Color is a distinguishing quality of human perception. Color can be used to communicate and draw attention efficiently. Color can assign significance to an object. However, color is a historical and cultural phenomenon and is subject to continuous aesthetical changes. It should also be noted that a large part of the population cannot perceive color in the same way that most people will.
A consistent color set helps create a familiar visual language throughout the user interface.
While the system color theme can be selected by the user, the Breeze color palette is used for the reference visual design of KDE Applications and Workspaces, and make up the default system color theme.
Primary colors are used throughout the main interface of the applications and workspaces. Plasma Blue is used as the primary highlight color.
Secondary colors are used sparingly as accents throughout the visual design.
Whenever transparency is used (e.g. shadows) consider using the opacities listed.
Avoid using color as a primary method of communication. Color is best used as a secondary method to reinforce meaning visually. You should not only rely on color to convey meaning but also typography, layout, sizes, etc.
Ensure sufficient contrast between foreground and background colors.
Keep in mind accessibility for users with color vision deficiency (~5% population). Use one of the many available online color blindness simulators to ensure colors intended to be distinguishable remain distinguishable for color-blind users.
When implementing colors in your application, select the appropriate theme color or system color from the palette provided by the Qt or KDE Platform/Frameworks library. You can use the CheckColorRoles theme to detect bugs regarding the use of system colors in your application.
KColorScheme provides methods to pick the colors from the system color scheme to avoid hardcoding colors where possible.
For QML use:
Color Mapping - The Breeze color palettes maps to the KColorScheme color roles as shown as follow: