshell-coords.c
+++ b/app/display/gimpdisplayshell-coords.c
@@ -33,6 +33,9 @@
 
 #define EVENT_FILL_PRECISION 6.0
 
+#define SMOOTH_FACTOR 0.3
+
+
 static void gimp_display_shell_interpolate_stroke (GimpDisplayShell *shell,
                                                    GimpCoords       *coords);
 
@@ -79,6 +82,7 @@ gimp_display_shell_eval_event (GimpDisplayShell *shell,
   gdouble  dir_delta_y = 0.0;
   gdouble  distance    = 1.0;
   gboolean event_fill  = (inertia_factor > 0);
+  gdouble  delta_pressure = 0.0;
 
   /* Smoothing causes problems with cursor tracking
    * when zoomed above screen resolution so we need to supress it.
@@ -88,6 +92,18 @@ gimp_display_shell_eval_event (GimpDisplayShell *shell,
       inertia_factor = 0.0;
     }
 
+
+  delta_time = (shell->last_motion_delta_time * (1 - SMOOTH_FACTOR)
+                +  (time - shell->last_motion_time) * SMOOTH_FACTOR);
+
+  delta_pressure = coords->pressure - shell->last_coords.pressure;
+
+  /* Try to detect a pen lift */
+  if ((delta_time < 50) && (fabs(delta_pressure) > 0.04) && (delta_pressure < 0.0))
+    {
+      return FALSE;
+    }
+
   if (shell->last_motion_time == 0)
     {
       /* First pair is invalid to do any velocity calculation,
@@ -104,8 +120,6 @@ gimp_display_shell_eval_event (GimpDisplayShell *shell,
       delta_x = shell->last_coords.x - coords->x;
       delta_y = shell->last_coords.y - coords->y;
 
-#define SMOOTH_FACTOR 0.3
-
       /* Events with distances less than the screen resolution are not
        * worth handling.
        */
@@ -265,7 +279,6 @@ gimp_display_shell_eval_event (GimpDisplayShell *shell,
         }
 
         /* do event fill for devices that do not provide enough events*/
-
         if (distance >= EVENT_FILL_PRECISION &&
             event_fill                       &&
             shell->event_history->len >= 2)