use PIL for image handling

iwii_photobooth.py

@@ -1,33 +1,40 @@
-import mimetypes
 import traceback
 
+from collections import namedtuple
 from collections.abc import Callable
-import tkinter as tk
+from tkinter import *
 import tkinter.messagebox as messagebox
 import tkinter.filedialog as filedialog
-import tkinter.ttk as ttk
+from tkinter.ttk import *
 
 from functools import wraps
 from pathlib import Path
 from platform import system
 
+from PIL import ImageOps 
+from PIL.ImageTk import Image, PhotoImage
 from serial import Serial
 
-if not mimetypes.inited:
+Resolution = namedtuple("Resolution", ("height", "width"))
-    mimetypes.init()
+IWII_RESOLUTION = Resolution(576, 720)
 
+SUPPORTED_IMAGE_TYPES = sorted("*"+ext for ext, type_ in Image.registered_extensions().items() if type_ in ("PNG", "GIF", "JPEG", "WEBP", "BMP"))
 
-def handle_action_exceptions(func: Callable):
+def widget_action(func: Callable):
+    # decorator to wrap widget actions in an error handler that displays exceptions in error message windows
     @wraps(func)
-    def wrapper(event: tk.Event):
+    def wrapper(event: Event):
         try:
             func(event)
         except NotImplementedError as e:
             messagebox.showwarning(
                 title="Warning",
-                message=f"{func.__name__} Not Implemented",
+                message=f"{func.__name__} not implemented",
                 parent=event.widget.master
             )
+        except SystemExit:
+            # probably unnecessary, but we don't want to accidentally intercept requests to exit
+            raise
         except Exception as e:
             messagebox.showerror(
                 title="Error",
@@ -41,51 +48,66 @@ def handle_action_exceptions(func: Callable):
     return wrapper
 
 
-@handle_action_exceptions
+@widget_action
-def open_preview(event: tk.Event):
+def open_preview(event: Event):
     file = filedialog.askopenfilename(
         parent=event.widget.master,
         title="Open Image",
         initialdir=Path.home(),
         filetypes=[
-            (mimetype, "*"+ext) for ext, mimetype in mimetypes.types_map.items()
+            ("Supported Image Files", " ".join(SUPPORTED_IMAGE_TYPES))
-            if ext in (".png",".gif", ".pgm", ".ppm")
         ]
     )
 
-    if Path(file).exists():
+    if not file:
-        # don't GC the photo when this function exits
+        return
-        global _photo
+    elif Path(file).exists() and Path(file).is_file():
-        _photo=tk.PhotoImage(file=file)
+        # load image data and resize to fit the IWII resolution preserving aspect ratio
-        event.widget.create_image(0,0, anchor=tk.NW, image=_photo)
+        image_data = ImageOps.contain(Image.open(file), IWII_RESOLUTION)
-        
+        photo = PhotoImage(image_data, size=IWII_RESOLUTION)
+        event.widget.create_image(0,0, anchor=NW, image=photo)
+        # tkinter does not maintain a reference to the local variables of this function upon return
+        # without references, the photo and its data get garbage collected and nothing is display
+        # therefore we must create references to them to keep them around
+        event.widget._displayed_photo=photo
+        event.widget.master.photobooth_image = image_data
 
-@handle_action_exceptions
+@widget_action
-def send_to_iwii(event: tk.Event):
+def send_to_iwii(event: Event):
     raise NotImplementedError        
 
 
 def photobooth():
-    app = tk.Tk()
+    app = Tk()
+    app.photobooth_image = None
     app.title("PhotoBooth")
-    style = ttk.Style()
+
+    style = Style()
 
     match system():
         case "Windows":
             try:
                 style.theme_use("winnative")
-            except tk.TclError:
+            except TclError:
                 style.theme_use("vista")
         case "Darwin":
             style.theme_use("aqua")
         case "Linux":
             style.theme_use("alt")
+            # https://python-forum.io/thread-31235.html
+            try:
+                # this is so stupid! you have to intentionally do this just to initialize the
+                # required namespace to set variables to hide hidden files by default
+                app.tk.call("tk_getOpenFile", "-intentionalnonsense")
+            except TclError:
+                app.setvar("::tk::dialog::file::showHiddenBtn", 1)
+                app.setvar("::tk::dialog::file::showHiddenVar", 0)
         case _:
             style.theme_use("default")
 
-    preview = tk.Canvas(master=app, height=576, width=720)
+    preview = Canvas(master=app, height=IWII_RESOLUTION.height, width=IWII_RESOLUTION.width)
     preview.bind("<space>", open_preview)
-    preview.bind("<return>", send_to_iwii)
+    preview.bind("<Return>", send_to_iwii)
     preview.focus_set()
     preview.pack(side="top")
     app.mainloop()