use signals to trigger rendering update

src/ui/bigtext/bigtext.py

@@ -39,7 +39,7 @@ class FileObserver(FileSystemEventHandler):
         # block the UI thread and make the UI unresponsive.
         # Note: we don't miss events, because they are queued and de-duplicated
         time.sleep(0.5)
-        self.big_text.update()
+        self.big_text.trigger_update.emit()
 
 
 class FileWatchdogThread(QRunnable):
@@ -60,6 +60,7 @@ class FileWatchdogThread(QRunnable):
 
 
 class BigText(QWidget):
+    trigger_update = Signal()
 
     def __init__(self, model: LogFileModel):
         super(BigText, self).__init__()
@@ -68,6 +69,7 @@ class BigText(QWidget):
 
         self.watchdog = FileWatchdogThread(self, model.get_file())
         QThreadPool.globalInstance().start(self.watchdog)
+        self.trigger_update.connect(self.update)
 
         self.grid = QGridLayout()
         self.grid.setContentsMargins(0, 0, 0, 0)
@@ -371,7 +373,7 @@ class InnerBigText(QWidget):
         self.update()
 
     def paintEvent(self, event: QPaintEvent) -> None:
-        # print("paintEvent")
+        # print("paintEvent %s" % (self.model.get_file()))
         painter = QPainter(self)
         # painter.setFont(self.model.settings.font())
         # Courier New, DejaVu Sans Mono, Monospace, Liberation Mono, Noto Mono, Nimbus Mono L, Tlwg Mono, Ubuntu Mono, FreeMono, Mitra Mono
@@ -380,8 +382,6 @@ class InnerBigText(QWidget):
         painter.setPen(QColor(0, 0, 0))
         self.update_font_metrics(painter)
 
-        tab_string = " " * constants.tab_width
-
         lines_to_show = self.lines_shown()
         # print("%s / %s = %s" %(self.height(), float(self.char_height), lines_to_show))