Device, method, and graphical user interface for adjusting a display property of an affordance over changing background content

摘要

A value of a display property of an affordance changes based a value of the same display property of a portion of content over which the affordance is displayed. The value of the display property of the affordance is constrained to vary within a second value range smaller than a first value range over which the value of the display property of the content is permitted to vary. If the change in appearance of the content meets range-switching criteria, the value of the display property of the affordance is changed within a third value range. The third value range is different from the second value range and is smaller than the first value range. If the change in appearance of the content does not meet the range-switching criteria, the value of the display property of the affordance is changed within the second value range.