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Learn how to use variables in Sketchlet to exchange messages, manipulate data, and trigger actions. Understand the scope, interface, and examples of working with variables.
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Sketchlet TutorialVariables sketchet.sf.net Željko Obrenović obren.info/
Agenda • Variables • Using variables
Variables • Many elements of Sketchlet communicate indirectly by exchanging messages through a centralized repository of variables. • Variables can have two scopes: page or global • Variables provide a simple and uniform abstraction mechanism, enabling a designer to work with very diverse elements using the same set of operations. • Properties of freehand sketches, such as their position or transparency, or user actions such as item selections, can be mapped to blackboard variables.
Variables • Spreadsheets or scripts can subsequently read, process, and update these variables. • I/O services can receive arguments and send back results through such variables. • Lastly, through extension mechanisms other platforms can update, read or register for the notification of variables.
Interface for Working with Variables System event variables Delete selected variables • Variables can be accessed through a spreadsheet-like interface, making all data immediately visible and manipulatable. • A designer can directly observe and update variables. Derived variables Disable variables’ updates Add new variable Dynamic variables Filter
Examples of Using Variables • Capturing user motion • Setting region and sketch properties • Updating variables based on events • Actions triggered by variable updates
Capturing User Motion in Variables • Step 1: Creating variable “rot”
Capturing User Motion in Variables • Step 2: drag-and-drop the variable on the active region motion mapping icon
Capturing User Motion in Variables • Step 3: select properties of motion that you want to capture in the variable • In this exampleit is “rotation”
Capturing User Motion in Variables • Step 4: interact with the region and observe variables changes • In this example, dragging the region with right mouse button will rotate it and update the variable “rot”
Setting Region and Sketch Properties • You can drag-and-drop the variable on the region properties icon, and select property
Setting Region and Sketch Properties • In this example we are using variable “rot” to control rotation property of another region
Updating Variables on Events • Events • Mouse Events • Keyboard Events • Sketch events: entry, exit • Variable Actions • Update variable • Increment variable • Append variable