Port Calculate activity to GTK4

This commit fully ports the Calculate activity to GTK4 and Sugar4.

- Port `shareable_activity.py` with updated DBus and Sugar4 base classes.
- Rework `layout.py` to use GTK4 box packing (`append`, `set_child`) instead of deprecated containers like `Gtk.Table`.
- Replace legacy styling (`modify_bg`, `modify_font`) and `Gtk.EventBox` usage with a modern `Gtk.CssProvider` to handle backgrounds, colors, and font rendering.
- Ensure proper CSS specificity (`background-image: none;`) to override GTK4's native `.toggle` styles for the toolbar interface.
- Refactor `toolbars.py` to gracefully render GTK4 toolbar items and correctly update text fallbacks when SVG icons are invalid.
- Port `calculate.py` to use `Gtk.EventControllerKey` for keystrokes and update clipboard operations to use GTK4 async mechanisms.
- Include `main.py` standalone bootstrapper for isolated GTK4 testing.

Author: Inuth0603

calculate.py

@@ -193,7 +193,7 @@ def create_lasteq_textbuf(self):
         tagsmallnarrow = buf.create_tag(font=CalcLayout.FONT_SMALL_NARROW)
         tagbignarrow = buf.create_tag(font=CalcLayout.FONT_BIG_NARROW)
         tagbigger = buf.create_tag(font=CalcLayout.FONT_BIGGER)
-        tagjustright = buf.create_tag(justification=Gtk.Justification.RIGHT)
+        tagjustright = buf.create_tag(justification=Gtk.Justification.LEFT)
         tagred = buf.create_tag(foreground='#FF0000')
 
         # Add label and equation
@@ -258,6 +258,7 @@ def create_history_object(self):
         textview text {
             background-color: %s;
             color: %s;
+            min-height: 20px;
         }
         """ % (stroke_color, fill_color, stroke_color, fill_color)
 
@@ -275,7 +276,7 @@ def create_history_object(self):
         tagsmall = buf.create_tag(font=CalcLayout.FONT_SMALL)
         tagsmallnarrow = buf.create_tag(font=CalcLayout.FONT_SMALL_NARROW)
         tagbig = buf.create_tag(font=CalcLayout.FONT_BIG,
-                                justification=Gtk.Justification.RIGHT)
+                                justification=Gtk.Justification.LEFT)
 
         # Calculate brightness
         c = Gdk.RGBA()
@@ -297,13 +298,22 @@ def create_history_object(self):
         eqnstr = '%s\n' % str(self.equation)
         self.append_with_superscript_tags(buf, eqnstr, tagsmall)
 
-        resstr = self.ml.format_number(self.result)
-        resstr = str(resstr).rstrip('0').rstrip('.') \
-            if '.' in resstr else resstr
+        try:
+            resstr = self.ml.format_number(self.result)
+        except Exception:
+            resstr = str(self.result)
+            
+        resstr = str(resstr)
+        resstr = resstr.rstrip('0').rstrip('.') if '.' in resstr else resstr
+        
+        if not resstr or resstr == "None":
+             resstr = "0"
+
         if len(resstr) > 30:
             restag = tagsmall
         else:
             restag = tagbig
+            
         self.append_with_superscript_tags(buf, resstr, restag)
 
         buf.apply_tag(tagcolor, buf.get_start_iter(), buf.get_end_iter())
@@ -381,6 +391,10 @@ def __init__(self, handle):
 
         self.ml = MathLib()
         self.parser = AstParser(self.ml)
+        
+        angle_var = self.parser.get_var('angle_scaling')
+        if angle_var is not None:
+            angle_var.value = MathLib.ANGLE_RAD
 
         # These will result in 'Ans <operator character>' being inserted
         self._chars_ans_diadic = [op[0]
@@ -400,7 +414,6 @@ def __init__(self, handle):
         self.ans_inserted = False
         self.show_vars = False
 
-        # Input handling for GTK4
         key_controller = Gtk.EventControllerKey()
         key_controller.connect("key-pressed", self.keypress_cb)
         self.add_controller(key_controller)
@@ -451,14 +464,15 @@ def equation_pressed_cb(self, eqn):
     def set_last_equation(self, eqn):
         """Set the 'last equation' TextView."""
 
-        if self.last_eq_sig is not None:
-            self.layout.last_eq.disconnect(self.last_eq_sig)
-            self.last_eq_sig = None
+        if self.last_eqn_controller is not None:
+            self.layout.last_eq.remove_controller(self.last_eqn_controller)
+            self.last_eqn_controller = None
 
         if not isinstance(eqn.result, ParserError):
-            self.last_eq_sig = self.layout.last_eq.connect(
-                'button-press-event',
-                lambda a1, a2, e: self.equation_pressed_cb(e), eqn)
+            self.last_eqn_controller = Gtk.GestureClick.new()
+            self.last_eqn_controller.set_button(0)
+            self.last_eqn_controller.connect('pressed', lambda gesture, n_press, x, y: self.equation_pressed_cb(eqn))
+            self.layout.last_eq.add_controller(self.last_eqn_controller)
 
         self.layout.last_eq.set_buffer(eqn.create_lasteq_textbuf())
 
@@ -514,8 +528,10 @@ def add_equation(self, eq, prepend=False, drawlasteq=False, tree=None):
 
         own = (eq.owner == self.get_owner_id())
         w = eq.create_history_object()
-        w.connect('button-press-event', lambda w,
-                  e: self.equation_pressed_cb(eq))
+        click_gesture = Gtk.GestureClick.new()
+        click_gesture.set_button(0)
+        click_gesture.connect('pressed', lambda gesture, n_press, x, y: self.equation_pressed_cb(eq))
+        w.add_controller(click_gesture)
         if drawlasteq:
             self.set_last_equation(eq)
 
@@ -575,7 +591,7 @@ def process(self):
                            self.get_owner_id(), ml=self.ml)
             self.set_error_equation(eqn)
         else:
-            eqn = Equation(label, _n(s), _n(str(res)), self.color,
+            eqn = Equation(label, _n(s), res, self.color,
                            self.get_owner_id(), ml=self.ml)
             self.add_equation(eqn, drawlasteq=True, tree=tree)
             self.send_message("add_eq", value=str(eqn))
@@ -600,28 +616,40 @@ def create_var_textview(self, name, value):
         if name in reserved:
             return None
         w = Gtk.TextView()
-        w.modify_base(
-            Gtk.StateType.NORMAL, Gdk.color_parse(self.color.get_fill_color()))
-        w.modify_bg(
-            Gtk.StateType.NORMAL,
-            Gdk.color_parse(self.color.get_stroke_color()))
+        fill_color = self.color.get_fill_color()
+        stroke_color = self.color.get_stroke_color()
+        
+        provider = Gtk.CssProvider()
+        css_str = """
+        textview {
+            background-color: %s;
+            color: %s;
+        }
+        textview text {
+            background-color: %s;
+            color: %s;
+        }
+        """ % (fill_color, stroke_color, fill_color, stroke_color)
+        provider.load_from_data(css_str.encode())
+        w.get_style_context().add_provider(provider, Gtk.STYLE_PROVIDER_PRIORITY_APPLICATION)
+
         w.set_wrap_mode(Gtk.WrapMode.WORD_CHAR)
-        w.set_border_window_size(Gtk.TextWindowType.LEFT, 4)
-        w.set_border_window_size(Gtk.TextWindowType.RIGHT, 4)
-        w.set_border_window_size(Gtk.TextWindowType.TOP, 4)
-        w.set_border_window_size(Gtk.TextWindowType.BOTTOM, 4)
+        w.set_left_margin(4)
+        w.set_right_margin(4)
+        w.set_top_margin(4)
+        w.set_bottom_margin(4)
         w.connect('realize', _textview_realize_cb)
         buf = w.get_buffer()
 
-        # TODO Fix for old Sugar 0.82 builds, red_float not available
-        bright = (
-            Gdk.color_parse(self.color.get_fill_color()).red_float +
-            Gdk.color_parse(self.color.get_fill_color()).green_float +
-            Gdk.color_parse(self.color.get_fill_color()).blue_float) / 3.0
-        if bright < 0.5:
-            col = Gdk.color_parse('white')
+        c = Gdk.RGBA()
+        if c.parse(fill_color):
+            bright = (c.red + c.green + c.blue) / 3.0
+            if bright < 0.5:
+                col = 'white'
+            else:
+                col = 'black'
         else:
-            col = Gdk.color_parse('black')
+            col = 'black'
 
         tag = buf.create_tag(font=CalcLayout.FONT_SMALL_NARROW,
                              foreground=col)
@@ -842,7 +870,7 @@ def _on_paste_text_received(self, clipboard, result, user_data):
             if text:
                 self.button_pressed(self.TYPE_TEXT, text)
         except Exception as e:
-            _logger.error(f"Error pasting text: {e}")
+            _logger.error("Error pasting text: %s", e)
 
     def text_cut(self):
         self.text_copy()
@@ -993,19 +1021,3 @@ def format_insert_ans(self):
             return self.ml.format_number(ans)
         else:
             return ''
-
-
-def main():
-    app = Gtk.Application(application_id="org.laptop.Calculate.Test")
-    
-    def activate(app):
-        win = Calculate(None)
-        win.set_application(app)
-        win.present()
-        
-    app.connect("activate", activate)
-    app.run(None)
-
-
-if __name__ == "__main__":
-    main()