如何在WinRT中通过一根手指触摸来获取总旋转角度

Question

我正在尝试按照Jerry的教程进行拨号控制。由于方法GetAngle基于触摸点的位置，因此计算的角度始终等于或小于 360°。但我需要的是，如果我把结旋转两圈半，我想得到900° (360°*2 + 180°).

我知道e.Cumulative.Rotation（e是ManipulationDeltaRoutedEventArgs）可以给我总旋转角度，但看起来旋转只能由两个手指触发。

我在这里错过了一些简单的解决方案吗？

Answer 1

我花

了一些时间，结果证明这是一个不错的程序（感谢 Jerry 的精彩博客文章）。最后，我以几乎没有不同的解决方案结束 - 下面一点。

如果您需要计算整个圆圈，那么您需要记住角度从 360 变为 0 的那一刻，并记住有一个完整的圆。在我的示例中，我记得最后一个象限，这有助于我处理问题。主代码如下所示：

private Quadrants currentQuadrant = Quadrants.I;
private Quadrants lastQuadrant = Quadrants.I;
private double lastAngle = 0;
public enum Quadrants { I, IV, III, II } // counterclockwise quadrants
private double CheckAngle(Point touchPoint, Size bounds)
{
    // find point position relative to bounds
    double valX = touchPoint.X - (bounds.Width / 2d);
    double valY = (bounds.Height / 2d) - touchPoint.Y;
    // determine the quadrant and save it
    currentQuadrant = (valX >= 0) ?
        (valY >= 0) ? Quadrants.I : Quadrants.IV :
        (valY >= 0) ? Quadrants.II : Quadrants.III;
    double quadrantAngle = Math.Atan(valX / valY) * (180 / Math.PI); // calculate angle within quadrant
    return currentQuadrant == Quadrants.II ? 360 + quadrantAngle :
            currentQuadrant != Quadrants.I ? 180 + quadrantAngle : quadrantAngle;
}
private void Grid_ManipulationDelta(object sender, ManipulationDeltaRoutedEventArgs e)
{
    double currentAngle = CheckAngle(e.Position, this.RenderSize);
    if (Math.Abs(lastAngle - currentAngle) < 1) return; // don't update UI always - performance
    if (currentQuadrant == Quadrants.I && lastQuadrant == Quadrants.II) // check for full circle
    { spinNumber++; RaiseProperty("SpinNumber"); } 
    else if ((currentQuadrant > lastQuadrant + 1)) return; // check if proper movement
    // update quadrants and Angle
    lastQuadrant = currentQuadrant;
    Angle = lastAngle = currentAngle;
}
private void Grid_ManipulationCompleted(object sender, ManipulationCompletedRoutedEventArgs e)
{
    // reset all things
    Angle = lastAngle = spinNumber =0;
    currentQuadrant = lastQuadrant = Quadrants.I;
}

和一些 XAML 部分：

<Grid>
    <Grid ManipulationMode="All" ManipulationDelta="Grid_ManipulationDelta" ManipulationCompleted="Grid_ManipulationCompleted">
        <Ellipse Width="300" Height="300" Fill="Red"/>
        <Path Fill="Green" Data="M 0 0 L 50 0 L 100 150 L 0 150 L 50 0 Z" HorizontalAlignment="Center" VerticalAlignment="Center" RenderTransformOrigin="0.5,0.5">
            <Path.RenderTransform>
                <RotateTransform Angle="{Binding Angle}"/>
            </Path.RenderTransform>
        </Path>
    </Grid>
    <TextBlock Text="{Binding AngleTxt}" VerticalAlignment="Bottom" Margin="0,0,0,50" HorizontalAlignment="Center"/>
    <TextBlock Text="{Binding SpinNumber}" VerticalAlignment="Bottom" Margin="0,0,0,25" HorizontalAlignment="Center"/>
</Grid>

请注意，如果您从第一象限开始顺时针方向移动手指，这将起作用。它还需要更多的改进，例如在逆时针移动时处理情况，尤其是从 0 度更改为 360 度。