How to increase the size of the ttk.Scale handle/button

[andrewguy]

I'm developing a touch-screen based app, and using the Scale widget from ttkbootstrap. However, the button/handle on the Scale widget is too small to really be useful in a touchscreen setting - it requires a bit of luck/precision to 'grab' with a finger.

I've tried the solution outlined in this issue, which involves setting scaling for high-dpi awareness (root.tk.call('tk', 'scaling', 2.0)). This appropriately scales the Scale handle, however it also affects other widgets (including Labels), which is less than ideal.

I'm wondering if anyone has any ideas for how to increase the size of the handle/button in the Scale widget independently of other widgets?

Many thanks,
Andrew

[israel-dryer]

There isn't a way to isolate the handle image resize. You could create your own layout for the scale, which is essentially what I did below. I copied and modified the code I use in the style builder. This demo shows a gigantic slider handle.

import ttkbootstrap as ttk
from ttkbootstrap.constants import *


def create_custom_scale_style(style_obj, style_name, handle_size, colorname=DEFAULT):
    """Create a style for the ttk.Scale widget.
    Parameters:
        colorname (str):
            The color label used to style the widget.
    """
    builder = style_obj._get_builder()
    images = builder.create_scale_assets(size=handle_size)
    STYLE = "TScale"

    if any([colorname == DEFAULT, colorname == ""]):
        h_ttkstyle = f"Horizontal.{STYLE}"
        v_ttkstyle = f"Vertical.{STYLE}"
    else:
        h_ttkstyle = f"{style_name}.Horizontal.{STYLE}"
        v_ttkstyle = f"{style_name}.Vertical.{STYLE}"

    # ( normal, pressed, hover, disabled, htrack, vtrack )
    images = builder.create_scale_assets(colorname, handle_size)

    # horizontal scale
    h_element = h_ttkstyle.replace(".TS", ".S")
    style_obj.element_create(
        f"{h_element}.slider",
        "image",
        images[0],
        ("disabled", images[3]),
        ("pressed", images[1]),
        ("hover", images[2]),
    )
    style_obj.element_create(f"{h_element}.track", "image", images[4])
    style_obj.layout(
        h_ttkstyle,
        [
            (
                f"{h_element}.focus",
                {
                    "expand": "1",
                    "sticky": NSEW,
                    "children": [
                        (f"{h_element}.track", {"sticky": EW}),
                        (
                            f"{h_element}.slider",
                            {"side": LEFT, "sticky": ""},
                        ),
                    ],
                },
            )
        ],
    )
    # vertical scale
    v_element = v_ttkstyle.replace(".TS", ".S")
    style_obj.element_create(
        f"{v_element}.slider",
        "image",
        images[0],
        ("disabled", images[3]),
        ("pressed", images[1]),
        ("hover", images[2]),
    )
    style_obj.element_create(f"{v_element}.track", "image", images[5])
    style_obj.layout(
        v_ttkstyle,
        [
            (
                f"{v_element}.focus",
                {
                    "expand": "1",
                    "sticky": NSEW,
                    "children": [
                        (f"{v_element}.track", {"sticky": NS}),
                        (
                            f"{v_element}.slider",
                            {"side": TOP, "sticky": ""},
                        ),
                    ],
                },
            )
        ],
    )
    # register ttkstyles
    style_obj._register_ttkstyle(h_ttkstyle)
    style_obj._register_ttkstyle(v_ttkstyle)


if __name__ == '__main__':

    app = ttk.Window(themename='superhero')

    create_custom_scale_style(app.style, 'custom', 50)

    scale = ttk.Scale(style='custom.Horizontal.TScale')
    scale.pack(fill=X, expand=YES)

    app.mainloop()

[andrewguy]

Amazing! That works perfectly. Really appreciate you taking the time to provide an answer.