Dr Lovegrove wrote:
Ah, the progress bars, yes.. They show the traversal through the
scan. The top one is the root directory, the next one is each folder
in the root, then the third is each item in that folder. Usually it's
just the top two which are useful, but it depends on the structure of
your collection. If you had say two directories 'flacs' and 'mp3s' in
your root, the 2nd progress bar would probably be more use as the
first would only be at 0% or 50%.. I know it's a bit confusing, but
it saves doing a pre-scan just to work out how many files, etc..
You can do a one-pass tree traversal on a single progress bar using the
following pseudocode algorithm:
updateProgressBar(0.0);
traverseDir(rootDir, 0.0, 1.0);
traverseDir(dir, start, dirTarget) {
children[] = dir.getChildren();
sharePerChild = (dirTarget - start)/children.size();
current = start;
for each child in children[] {
if(child.isDirectory()) {
traverseDir(dir, current, current+sharePerChild);
} else {
processFile(child);
}
current += sharePerChild;
updateProgressBar(current);
}
}
It won't move the progress bar a uniform amount for each file, but
assuming a fairly uniform distribution of files in the directory tree,
it should behave rationally.
- Marc
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