Huawei MATE 9 Use Manual page 194

Browse a magnified area: Swipe the screen using two fingers.
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Adjust the zoom: To zoom in, spread your fingers apart on the screen. To zoom out, pinch
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two or more fingers together on the screen.
Zoom in temporarily: Touch the screen three times in quick succession, and then hold
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your finger on the screen. Swipe to browse a magnified area. Release your finger to zoom
back out.
System Features and Settings
188