在处理CameraPostion、CameraPostion.Builder时，正确的单位是什么？

Question

从文档中看，CameraPosition似乎应该对其承载成员使用度。然而，它的构建器类将传入的度数转换为弧度。

/**
 * Sets the direction that the camera is pointing in, in degrees clockwise from north.
 *
 * @param bearing Bearing
 * @return Builder
 */
public Builder bearing(double bearing) {
    if (isRadiant) {
        this.bearing = bearing;
    } else {
        // converting degrees to radiant
        this.bearing = (float) (-bearing * MathConstants.DEG2RAD);
    }
    return this;
}

下面是CameraPosition的构造函数。看起来，由于构造者期望的是度，所以构造者应该以度为单位来保持方向角，或者如果以弧度为单位，则将其转换为度。

/**
 * Constructs a CameraPosition.
 *
 * @param target  The target location to align with the center of the screen.
 * @param zoom    Zoom level at target. See zoom(float) for details of restrictions.
 * @param tilt    The camera angle, in degrees, from the nadir (directly down). See tilt(float) for details of restrictions.
 * @param bearing Direction that the camera is pointing in, in degrees clockwise from north. This value will be normalized to be within 0 degrees inclusive and 360 degrees exclusive.
 * @throws NullPointerException     if target is null
 * @throws IllegalArgumentException if tilt is outside the range of 0 to 90 degrees inclusive.
 */
CameraPosition(LatLng target, double zoom, double tilt, double bearing) {
    this.target = target;
    this.bearing = bearing;
    this.tilt = tilt;
    this.zoom = zoom;

Answer 1

默认单位为degrees。

正如您所提到的，构建器将度数转换为弧度。除非生成器使用isRadiant并将其设置为true，否则弧度始终作为double保留。看起来isRadiant是在Mapbox、Android SDK3.x和4.0.0之间引入的。

if (isRadiant) {
    this.bearing = bearing;
} else {
    // converting degrees to radiant
    this.bearing = (float) (-bearing * MathConstants.DEG2RAD);
}

构建器执行算术提升。在内部，方向角显然是弧度，但开发人员输入的是degrees。

从文档中

• @参数相机指向的方向，从北顺时针方向。该值将被标准化为0度(含)和360度(不含)。

Mapbox Android SDK4.0中的示例显式设置了isRadiant(false) -

                CameraPosition position = new CameraPosition.Builder()
                        .target(new LatLng(32.9, -116.9))
                        .zoom(17) // Sets the zoom
                        .isRadiant(false)
                        .bearing(180) // Rotate the camera 180 degrees
                        .tilt(30) // Set the camera tilt
                        .build(); // Creates a CameraPosition from the builder

                mapboxMap.animateCamera(CameraUpdateFactory
                        .newCameraPosition(position), 7000);