Metrics and placement

Purpose

All controls have a default height and width to establish a harmonic overall picture. Nevertheless, size is used to direct users’ attention. For instance, a list that captures most of screen’s space points to its central role in the current work flow. And, size can be used to indicate possible interactions. Smaller edits are probably constrained, for instance.

Similar to size, the space between controls generates a visual impression and supports layout. Space between controls indicates their relatedness. Objects with smaller distances are mentally associated according to the Gestalt theory. Whitespace is an important element of design which enables the objects in it to exist at all. The balance between content and whitespace is key to grouping.

Please read Units & measurements for more information which and how different units such as px, dpi independent pixels, smallSpacing and largeSpacing are used.

Guidelines

Size

  • If the control appears in a dialog or utility window, consider making the window and the control within it resizeable so that the user can choose how many items are visible at a time without scrolling. Each time the user opens this dialog, set its dimensions to those that the user last resized it to.

  • Size controls with a minimum of - Icon:16x16px - Buttons: 72 x 32px - Line edits, Drop-downs, Combo boxes ≥80 x 32 px - Text edits: ≥80 x ≥36 px (text should not exceed 80 characters per

    line)

    • Checkbox, Radio button including label: ≥80 x 24 px
    • Group boxes: ≥120 x ≥96 px
    • Tree view: ≥120 x ≥96 px
    • List view: ≥80 px (per column) x ≥96
  • KDE seeks to support XGA (1024x768px) or WXGA (1280x768px) at least.

    • Keep in mind that not everyone is provided with a high resolution display.
    • Avoid to have a large number of controls visible at once, which in turn requires a huge minimal size.
    • Keep in mind that the available screen area typically also will be shrunk by panels and the window titlebar. Also, user’s font might be bigger than yours (e.g. for accessibility reason).
    • You therefore should ideally preserve ~10% to catch those variables and try to not exceed 920x690px.

Space

Qt widgets

If you are using Qt widgets you should use one of Qt’s Layout Classes, which will take care of laying out and spacing of your controls.

QML

For consistency you should try to use Kirigami and Plasma’s smallSpacing and largeSpacing for margins and paddings whenever possible. See Units & measurements for more details.

Use multiples of smallSpacing or largeSpacing, where more spacing is required.

Use of base units

Use of base units

Resize

  • Provide resizing for all primary and mode-less windows.
  • If form resizing is not provided disable border icons and adjust form style.
  • Define a minimum size for resizable forms.
  • Make the content area scrollable if size is too small for all controls; do not scale controls.
Give hints how to resize

Give hints how to resize