[Qgis-developer] [Qgis-user] WMS Rendering Problems

[Tim Sutton]

Hi

2007/11/1, Jürgen E. Fischer <jef at norbit.de>:
> Hi Tim,
>
> On Wed, 31. Oct 2007 at 22:55:39 -0300, Tim Sutton wrote:
> > Was anyone able to test Toms patch? Can we go ahead and apply it to
> > trunk? We would like to do a follow up release of QGIS 0.9.1 in the
> > next few days - in particular to provide updated binaries to address
> > some GRASS issues Martin fixed, and to provide a Toms WMS fix.
>
> I tested.  The attached path includes a few more changes that made it
> work for me (notably the handling of redirections in
> QgsHttpTransaction).
>

Great!

> Have you looked at the patch?  We probably don't want the upper layers
> to know about WMS and need a more generic way to handle data providers
> asynchronously.
>

I had a look at Toms patch. From what I can see the main upper level
API that does this is here:

@@ -617,7 +657,24 @@

 void QgsMapRender::setLayerSet(const QStringList& layers)
 {
+  QgsMapLayerRegistry* registry = QgsMapLayerRegistry::instance();
+  QStringList::iterator it = mLayerSet.begin();
+  while (it != mLayerSet.end())
+  {
+    QgsRasterLayer *rl = dynamic_cast<QgsRasterLayer
*>(registry->mapLayer(*it));
+    if (rl && rl->providerKey() == "wms")
+      disconnect(rl, SIGNAL(imageAvailable()), this, SLOT(asyncLayerDone()));
+    ++it;
+  }
   mLayerSet = layers;
+  it = mLayerSet.begin();
+  while (it != mLayerSet.end())
+  {
+    QgsRasterLayer *rl = dynamic_cast<QgsRasterLayer
*>(registry->mapLayer(*it));
+    if (rl && rl->providerKey() == "wms")
+      connect(rl, SIGNAL(imageAvailable()), this, SLOT(asyncLayerDone()));
+    ++it;
+  }
   updateFullExtent();
 }

The other parts dont look problematic to me. So basically we just need
to figure out a way to move that logic down the stack somehow. I do
wonder if the imageAvailable() could not be implemented rather as a
more generic QgsMapLayer::dataAvailable() - I can envisage a situation
where this same functionality could be useful for WFS or indeed for
renderers that spawn a separate thread in the future (might be nice
e.g. in postgres/postgis to fetch large queries back for example).

Regards

Tim

>
> Jürgen
>
> --
> Jürgen E. Fischer         norBIT GmbH               Tel. +49-4931-918175-0
> Dipl.-Inf. (FH)           Rheinstraße 13            Fax. +49-4931-918175-50
> Software Engineer         D-26506 Norden               http://www.norbit.de
>
> --
> norBIT Gesellschaft fuer Unternehmensberatung und Informationssysteme mbH
> Rheinstrasse 13, 26506 Norden
> GF: Jelto Buurman, HR: Amtsgericht Emden, HRB 5502
>
>
>


-- 
Tim Sutton
QGIS Project Steering Committee Member - Release  Manager
Visit http://qgis.org for a great open source GIS
openModeller Desktop Developer
Visit http://openModeller.sf.net for a great open source ecological
niche modelling tool
Home Page: http://tim.linfiniti.com
Skype: timlinux
Irc: timlinux on #qgis at freenode.net