add Slot decorator and modified button callback

Modify button event callback to fit buttton callback function signature.
Also, add Slot decorator, according to PySide6 official documentation
recommandation, every callback connected to signal should be indicated
by Slot decorator for good reliability and performance.

modmesh/app/euler1d.py

@@ -41,7 +41,7 @@
 from PySide6.QtWidgets import (QApplication, QWidget, QScrollArea,
                                QGridLayout, QVBoxLayout, QPushButton,
                                QHBoxLayout, QFileDialog, QLayout, QCheckBox)
-from PySide6.QtCore import Qt, QEvent, QMimeData, QTimer
+from PySide6.QtCore import Qt, QEvent, QMimeData, QTimer, QObject, Slot
 from PySide6.QtGui import QDrag, QPixmap
 
 import modmesh as mm
@@ -145,7 +145,8 @@ def __init__(self, shocktube):
 
         self.checkbox_select_num = 3
 
-    def save_all(self):
+    @Slot(bool)
+    def save_all(self, checked=False):
         fig = QPixmap(self.figure_container.size())
         self.figure_container.render(fig)
 
@@ -175,7 +176,8 @@ def _update_layout(self):
         # deleteLater() and a QWidget only accept one layout at
         # the same time, therefore a object delete callback is
         # needed to set new layout after old layout deleted.
-        def del_cb():
+        @Slot(QObject)
+        def del_cb(obj=None):
             if self.use_grid_layout:
                 self.build_lines_grid_layout()
             else:
@@ -186,7 +188,8 @@ def del_cb():
         self.main_layout.update()
         self.main_container.update()
 
-    def switch_layout(self):
+    @Slot(bool)
+    def switch_layout(self, checked=False):
         self.use_grid_layout = not self.use_grid_layout
         self._update_layout()
 
@@ -448,7 +451,8 @@ def _build_checkbox(self, layout):
             check_box.clicked.connect(self._checkbox_cb)
             layout.addWidget(check_box)
 
-    def _checkbox_cb(self):
+    @Slot(bool)
+    def _checkbox_cb(self, checked=False):
         # Under a single plot layout, that allow 3 lines on the same chart
         # simultaneously to avoid it looking too crowded.
         # I have chosen to use checkboxes for user to select
@@ -547,21 +551,29 @@ def show(self):
         if self.use_sub:
             self._subwin.show()
 
-    def start(self):
+    @Slot(bool)
+    def start(self, checked=False):
         self.timer.start(self.interval)
 
-    def stop(self):
+    @Slot(bool)
+    def stop(self, checked=False):
         self.timer.stop()
 
-    def step_button_cb(self):
+    @Slot(bool)
+    def step_button_cb(self, checked=False):
         self.step()
 
     def step(self, steps=1):
         self.march_alpha2(steps=steps)
         if self.max_steps and self.current_step > self.max_steps:
             self.stop()
 
-    def reset(self):
+    @Slot()
+    def timer_timeout_cb(self):
+        self.step()
+
+    @Slot(bool)
+    def reset(self, checked=False):
         self.stop()
         self.current_step = 0
         self.shocktube = euler1d.ShockTube()
@@ -596,7 +608,7 @@ def setup_timer(self, interval):
         """
         self.interval = interval
         self.timer = QTimer()
-        self.timer.timeout.connect(self.step)
+        self.timer.timeout.connect(self.timer_timeout_cb)
 
     @staticmethod
     def log(msg):