On Thu, May 10, 2012 at 10:03 AM, Etienne Tourigny <[email protected]> wrote: > You are right, that is the best approach. However, it might be best > to auto-load when the user actually switches to the tab. > > A pain gdal does not have an API to query if the histogram is already > computed - this would require adding PAM-aware code to the gdal > provider. >
I need to correct myself - PamFindMatchingHistogram() is available in gdal_pam.h and could be used to test if a cached histogram exists - provided the raster is a pam raster. However, it seems the raster provider uses the C GDAL API - rather than the C++ API , could this be changed easily? Etienne > Etienne > > On Wed, May 9, 2012 at 9:53 PM, Nathan Woodrow <[email protected]> wrote: >> Generally it is good practice that the UI remembers where the user left it >> last time. In this case this has a bad user experience because of the slow >> loading. My suggestion would be to just add a "Load histogram" button in >> the histogram tab that loads the histogram rather then when the tab is >> switched to. This way even if the histogram tab is remembered as the >> current tab it will load like normal and user has to click "Load histogram" >> to show it. >> >> - Nathan >> >> >> On Thu, May 10, 2012 at 10:49 AM, Etienne Tourigny <[email protected]> >> wrote: >>> >>> I agree that this should not happen, should the default be always open >>> the first tab, or only when the histogram tab was previously selected? >>> >>> Unfortunately there is no function in the provider API to know if >>> there is a cached histogram, so it would be better to never allow the >>> properties window to start on the histogram tab. >>> >>> I have implemented this in a branch of mine to improve the histogram >>> tab, here is a snippet: >>> >>> - tabBar->setCurrentIndex( settings.value( >>> "/Windows/RasterLayerProperties/row" ).toInt() ); >>> + int currentTabIndex = settings.value( >>> "/Windows/RasterLayerProperties/row" ).toInt(); >>> + // if current tab is disabled, use first tab >>> + if ( ! tabBar->widget( currentTabIndex )->isEnabled() ) >>> + currentTabIndex = 0; >>> + // if current tab is histogram, use first tab (to avoid long >>> histogram queries) >>> + // there is currently no way to know if there ia a cached histogram >>> int myHistogramTab = 6; >>> - if ( tabBar->currentIndex() == myHistogramTab ) >>> - { >>> - refreshHistogram(); >>> - } >>> + if ( currentTabIndex == myHistogramTab ) >>> + currentTabIndex = 0; >>> + tabBar->setCurrentIndex( currentTabIndex ); >>> >>> >>> Etienne >>> >>> On Mon, May 7, 2012 at 10:15 AM, G. Allegri <[email protected]> wrote: >>> > A complex object to say something simple :( >>> > When a user opens a layer settings window and hits a tab, the same tab >>> > index >>> > is kept when opening another layer settings, or in a new qgis sessions. >>> > I had a small raster layer, and I opened the histogram tab. >>> > The today I've opened a big raster layer, and opening the layer settings >>> > caused my pc running and running, till a complete qgis crash. >>> > I supposed it was something with the settings, so I opened the smalle >>> > raster, changed the tab to Style, then I was able to open the large >>> > raster >>> > settings >>> > It's corner case probably, and qgis shouldn't crash with huge raster >>> > histograms. Anyway, opening the layer settings to the frist tab would >>> > avoid >>> > heartbreaks :) >>> > >>> > giovanni >>> > >>> > _______________________________________________ >>> > Qgis-developer mailing list >>> > [email protected] >>> > http://lists.osgeo.org/mailman/listinfo/qgis-developer >>> > >>> _______________________________________________ >>> Qgis-developer mailing list >>> [email protected] >>> http://lists.osgeo.org/mailman/listinfo/qgis-developer >> >> _______________________________________________ Qgis-developer mailing list [email protected] http://lists.osgeo.org/mailman/listinfo/qgis-developer
