Utilities

Utilities#

fUtil#

fUtil provides font creation and automatic text sizing. Import from VIStk.

from VIStk import fUtil

fUtil.mkfont(size, bold=False, font="default")#

Returns a font string compatible with Tkinter’s font option. The default font is Arial on Windows and LiberationSans on Linux.

Label(parent, font=fUtil.mkfont(10))
Label(parent, font=fUtil.mkfont(14, bold=True))

fUtil.autosize(event, relations=None, offset=None, shrink=0)#

Automatically adjusts font size so the text fills the widget as tightly as possible. Bind to <Configure> on the widget to keep the font size updated as the widget resizes.

btn = Button(parent, text="Click Me", font=fUtil.mkfont(12))
btn.bind("<Configure>", lambda e: fUtil.autosize(e))

Parameter

Description

event

The <Configure> event — provides the widget reference

relations

A list of additional widgets to resize to the same font size

offset

Integer subtracted from the calculated font size

shrink

Pixel margin subtracted from the widget width before calculating

With relations (uniform button group):

btns = [Button(parent, text=t, font=fUtil.mkfont(12)) for t in ["First","Prev","Next","Last"]]
btns[0].bind("<Configure>", lambda e: fUtil.autosize(e, relations=btns[1:]))

Templates and the #% System#

VIStk templates use #% comment markers as searchable section headers. The stitch command uses these markers to locate and rewrite specific blocks in a screen script.

Warning

Do not delete or rename #% comment lines. They are not standard comments — they are structural anchors that VIStk searches for by text pattern.

The critical blocks are:

#%Screen Elements
import Screens.MyScreen.f_header
import Screens.MyScreen.f_body

#%Screen Modules
import modules.MyScreen.m_header
import modules.MyScreen.m_body

stitch replaces the content under #%Screen Elements with fully-qualified imports for each Screens/<screen>/f_*.py file, and #%Screen Modules with fully-qualified imports for each modules/<screen>/m_*.py file. It also populates #%Build Screen Elements (inside setup()) and #%Predefined Loop Functions (inside loop()).

If the VSCode VIStk extension is installed, #% lines are highlighted differently from regular comments.

Screen template structure#

The full generated screen template:

#%Default Imports
from Screens.defaults import *
#%File Specific Imports

#%Screen Modules

#%Screen Elements

#%Define Loop Modules
def loop():
    """Called every tick by the Host (or standalone main loop)."""
    #%Predefined Loop Functions
    pass

    #%User Defined Loop Functions
    pass

#%Menu Functions

#%Host Hooks
def configure_menu(menubar):
    """Register menu items with the containing TabManager."""
    menubar.set_screen_items([], label="ScreenName")

def on_activate():
    """Called when this tab gains focus."""
    pass

def on_deactivate():
    """Called when this tab loses focus."""
    pass

def on_quit() -> bool:
    """Called when this screen is about to be destroyed.
    Return False to prevent destruction (e.g. unsaved changes prompt)."""
    pass

def setup(parent):
    """Build this screen's UI into parent."""
    pane = LayoutFrame(parent)
    pane.place(relx=0, rely=0, relwidth=1, relheight=1)

    #%Screen Grid
    pane.Layout.colSize([1.0])
    pane.Layout.rowSize([1.0])

    #%Build Screen Elements

    #%Other Setup

#%Standalone Entry
if __name__ == "__main__":
    from Screens.root import root, frame
    setup(frame)
    root.Active = True
    root.WindowGeometry.setGeometry(width=66, height=66, align="center", size_style="screen_relative")
    root.screenTitle("ScreenName")
    root.setIcon("ScreenName")

    while True:
        try:
            if root.Active:
                try:
                    loop()
                except Exception as _e:
                    print(f"ScreenName loop error: {_e}", file=sys.stderr)
                root.update()
            else:
                break
        except Exception as _e:
            print(f"ScreenName main loop error: {_e}", file=sys.stderr)
            break

Screens/defaults.py#

Every project includes a Screens/defaults.py that centralizes the default imports shared by all screen scripts and element files:

from tkinter import *
from tkinter import ttk
import sys
from VIStk.Structures._Project import Project
from VIStk.Widgets import LayoutFrame

__all__ = [
    *[name for name in dir() if not name.startswith('_')],
]

from Screens.defaults import * re-exports all names through __all__, making them available in the importing module. Static analysis tools (Pylance) and the Nuitka compiler both resolve import * chains correctly.

Warnings#

Do not call root.mainloop()#

Using mainloop() traps the application in Tkinter’s event loop and prevents the while root.Active pattern from working. Screen switching via os.execl cannot occur from inside mainloop().

Do not call root.destroy() to quit#

Call root.Active = False instead. The while loop will exit naturally. Calling destroy() directly can leave VIStk in an inconsistent state if any exit actions or redirects are queued.

Do not edit #% lines#

The stitch command and VSCode extension locate blocks by searching for these exact strings. Modifying them will break the CLI’s ability to update your screen scripts automatically.