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State Diagram for a Mobile Camera — Key Stimuli
publish date: 2026/06/08 22:17:22.120681 UTC
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You are asked to model the state diagram for the camera control software on a mobile phone. Which of the following are valid stimuli (events that trigger state transitions) for such a system? Select all that apply.
Correct Answer
(1) Shutter button half-pressed (triggers autofocus)
(2) Shutter button fully pressed (triggers photo capture)
(3) Switching from photo mode to video mode
(4) The battery level dropping below 10%
(5) Pinch-to-zoom gesture on the screen
Explanation
Stimuli in a state diagram are events that cause state transitions. All of these are valid stimuli: half-press triggers focusing, full press triggers capture, mode switching transitions between photo and video states, low battery triggers a warning or disabled state, and pinch-to-zoom triggers a zoom state. The image sensor megapixel count is a static hardware specification — it is not an event that triggers a state transition.
Reference
Software Engineering, Ian Sommerville, 9th edition