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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.

Shutter button half-pressed (triggers autofocus)

Shutter button fully pressed (triggers photo capture)

The size of the image sensor in megapixels

Switching from photo mode to video mode

The battery level dropping below 10%

Pinch-to-zoom gesture on the screen

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

Quizzes you can take where this question appears

Applied System Modeling: Exercises