Detailed Description

The Label widget main function is to display plain text or a CDP object/property.

To enter a text to be displayed, double click on the widget and type the text or use the text property.

To show the text or numeric value of a CDP object/property, enter the path in the cdpRouting property.

The Label must be used to display all texts and values in a GUI to enable elements like titles, sub-titles, information and values to show correctly in all themes. For instance, one theme might have left-aligned titles while another might have the titles centered.

The stylingType property allows styling text and values consistently in the GUI according to selected theme. Pre-defined styles exist for title, sub-title, plain text, values and units.

The cdpScaling property is used to scale the value that is displayed. E.g. if a signal in the system is in meter, we can set cdpScaling to 0.001 if we rather want it to display in km.

The postfix property is used to add a text after the actual value. E.g. to add the word “bar” behind a pressure reading, set postfix to “ bar”.

The Label also has lots of other properties to explore. Like options for styling, setting min/max size, layout size policies, number precision etc.

Styling by SVG

The Label is usually styled by selecting one of the predefined types in the stylingType property, like Title, Value, Unit etc. Selecting one of these types will read the styling from a general theme SVG file, located in "themes/${theme_name}/general/theme.svg". The structure of the theme.svg file is not similar to the one used when setting stylingType to SVG and providing a SVG file in the svgFile property. That one uses the same styling as the Line Edit as described in the bottom of this section. The theme.svg file has the following SVG structure.

svg
└─── Layer1
  ├─── cdpValuePostfix          (text)
  ├─── cdpValue                 (text)
  ├─── cdpSubHeading            (text)
  ├─── cdpTitle                 (text)
  ├─── cdpFontColorUnit         (text)
  ├─── cdpFontColorMain         (text)
  └─── cdpFontColorMainInv      (text)

The following table explains the named elements in more detail. Note that some of them are not relevant for the Label.

When not styling using the general theme file, the svgFile property can be used to style the widget. Styling by SVG enables switching between different themes in runtime (as long as the files are placed at identical locations within theme directories).

The CDPBaseLabel supports reading both background image and text color from SVG similar to that of CDPBaseLineEdit described here. To enable the background to show on the label we have to make sure that the property named noSystemBackground is set to false.

Note: The SVG doesn't have to include background image though it is supported, but when present, the widget will generate raster images as described here.