Xamarin pan手势识别器无法提供准确的坐标
我正在用平移手势识别器做一些测试。设置非常简单,我有一个20x20的长方体视图,由一个相对布局设置。平移手势的处理程序Xamarin pan手势识别器无法提供准确的坐标,xamarin,xamarin.forms,Xamarin,Xamarin.forms,我正在用平移手势识别器做一些测试。设置非常简单,我有一个20x20的长方体视图,由一个相对布局设置。平移手势的处理程序 switch (args.StatusType) { case GestureStatus.Running: box.TranslationX = box.X + args.TotalX; box.TranslationY = box.Y +
switch (args.StatusType)
{
case GestureStatus.Running:
box.TranslationX = box.X + args.TotalX;
box.TranslationY = box.Y + args.TotalY;
break;
case GestureStatus.Completed:
box.TranslationX = 0;
box.TranslationY = 0;
break;
}
所以它运行正常,但当我尝试在屏幕上拖动boxview时,它无法正确转换值。当它试图重新绘制方框时,也会产生这种令人讨厌的闪烁效果。有没有更好的方法来做这件事?有什么方法可以消除闪烁吗?我在Xamarin论坛上找到了一个可以帮助您解决问题的实现()。这是Pan实现,我用我的项目对其进行了测试,发现“闪烁”效果不再存在:
private double startScale, currentScale, xOffset, yOffset, startX, startY;
...
public void OnPanUpdated(object sender, PanUpdatedEventArgs e)
{
switch (e.StatusType)
{
case GestureStatus.Started:
startX = e.TotalX;
startY = e.TotalY;
Content.AnchorX = 0;
Content.AnchorY = 0;
break;
case GestureStatus.Running:
var maxTranslationX = Content.Scale * Content.Width - Content.Width;
Content.TranslationX = Math.Min(0, Math.Max(-maxTranslationX, xOffset + e.TotalX - startX));
var maxTranslationY = Content.Scale * Content.Height - Content.Height;
Content.TranslationY = Math.Min(0, Math.Max(-maxTranslationY, yOffset + e.TotalY - startY));
break;
case GestureStatus.Completed:
xOffset = Content.TranslationX;
yOffset = Content.TranslationY;
break;
}
}
如果有帮助,请告诉我。我终于做到了,
假设我想在屏幕上拖动一个boxview,而不存在任何闪烁或协调精度问题,
我为要在屏幕上拖动的视图创建了一个容器,创建了一个
DragEnd事件和特定的EventArgs,当在主窗体中引发此事件时,我从布局的子列表中删除了此容器,并使用EventArgs携带的数据重新添加了新容器:
PanContainer.cs:
public class PanContainer : ContentView
{
public delegate void DragEndEventHandler(object sender, DragEventArgs e);
public PanContainer()
{
var panGesture = new PanGestureRecognizer();
panGesture.PanUpdated += OnPanUpdated;
GestureRecognizers.Add(panGesture);
}
public event DragEndEventHandler DragEnd;
private void OnPanUpdated(object sender, PanUpdatedEventArgs e)
{
switch (e.StatusType)
{
case GestureStatus.Running:
Content.TranslationX = e.TotalX;
Content.TranslationY = e.TotalY;
break;
case GestureStatus.Completed:
OnDragEnd(new DragEventArgs(Content.TranslationX, Content.TranslationY, Width, Height, X, Y));
break;
case GestureStatus.Started:
break;
case GestureStatus.Canceled:
break;
default:
throw new ArgumentOutOfRangeException();
}
}
protected virtual void OnDragEnd(DragEventArgs e)
{
DragEnd?.Invoke(this, e);
}
}
public class DragEventArgs : EventArgs
{
public DragEventArgs(double translationX, double translationY, double w, double h, double x, double y)
{
ContentTranslationX = translationX;
ContentTranslationY = translationY;
Width = w;
Height = h;
X = x;
Y = y;
}
public double ContentTranslationX { get; set; }
public double ContentTranslationY { get; set; }
public double Width { get; set; }
public double Height { get; set; }
public double X { get; set; }
public double Y { get; set; }
}
以主要形式:
private void DraggableOnDragEnd(object sender, DragEventArgs e)
{
var bv = new BoxView
{
BackgroundColor = Color.Brown
};
var pc = new PanContainer
{
Padding = 4,
BackgroundColor = Color.Chartreuse,
Content = bv
};
absoluteLayout.Children.Add(pc,
new Rectangle(e.X + e.ContentTranslationX, e.Y + e.ContentTranslationY, e.Width, e.Height));
Task.Run(() =>
{
Device.BeginInvokeOnMainThread(() =>
{
absoluteLayout.Children.Remove(
absoluteLayout.Children.First(x => x.GetType() == typeof(PanContainer)));
var v = absoluteLayout.Children.First(x => x.GetType() == typeof(PanContainer));
((PanContainer) v).DragEnd += DraggableOnDragEnd;
});
});
}
它工作正常,但可能有更好的方法来实现这一点。好吧,如果是您的长方体具有PangestureRecognitor,闪烁效果只是因为TotalX和TotalY与长方体平移坐标相关 试着改变
box.TranslationX = box.X + args.TotalX;
box.TranslationY = box.Y + args.TotalY;
借
它应该会起作用
编辑:它只涉及Xamarin Android,它对UWP的工作方式不同。扩展Julien的解决方案,该解决方案为我(在Android上)解决了这个问题 可以截取并重新计算包含在PanUpdatedEventArgs中的平移手势坐标,以抵消BoxView本身的移动。然后将新的参数传递给另一个处理程序:
public void Handle_PanUpdated(object sender, Xamarin.Forms.PanUpdatedEventArgs e)
{
double TranslationX = box.TranslationX;
double TranslationY = box.TranslationY;
double TotalX_Modified = e.TotalX + TranslationX;
double TotalY_Modified = e.TotalY + TranslationY;
if (Device.RuntimePlatform == Device.Android)
{
e = new PanUpdatedEventArgs(e.StatusType, e.GestureId, TotalX_Modified, TotalY_Modified);
}
Handle_PanUpdate_Modified(sender, e);
}
您使用的是什么布局?它位于相对布局中。我已经实现了Xamarin()提供的示例,并且出现了相同的行为。我尝试移动的元素在手势过程中闪烁(实际上,它从一个位置快速切换到另一个位置,这导致了这种“闪烁”效果)。感谢您的回复!我现在正在处理它,但是maxTranslation总是返回为0。看起来应该是var maxtransationx=Content.Scale*Screen.Width-Content.Width?您使用屏幕宽度而不是内容宽度的位置?还是我走错了方向?
public void Handle_PanUpdated(object sender, Xamarin.Forms.PanUpdatedEventArgs e)
{
double TranslationX = box.TranslationX;
double TranslationY = box.TranslationY;
double TotalX_Modified = e.TotalX + TranslationX;
double TotalY_Modified = e.TotalY + TranslationY;
if (Device.RuntimePlatform == Device.Android)
{
e = new PanUpdatedEventArgs(e.StatusType, e.GestureId, TotalX_Modified, TotalY_Modified);
}
Handle_PanUpdate_Modified(sender, e);
}