void
TopographyThread::Trigger(const WindowProjection &_projection)
{
assert(_projection.IsValid());
const GeoBounds new_bounds = _projection.GetScreenBounds();
if (last_bounds.IsValid() && last_bounds.IsInside(new_bounds)) {
/* still inside cache bounds - now check if we crossed a scale
threshold for at least one file, which would mean we have to
update a file which was not updated for the current cache
bounds */
if (scale_threshold < 0 ||
_projection.GetMapScale() >= scale_threshold)
/* the cache is still fresh */
return;
}
last_bounds = new_bounds.Scale(1.1);
scale_threshold = store.GetNextScaleThreshold(_projection.GetMapScale());
{
const ScopeLock protect(mutex);
next_projection = _projection;
StandbyThread::Trigger();
}
}
bool
TopographyFile::Update(const WindowProjection &map_projection)
{
if (IsEmpty())
return false;
if (map_projection.GetMapScale() > scale_threshold)
/* not visible, don't update cache now */
return false;
const GeoBounds screenRect =
map_projection.GetScreenBounds();
if (cache_bounds.IsValid() && cache_bounds.IsInside(screenRect))
/* the cache is still fresh */
return false;
cache_bounds = screenRect.Scale(2);
rectObj deg_bounds = ConvertRect(cache_bounds);
// Test which shapes are inside the given bounds and save the
// status to file.status
switch (msShapefileWhichShapes(&file, dir, deg_bounds, 0)) {
case MS_FAILURE:
ClearCache();
return false;
case MS_DONE:
/* screen is outside of map bounds */
return false;
case MS_SUCCESS:
break;
}
assert(file.status != nullptr);
// Iterate through the shapefile entries
const ShapeList **current = &first;
auto it = shapes.begin();
for (int i = 0; i < file.numshapes; ++i, ++it) {
if (!msGetBit(file.status, i)) {
// If the shape is outside the bounds
// delete the shape from the cache
if (it->shape != nullptr) {
assert(*current == it);
/* remove from linked list (protected) */
{
const ScopeLock lock(mutex);
*current = it->next;
++serial;
}
/* now it's unreachable, and we can delete the XShape without
holding a lock */
delete it->shape;
it->shape = nullptr;
}
} else {
// is inside the bounds
if (it->shape == nullptr) {
assert(*current != it);
// shape isn't cached yet -> cache the shape
it->shape = LoadShape(&file, center, i, label_field);
it->next = *current;
/* insert into linked list (protected) */
{
const ScopeLock lock(mutex);
*current = it;
++serial;
}
}
current = &it->next;
}
}
// end of list marker
assert(*current == nullptr);
return true;
}