Implement project saving

main.py

@@ -46,7 +46,26 @@ def menu_file_open_project_click():
 
 
 def menu_file_save_project_click():
-    pass
+    global project
+
+    path=None
+    if project.loaded:
+        path=project.path
+    else:
+        # show file save dialog
+        path=filedialog.asksaveasfilename(
+            title="Save font project",
+            filetypes=[("Font project (json)", "*.fontproj")],
+            defaultextension=".fontproj"
+        )
+        if path=="":
+            return
+
+    try:
+        project.save(path)
+    except IOError as e:
+        tkinter.messagebox.showerror("Saving project",f"Failed to save project '{path}': {e}")
+
 
 def menu_file_save_project_as_click():
     pass

project.py

@@ -25,5 +25,17 @@ class Project:
             self.loaded=True
 
 
+    def save(self,path):
+        # save project data to file
+        with open(path, "w") as f:
+            json.dump({
+                "char_width": self.char_res[0],
+                "char_height": self.char_res[1],
+                "chars": self.chars
+            }, f, indent=4)
+        self.path=path
+        self.loaded=True
+
+
     def does_char_exist(self,c):
         return chr(c) in self.chars