Refactor: Extract additional constants for better code clarity

- Extract MOUSE_BUTTON_LEFT constant to replace magic number 1
- Extract ZOOM_PERCENTAGE_MULTIPLIER constant for zoom display
- Extract HSV_HUE_MAX_DEGREES constant for color generation
- Improve zoom display calculation readability

These changes improve code maintainability by replacing magic numbers
with named constants that clearly express their purpose.

MyTimeline.py

@@ -130,6 +130,10 @@ FONT_SIZE_LARGE = 24
 MARKER_HOVER_SIZE_MULTIPLIER = 1.3
 MARKER_SELECTED_SIZE_MULTIPLIER = 1.2
 DEFAULT_EVENT_SHAPE = 'square'  # Default shape for events without specific shape mapping
+
+# Mouse Button Constants
+MOUSE_BUTTON_LEFT = 1  # Left mouse button
+ZOOM_PERCENTAGE_MULTIPLIER = 100  # Multiplier to convert zoom level (0.0-1.0) to percentage
 GRADIENT_BRIGHTNESS_OFFSET = 0.2
 GRADIENT_DARKNESS_OFFSET = 0.1
 SHADOW_OFFSET_X = 1
@@ -157,6 +161,7 @@ CONNECTION_LINE_MIN_DISTANCE = EVENT_MARKER_SIZE * 2  # Minimum distance between
 PERSON_COLOR_SATURATION = 0.7  # High saturation for vibrant colors
 PERSON_COLOR_LIGHTNESS = 0.5   # Medium lightness for good visibility
 PERSON_COLOR_ALPHA = 0.75      # Semi-transparent
+HSV_HUE_MAX_DEGREES = 360  # Maximum value for hue in HSV color space (degrees)
 
 # Marker State Colors
 SELECTED_MARKER_COLOR = (0.2, 0.4, 0.9)  # Blue highlight for selected person's events
@@ -2287,7 +2292,7 @@ class MyTimelineView(NavigationView):
         # Generate color using HSV: vary hue, keep saturation and lightness constant
         # Use hash of handle for consistent color even when selection order changes
         handle_hash = hash(person_handle)
-        hue = (abs(handle_hash) % 360) / 360.0  # 0-1 range
+        hue = (abs(handle_hash) % HSV_HUE_MAX_DEGREES) / float(HSV_HUE_MAX_DEGREES)  # 0-1 range
         
         # Convert HSV to RGB (HSV is Hue, Saturation, Value)
         r, g, b = colorsys.hsv_to_rgb(hue, PERSON_COLOR_SATURATION, PERSON_COLOR_LIGHTNESS)
@@ -2526,7 +2531,8 @@ class MyTimelineView(NavigationView):
     def update_zoom_display(self) -> None:
         """Update the zoom level display."""
         if hasattr(self, 'zoom_label'):
-            self.zoom_label.set_text(f"{int(self.zoom_level * 100)}%")
+            zoom_percentage = int(self.zoom_level * ZOOM_PERCENTAGE_MULTIPLIER)
+            self.zoom_label.set_text(f"{zoom_percentage}%")
 
     def on_button_press(self, widget: Gtk.Widget, event: Gdk.Event) -> bool:
         """
@@ -2539,7 +2545,7 @@ class MyTimelineView(NavigationView):
         Returns:
             bool: False to allow other handlers to process the event.
         """
-        if event.button == 1:  # Left click
+        if event.button == MOUSE_BUTTON_LEFT:
             # Find which event was clicked
             clicked_index = self.find_event_at_position(event.x, event.y)
             if clicked_index is not None: