changing input layers adds its band names to the table

BandTableWidget.py

@@ -27,7 +27,6 @@ import codecs
 
 from qgis.PyQt import uic
 from qgis.PyQt.QtCore import pyqtSlot, QDir
-from qgis.PyQt.QtGui import QColor, QBrush
 from qgis.PyQt.QtWidgets import (QTreeWidgetItem,
                                  QFileDialog,
                                  QMessageBox,
@@ -36,11 +35,14 @@ from qgis.PyQt.QtWidgets import (QTreeWidgetItem,
                                  )
 from qgis.PyQt.QtXml import QDomDocument
 
-from qgis.core import QgsApplication, QgsMapLayer
+from qgis.core import (QgsApplication, 
+                       QgsMapLayer,
+                       QgsMapLayerProxyModel)
 from qgis.analysis import QgsRelief
 
 from processing.gui.wrappers import WidgetWrapper
 from processing.tools import system
+from osgeo import gdal
 
 pluginPath = os.path.dirname(__file__)
 WIDGET, BASE = uic.loadUiType(os.path.join(pluginPath, 'bandtablewidgetbase.ui'))
@@ -51,12 +53,41 @@ class BandTableWidget(BASE, WIDGET):
     def __init__(self):
         super(BandTableWidget, self).__init__(None)
         self.setupUi(self)
-
+        
+        self.cmbLayers.setFilters(QgsMapLayerProxyModel.RasterLayer)
+        self.cmbLayers.layerChanged.connect(self.layerChanged)
         self.btnAdd.setIcon(QgsApplication.getThemeIcon('/symbologyAdd.svg'))
         self.btnRemove.setIcon(QgsApplication.getThemeIcon('/symbologyRemove.svg'))
         self.btnUp.setIcon(QgsApplication.getThemeIcon('/mActionArrowUp.svg'))
         self.btnDown.setIcon(QgsApplication.getThemeIcon('/mActionArrowDown.svg'))
         self.layer = None
+      
+    # when user changes selected layer in combobox
+    def layerChanged(self):
+        # remove table content
+        self._removeBandData()
+        # get raster layer
+        layer = self.cmbLayers.currentLayer()
+        #QMessageBox.information(None, self.tr('tralala'), self.tr(str(layer)))
+        input_raster = gdal.Open(layer.source())
+        # get number of bands in raster
+        nbands = input_raster.RasterCount
+        # for each band
+        for band_number in range(nbands):
+            band = input_raster.GetRasterBand(band_number + 1)
+            # add band name to table in first column
+            self._addBandData(band.GetDescription())
+    
+    # add selected raster band names to table
+    def _addBandData(self, bandname):
+        item = QTreeWidgetItem()
+        item.setText(0, bandname)
+        item.setText(1, '')
+        self.bandClassTree.addTopLevelItem(item)
+    
+    # remove all rows from table    
+    def _removeBandData(self,):
+        self.bandClassTree.clear()
 
     @pyqtSlot()
     def on_btnAdd_clicked(self):
@@ -126,7 +157,15 @@ class BandTableWidget(BASE, WIDGET):
         return colors
 
     def setLayer(self, layer):
+        QMessageBox.information(None, self.tr('tralala'), self.tr('coucou'))
         self.layer = layer
+        self.updateTable(layer)
+        
+    def updateTable(self, layer):
+        item = QTreeWidgetItem()
+        item.setText(0, '0.00')
+        item.setText(1, '0.00')
+        self.bandClassTree.addTopLevelItem(item)
 
     def setValue(self, value):
         self.bandClassTree.clear()
@@ -165,6 +204,7 @@ class BandTableWidgetWrapper(WidgetWrapper):
         if isinstance(layer, QgsMapLayer):
             layer = layer.source()
         self.widget.setLayer(layer)
+        self.widget.updateTable(layer)
 
     def setValue(self, value):
         self.widget.setValue(value)

merge_rename_bands_algorithm.py

@@ -48,17 +48,17 @@ from osgeo import gdal
 # custom band table widget
 class ParameterBandTable(QgsProcessingParameterDefinition):
 
-    def __init__(self, name='', description='', parent=None, optional=True):
+    def __init__(self, name='', description='', parent=None, optional=False):
         super().__init__(name, description, None, optional)
         self.parent = parent
         self.setMetadata({'widget_wrapper': 'BandTableWidget.BandTableWidgetWrapper'})
 
     def type(self):
-        return 'band table'
+        return 'Input parameters'
 
     def clone(self):
         return ParameterBandTable(self.name(), self.description(), self.parent,
-                                     self.flags() & QgsProcessingParameterDefinition.FlagOptional)
+                                     self.flags())
     
     
 class TableWidget(WidgetWrapper):
@@ -110,9 +110,9 @@ class MergeAndRenameAlgorithm(QgsProcessingAlgorithm):
         self.addParameter(
             ParameterBandTable(
                 self.INPUT,
-                self.tr('Band table'),
+                self.tr('Input parameters'),
                 self.INPUT,
-                True
+                False # True if optional
             )
         )
             
@@ -131,10 +131,10 @@ class MergeAndRenameAlgorithm(QgsProcessingAlgorithm):
         """
 
         # RETRIEVE INPUTS AND OUTPUT
-        input_raster = self.parameterAsRasterLayer(parameters, self.INPUT, context)
+        input_param = self.parameterAsRasterLayer(parameters, self.INPUT, context)
         output_raster_path = self.parameterAsOutputLayer(parameters, self.OUTPUT, context)
         
-#        # GETTING USEFUL PAREMETERS
+#        # GETTING USEFUL PARAMETERS
 #        
 #        # number of columns in table is used later on, change it here if necessary
 #        nb_col = 2