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Bug1682, maybe: More careful treatment of some Envelope corner cases

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This commit is contained in:
Paul Licameli
2017-07-14 22:49:46 -04:00
parent 8fae9802dc
commit 52d8dc1525
2 changed files with 30 additions and 2 deletions
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31
src/Envelope.cpp
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@@ -1174,6 +1174,28 @@ void Envelope::BinarySearchForTime( int &Lo, int &Hi, double t ) const
mSearchGuess = Lo;
}
// relative time
/// @param Lo returns last index before this time, maybe -1
/// @param Hi returns first index at or after this time, maybe past the end
void Envelope::BinarySearchForTime_LeftLimit( int &Lo, int &Hi, double t ) const
{
Lo = -1;
Hi = mEnv.size();
// Invariants: Lo is not less than -1, Hi not more than size
while (Hi > (Lo + 1)) {
int mid = (Lo + Hi) / 2;
// mid must be strictly between Lo and Hi, therefore a valid index
if (t <= mEnv[mid].GetT())
Hi = mid;
else
Lo = mid;
}
wxASSERT( Hi == ( Lo+1 ));
mSearchGuess = Lo;
}
/// GetInterpolationStartValueAtPoint() is used to select either the
/// envelope value or its log depending on whether we are doing linear
/// or log interpolation.
@@ -1226,7 +1248,7 @@ void Envelope::GetValuesRelative
auto tplus = t + increment;
// IF before envelope THEN first value
if ( tplus <= mEnv[0].GetT() ) {
if ( leftLimit ? tplus <= mEnv[0].GetT() : tplus < mEnv[0].GetT() ) {
buffer[b] = mEnv[0].GetVal();
t += tstep;
continue;
@@ -1249,9 +1271,14 @@ void Envelope::GetValuesRelative
// points to move over. That's why we binary search.
int lo,hi;
BinarySearchForTime( lo, hi, tplus );
if ( leftLimit )
BinarySearchForTime_LeftLimit( lo, hi, tplus );
else
BinarySearchForTime( lo, hi, tplus );
// mEnv[0] is before tplus because of eliminations above, therefore lo >= 0
// mEnv[len - 1] is after tplus, therefore hi <= len - 1
wxASSERT( lo >= 0 && hi <= len - 1 );
tprev = mEnv[lo].GetT();
tnext = mEnv[hi].GetT();