Bug report #20104

GDAL data provider cache is not cleared after triggerRepaint

Added by Radek Pasiok over 1 year ago. Updated over 1 year ago.

Status:Closed
Priority:Normal
Assignee:Even Rouault
Category:Data Provider
Affected QGIS version:3.3(master) Regression?:No
Operating System:Observed on Windows 7 and Ubuntu 18 Easy fix?:No
Pull Request or Patch supplied:No Resolution:
Crashes QGIS or corrupts data:No Copied to github as #:27926

Description

While porting Serval plugin [1] to QGIS 3.2 I have discovered that after a raster datasource is modified and triggerRepaint() is called [2] the provider cache is not cleared properly. As a consequence, map canvas will display old and new raster cells values at different zoom levels.

When the provider cache is not used, i.e. when QgsGdalProvider::getCachedGdalHandles would be set to only return false, then canvas properly display new cell values at all zoom levels.

Steps to reproduce:

1. Add a raster to QGIS project, for example band1_byte_ct_epsg4326.tif from QGIS test data.
2. In the Python console run:

rlyr = iface.activeLayer()
rdp = rlyr.dataProvider()
dtype = rdp.dataType(1)

rdp.setEditable(True)
rblock = QgsRasterBlock(dtype, 1, 1)
rblock.setValue(0, 0, 255)
rdp.writeBlock(rblock, 1, 0, 0)
rdp.setEditable(False)

rlyr.triggerRepaint()

3. Zoom in and out a bit to left upper raster corner to see different values of the first cell at different zoom levels.

[1] https://github.com/erpas/serval/tree/QGIS_3_port
[2] https://github.com/erpas/serval/blob/a7ebbaf7653715ebdcaf7b59ee9d069ce895a91b/serval.py#L366

Associated revisions

Revision e7d15b64
Added by Even Rouault over 1 year ago

[GDAL provider] Make sure that setEditable(true) invalides cached GDAL handles to get proper refresh (fixes #20104)

Revision d5e57d31
Added by Even Rouault over 1 year ago

Merge pull request #8186 from rouault/fix_20104

[GDAL provider] Make sure that setEditable(true) invalides cached GDAL handles to get proper refresh (fixes #20104)

History

#1 Updated by Even Rouault over 1 year ago

  • Status changed from Open to In Progress

#2 Updated by Even Rouault over 1 year ago

  • % Done changed from 0 to 100
  • Status changed from In Progress to Closed

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