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Add binary search for text paths with lineCount >= 16

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This commit is contained in:
Mikael Sand
2017-12-31 01:38:28 +02:00
parent f07e8f041c
commit 9ab405cbec
1 changed files with 18 additions and 13 deletions
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ios/Text/RNSVGTSpan.m
+18 -13
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@@ -785,20 +785,25 @@ NSCharacterSet *separators = nil;
continue;
}
int i = 0;
CGFloat totalLength = 0;
CGFloat prevLength = 0;
// Investigation suggests binary search is faster at lineCount >= 16
// https://gist.github.com/msand/4c7993319425f9d7933be58ad9ada1a4
NSUInteger i = lineCount < 16 ?
[lengths
indexOfObjectPassingTest:^(NSNumber* length, NSUInteger index, BOOL * _Nonnull stop) {
BOOL contains = midPoint <= [length doubleValue];
return contains;
}]
:
[lengths
indexOfObject:[NSNumber numberWithDouble:midPoint]
inSortedRange:NSMakeRange(0, lineCount)
options:NSBinarySearchingInsertionIndex
usingComparator:^(NSNumber* obj1, NSNumber* obj2) {
return [obj1 compare:obj2];
}];
// TODO investigate at what lineCount a binary search is faster
while (i < lineCount - 1) {
prevLength = totalLength;
totalLength = [[lengths objectAtIndex: i] floatValue];
if (totalLength < midPoint) {
i++;
} else {
break;
}
};
CGFloat totalLength = [lengths[i] doubleValue];
CGFloat prevLength = i == 0 ? 0 : [lengths[i - 1] doubleValue];
CGFloat length = totalLength - prevLength;
CGFloat targetPercent = (midPoint - prevLength) / length;