Interaction Programming (CSE 340) |
您所在的位置：网站首页 › normalbutton › Interaction Programming (CSE 340) |
|
How to turn the Propositional Production System (PPS) for a button into code
How to turn the Propositional Production System (PPS) for a button into code
The code implementation should spiritually follow the PPS; that is, your code should only take action when moving from state to state (along the arrows in the PPS). This behavior is best represented by a switch statement, where each case represents a state in our PPS. Within each case, there can be nested if statement to handle transitioning to another state. Each case should be broken out of and should properly handle input, propagating input to later views or stopping the input propagation as necessary. We typically do this through the onTouchEvent method. In onTouchEvent, returning true will stop the input propagation to views below it, while returning false allows views below it to handle the event. Button ExamplesGiven the essential geometry for this button is: Inside Outsideand methods for that will be used are: indentButton() (when button is pressed, also invalidate() the view) normalButton() (when button is not pressed, also invalidate() the view) invokeAction() (when the user releases in the button) cancelAction() (when the user releases outside the button)The PPS for this interaction is as follows: stateDiagram-v2 [*] -->PRESSED: DOWN/Inside?>indentButton() PRESSED --> PRESSED: MOVE/Outside?>normalButton() PRESSED --> [*]: UP/Outside?cancelAction() PRESSED --> [*]: UP/Inside?invokeAction() PRESSED --> PRESSED: MOVE/Inside?indentButton()The code is generated thusly @Override public boolean onTouch(MotionEvent e) { EssentialGeometry geometry = essentialGeometry(event); switch (state) { case State.START: if (geometry == Geometry.INSIDE && e.getAction() == MotionEvent.ACTION_DOWN) { indentButton(); state = State.PRESSED; return true; } break; case PRESSED if (e.getAction() == MotionEvent.ACTION_MOVE) { if (geometry == Geometry.INSIDE) { indentButton(); } else { normalButton(); } return true; } else if (e.getAction() == MotionEvent.ACTION_UP) { state = State.START; // note we don't actually use the END state if (geometry == Geometry.INSIDE) { invokeAction(); } else { cancelAction(); } return true; } break; default: break; } return false; }The material taught in this class was inspired by many others, including Scott Hudson's SSUI class (at CMU's HCII) and James Landay's CS 160 class and Eric Paulos' class of the same title (at UC Berkeley). The University of Washington acknowledges the Coast Salish peoples of this land, the land which touches the shared waters of all tribes and bands within the Suquamish, Tulalip and Muckleshoot nations. Interaction Programming (CSE 340) is maintained by Lauren Bricker 聽([email protected]). |
| CopyRight 2018-2019 办公设备维修网 版权所有 豫ICP备15022753号-3 |