|Control properties / Primary properties|
The positional properties of a control specify its location and dimensions.
The left and top TA properties of a control specify its position in the display. Specifically, they specify the position of the top left corner of the control.
The reference point for the left/top positional
values is generally the top-left corner of the display screen. An exception to that rule
applies to web applications running in mobile device browsers. In such cases, the reference
point is actually the top-left corner of the browser display window:
|iOS device(s)||Display technology||Scale factor|
|iPad Mini, iPad 2||1.0|
|iPhone 6, 5S, 5C, 5, 4S; iPad Air, iPad with Retina Display, iPad 3||Retina||2.0|
|iPhone 6 Plus||Retina HD||3.0|
Deriving the pixel value for a given positional TA property on an iOS device is a simple matter of multiplying by the applicable scale factor. For example, an iPhone 5 has a scale factor of 2.0. Hence a button in an iOS application on an iPhone 5 whose TA property width = 40 is, in fact, 80 pixels wide.