[QGIS-Developer] PyQGIS WMS tiles don't load on Windows

[Tim Sutton]

I suggest taking a look at the source of the QuickMapServices plugin to see how they do it. Make sure to get the extra datasets from the plugin settings dialog.

Regards

Tim

> On 9 Apr 2019, at 08:54, Erik Polzin <eriktpol at gmail.com> wrote:
> 
> I'm busy developing an app using the QGIS Python api, PyQGIS, and am noticing some strange behaviour when loading WMS tiles: Running the python script on Linux Mint loads xyz layers from Google Maps and Google Satellite just fine. On Windows, only the Google Maps layer loads.  
> 
> Here is a test script I wrote to demonstrate the problem:
> 
> from qgis.core import QgsApplication, QgsProject, QgsRasterLayer
> from qgis.gui import QgsMapCanvas, QgsLayerTreeMapCanvasBridge
> 
> from PyQt5.QtWidgets import QMainWindow
> import os
> 
> GOOGLE_MAPS_SOURCE = "type=xyz&url=https://mt1.google.com/vt?lyrs%3Dm%26x%3D%7Bx%7D%26y%3D%7By%7D%26z%3D%7Bz%7D&zmax=19&zmin=0 <https://mt1.google.com/vt?lyrs%3Dm%26x%3D%7Bx%7D%26y%3D%7By%7D%26z%3D%7Bz%7D&zmax=19&zmin=0>"
> GOOGLE_SATELLITE_SOURCE = "type=xyz&url=https://mt1.google.com/vt?lyrs%3Ds%26x%3D%7Bx%7D%26y%3D%7By%7D%26z%3D%7Bz%7D&zmax=19&zmin=0 <https://mt1.google.com/vt?lyrs%3Ds%26x%3D%7Bx%7D%26y%3D%7By%7D%26z%3D%7Bz%7D&zmax=19&zmin=0>"
> 
> class WMSTestApp(QMainWindow):
> 
>     def __init__(self):
>         super().__init__()
> 
>         self.canvas = QgsMapCanvas(self)
>         self.bridge = QgsLayerTreeMapCanvasBridge(QgsProject.instance().layerTreeRoot(), self.canvas)
>             
>         layer = QgsRasterLayer(GOOGLE_SATELLITE_SOURCE, "Test WMS Layer", "wms")
>         
>         QgsProject.instance().addMapLayer(layer)
>         self.canvas.setLayers([layer])
> 
>         self.setCentralWidget(self.canvas)
> 
> 
> QgsApplication.setPrefixPath(os.environ.get("QGIS_PREFIX_PATH", "C:\Program Files\QGIS 3.4\apps\qgis"), True)
> qgs = QgsApplication([], True)
> qgs.initQgis()
> 
> app = WMSTestApp()
> app.show()
> qgs.exec_()
> qgs.exitQgis()
> 
> Interestingly, the layers (from the same sources!) both load from the Windows QGIS app.
> So I did some digging and noticed that the default Google Maps url returns PNG files, while the Satellite url returns JPEGs. I tested a couple of other links, and it seems like only PNG tile servers have any effect on windows systems.
> 
> Have tested this on Windows 7 and 10, with the same results.
> 
> Does PyQgis need to be reconfigured in some way to get this to work? Or is it a known issue with the version (3.4) I'm using?
> 
> Cheers and thanks,
> Erik
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—









Tim Sutton

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