Upscale small previews to fill canvas

Add minimize/maximize buttons, double-click maximize behaviour, and proper window state handling for the custom title bar.

app/app.py

@@ -76,8 +76,15 @@ class ICRAApp(
         self.root.overrideredirect(True)
         screen_width = self.root.winfo_screenwidth()
         screen_height = self.root.winfo_screenheight()
+        default_width = int(screen_width * 0.8)
+        default_height = int(screen_height * 0.8)
+        default_x = (screen_width - default_width) // 2
+        default_y = (screen_height - default_height) // 4
+        self._window_geometry = f"{default_width}x{default_height}+{default_x}+{default_y}"
+        self._is_maximized = True
         self.root.geometry(f"{screen_width}x{screen_height}+0+0")
         self.root.configure(bg="#f2f2f7")
+        self.root.bind("<Map>", lambda _e: self.root.overrideredirect(True))
 
 
 def start_app() -> None:

app/gui/ui.py

@@ -422,28 +422,41 @@ class UIBuilderMixin:
         )
         title_label.pack(side=tk.LEFT, padx=6)
 
-        close_btn = tk.Button(
+        btn_kwargs = {
-            title_bar,
+            "bg": bar_bg,
-            text="✕",
+            "fg": "#f5f5f5",
-            command=self._close_app,
+            "activebackground": "#3a3a40",
-            bg=bar_bg,
+            "activeforeground": "#ffffff",
-            fg="#f5f5f5",
+            "borderwidth": 0,
-            activebackground="#ff3b30",
+            "highlightthickness": 0,
-            activeforeground="#ffffff",
+            "relief": "flat",
-            borderwidth=0,
+            "font": ("Segoe UI", 10, "bold"),
-            highlightthickness=0,
+            "cursor": "hand2",
-            relief="flat",
+            "width": 3,
-            font=("Segoe UI", 10, "bold"),
+        }
-            cursor="hand2",
+
-            width=3,
+        close_btn = tk.Button(title_bar, text="✕", command=self._close_app, **btn_kwargs)
-        )
+        close_btn.pack(side=tk.RIGHT, padx=6, pady=4)
-        close_btn.pack(side=tk.RIGHT, padx=8, pady=4)
         close_btn.bind("<Enter>", lambda _e: close_btn.configure(bg="#cf212f"))
         close_btn.bind("<Leave>", lambda _e: close_btn.configure(bg=bar_bg))
 
+        max_btn = tk.Button(title_bar, text="❐", command=self._toggle_maximize_window, **btn_kwargs)
+        max_btn.pack(side=tk.RIGHT, padx=0, pady=4)
+        max_btn.bind("<Enter>", lambda _e: max_btn.configure(bg="#2c2c32"))
+        max_btn.bind("<Leave>", lambda _e: max_btn.configure(bg=bar_bg))
+        self._max_button = max_btn
+
+        min_btn = tk.Button(title_bar, text="—", command=self._minimize_window, **btn_kwargs)
+        min_btn.pack(side=tk.RIGHT, padx=0, pady=4)
+        min_btn.bind("<Enter>", lambda _e: min_btn.configure(bg="#2c2c32"))
+        min_btn.bind("<Leave>", lambda _e: min_btn.configure(bg=bar_bg))
+
         for widget in (title_bar, title_label):
             widget.bind("<ButtonPress-1>", self._start_window_drag)
             widget.bind("<B1-Motion>", self._perform_window_drag)
+            widget.bind("<Double-Button-1>", lambda _e: self._toggle_maximize_window())
+
+        self._update_maximize_button()
 
     def _close_app(self) -> None:
         try:
@@ -452,6 +465,14 @@ class UIBuilderMixin:
             pass
 
     def _start_window_drag(self, event) -> None:
+        if getattr(self, "_is_maximized", False):
+            cursor_x, cursor_y = event.x_root, event.y_root
+            self._toggle_maximize_window(force_state=False)
+            self.root.update_idletasks()
+            new_x = self.root.winfo_rootx()
+            new_y = self.root.winfo_rooty()
+            self._drag_offset = (cursor_x - new_x, cursor_y - new_y)
+            return
         self._drag_offset = (event.x_root - self.root.winfo_rootx(), event.y_root - self.root.winfo_rooty())
 
     def _perform_window_drag(self, event) -> None:
@@ -461,6 +482,58 @@ class UIBuilderMixin:
         x = event.x_root - offset[0]
         y = event.y_root - offset[1]
         self.root.geometry(f"+{x}+{y}")
+        if not getattr(self, "_is_maximized", False):
+            self._remember_window_geometry()
+
+    def _remember_window_geometry(self) -> None:
+        try:
+            self._window_geometry = self.root.geometry()
+        except Exception:
+            pass
+
+    def _maximize_window(self) -> None:
+        self._remember_window_geometry()
+        screen_width = self.root.winfo_screenwidth()
+        screen_height = self.root.winfo_screenheight()
+        self.root.geometry(f"{screen_width}x{screen_height}+0+0")
+        self._is_maximized = True
+        self._update_maximize_button()
+
+    def _restore_window(self) -> None:
+        geometry = getattr(self, "_window_geometry", None)
+        if not geometry:
+            screen_width = self.root.winfo_screenwidth()
+            screen_height = self.root.winfo_screenheight()
+            width = int(screen_width * 0.8)
+            height = int(screen_height * 0.8)
+            x = (screen_width - width) // 2
+            y = (screen_height - height) // 4
+            geometry = f"{width}x{height}+{x}+{y}"
+        self.root.geometry(geometry)
+        self._is_maximized = False
+        self._update_maximize_button()
+
+    def _toggle_maximize_window(self, force_state: bool | None = None) -> None:
+        desired = force_state if force_state is not None else not getattr(self, "_is_maximized", False)
+        if desired:
+            self._maximize_window()
+        else:
+            self._restore_window()
+
+    def _minimize_window(self) -> None:
+        try:
+            self.root.overrideredirect(False)
+            self.root.iconify()
+            self.root.after(50, lambda: self.root.overrideredirect(True))
+        except Exception:
+            pass
+
+    def _update_maximize_button(self) -> None:
+        button = getattr(self, "_max_button", None)
+        if button is None:
+            return
+        symbol = "❐" if getattr(self, "_is_maximized", False) else "□"
+        button.configure(text=symbol)
 
     def _maybe_focus_window(self, _event) -> None:
         try:

app/logic/image_processing.py

@@ -194,7 +194,9 @@ class ImageProcessingMixin:
             return
         width, height = self.orig_img.size
         max_w, max_h = PREVIEW_MAX_SIZE
-        scale = min(max_w / width, max_h / height, 1.0)
+        scale = min(max_w / width, max_h / height)
+        if scale <= 0:
+            scale = 1.0
         size = (max(1, int(width * scale)), max(1, int(height * scale)))
         self.preview_img = self.orig_img.resize(size, Image.LANCZOS)
         self.preview_tk = ImageTk.PhotoImage(self.preview_img)