[Qgis-developer] Contrast Enhancement

[Alexia Mondot]

Hi all,

I have some problems to apply new stretching values to my layer

I have a function which allows to adapt the stretching of my image 
without the raster layer properties dialog.

When I open an image with my plugin, I display it on the canvas, I open 
my own histograms, and I can move the min max stretch of the 3 displayed 
bands.

It works well. But, when i save the project, i reopen it, I want to 
change the image stretching, it does nothing. The values are set, but it 
seems that the layer renderer is not updated.

Here is my stretching code :

>     print canvas
>     print "layer :", theRasterLayer
>
>     # type of layer : raster, vector, other
>     typeOfLayer = theRasterLayer.type()
>
>     dataProvider = theRasterLayer.dataProvider()
>
>     # the layer has to be a raster layer
>     if typeOfLayer == 1 :
>         if (theRasterLayer.rasterType() == 0 ) and 
> theRasterLayer.renderer():
> [...]
>
>         elif theRasterLayer.rasterType() == 2  and 
> theRasterLayer.renderer():
>             min_red, max_red = values[0]
>             min_green, max_green = values[1]
>             min_blue, max_blue = values[2]
>
>             redEnhancement = QgsContrastEnhancement( 
> dataProvider.dataType( 0 ) )
>             greenEnhancement = QgsContrastEnhancement( 
> dataProvider.dataType( 1 ) )
>             blueEnhancement = QgsContrastEnhancement( 
> dataProvider.dataType( 2 ) )
>             #set stretch to min max
>             redEnhancement.setMinimumValue( min_red )
>             redEnhancement.setMaximumValue( max_red )
>             greenEnhancement.setMinimumValue( min_green )
>             greenEnhancement.setMaximumValue( max_green )
>             blueEnhancement.setMinimumValue( min_blue )
>             blueEnhancement.setMaximumValue( max_blue )
>             redEnhancement.setContrastEnhancementAlgorithm(1)
>             greenEnhancement.setContrastEnhancementAlgorithm(1)
>             blueEnhancement.setContrastEnhancementAlgorithm(1)
>
>             print "blue enhancement", blueEnhancement
>             print "blue max", blueEnhancement.maximumValue()
>             print "blue min", blueEnhancement.minimumValue()
>
>             theRasterLayer.renderer().setRedContrastEnhancement( 
> redEnhancement)
>             theRasterLayer.renderer().setGreenContrastEnhancement( 
> greenEnhancement )
>             theRasterLayer.renderer().setBlueContrastEnhancement( 
> blueEnhancement)
>
>         theRasterLayer.triggerRepaint()
>
>         print theRasterLayer.renderer().blueContrastEnhancement()
>         print 
> theRasterLayer.renderer().blueContrastEnhancement().minimumValue()
>         print 
> theRasterLayer.renderer().blueContrastEnhancement().maximumValue()
>     canvas.refresh()
>     canvas.repaint()

In my case, the canvas, is the main canvas, I have checked I work on the 
good one comparing  the print canvas and the python console with 
iface.mapCanvas().

I know :
* both cases run this function.
* the minimum and maximum values of contrast enhancement are the same in 
my two prints (before and after the setXContrastEnhancement) (so the 
theRasterLayer.renderer().blueContrastEnhancement() seems to be well set)
* these values are the good ones
* they aren't displayed in the raster layer properties dialog
* my raster layer source is ok
* when i do these steps on the QGIS python console with the layer 
iface.mapCanvas().currentLayer() which points to the same file, it works

> layer = iface.mapCanvas().currentLayer()
> blue_en = QgsContrastEnhancement( layer.dataProvider().dataType(2))
> blue_en.setMinimumValue(150)
> blue_en.setMaximumValue(350)
> blue_en.setContrastEnhancementAlgorithm(1)
> layer.renderer().setBlueContrastEnhancement(blue_en)
> layer.triggerRepaint()

What have I missed ?

Thanks by advance,
Alexia
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.osgeo.org/pipermail/qgis-developer/attachments/20141126/8d1f7f3e/attachment-0001.html>