feat: implement flashing support (0x08/0x09) with 1Hz timer

src/teletext/renderer.py

@@ -63,6 +63,12 @@ class TeletextCanvas(QWidget):
         self.service = None # Reference to TeletextService for DRCS/Shared data
         self.subset_idx = 0 # Default English
         
+        # Flashing state
+        self.flash_on = True
+        self.flash_timer = QTimer(self)
+        self.flash_timer.timeout.connect(self.toggle_flash)
+        self.flash_timer.start(500) # 500ms toggle (1Hz flash rate)
+
         # Teletext is 40 columns x 25 rows
         # We will render to a fixed size QImage and scale it
         self.cols = 40
@@ -87,6 +93,12 @@ class TeletextCanvas(QWidget):
         self.cursor_is_graphics = False # Tracked during draw
         # Blinking cursor timer could be added, for now static inverted is fine or toggle on timer elsewhere
 
+    def toggle_flash(self):
+        self.flash_on = not self.flash_on
+        if self.page:
+            self.redraw()
+            self.update()
+
     def get_byte_at(self, x, y):
         if not self.page: return 0
         
@@ -274,6 +286,7 @@ class TeletextCanvas(QWidget):
         hold_graphics = False
         held_char = 0x20 # Space
         double_height = False
+        flashing = False
         
         last_visible_idx = -1
         bg_segments = [(0, bg)] # Track BG changes: (index, color)
@@ -364,6 +377,10 @@ class TeletextCanvas(QWidget):
                                         break
                                 painter.fillRect(k * self.cell_w, y, self.cell_w, self.cell_h * 2, cell_bg)
 
+                elif byte_val == 0x08: # Start Flashing
+                    flashing = True
+                elif byte_val == 0x09: # Steady
+                    flashing = False
                 elif byte_val == 0x19: # Contiguous Graphics
                     contiguous = True
                 elif byte_val == 0x1A: # Separated Graphics
@@ -410,6 +427,8 @@ class TeletextCanvas(QWidget):
             
             # Draw Foreground
             if draw_fg:
+                # If flashing is active and flash is in 'off' state, skip drawing FG
+                if not (flashing and not self.flash_on):
                     # Calculate height
                     # For Mosaics, we use the height param.
                     # For Alphanumerics, we scale the painter.