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 two critical blocks are:

#%Screen Elements
from Screens.myscreen.f_header import *
from Screens.myscreen.f_body import *
#%Screen Grid

#%Screen Modules
from modules.myscreen.m_header import *
from modules.myscreen.m_body import *
#%Handle Arguments

stitch replaces everything between #%Screen Elements and #%Screen Grid with fresh imports from Screens/<screen>/f_*.py, and everything between #%Screen Modules and #%Handle Arguments with fresh imports from modules/<screen>/m_*.py.

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

Screen template structure (0.4+)#

The full generated screen template:

#%Default Imports
from tkinter import *
from tkinter import ttk
import sys
#%File Specific Imports

#%Handle Arguments

#%Screen Modules

#%Define Loop Modules
def loop():
    pass

def configure_menu(menubar):
    """Contribute menu items to the Host's persistent menu bar."""
    pass

def on_focused():
    """Called when this tab gains focus inside the Host."""
    pass

def on_unfocused():
    """Called when this tab loses focus or is closed inside the Host."""
    pass

def setup(parent):
    """Build this screen's UI into parent."""
    #%Screen Grid

    #%Screen Elements
#%Update Loop
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("<title>")
    root.setIcon("<icon>")

    while True:
        try:
            if root.Active:
                try: loop()
                except: pass
                root.update()
            else:
                break
        except:
            break

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.