python ui: fix scroll issues (#34600)

fix scroll issues

system/ui/lib/scroll_panel.py

@@ -1,54 +1,67 @@
 import pyray as rl
-from cffi import FFI
+from enum import IntEnum
 
 MOUSE_WHEEL_SCROLL_SPEED = 30
 INERTIA_FRICTION = 0.95  # The rate at which the inertia slows down
 MIN_VELOCITY = 0.1  # Minimum velocity before stopping the inertia
 
 
+class ScrollState(IntEnum):
+  IDLE = 0
+  DRAGGING_CONTENT = 1
+  DRAGGING_SCROLLBAR = 2
+
+
 class GuiScrollPanel:
-  def __init__(self, bounds: rl.Rectangle, content: rl.Rectangle, show_vertical_scroll_bar: bool = False):
-    self._dragging: bool = False
+  def __init__(self, show_vertical_scroll_bar: bool = False):
+    self._scroll_state: ScrollState = ScrollState.IDLE
     self._last_mouse_y: float = 0.0
-    self._bounds = bounds
-    self._content = content
-    self._scroll = rl.Vector2(0, 0)
+    self._offset = rl.Vector2(0, 0)
     self._view = rl.Rectangle(0, 0, 0, 0)
     self._show_vertical_scroll_bar: bool = show_vertical_scroll_bar
     self._velocity_y = 0.0  # Velocity for inertia
 
-  def handle_scroll(self) -> rl.Vector2:
+  def handle_scroll(self, bounds: rl.Rectangle, content: rl.Rectangle) -> rl.Vector2:
     mouse_pos = rl.get_mouse_position()
 
     # Handle dragging logic
-    if rl.check_collision_point_rec(mouse_pos, self._bounds) and rl.is_mouse_button_pressed(rl.MouseButton.MOUSE_BUTTON_LEFT):
-      if not self._dragging:
-        self._dragging = True
+    if rl.check_collision_point_rec(mouse_pos, bounds) and rl.is_mouse_button_pressed(rl.MouseButton.MOUSE_BUTTON_LEFT):
+      if self._scroll_state == ScrollState.IDLE:
+        self._scroll_state = ScrollState.DRAGGING_CONTENT
+        if self._show_vertical_scroll_bar:
+          scrollbar_width = rl.gui_get_style(rl.GuiControl.LISTVIEW, rl.GuiListViewProperty.SCROLLBAR_WIDTH)
+          scrollbar_x = bounds.x + bounds.width - scrollbar_width
+          if mouse_pos.x >= scrollbar_x:
+            self._scroll_state = ScrollState.DRAGGING_SCROLLBAR
+
         self._last_mouse_y = mouse_pos.y
         self._velocity_y = 0.0  # Reset velocity when drag starts
 
-    if self._dragging:
+    if self._scroll_state != ScrollState.IDLE:
       if rl.is_mouse_button_down(rl.MouseButton.MOUSE_BUTTON_LEFT):
         delta_y = mouse_pos.y - self._last_mouse_y
-        self._scroll.y += delta_y
+
+        if self._scroll_state == ScrollState.DRAGGING_CONTENT:
+          self._offset.y += delta_y
+        else:
+          delta_y = -delta_y
+
         self._last_mouse_y = mouse_pos.y
         self._velocity_y = delta_y  # Update velocity during drag
       else:
-        self._dragging = False
+        self._scroll_state = ScrollState.IDLE
 
     # Handle mouse wheel scrolling
     wheel_move = rl.get_mouse_wheel_move()
     if self._show_vertical_scroll_bar:
-      self._scroll.y += wheel_move * (MOUSE_WHEEL_SCROLL_SPEED - 20)
-      rl.gui_scroll_panel(self._bounds, FFI().NULL, self._content, self._scroll, self._view)
+      self._offset.y += wheel_move * (MOUSE_WHEEL_SCROLL_SPEED - 20)
+      rl.gui_scroll_panel(bounds, rl.ffi.NULL, content, self._offset, self._view)
     else:
-      self._scroll.y += wheel_move * MOUSE_WHEEL_SCROLL_SPEED
-      max_scroll_y = self._content.height - self._bounds.height
-      self._scroll.y = max(min(self._scroll.y, 0), -max_scroll_y)
+      self._offset.y += wheel_move * MOUSE_WHEEL_SCROLL_SPEED
 
     # Apply inertia (continue scrolling after mouse release)
-    if not self._dragging:
-      self._scroll.y += self._velocity_y
+    if self._scroll_state == ScrollState.IDLE:
+      self._offset.y += self._velocity_y
       self._velocity_y *= INERTIA_FRICTION  # Slow down velocity over time
 
       # Stop scrolling when velocity is low
@@ -56,7 +69,7 @@ class GuiScrollPanel:
         self._velocity_y = 0.0
 
     # Ensure scrolling doesn't go beyond bounds
-    max_scroll_y = max(self._content.height - self._bounds.height, 0)
-    self._scroll.y = max(min(self._scroll.y, 0), -max_scroll_y)
+    max_scroll_y = max(content.height - bounds.height, 0)
+    self._offset.y = max(min(self._offset.y, 0), -max_scroll_y)
 
-    return self._scroll
+    return self._offset

system/ui/text.py

@@ -42,10 +42,10 @@ def main():
   textarea_rect = rl.Rectangle(MARGIN, MARGIN, gui_app.width - MARGIN * 2, gui_app.height - MARGIN * 2 - BUTTON_SIZE.y - SPACING)
   wrapped_lines = wrap_text(text_content, FONT_SIZE, textarea_rect.width - 20)
   content_rect = rl.Rectangle(0, 0, textarea_rect.width - 20, len(wrapped_lines) * LINE_HEIGHT)
-  scroll_panel = GuiScrollPanel(textarea_rect, content_rect, show_vertical_scroll_bar=True)
+  scroll_panel = GuiScrollPanel(show_vertical_scroll_bar=True)
 
   for _ in gui_app.render():
-    scroll = scroll_panel.handle_scroll()
+    scroll = scroll_panel.handle_scroll(textarea_rect, content_rect)
 
     rl.begin_scissor_mode(int(textarea_rect.x), int(textarea_rect.y), int(textarea_rect.width), int(textarea_rect.height))
     for i, line in enumerate(wrapped_lines):