Widget Execution

When a widget is started in a Iotellect Server User Interface, a new window is created for it. The widget engine renders the contents of the widget's root panel in this window. The window's size may be defined by the Width and Height parameters of the root panel (in pixels), or calculated automatically based on the optimal sizes of the widget's internal components if Width or Height of the root panel are not specified (i.e. set to zero). An optimal size is whatever size a component has to be so it could display all of its information without hiding any or requiring the user to scroll to see it. For a label, the optimal size is however big the label has to be to show all text. For a slider, it's however long the slider has to be to fit in all ticks, etc. If only the width or the height is specified, the other dimension is optimally sized.

If a widget window is resized, its internal components are moved and resized according to their individual constraints and sizes. A widget's layout may also change on execution, when components properties are modified by bindings according to user input or changes in context data.

When a widget starts up, the widget engine processes any bindings within it which are scheduled for processing on startup. Usually, bindings executed on startup are used to read certain context values and initialize the widget components.

While working, the widget monitors changes in contexts and component properties, and processes the bindings again when such changes are detected. Also, some bindings can be configured for periodic processing.

Every processed binding may change server data, properties of widget components, or execute widget script.

See the bindings article for more information.

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