... you are too slow and QJson API is so ugly.
Now using this wonderful json lib:
https://github.com/nlohmann/json
Results in release mode (QJson tests are not shown but
QJson was even slower than string concat).
PASS : TestQgsJsonUtils::testExportAttributesJson(Use json)
RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use json":
0.0022 msecs per iteration (total: 75, iterations: 32768)
PASS : TestQgsJsonUtils::testExportAttributesJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportAttributesJson():"Use old string concat":
0.0032 msecs per iteration (total: 54, iterations: 16384)
PASS : TestQgsJsonUtils::testExportFeatureJson(Use json)
RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use json":
0.011 msecs per iteration (total: 96, iterations: 8192)
PASS : TestQgsJsonUtils::testExportFeatureJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportFeatureJson():"Use old string concat":
0.015 msecs per iteration (total: 64, iterations: 4096)
PASS : TestQgsJsonUtils::testExportGeomToJson(Use json)
RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use json":
0.76 msecs per iteration (total: 98, iterations: 128)
PASS : TestQgsJsonUtils::testExportGeomToJson(Use old string concat)
RESULT : TestQgsJsonUtils::testExportGeomToJson():"Use old string concat":
0.85 msecs per iteration (total: 55, iterations: 64)
PASS : TestQgsJsonUtils::cleanupTestCase()
For the c++ api dox this expands to "\c nullptr" (the
\c directive indicates a code literal value), and for sipify/Python
it expands to ``None`` (`` is sphinx annotation for literal values)
Makes for nicer dox for both c++ and Python!
When a new QgsAbstractGeometry is set on a geometry object, the previous child is deleted.
If the previous object was constructed by Python, it's wrapper will still be alive for
as long as the QgsGeometry is alive. If a new QgsAbstractGeometry is constructed at the same
memory address as the old one, the wrapper will be reused with wrong type (and other)
information, leading to all kind of weird issues.
See also https://www.riverbankcomputing.com/pipermail/pyqt/2019-January/041251.html
and asMultiPolygon()
- raise ValueError when these methods are called with null geometries
- raise TypeError when these methods are called with incompatible
geometry types, instead of silently returning empty lists
is called on non-single-polygon geometries
Previously we would just return an empty list when geometries of invalid
type were used, but this is dangerous and we are safer to explicitly
raise errors preventing use of asPolygon() with incompatible geometry types.
Also avoid massive long __repr__ strings for complex geometries,
as these can flood the Python console (and first aid plugin),
and aren't useful for debugging anyway.
Refs #14640
is called on non-single-line geometries
Previously we would just return an empty list when geometries of invalid
type were used, but this is dangerous and we are safer to explicitly
raise errors preventing use of asPolyline() with incompatible geometry types.
is called on non-single-point geometries
Previously we would just return QgsPointXY(0,0) when geometries of invalid
type were used, but this is dangerous and we are safer to explicitly
raise errors preventing use of asPoint() with incompatible geometry types.
This allows easy iteration over all the parts of a geometry,
regardless of the geometry's type. E.g.
geometry = QgsGeometry.fromWkt( 'MultiPoint( 0 0, 1 1, 2 2)' )
for part in geometry.parts():
print(part.asWkt())
geometry = QgsGeometry.fromWkt( 'LineString( 0 0, 10 10 )' )
for part in geometry.parts():
print(part.asWkt())
There are two iterators available. QgsGeometry.parts() gives
a non-const iterator, allowing the parts to be modified in place:
geometry = QgsGeometry.fromWkt( 'MultiPoint( 0 0, 1 1, 2 2)' )
for part in geometry.parts():
part.transform(ct)
For a const iteration, calling .const_parts() gives a const
iterator, which cannot edit the parts but avoids a potentially expensive
QgsGeometry detach and clone
geometry = QgsGeometry.fromWkt( 'MultiPoint( 0 0, 1 1, 2 2)' )
for part in geometry.const_parts():
print(part.x())
All your uses of toUtf8().data() actually just need a const char*
So use constData() that is semantically more correct, and documented
to be faster.
From http://doc.qt.io/qt-5/qbytearray.html#data
"For read-only access, constData() is faster because it never
causes a deep copy to occur."
Because:
- Exactly follows curves and doesn't require segmentizing input geometry
- Also interpolates z/m values if they are present in input geometry
- Is faster
Checks whether a function declaration has parameters that are
top level const.
const values in declarations do not affect the signature of a
function, so they should not be put there.
