Created attachment 20242 [details]
Data set

Created attachment 20243 [details]
Proposed patch

Prevent an infinite loop in KstColorSequence::next( )

The patch works, but why do you insist upon putting all local variable declarations at the top of the method?  Why not declare 'start' where you initialize it?

SVN commit 653140 by arwalker:

BUG:144099 prevent infinite loop in color sequence

 M  +21 -21    kstcolorsequence.cpp  


--- branches/work/kst/1.5/kst/src/libkstmath/kstcolorsequence.cpp #653139:653140
@@ -95,16 +95,12 @@
   // check we are not already using this color, but if
   //  we are then count the number of usages of each color
   //  in the palette.
+  if (_self->_ptr >= _self->_count * 2) {
+    _self->_ptr = 0;
+  }
   start = _self->_ptr;
-  if (start >= _self->_count * 2) {
-    start = 0;
-  }
 
-  while (_self->_ptr != start) {
-    if (_self->_ptr >= _self->_count * 2) {
-      _self->_ptr = 0;
-    }
-
+  do {
     dark_factor = 100 + ( 50 * ( _self->_ptr / _self->_count ) );
     color = _self->_pal->color( _self->_ptr % _self->_count).dark(dark_factor);
 
@@ -125,23 +121,26 @@
     }
 
     _self->_ptr++;
-  }
+    if (_self->_ptr >= _self->_count * 2) {
+      _self->_ptr = 0;
+    }
+  } while (_self->_ptr != start);
 
   // if we are already using this color then use the least used color for all the curves.
   if (usage[_self->_ptr] != 0) {
+    _self->_ptr = start;
     ptrMin = _self->_ptr;
 
-    while (_self->_ptr != start) {
-      if (_self->_ptr >= _self->_count * 2) {
-        _self->_ptr = 0;
-      }
-
+    do {
       if (usage[_self->_ptr] < usage[ptrMin]) {
         ptrMin = _self->_ptr;
       }
 
       _self->_ptr++;
-    }
+      if (_self->_ptr >= _self->_count * 2) {
+        _self->_ptr = 0;
+      }
+    } while (_self->_ptr != start);
 
     _self->_ptr = ptrMin;
   }
@@ -171,30 +170,31 @@
 QColor KstColorSequence::next(const QColor& badColor) {
   QColor color;
   int dark_factor;
+  int start;
 
   if (!_self) {
     sdColorSequence.setObject(_self, new KstColorSequence);
   }
   _self->createPalette();
 
-  int start = _self->_ptr;
+  if (_self->_ptr >= _self->_count * 2) {
+    _self->_ptr = 0;
+  }
+  start = _self->_ptr;
 
   // find the next color in the sequence that it not too close to the bad color.
   if (badColor.isValid()) {
     do {
+      dark_factor = 100 + ( 50 * ( _self->_ptr / _self->_count ) );
+      color = _self->_pal->color( _self->_ptr++ % _self->_count).dark(dark_factor);
       if (_self->_ptr >= _self->_count * 2) {
         _self->_ptr = 0;
       }
-      dark_factor = 100 + ( 50 * ( _self->_ptr / _self->_count ) );
-      color = _self->_pal->color( _self->_ptr++ % _self->_count).dark(dark_factor);
     } while (colorsTooClose(color, badColor) && start != _self->_ptr);
   }
 
   // if we couldn't find one then just use the next color in the sequence.
   if (start == _self->_ptr) {
-    if (_self->_ptr >= _self->_count * 2) {
-      _self->_ptr = 0;
-    }
     dark_factor = 100 + ( 50 * ( _self->_ptr / _self->_count ) );
     color = _self->_pal->color( _self->_ptr++ % _self->_count).dark(dark_factor);
   }