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<p class="MsoNormal">Hi Devs,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I'm trying to load a raster/vector layer to the current project at the end of the run of a processing algorithm script. I know about QgsProcessingParameterFeatureSink() and I use it when creating a new layer during processing, but how to
add an existing layer that will be shown on the map? I tried using <span style="font-family:"Courier New"">
context.project().addMapLayer(rlayer, True)</span> but it obviously doesn't work because the process is running in a separate thread. Speaking of thread, I would prefer avoiding running the script in the main thread with<o:p></o:p></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">def flags(self):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> return super().flags() | QgsProcessingAlgorithm.FlagNoThreading<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I saw this answer from Nyall on <a href="https://gis.stackexchange.com/questions/280520/let-qgis-3-0-processing-algorithm-output-a-vectorlayer-loaded-via-the-delimited">
SO</a> for something similar but I haven't been able to emulate. Below is a short example of what I last tried and which gives me the following error:
<i>The following layers were not correctly generated. • image_73e75830_4808_4993_abc7_24a5ee61217e You can check the 'Log Messages Panel' in QGIS main window to find more information about the execution of the algorithm.</i>
<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><span style="font-family:"Courier New"">class addLayerToCanvas(QgsProcessingAlgorithm):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> OUTPUT_raster = 'OUTPUT_raster'<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> def initAlgorithm(self, config):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> self.addOutput(QgsProcessingOutputMultipleLayers(self.OUTPUT_raster,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> self.tr('Output raster')))<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> def processAlgorithm(self, parameters, context, feedback):<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> rlayer = QgsRasterLayer("F:/image.tif", "image") # The layer I want to add to the current project/canvas<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> context.addLayerToLoadOnCompletion(rlayer.id(), QgsProcessingContext.LayerDetails('image_layer', QgsProject.instance(), ''))<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> <o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Courier New""> return {self.OUTPUT_raster: rlayer.id()}<o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks for any help<o:p></o:p></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto"><span style="color:black;mso-fareast-language:FR-CA"><o:p> </o:p></span></p>
<p class="MsoNormal" style="mso-margin-top-alt:auto"><b><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:black;mso-fareast-language:FR-CA">Jean-François Bourdon, ing.f.</span></b><span style="font-size:9.0pt;font-family:"Arial",sans-serif;color:black;mso-fareast-language:FR-CA"><o:p></o:p></span></p>
<p class="MsoNormal"><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#2E74B5;mso-fareast-language:FR-CA">Analyste en télédétection</span></b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;mso-fareast-language:FR-CA"><br>
<b><span style="color:#2E74B5">Direction des inventaires forestiers</span></b><br>
<b><span style="color:#2E74B5">Ministère des Forêts, de la Faune et des Parcs</span></b><br>
<span style="color:#2E74B5">5700, 4<sup>e</sup> Avenue Ouest, local A-108</span><br>
<span style="color:#2E74B5">Québec (Québec) G1H 6R1</span><br>
<span style="color:#2E74B5">Téléphone : <s>418 627-8669, poste 704304</s></span><br>
<b><u><span style="color:#2E74B5">jean-francois.bourdon@mffp.gouv.qc.ca</span></u></b>
<br>
</span><span style="mso-fareast-language:FR-CA"><a href="http://www.mffp.gouv.qc.ca/accueil.jsp"><b><span style="font-size:10.0pt;font-family:"Arial",sans-serif;color:#2E74B5">mffp.gouv.qc.ca</span></b></a></span><span style="mso-fareast-language:FR-CA"><o:p></o:p></span></p>
<p class="MsoNormal"><o:p> </o:p></p>
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