From 572ecef486f972cc10475e201e211e9ce63733d8 Mon Sep 17 00:00:00 2001
From: Nicolas Pennequin <nicolas.pennequin@free.fr>
Date: Sun, 18 Nov 2007 13:24:39 +0000
Subject: Smarter conditional handling by storing the previous value. Updates
 are done only if the value has changed. This avoids unnecessary line or
 picture clearing, and should help fix some problems WPS creators were having.

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@15657 a1c6a512-1295-4272-9138-f99709370657
---
 apps/gui/gwps-common.c | 28 +++++++++++++++++++---------
 1 file changed, 19 insertions(+), 9 deletions(-)

(limited to 'apps')

diff --git a/apps/gui/gwps-common.c b/apps/gui/gwps-common.c
index 7f1c52c7bf..ca6fd6679d 100644
--- a/apps/gui/gwps-common.c
+++ b/apps/gui/gwps-common.c
@@ -1383,16 +1383,18 @@ static int find_conditional_end(struct wps_data *data, int index)
 /* Return the index of the appropriate case for the conditional
    that starts at cond_index.
 */
-static int evaluate_conditional(struct gui_wps *gwps, int cond_index)
+static bool evaluate_conditional(struct gui_wps *gwps, int *token_index)
 {
     if (!gwps)
-        return 0;
+        return false;
 
     struct wps_data *data = gwps->data;
 
-    int ret, i;
+    int i;
+    int cond_index = *token_index;
     char result[128], *value;
-    int num_options = data->tokens[cond_index].value.i;
+    unsigned char num_options = data->tokens[cond_index].value.i & 0xFF;
+    unsigned char prev_val = (data->tokens[cond_index].value.i & 0xFF00) >> 8;
 
     /* treat ?xx<true> constructs as if they had 2 options. */
     if (num_options < 2)
@@ -1410,13 +1412,22 @@ static int evaluate_conditional(struct gui_wps *gwps, int cond_index)
     else if (intval > num_options || intval < 1)
         intval = num_options;
 
+    data->tokens[cond_index].value.i = (intval << 8) + num_options;
+
     /* skip to the right enum case */
     int next = cond_index + 2;
     for (i = 1; i < intval; i++)
     {
         next = data->tokens[next].value.i;
     }
-    ret = next;
+    *token_index = next;
+
+    if (prev_val == intval)
+    {
+        /* Same conditional case as previously. Return without clearing the
+           pictures */
+        return false;
+    }
 
 #ifdef HAVE_LCD_BITMAP
     /* clear all pictures in the conditional */
@@ -1435,7 +1446,7 @@ static int evaluate_conditional(struct gui_wps *gwps, int cond_index)
     }
 #endif
 
-    return ret;
+    return true;
 }
 
 /* Read a (sub)line to the given alignment format buffer.
@@ -1480,8 +1491,7 @@ static bool get_line(struct gui_wps *gwps,
         {
             case WPS_TOKEN_CONDITIONAL:
                 /* place ourselves in the right conditional case */
-                i = evaluate_conditional(gwps, i);
-                update = true;
+                update |= evaluate_conditional(gwps, &i);
                 break;
 
             case WPS_TOKEN_CONDITIONAL_OPTION:
@@ -1589,7 +1599,7 @@ static void get_subline_timeout(struct gui_wps *gwps, int line, int subline)
         {
             case WPS_TOKEN_CONDITIONAL:
                 /* place ourselves in the right conditional case */
-                i = evaluate_conditional(gwps, i);
+                evaluate_conditional(gwps, &i);
                 break;
 
             case WPS_TOKEN_CONDITIONAL_OPTION:
-- 
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