c# - 如何使用 xamarin.ios 创建圆形脉冲动画?
问题描述
我想在 xamarin.iOS 中创建循环脉冲动画。我参考了这个链接:https ://www.iostutorialjunction.com/2018/08/create-pulse-animaion-in-swift-tutorial-step-by-step-guide.html
初始化数组 CAShapeLayer[] arrLayerShapes = new CAShapeLayer[2];
并在 C# 中创建了相同的代码
void createPulse()
{
vwShowAnimation.UserInteractionEnabled = false;
for (int i = 0; i < 2; i++)
{
var centerPoint = new PointF((float)0, (float)0);
var circularPath = UIBezierPath.FromArc(center: centerPoint, radius: UIScreen.MainScreen.Bounds.Size.Width / 2, startAngle: 0, endAngle: 2 * (float)Math.PI, clockwise: true);
circularPulseLayer = new CAShapeLayer();
circularPulseLayer.Path = circularPath.CGPath;
circularPulseLayer.LineWidth = 2.5f;
circularPulseLayer.FillColor = UIColor.Clear.CGColor;
circularPulseLayer.StrokeColor = UIColor.FromRGB(36, 229, 186).CGColor;
circularPulseLayer.Opacity = 0;
circularPulseLayer.LineCap = CAShapeLayer.CapRound;
circularPulseLayer.Position = new CGPoint(vwAnimateLayer.Frame.Size.Width / 2, vwAnimateLayer.Frame.Size.Width / 2);
vwAnimateLayer.Layer.AddSublayer(circularPulseLayer);
arrLayerShapes.SetValue(circularPulseLayer, i);
}
var popTime = new DispatchTime(DispatchTime.Now, (long)(0.2));
var popTime2 = new DispatchTime(DispatchTime.Now, (long)(0.4));
var popTime3 = new DispatchTime(DispatchTime.Now, (long)(0.5));
//animateCircularPulseAt(0);
NSTimer.CreateScheduledTimer(2.3, true, (obj) =>
{
DispatchQueue.MainQueue.DispatchAfter(popTime, () =>
{
animateCircularPulseAt(0);
DispatchQueue.MainQueue.DispatchAfter(popTime2, () =>
{
animateCircularPulseAt(1);
});
});
});
}
动画方法
void animateCircularPulseAt(int index)
{
arrLayerShapes[index].StrokeColor = UIColor.FromRGB(36, 229, 186).CGColor;
var scaleAnimation = CABasicAnimation.FromKeyPath("transform.scale.xy");
scaleAnimation.From = NSNumber.FromFloat(0);
scaleAnimation.To = NSNumber.FromFloat(0.9f);
var opacityAnimation = CABasicAnimation.FromKeyPath("opacity");
opacityAnimation.From = NSNumber.FromFloat(0.9f);
opacityAnimation.To = NSNumber.FromFloat(0);
var groupAnimation = new CAAnimationGroup();
groupAnimation.Animations = new CAAnimation[] { scaleAnimation, opacityAnimation };
groupAnimation.Duration = 2.3f;
groupAnimation.RepeatCount = (nint)float.MaxValue;
groupAnimation.TimingFunction = CAMediaTimingFunction.FromName(CAMediaTimingFunction.EaseOut);
arrLayerShapes[index].AddAnimation(groupAnimation, "groupanimation");
}
解决方案
您不需要使用示例中显示的调度程序。您可以使用常规任务并等待它们:
while(pulse)
{
await Task.Delay(TimeSpan.FromMilliseconds(200));
AnimateCircularPulseAt(0);
await Task.Delay(TimeSpan.FromMilliseconds(400));
AnimateCircularPulseAt(1);
await Task.Delay(TimeSpan.FromMilliseconds(500));
AnimateCircularPulseAt(2);
await Task.Delay(TimeSpan.FromMilliseconds(500));
}
pulse
这会在is时不断脉冲动画true
。