Restore progress bar functionality

A previous fix (5f9ea3) inadvertently broke the progress bar by
converting to the wrong data type. (See issue #561 / PR #609).

While checking the code I realized the problem occurred primarily
because we weren't checking the validity of the values closer to the
source. Doing so alleviates the need to check elsewhere.

In the hope of inspiring a more systematic approach, a new uiParse()
utility function has been added to curb the further growth of toXxx()
functions that exist solely to validate user input.

There is no doubt room for improvement, both on the end of the new
uiParse() function as well as the spot where it is used. Ideally, the
data that comes out of the model should already be 'safe', but since
this is a bugfix for a bugfix I want to keep waves to a minimum.

This commit fixes issue #652.

manuskript/functions/__init__.py

@@ -23,6 +23,27 @@ def wordCount(text):
     t = [l for l in t if l]
     return len(t)
 
+validate_ok = lambda *args, **kwargs: True
+def uiParse(input, default, converter, validator=validate_ok):
+    """
+    uiParse is a utility function that intends to make it easy to convert
+    user input to data that falls in the range of expected values the
+    program is expecting to handle.
+
+    It swallows all exceptions that happen during conversion.
+    The validator should return True to permit the converted value.
+    """
+    result = default
+    try:
+        result = converter(input)
+    except:
+        pass  # failed to convert
+
+    # Whitelist default value in case default type differs from converter output.
+    if (result != default) and not validator(result):
+        result = default
+    return result
+
 
 def toInt(text):
     if text:
@@ -50,15 +71,15 @@ def toString(text):
 
 def drawProgress(painter, rect, progress, radius=0):
     from manuskript.ui import style as S
+    progress = toFloat(progress)  # handle invalid input (issue #561)
     painter.setPen(Qt.NoPen)
     painter.setBrush(QColor(S.base)) # "#dddddd"
     painter.drawRoundedRect(rect, radius, radius)
 
     painter.setBrush(QBrush(colorFromProgress(progress)))
 
     r2 = QRect(rect)
-    r2.setWidth(r2.width() * min(toInt(progress), 1))
-    #                            ^^^^^ Avoid crash - issue #561
+    r2.setWidth(r2.width() * min(progress, 1))
     painter.drawRoundedRect(r2, radius, radius)
 
 

manuskript/ui/editors/mainEditor.py

@@ -9,7 +9,7 @@
 
 from manuskript import settings
 from manuskript.enums import Outline
-from manuskript.functions import AUC, mainWindow, drawProgress, appPath, toInt
+from manuskript.functions import AUC, mainWindow, drawProgress, appPath, uiParse
 from manuskript.ui import style
 from manuskript.ui.editors.editorWidget import editorWidget
 from manuskript.ui.editors.fullScreenEditor import fullScreenEditor
@@ -303,7 +303,9 @@ def updateStats(self):
         wc = item.data(Outline.wordCount)
         goal = item.data(Outline.goal)
         progress = item.data(Outline.goalPercentage)
-        # mw = qApp.activeWindow()
+
+        goal = uiParse(goal, None, int, lambda x: x>=0)
+        progress = uiParse(progress, 0.0, float)
 
         if not wc:
             wc = 0
@@ -319,8 +321,7 @@ def updateStats(self):
             self.lblRedacProgress.setPixmap(self.px)
             self.lblRedacWC.setText(self.tr("{} words / {} ").format(
                     locale.format_string("%d", wc, grouping=True),
-                    locale.format_string("%d", toInt(goal), grouping=True)))
-                    #                          ^^^^^ Avoid crash - issue #561
+                    locale.format_string("%d", goal, grouping=True)))
         else:
             self.lblRedacProgress.hide()
             self.lblRedacWC.setText(self.tr("{} words ").format(