Handling application events – roku sdk documentation – developer documentation


There are one or more keys on any Roku remote control which are not handled by the onKeyEvent() function (or any Roku application event handler), such as the Home key. Usd jpy forecast today Presses of these keys are handled by the global Roku firmware event handler in a default manner that cannot be modified by application code. Vnd to usd conversion Also note that several node classes handle certain remote control key events automatically, so onKeyEvent() is not required to handle those events, and should not be used for those events in those nodes. Vkc forex As an example of node classes that automatically handle certain remote control key events, grid node classes such as PosterGrid automatically handle Up, Down, Right, and Left key presses when the poster grid has focus. Famous quotes about time Typically, you should use the ifSGNodeField observeField() method to handle changes in the subject node fields caused by automatic key event handling of the node.

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The following onKeyEvent() example handles supported remote control key presses other than the Back key by displaying a warning message until the OK key is pressed.
This second case is used when you want a field change to trigger an event in a BrightScript message loop. Binary number system This is useful when using BrightScript components (such as roChannelStore) which can only be instantiated in the main BrightScript thread or a Task node thread. Usd zar exchange rate In this case, when the observed field changes, an roSGNodeEvent is sent to the port passed to the observeField() call. Python print The event getField() and getData() functions can be called to determine the specific node field that changed, and the new value of the field, respectively. 444 angel number meaning Event Cascades
Setting the value of a field triggers any field observer functions that may be associated with the field as the result of an observeField() call. Dollar news today These observer functions may set other component fields, triggering calls to their observer functions. Binary to decimal formula Such a situation triggers what is called an event cascade. Simply put, this is the chain of field setting and observer function calls that result from setting a single field of a node.
For example, if the width field of a Rectangle that contains a Label is set, an observer of that width field might set the width field of the Label. Usd eur conversion The width field of the Label might have an observer function that sets the Label’s wrap field. Exchange rate chf usd The chain of field settings and observer callback functions that result from setting a field (in this case, the Rectangle’s width field) is an event cascade.
With the release of firmware v7.5, nested observer callbacks are no longer deferred. Usa today sudoku Observer callbacks now happen recursively. Market futures news See the Queued Callback Model section above for details. Usd today rate Handling Component Field Value Changes
Any  element defined in a component  element can have an observer attached by setting the value of the optional onChange attribute. Usd pound sterling exchange rate Set the onChange attribute to the callback function name that will handle the component field value change.
Note that the  element also includes a related optional attribute, alwaysNotify. Gender differences in education You can set this attribute to true to have the callback function triggered every time the component field value is set, even if the value itself does not change. Dow jones futures market To have the callback function triggered only when the component field value changes, set the alwaysNotify attribute to false. Funny jokes for adults Functional Fields