blocks|key|601120|text|我在Xamarin论坛上找到了一个可以帮助你解决问题的实现(Pinch+and+Pan+gesture+recognizers+not+working+on+Android+project)。下面是Pan的实现，我用我的项目测试了它，并注意到“闪烁”效果不再存在：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|601121|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+%2B+e.TotalX+-+startX));

++++++++++++var+maxTranslationY+=+Content.Scale+*+Content.Height+-+Content.Height;
++++++++++++Content.TranslationY+=+Math.Min(0,+Math.Max(-maxTranslationY,+yOffset+%2B+e.TotalY+-+startY));
++++++++++++break;

++++++++case+GestureStatus.Completed:
++++++++++++xOffset+=+Content.TranslationX;
++++++++++++yOffset+=+Content.TranslationY;
++++++++++++break;
++++}
}|code-block|syntax|javascript|601122|如果这有帮助，请告诉我。|601123|entityMap|0|LINK|mutability|MUTABLE|url|https://forums.xamarin.com/discussion/60374/pinch-and-pan-gesture-recognizers-not-working-on-android-project^0|U|1S|0|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@$A|T|B|U|1|V]]|C|$]]|$1|D|3|E|5|F|7|W|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|X|8|@]|9|@]|C|$]]|$1|K|3|-4|5|6|7|Y|8|@]|9|@]|C|$]]]|L|$M|$5|N|O|P|C|$Q|R]]]]

I found an implementation on Xamarin Forums that can help you to fix your problem (<a href="https://forums.xamarin.com/discussion/60374/pinch-and-pan-gesture-recognizers-not-working-on-android-project" rel="nofollow">Pinch and Pan gesture recognizers not working on Android project</a>). Here is the Pan implementation, I tested it with my project and noticed that the "flashing" effect is no more present:

<pre><code>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;
 }
}
</code></pre>

Let me know if this helps.

blocks|key|3780706|text|我终于完成了，假设我想要在屏幕上拖动一个框视图而没有任何闪烁或协调精度问题，我为我想要在屏幕上拖动的视图创建了一个容器，创建了一个DragEnd事件和它上的特定EventArgs，当这个事件在主窗体中引发时，我从布局的子列表中删除了这个容器，并使用EventArgs携带的数据重新添加了一个新的容器：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3780707|PanContainer.cs：|3780708|public+class+PanContainer+:+ContentView
{
++++public+delegate+void+DragEndEventHandler(object+sender,+DragEventArgs+e);

++++public+PanContainer()
++++{
++++++++var+panGesture+=+new+PanGestureRecognizer();
++++++++panGesture.PanUpdated+%2B=+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;+}
}|code-block|syntax|javascript|3780709|在主要形式中：|3780710|++++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+%2B+e.ContentTranslationX,+e.Y+%2B+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+%2B=+DraggableOnDragEnd;
++++++++++++});
++++++++});
++++}|3780711|enter+image+description+here|offset|length|3780712|它可以正常工作，但也许有更好的方法。|3780713|entityMap|0|LINK|mutability|MUTABLE|url|https://i.stack.imgur.com/teU0v.gif^0|0|0|0|0|0|0|S|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|11|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|12|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|13|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|14|8|@]|9|@]|A|$G|H]]|$1|M|3|N|5|6|7|15|8|@]|9|@$O|16|P|17|1|18]]|A|$]]|$1|Q|3|R|5|6|7|19|8|@]|9|@]|A|$]]|$1|S|3|-4|5|6|7|1A|8|@]|9|@]|A|$]]]|T|$U|$5|V|W|X|A|$Y|Z]]]]

I've finally done it, 
Assume I want to drag a boxview over the screen without any flashing or coordination accuracy issue, 
I created a container for the view that I want to drag over the screen, Created a 
DragEnd event and specific EventArgs on it and when this event raised in the main form I deleted this container from layout's children list and re added new one with data that carried by EventArgs :

PanContainer.cs :

<pre><code>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; }
}
</code></pre>

and in the Main form :

<pre><code> 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(() =&gt;
 {
 Device.BeginInvokeOnMainThread(() =&gt;
 {
 absoluteLayout.Children.Remove(
 absoluteLayout.Children.First(x =&gt; x.GetType() == typeof(PanContainer)));
 var v = absoluteLayout.Children.First(x =&gt; x.GetType() == typeof(PanContainer));
 ((PanContainer) v).DragEnd += DraggableOnDragEnd;
 });
 });
 }
</code></pre>

<a href="https://i.stack.imgur.com/teU0v.gif" rel="nofollow noreferrer">enter image description here</a>

It works correctly but maybe there is better way to do it ..

blocks|key|137|text|好吧，如果是你的盒子有PanGestureRecognizer，闪烁的效果很简单，因为TotalX和TotalY是相对于盒子转换坐标的。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|138|试着改变|139|box.TranslationX+=+box.X+%2B+args.TotalX;
box.TranslationY+=+box.Y+%2B+args.TotalY;|code-block|syntax|javascript|140|通过|141|box.TranslationX+=+box.TranslationX+%2B+args.TotalX;
box.TranslationY+=+box.TranslationY+%2B+args.TotalY;|142|应该能行得通。|143|编辑:它只与Xamarin+Android有关，它对UWP的工作方式不同。|144|entityMap^0|1Q|2|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@$9|X|A|Y|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|Z|8|@]|D|@]|E|$]]|$1|H|3|I|5|J|7|10|8|@]|D|@]|E|$K|L]]|$1|M|3|N|5|6|7|11|8|@]|D|@]|E|$]]|$1|O|3|P|5|J|7|12|8|@]|D|@]|E|$K|L]]|$1|Q|3|R|5|6|7|13|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|14|8|@]|D|@]|E|$]]|$1|U|3|-4|5|6|7|15|8|@]|D|@]|E|$]]]|V|$]]

Well, if it is your box which have the PanGestureRecognizer, the flashing effect is simply because TotalX and TotalY are relative to box translation coordinates.

Try changing

<pre><code>box.TranslationX = box.X + args.TotalX;
box.TranslationY = box.Y + args.TotalY;
</code></pre>

by

<pre><code>box.TranslationX = box.TranslationX + args.TotalX;
box.TranslationY = box.TranslationY + args.TotalY;
</code></pre>

It should work.

edit: it only concerns Xamarin Android, it work differently for UWP.

blocks|key|601222|text|扩展Julien的解决方案，它为我解决了这个问题(在安卓上)……|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|601223|包含在PanUpdatedEventArgs，中的平移手势坐标可以被截取并重新计算，以对BoxView本身的移动进行计数。然后将新的参数传递给另一个处理程序：|601224|++++public+void+Handle_PanUpdated(object+sender,+Xamarin.Forms.PanUpdatedEventArgs+e)
++++{
++++++++double+TranslationX+=+box.TranslationX;
++++++++double+TranslationY+=+box.TranslationY;

++++++++double+TotalX_Modified+=+e.TotalX+%2B+TranslationX;
++++++++double+TotalY_Modified+=+e.TotalY+%2B+TranslationY;

++++++++if+(Device.RuntimePlatform+==+Device.Android)
++++++++{+
++++++++++++e+=+new+PanUpdatedEventArgs(e.StatusType,+e.GestureId,+TotalX_Modified,+TotalY_Modified);
++++++++}

++++++++Handle_PanUpdate_Modified(sender,+e);
++++}|code-block|syntax|javascript|601225|entityMap^0|2|7|0|3|J|1U|2|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|6|7|R|8|@$9|S|A|T|B|C]|$9|U|A|V|B|C]]|D|@]|E|$]]|$1|H|3|I|5|J|7|W|8|@]|D|@]|E|$K|L]]|$1|M|3|-4|5|6|7|X|8|@]|D|@]|E|$]]]|N|$]]

Expanding on Julien's solution which solved the issue for me (on Android)...

The Pan Gesture coordinates, contained in the PanUpdatedEventArgs, can be intercepted and recalculated to counter for the movement of the BoxView itself. Then pass the new Args on to another handler:

<pre><code> 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);
 }
</code></pre>

I'm doing some testing with a pan gesture recognizer. The setup is pretty simple, I have a box view that is 20x20 and is being set by a relative layout. The handler for the pan gesture 

<pre><code>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;
 }
</code></pre>

So it runs ok, but when I try dragging the boxview around the screen, it doesn't translate the values properly. It also gives this really nasty flashing effect as it tries to redraw the box. Is there a better way to go about doing this? Is there a way to get rid of the flashing?

Xamarin pan gesture recognizer not giving accurate coordinates

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

文章

问答

视频

学习中心

腾讯云实验室

直播

竞赛

腾讯云代码分析专区

腾讯iOA零信任安全管理系统专区

腾讯云架构师技术同盟交流圈

腾讯云数据库专区

腾讯云顾问专区

腾讯云原生专区

腾讯混元专区

腾讯云TCE专区

腾讯云Lighthouse专区

腾讯云HAI专区

腾讯云Edgeone专区

腾讯云存储专区

腾讯云智能专区

腾讯轻联专区 

腾讯云开发专区

TAPD专区

腾讯轻量云游戏服专区

腾讯云最具价值专家

腾讯云架构师技术同盟

腾讯云创作之星

腾讯云开发者先锋

腾讯云代码助手

云原生构建

TAPD 敏捷项目管理

Cloud Studio

SDK中心

API中心

命令行工具

涵盖代码开发、场景应用、自动测试全流程，助你从零构建专属AI助手

一站式MCP教程库，解锁AI应用新玩法

我正在用一个手势识别器做一些测试。设置非常简单，我有一个20x20的框视图，并且是由相对布局设置的。平移手势的处理程序switch (args.StatusType)            {                case GestureStatus.Running:                    b...

问Xamarin pan手势识别器没有给出准确的坐标
EN

Stack Overflow用户

社区

活动

圈层

关于

腾讯云开发者

热门产品

热门推荐

更多推荐

问Xamarin pan手势识别器没有给出准确的坐标EN