Use pyqt4v2 which is automatically selected by qtpy with pyqt4>=4.6

.travis.yml

@@ -7,7 +7,7 @@ env:
     # used by ci-helpers
     - SETUP_XVFB=true PIP_DEPENDENCIES='hacking pytest pytest-qt'
   matrix:
-    - PYTEST_QT_API=pyqt4 PYQT_PACKAGE='pyqt=4' PYTHON_VERSION=2.7
+    - PYTEST_QT_API=pyqt4v2 PYQT_PACKAGE='pyqt=4' PYTHON_VERSION=2.7
     - PYTEST_QT_API=pyside2 CONDA_CHANNELS='conda-forge' PYQT_PACKAGE='pyside2' PYTHON_VERSION=2.7
     - PYTEST_QT_API=pyside2 CONDA_CHANNELS='conda-forge' PYQT_PACKAGE='pyside2' PYTHON_VERSION=3.6
     - PYTEST_QT_API=pyqt5 PYQT_PACKAGE='pyqt=5' PYTHON_VERSION=2.7

labelme/labelDialog.py

@@ -78,18 +78,21 @@ class LabelDialog(QtWidgets.QDialog):
         self.edit.setText(item.text())
 
     def validate(self):
-        if QT5:
-            if self.edit.text().strip():
-                self.accept()
+        text = self.edit.text()
+        if hasattr(text, 'strip'):
+            text = text.strip()
         else:
-            if self.edit.text().trimmed():
-                self.accept()
+            text = text.trimmed()
+        if text:
+            self.accept()
 
     def postProcess(self):
-        if QT5:
-            self.edit.setText(self.edit.text().strip())
+        text = self.edit.text()
+        if hasattr(text, 'strip'):
+            text = text.strip()
         else:
-            self.edit.setText(self.edit.text().trimmed())
+            text = text.trimmed()
+        self.edit.setText(text)
 
     def popUp(self, text=None, move=True):
         # if text is None, the previous label in self.edit is kept