error can be locked within properties()

and simplified the componenterrors again

src/component.py

@@ -19,7 +19,7 @@ class ComponentMetaclass(type(QtCore.QObject)):
                 return func(self, *args, **kwargs)
             except Exception:
                 try:
-                    raise ComponentInitError(self, 'initialization process')
+                    raise ComponentError(self, 'initialization process')
                 except ComponentError:
                     return
         return initializationWrapper
@@ -63,7 +63,13 @@ class ComponentMetaclass(type(QtCore.QObject)):
             if self._lockedProperties is not None:
                 return self._lockedProperties
             else:
-                return func(self)
+                try:
+                    return func(self)
+                except Exception:
+                    try:
+                        raise ComponentError(self, 'properties')
+                    except ComponentError:
+                        return []
         return propertiesWrapper
 
     def errorWrapper(func):
@@ -396,18 +402,18 @@ class Component(QtCore.QObject, metaclass=ComponentMetaclass):
     '''
 
 
-class ComponentException(RuntimeError):
+class ComponentError(RuntimeError):
-    '''A base class for component errors'''
+    '''Gives the MainWindow a traceback to display, and cancels the export.'''
 
-    _prevErrors = []
+    prevErrors = []
 
-    def __init__(self, caller, name, immediate):
+    def __init__(self, caller, name):
         print('ComponentError by %s: %s' % (caller.name, name))
         super().__init__()
-        if len(ComponentException._prevErrors) > 1:
+        if len(ComponentError.prevErrors) > 1:
-            ComponentException._prevErrors.pop()
+            ComponentError.prevErrors.pop()
-        ComponentException._prevErrors.insert(0, name)
+        ComponentError.prevErrors.insert(0, name)
-        if name in ComponentException._prevErrors[1:]:
+        if name in ComponentError.prevErrors[1:]:
             # Don't create multiple windows for repeated messages
             return
 
@@ -434,28 +440,4 @@ class ComponentException(RuntimeError):
                 )
             )
 
-        if immediate:
+        caller._error.emit(string, detail)
-            caller._error.emit(string, detail)
-        else:
-            caller.lockProperties(['error'])
-            caller.lockError((string, detail))
-
-
-class ComponentError(ComponentException):
-    '''
-        Use for general Python errors caused by a component at any time.
-        Raising this gives the MainWindow a traceback to display and
-        cancels any export in progress.
-    '''
-    def __init__(self, caller, name):
-        ComponentException.__init__(self, caller, name, True)
-
-
-class ComponentInitError(ComponentError):
-    '''
-        Use for Python errors in preFrameRender, while the export is starting.
-        This will end the video thread in a clean way by locking the component
-        into an error state so the export definitely won't begin.
-    '''
-    def __init__(self, caller, name):
-        ComponentException.__init__(self, caller, name, False)

src/components/video.py

@@ -154,33 +154,28 @@ class Component(Component):
             return frame
 
     def properties(self):
-        # TODO: Disallow selecting the same video you're exporting to
         props = []
-        if not self.videoPath or self.badVideo \
+
-                or not os.path.exists(self.videoPath):
+        if not self.videoPath:
-            return ['error']
+            self.lockError("There is no video selected.")
+        elif self.badVideo:
+            self.lockError("Could not identify an audio stream in this video.")
+        elif not os.path.exists(self.videoPath):
+            self.lockError("The video selected does not exist!")
+        elif (os.path.realpath(self.videoPath) ==
+                os.path.realpath(
+                    self.parent.window.lineEdit_outputFile.text())):
+            self.lockError("Input and output paths match.")
 
         if self.useAudio:
             props.append('audio')
-            self.testAudioStream()
+            if not testAudioStream(self.videoPath) \
-            if self.badAudio:
+                    and self.error() is None:
-                return ['error']
+                self.lockError(
+                    "Could not identify an audio stream in this video.")
 
         return props
 
-    def error(self):
-        if self.badAudio:
-            return "Could not identify an audio stream in this video."
-        if not self.videoPath:
-            return "There is no video selected."
-        if not os.path.exists(self.videoPath):
-            return "The video selected does not exist!"
-        if self.badVideo:
-            return "The video selected is corrupt!"
-
-    def testAudioStream(self):
-        self.badAudio = testAudioStream(self.videoPath)
-
     def audio(self):
         params = {}
         if self.volume != 1.0:

src/mainwindow.py

@@ -573,16 +573,16 @@ class MainWindow(QtWidgets.QMainWindow):
 
     @QtCore.pyqtSlot(str, str)
     def videoThreadError(self, msg, detail):
-        self.showMessage(
-            msg=msg,
-            detail=detail,
-            icon='Warning',
-        )
         try:
             self.stopVideo()
         except AttributeError as e:
             if 'videoWorker' not in str(e):
                 raise
+        self.showMessage(
+            msg=msg,
+            detail=detail,
+            icon='Warning',
+        )
 
     def changeEncodingStatus(self, status):
         self.encoding = status

src/toolkit/ffmpeg.py

@@ -224,9 +224,9 @@ def testAudioStream(filename):
     try:
         checkOutput(audioTestCommand, stderr=subprocess.DEVNULL)
     except subprocess.CalledProcessError:
-        return True
-    else:
         return False
+    else:
+        return True
 
 
 def getAudioDuration(filename):

src/video_thread.py

@@ -163,24 +163,27 @@ class Worker(QtCore.QObject):
             except ComponentError:
                 pass
 
-            if 'error' in comp.properties():
+            compProps = comp.properties()
+            if 'error' in compProps or comp.error() is not None:
                 self.cancel()
                 self.canceled = True
                 canceledByComponent = True
                 compError = comp.error() \
                     if type(comp.error()) is tuple else (comp.error(), '')
                 errMsg = (
-                    "Component #%s encountered an error!" % compNo
+                    "Component #%s (%s) encountered an error!" % (
+                        str(compNo), comp.name
+                    )
                     if comp.error() is None else
                     'Export cancelled by component #%s (%s): %s' % (
                         str(compNo),
-                        str(comp),
+                        comp.name,
                         compError[0]
                     )
                 )
                 comp._error.emit(errMsg, compError[1])
                 break
-            if 'static' in comp.properties():
+            if 'static' in compProps:
                 self.staticComponents[compNo] = \
                     comp.frameRender(compNo, 0).copy()