[Qgis-user] Maps generation with Python (or Atlas ?)

[Benoît Laurent]

Thank you for your help.

> Hi,
>
> 2015-05-18 17:51 GMT+02:00 Benoît Laurent <blaurent at heurisis.eu 
> <mailto:blaurent at heurisis.eu>>:
>
>     Hello,
>
>     I would like to generate a series of maps representing tracks with
>     stops along them.
>
>     For each track, I have got a group of two layers, one for the
>     linear, one for the points that have associated information
>     (basically name and time of the stops). First, is there a better
>     way to achieve this ? For the moment, I have to handle two types
>     of layer. It is the beginning of my problems.
>
>     As the tracks overlap, I would like to generate a map for each
>     track where only the current selected track appears. The others
>     would be hidden.
>
>     I had a try with Atlas generation. It perfectly works except that
>     I can't hide the other tracks.
>
> You can style your coverage layer so that only atlas current feature 
> will appear. In categorized style, use an expression like 
> $id=$atlasfeatureid. You'll get 0 (false) and 1 (true) when classing. 
> Set the 0 features style so that they become invisible or transparent.
It is a little better : with your help, I can highlight the current 
linear layer. Actually, I aggregated all my linear layers to constitute 
the coverage layer. However, I can't hide the points layers.

>
>     I also had a try with a Python script. I managed to iterate over
>     the groups of layers but I can't refresh the map canvas during the
>     Python script. So, it doesn't work.
>
> A snippet of your code may help but I remember I had to face such a 
> problem and it was because after *myatlas.beginRender()*, I forgot to 
> set active the export of the atlas, sthg like 
> *mycomposition.setAtlasMode(QgsComposition.ExportAtlas)*
>
Actually, I did not use the Atlas generator (maybe a mistake ?). I 
wanted to reproduce/modify its behavior. Here is a piece of code 
(remember that for each track, there is linear layer and a points layer) :

|         # Iterate over groups of pair of layers
         for  gin  range(0,nbGroups-1):

                 # Display layers of the current group
                 layer=  layers[2*g]
                 rectTrajet=  layer.extent()                     
                 legend.setLayerVisible(layer,  True)
                 layer=  layers[2*g+1]
                 rectPtsArr=  layer.extent()
                 legend.setLayerVisible(layer,  True)                                 

                 # extent area
                 rectGlb=  QgsRectangle
                 xMin=  min(rectTrajet.xMinimum(),  rectPtsArr.xMinimum())
                 xMax=  max(rectTrajet.xMaximum(),  rectPtsArr.xMaximum())
                 yMin=  min(rectTrajet.yMinimum(),  rectPtsArr.yMinimum())
                 yMax=  max(rectTrajet.yMaximum(),  rectPtsArr.yMaximum())
                 rectGlb=  QgsRectangle(xMin,  yMin,  xMax,  yMax)
                 self.iface.mapCanvas().setExtent(rectGlb)

                 self.iface.mapCanvas().zoomToSelected()
                 self.iface.mapCanvas().updateScale()
                 self.iface.mapCanvas().zoomByFactor(1.5)

                 # Nothing works here !!
                 self.iface.mapCanvas().updateOverview()
                 self.iface.mapCanvas().refresh()
                 layers[2*g].triggerRepaint()
                 layers[2*g+1].triggerRepaint()


                 # Map composer
                 composerMap=  QgsComposerMap(c,x,y,w,h)
                 composerMap.setPreviewMode(QgsComposerMap.Render)
                 composerMap.updateBoundingRect()
                 composerMap.renderModeUpdateCachedImage()
                 composerMap.setFrameEnabled(True)
                 c.addItem(composerMap)


                 # Launch printing
                 printer=  QtGui.QPrinter()
                 printer.setOutputFormat(QtGui.QPrinter.PdfFormat)
                 printer.setOutputFileName(nomFichier)
                 printer.setPaperSize(QSizeF(c.paperWidth(),  c.paperHeight()),  QtGui.QPrinter.Millimeter)
                 printer.setFullPage(True)
                 printer.setColorMode(QtGui.QPrinter.Color)
                 printer.setResolution(c.printResolution())

                 pdfPainter=  QPainter(printer)
                 paperRectMM=  printer.pageRect(QtGui.QPrinter.Millimeter)
                 paperRectPixel=  printer.pageRect(QtGui.QPrinter.DevicePixel)
                 c.render(pdfPainter,  paperRectPixel,  paperRectMM)
                 pdfPainter.end()

                 # Remove map composer
                 c.removeItem(composerMap)

                 # Hide layers of the current group
                 legend.setLayerVisible(layers[2*g],  False)
                 legend.setLayerVisible(layers[2*g+1],  False)

  |




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