From 88055b2f2e8059fdf6e146efcd8ebe8939eeea79 Mon Sep 17 00:00:00 2001
From: Jonathan Gordon <rockbox@jdgordon.info>
Date: Wed, 2 Jul 2008 09:42:36 +0000
Subject: [PATCH] fix FS#9140 by changing stop_scroll so it stops scrolling
 lines which would overlap the current viewport. This shouldnt cause any
 problems because when this happens the vp owning the line should redraw when
 the new vp's screen is exited. Also fix a potential bug where only one
 scrolling line in a viewport was stopped

git-svn-id: svn://svn.rockbox.org/rockbox/trunk@17913 a1c6a512-1295-4272-9138-f99709370657
---
 firmware/scroll_engine.c | 38 ++++++++++++++++++++++++++++++--------
 1 file changed, 30 insertions(+), 8 deletions(-)

diff --git a/firmware/scroll_engine.c b/firmware/scroll_engine.c
index 200695b5d6..9607c90448 100644
--- a/firmware/scroll_engine.c
+++ b/firmware/scroll_engine.c
@@ -84,6 +84,18 @@ void lcd_stop_scroll(void)
     lcd_scroll_info.lines = 0;
 }
 
+/* returns true if the 'line' in 'lines_vp' would scroll into 'othervp' */
+static bool line_overlaps_viewport(struct viewport *lines_vp, int line,
+                                   struct viewport *othervp)
+{
+    int y = (font_get(lines_vp->font)->height*line) + lines_vp->y;
+    if (y < othervp->y || y > othervp->y + othervp->height)
+        return false;
+    else if ((lines_vp->x + lines_vp->width < othervp->x) ||
+             (othervp->x + othervp->width < lines_vp->x))
+        return false;
+    return true;
+}
 /* Stop scrolling line y in the specified viewport, or all lines if y < 0 */
 void lcd_scroll_stop_line(struct viewport* current_vp, int y)
 {
@@ -91,8 +103,11 @@ void lcd_scroll_stop_line(struct viewport* current_vp, int y)
 
     while (i < lcd_scroll_info.lines)
     {
-        if ((lcd_scroll_info.scroll[i].vp == current_vp) && 
-            ((y < 0) || (lcd_scroll_info.scroll[i].y == y)))
+        if (((lcd_scroll_info.scroll[i].vp == current_vp) && 
+                ((y < 0) || (lcd_scroll_info.scroll[i].y == y))) ||
+            ((lcd_scroll_info.scroll[i].vp != current_vp) &&
+                line_overlaps_viewport(lcd_scroll_info.scroll[i].vp, 
+                                   lcd_scroll_info.scroll[i].y, current_vp)))
         {
             /* If i is not the last active line in the array, then move
                the last item to position i */
@@ -102,8 +117,10 @@ void lcd_scroll_stop_line(struct viewport* current_vp, int y)
             }
             lcd_scroll_info.lines--;
 
-            /* A line can only appear once, so we're done. */
-            return ;
+            /* A line can only appear once, so we're done, 
+             * unless we are clearing the whole viewport */
+            if (y >= 0)
+                return ;
         }
         else
         {
@@ -165,8 +182,11 @@ void lcd_remote_scroll_stop_line(struct viewport* current_vp, int y)
 
     while (i < lcd_remote_scroll_info.lines)
     {
-        if ((lcd_remote_scroll_info.scroll[i].vp == current_vp) && 
-            ((y < 0) || (lcd_remote_scroll_info.scroll[i].y == y)))
+        if (((lcd_remote_scroll_info.scroll[i].vp == current_vp) && 
+                ((y < 0) || (lcd_remote_scroll_info.scroll[i].y == y))) ||
+            (((lcd_remote_scroll_info.scroll[i].vp != current_vp) &&
+                line_overlaps_viewport(lcd_scroll_info.scroll[i].vp, 
+                                   lcd_scroll_info.scroll[i].y, current_vp))))
         {
             /* If i is not the last active line in the array, then move
                the last item to position i */
@@ -176,8 +196,10 @@ void lcd_remote_scroll_stop_line(struct viewport* current_vp, int y)
             }
             lcd_remote_scroll_info.lines--;
 
-            /* A line can only appear once, so we're done. */
-            return ;
+            /* A line can only appear once, so we're done, 
+             * unless we are clearing the whole viewport */
+            if (y >= 0)
+                return ;
         }
         else
         {