Multipoint layer problems - zoom to selection doesn't work; layer extent has wild values on editing

[m-kuhn]

This issue has been migrated from the old QGIS issue tracker.

Vector layers of type Multipoint have the following problems:

1. Zoom to selection doesn't do anything.
2. When editing - adding or deleting points - the extent as shown in properties, Metadata goes to some wild values.

This causes zoom to layer extent to zoom to a very small scale, such that the scale bar on the map shows a distance on the order of 1e+200km

The points added are correctly positioned. Reloading the layer fixes the extents display.

some examples of the extents shown in Metadata (layer has a few points over about 1000m):

start:      xMin,yMin 499999,5e+06 : xMax,yMax 501001,5.001e+06

add point:  xMin,yMin 499999,-1.51934e-93 : Max,yMax2.95439e+202,5.001e+06

        xMin,yMin 499999,5e+06 : xMax,yMax 1.09228e+209,1.2796e+156

delete point:   xMin,yMin 4.94066e-324,-2 : xMax,yMax 4.94066e-324,2

I have tested with [[PostGIS]] and shapefiles.

Expected behaviors: Zoom to selection operates as it does for Points - a single point is displayed at a fairly large scale; multiple points should be displayed over most of the map view.

On add and delete points the extents should reflect the minimum/maximum of the locations of the layer.

Comments

Steven Mizuno:

I provide a patch for [[QgsGeometry]] to fix the above problems.

The details:

1. have found in boundingBox() that an increment of ptr to the beginning of the point array was missing, so the points retrieved had wild values.
2. and on a cursory inspection of the class I found in deleteVertext() that there is a missing break statement in the WKBMultiPoint case - there is a TODO note, but the case just fell through to the next, potentially causing odd problems.

Marco Hugentobler:

Applied in commit:d367081e (SVN r9754). thanks!
Still it would be good to implement the delete vertex method for multipoints.

Giovanni Manghi:

If the patch has already been applied can we close this ticket?

Steven Mizuno:

Yes, as the reported problem has been fixed.