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NAME
- FilterTagChanges
-
eliminate tags which specify no change. (V36)
SYNOPSIS
FilterTagChanges(changeList,originalList,apply);
VOID FilterTagChanges(struct TagItem *, struct TagItem *, ULONG);
A0 A1 D0
FUNCTION
This function goes through changeList. For each item found in changeList, if the item is also present in originalList, and their data values are identical, then the tag is removed from changeList. If the two tag's data values are different and the 'apply' value is non-zero, then the tag data in originalList will be updated to match the value from changeList.
INPUTS
- changeList
-
list of new tags (may be NULL)
- originalList
-
a list of existing tags (may be NULL)
- apply
-
boolean specification as to whether the data values in originalList are to be updated to the data values in changeList.
EXAMPLE
Assume you have an attribute list for an object (originalList)
which looks like this:
If you receive a new tag list containing some changes (changeList),
which looks like this:
If you call FilterTagChanges(), changeList will be modified to
contain only those attributes which are different from those
in originalList. All other items will have their tag values set to
TAG_IGNORE. The resulting changeList will become:
If 'apply' was set to 0, originalList would be unchanged. If 'apply'
was non-zero, originalList would be changed to:
which looks like this:
{ATTR_Size, "large"},
{ATTR_Color, "orange"},
{ATTR_Shape, "square"}
{ATTR_Color, "orange"},
{ATTR_Shape, "square"}
which looks like this:
{ATTR_Size, "large"},
{ATTR_Shape, "triangle"}
{ATTR_Shape, "triangle"}
contain only those attributes which are different from those
in originalList. All other items will have their tag values set to
TAG_IGNORE. The resulting changeList will become:
{TAG_IGNORE, "large"},
{ATTR_Shape, "triangle"}
{ATTR_Shape, "triangle"}
was non-zero, originalList would be changed to:
{ATTR_Size, "large"},
{ATTR_Color, "orange"},
{ATTR_Shape, "triangle"}
{ATTR_Color, "orange"},
{ATTR_Shape, "triangle"}