const PolyphaseFilter *MakePolyphaseFilter( int iUpFactor, float fCutoffFrequency )
{
PolyphaseFiltersLock.Lock();
pair<int,float> params( make_pair(iUpFactor, fCutoffFrequency) );
FilterMap::const_iterator it = g_mapPolyphaseFilters.find(params);
if( it != g_mapPolyphaseFilters.end() )
{
/* We already have a filter for this upsampling factor and cutoff; use it. */
PolyphaseFilter *pPolyphase = it->second;
PolyphaseFiltersLock.Unlock();
return pPolyphase;
}
int iWinSize = L*iUpFactor;
float *pFIR = new float[iWinSize];
GenerateSincLowPassFilter( pFIR, iWinSize, fCutoffFrequency );
ApplyKaiserWindow( pFIR, iWinSize, 8 );
NormalizeVector( pFIR, iWinSize );
MultiplyVector( &pFIR[0], &pFIR[iWinSize], (float) iUpFactor );
PolyphaseFilter *pPolyphase = new PolyphaseFilter( iUpFactor );
pPolyphase->Generate( pFIR );
delete [] pFIR;
g_mapPolyphaseFilters[params] = pPolyphase;
PolyphaseFiltersLock.Unlock();
return pPolyphase;
}
// Just checks whether style can be created without constructing actual style.
void check(const std::vector<Tag>& tags, const FilterMap& filters)
{
FilterMap::const_iterator iter = filters.find(levelOfDetails_);
if (iter != filters.end()) {
for (const Filter& filter : iter->second) {
bool isMatched = true;
for (auto it = filter.conditions.cbegin(); it != filter.conditions.cend() && isMatched; ++it) {
isMatched &= match_tags(tags.cbegin(), tags.cend(), *it);
}
if (isMatched) {
canBuild_ = true;
return;
}
}
}
}
// Builds style object. More expensive to call than check.
void build(const std::vector<Tag>& tags, const FilterMap& filters)
{
FilterMap::const_iterator iter = filters.find(levelOfDetails_);
if (iter != filters.end()) {
for (const Filter &filter : iter->second) {
bool isMatched = true;
for (auto it = filter.conditions.cbegin(); it != filter.conditions.cend() && isMatched; ++it) {
isMatched &= match_tags(tags.cbegin(), tags.cend(), *it);
}
// merge declarations to style
if (isMatched) {
canBuild_ = true;
for (const auto &d : filter.declarations) {
style_.put(d.second);
}
}
}
}
}
