将HTML5 Canvas.arc移植到Android和逆时针

Question

我正在将Skycons移植到Android上,我的大部分工作都在工作,除了月亮使用Canvas.arc带有逆时针参数的HTML5 .

我试图这样实现:

RectF rect = new RectF();

public void arcR( Path path, float x, float y, float radius, double startAngle, double endAngle, boolean anticlockwise ){
    // Set bounds
    rect.set( x - radius, y - radius, x + radius, y + radius );

    // Convert to degrees
    startAngle = Math.toDegrees(startAngle);
    endAngle = Math.toDegrees(endAngle);

    if(anticlockwise){
        startAngle = 360 - startAngle;
        endAngle = 360 - endAngle;
    }

    endAngle = endAngle - startAngle;

    path.addArc(rect, (float)startAngle, (float)endAngle);
}

我认为我没有正确实施逆时针,因为在我的设备上绘制月球(基于Skycons)看起来像这样:

Answer 1

对于逆时针弧,扫掠角需要为负

float sweepAngle = ((endAngle + 360) - startAngle) % 360;
if (anticlockwise) {
  sweepAngle = sweepAngle - 360;
}
path.addArc(rect, startAngle, sweepAngle);