Bug report #3998: Zoom to selected don't work with point layers and OTF reprojection - QGIS Application - QGIS Issue Tracking

Bug report #3998

Zoom to selected don't work with point layers and OTF reprojection

Added by Alexander Bruy over 13 years ago. Updated over 10 years ago.

Status:	Closed
Priority:	Normal
Assignee:	Magnus Homann
Category:	Projection Support
Affected QGIS version:	master	Regression?:	No
Operating System:	All	Easy fix?:	No
Pull Request or Patch supplied:	Yes	Resolution:	fixed/implemented
Crashes QGIS or corrupts data:	No	Copied to github as #:	13986

Description

Testcase:

open any point layer in WGS84
open attribute table, select some records (features)
press "Zoom map to the selected rows" button
all works fine and map zoomed to the selected features
now turn on "on the fly" reprojection and select any projected CRS, for example WGS84/UTM Zone 39N
zoom to full extent
again open attribute table and selecy some features
press "Zoom map to the selected rows" button
canvas was zoomed to blank area

This issue affects only point layers, with polygon or line layers all works as expected

patch_for_3998.diff (568 Bytes) Steven Mizuno, 2011-08-22 11:28 AM

History

#1 Updated by Paolo Cavallini over 13 years ago

Pull Request or Patch supplied set to No
Tracker changed from Bug report to 4

#2 Updated by Steven Mizuno over 13 years ago

Pull Request or Patch supplied changed from No to Yes
File patch_for_3998.diff added

Here is a possible fix for the bug.

What happens is the area zoomed to is the latitude/longitude values used in the UTM projection with no transformation, in the example given.

In Identify Results, the Zoom to feature also has the same behavior.

Actually any feature(s) that have no width or height (an empty extent) will do the same. Points along a line of either longitude or latitude (but not both), for example.

In QgsCoordinateTransform::transformBoundingBox(rect,direction) returns immediately when rect is empty, so there is no transformation done.

I tried eliminating the test

|| rect.isEmpty()

in the first line of the function. Now zoom to a point works. And zooming to points along a line of longitude also works, with the extent of the points setting the zoom factor.

Looking through the function I see no place where divide by width or height of the input rect is used, so a 0 value won't cause a divide by zero error.

I have tried a point layer in UTM zone 15, map in WGS84 geog. and zooming to a selected or identified point works as well.