[processing] added predefined expressions to raster calculator

python/plugins/processing/algs/qgis/ui/ExpressionWidget.ui

@@ -7,7 +7,7 @@
     <x>0</x>
     <y>0</y>
     <width>644</width>
-    <height>296</height>
+    <height>493</height>
    </rect>
   </property>
   <property name="windowTitle">
@@ -343,9 +343,6 @@
       <string>Expression</string>
      </property>
      <layout class="QVBoxLayout" name="verticalLayout_2">
-      <property name="margin">
-       <number>0</number>
-      </property>
       <item>
        <widget class="QPlainTextEdit" name="text">
         <property name="sizePolicy">
@@ -362,6 +359,34 @@
         </property>
        </widget>
       </item>
+      <item>
+       <widget class="QGroupBox" name="groupBox_2">
+        <property name="title">
+         <string>Predefined expressions</string>
+        </property>
+        <layout class="QHBoxLayout" name="horizontalLayout">
+         <item>
+          <widget class="QComboBox" name="comboPredefined"/>
+         </item>
+         <item>
+          <widget class="QPushButton" name="buttonAddPredefined">
+           <property name="sizePolicy">
+            <sizepolicy hsizetype="Fixed" vsizetype="Fixed">
+             <horstretch>0</horstretch>
+             <verstretch>0</verstretch>
+            </sizepolicy>
+           </property>
+           <property name="text">
+            <string>Add...</string>
+           </property>
+          </widget>
+         </item>
+        </layout>
+        <zorder>buttonAddPredefined</zorder>
+        <zorder>buttonAddPredefined</zorder>
+        <zorder>comboPredefined</zorder>
+       </widget>
+      </item>
      </layout>
     </widget>
    </item>

python/plugins/processing/algs/qgis/ui/RasterCalculatorWidgets.py

@@ -2,21 +2,62 @@ from processing.gui.wrappers import WidgetWrapper, DIALOG_STANDARD, DIALOG_BATCH
 from processing.tools import dataobjects
 from processing.gui.BatchInputSelectionPanel import BatchInputSelectionPanel
 from qgis.PyQt.QtWidgets import QListWidget, QLineEdit, QPushButton
-from qgis.PyQt.QtGui import QTextCursor
+from qgis.PyQt.QtGui import QTextCursor, QLabel, QComboBox, QSizePolicy, QSpacerItem
 from processing.core.outputs import OutputRaster
 from processing.core.parameters import ParameterRaster
 from processing.gui.wrappers import InvalidParameterValue
 import os
 from qgis.PyQt import uic
 from functools import partial
+import re
 
 pluginPath = os.path.dirname(__file__)
+WIDGET_DLG, BASE_DLG = uic.loadUiType(
+    os.path.join(pluginPath, 'PredefinedExpressionDialog.ui'))
+
+class PredefinedExpressionDialog(BASE_DLG, WIDGET_DLG):
+    
+    def __init__(self, expression, options):
+        super(PredefinedExpressionDialog, self).__init__()
+        self.setupUi(self)
+        
+        self.filledExpression = None
+        self.options = options
+        self.expression = expression
+        self.variables = set(re.findall('\[.*?\]', expression))
+        self.comboBoxes = {}
+        for variable in self.variables:
+            label = QLabel(variable[1:-1])
+            combo = QComboBox()
+            for opt in self.options.keys():
+                combo.addItem(opt)
+            self.comboBoxes[variable] = combo
+            self.groupBox.layout().addWidget(label)
+            self.groupBox.layout().addWidget(combo)
+            
+        verticalSpacer = QSpacerItem(20, 40, QSizePolicy.Minimum, QSizePolicy.Expanding)
+        self.groupBox.layout().addItem(verticalSpacer)
+            
+        self.buttonBox.rejected.connect(self.cancelPressed)
+        self.buttonBox.accepted.connect(self.okPressed)
+
+    def cancelPressed(self):
+        self.close()
+        
+    def okPressed(self):
+        self.filledExpression = self.expression
+        for name, combo in self.comboBoxes.items():
+            self.filledExpression = self.filledExpression.replace(name, 
+                                            self.options[combo.currentText()])
+        self.close()
+
 WIDGET, BASE = uic.loadUiType(
     os.path.join(pluginPath, 'ExpressionWidget.ui'))
 
-
 class ExpressionWidget(BASE, WIDGET):
 
+    expressions = {"NDVI": "([NIR] - [Red]) % ([NIR] + [Red])"}
+
     def __init__(self, options):
         super(ExpressionWidget, self).__init__(None)
         self.setupUi(self)
@@ -36,6 +77,20 @@ class ExpressionWidget(BASE, WIDGET):
         for button in buttons:
             button.clicked.connect(partial(addButtonText, button.text()))
         self.listWidget.itemDoubleClicked.connect(doubleClicked)
+        
+        self.fillPredefined()
+        self.buttonAddPredefined.clicked.connect(self.addPredefined)
+        
+    def addPredefined(self):
+        expression = self.expressions[self.comboPredefined.currentText()]
+        dlg = PredefinedExpressionDialog(expression, self.options)
+        dlg.exec_()
+        if dlg.filledExpression:
+            self.text.setPlainText(dlg.filledExpression)
+            
+    def fillPredefined(self):
+        for expression in self.expressions:
+            self.comboPredefined.addItem(expression)
 
     def setList(self, options):
         self.options = options