The QIRProximityReading class holds readings from the IR proximity sensor. 更多...
| 头： | #include <QIRProximityReading> |
| qmake: | QT += sensors |
| Since: | Qt 5.1 |
| 继承： | QSensorReading |
该类在 Qt 5.1 引入。
| qreal | reflectance () const |
| void | setReflectance (qreal reflectance ) |
The IR (infra-red) proximity sensor detects proximity by beaming out infra-red light and detecting how much of the light returns.
The biggest limitation of this technology is that there is no reliable way to turn the reflectance values into distances unless both the item being detected and the ambient conditions are known.
The sensor reports reflectance as a decimal fraction in the range of 0 - 1. That is, 0 indicates nothing was detected within the range of the sensor and 1 indicates the infra-red signal returned at the full power level that it was sent at.
With some IR sensors, it is quite uncommon to reach the top and the bottom of the value range, and some parts of the range ends might not be obtainable at all. This is due to the behavior of the sensor hardware. With these sensors, the absolute value of reflectance should never be used directly. Instead, applications should react to the relative change of the reading values. Use QProximitySensor if it is only necessary to check if something is close to the device or not.
Holds the reflectance value.
The reflectance is a decimal fraction (from 0 to 1) indicating how much of the transmitted infra-red light was returned.
访问函数：
| qreal | reflectance () const |
另请参阅 QIRProximityReading Units .
Sets the reflectance value to reflectance .
另请参阅 reflectance ().
