| # input_pipeline > Gestures > Scroll Recognizer |
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| Reviewed-on: 2022-07-20 |
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| # Purpose |
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| The scroll recognizer detects 2 finger swipe on the touchpad, and converts all related |
| touchpad events to mouse wheel events. |
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| A scroll occurs when the user places 2 fingers on the touchpad surface. And 2 fingers move |
| approximately horizontal or vertical. |
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| # State machine |
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| The scroll recognizer implements the state machine below. |
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| The state machine is also available in other formats: |
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| - [state machine as graphviz source](scroll_state_machine.dot) |
| - [state machine as SVG](scroll_state_machine.svg) |
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| The scroll recognizer tolerate a certain degree of angle in the direction. |
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