From dda667023a6cdedb813b1926f0c3d79276255ba3 Mon Sep 17 00:00:00 2001
From: "arnaud.morvan@camptocamp.com" <arnaud.morvan@camptocamp.com>
Date: Thu, 9 Feb 2017 16:06:34 +0100
Subject: [PATCH] [processing] Add class ExpressionEnabledWidgetWrapper

---
 python/plugins/processing/gui/wrappers.py | 68 +++++++++++++++++++----
 1 file changed, 58 insertions(+), 10 deletions(-)

diff --git a/python/plugins/processing/gui/wrappers.py b/python/plugins/processing/gui/wrappers.py
index 83bab557c6c..8b318721b74 100644
--- a/python/plugins/processing/gui/wrappers.py
+++ b/python/plugins/processing/gui/wrappers.py
@@ -32,16 +32,34 @@ import locale
 import os
 from functools import cmp_to_key
 
-from qgis.core import QgsCoordinateReferenceSystem, QgsApplication, QgsWkbTypes, QgsMapLayerProxyModel
-from qgis.PyQt.QtWidgets import QCheckBox, QComboBox, QLineEdit, QPlainTextEdit, QWidget, QHBoxLayout, QToolButton, QFileDialog
-from qgis.gui import (QgsFieldExpressionWidget,
-                      QgsExpressionLineEdit,
-                      QgsProjectionSelectionWidget,
-                      QgsGenericProjectionSelector,
-                      QgsFieldComboBox,
-                      QgsFieldProxyModel,
-                      QgsMapLayerComboBox
-                      )
+from qgis.core import (
+    QgsApplication,
+    QgsCoordinateReferenceSystem,
+    QgsExpression,
+    QgsMapLayerProxyModel,
+    QgsWkbTypes,
+)
+from qgis.PyQt.QtWidgets import (
+    QCheckBox,
+    QComboBox,
+    QDialog,
+    QFileDialog,
+    QHBoxLayout,
+    QLineEdit,
+    QPlainTextEdit,
+    QToolButton,
+    QWidget,
+)
+from qgis.gui import (
+    QgsExpressionLineEdit,
+    QgsExpressionBuilderDialog,
+    QgsFieldComboBox,
+    QgsFieldExpressionWidget,
+    QgsFieldProxyModel,
+    QgsGenericProjectionSelector,
+    QgsMapLayerComboBox,
+    QgsProjectionSelectionWidget,
+)
 from qgis.PyQt.QtCore import pyqtSignal, QObject, QVariant, QSettings
 
 from processing.gui.NumberInputPanel import NumberInputPanel, ModellerNumberInputPanel
@@ -175,6 +193,36 @@ class WidgetWrapper(QObject):
         return filename, selected_filter
 
 
+class ExpressionEnabledWidgetWrapper(WidgetWrapper):
+
+    def createWidget(self, basewidget):
+        expr_button = QToolButton()
+        expr_button.clicked.connect(self.showExpressionsBuilder)
+        expr_button.setText('...')
+
+        layout = QHBoxLayout()
+        layout.setContentsMargins(0, 0, 0, 0)
+        layout.addWidget(basewidget)
+        layout.addWidget(expr_button)
+
+        widget = QWidget()
+        widget.setLayout(layout)
+
+        return widget
+
+    def showExpressionsBuilder(self):
+        context = self.param.expressionContext()
+        value = self.value()
+        if not isinstance(value, str):
+            value = ''
+        dlg = QgsExpressionBuilderDialog(None, value, self.widget, 'generic', context)
+        dlg.setWindowTitle(self.tr('Expression based input'))
+        if dlg.exec_() == QDialog.Accepted:
+            exp = QgsExpression(dlg.expressionText())
+            if not exp.hasParserError():
+                self.setValue(dlg.expressionText())
+
+
 class BasicWidgetWrapper(WidgetWrapper):
 
     def createWidget(self):