.net 构造此Linq to事件拖放代码的最佳方法是什么?
我正在尝试处理一个拖放交互,包括鼠标下移、鼠标移动和鼠标上移 以下是我的解决方案的简化副本: 按下鼠标,创建椭圆并将其添加到画布 移动鼠标时,重新定位椭圆以跟随鼠标 鼠标向上移动时,更改画布的颜色,以便可以清楚地看到正在拖动的画布.net 构造此Linq to事件拖放代码的最佳方法是什么?,.net,drag-and-drop,c#-4.0,system.reactive,.net,Drag And Drop,C# 4.0,System.reactive,我正在尝试处理一个拖放交互,包括鼠标下移、鼠标移动和鼠标上移 以下是我的解决方案的简化副本: 按下鼠标,创建椭圆并将其添加到画布 移动鼠标时,重新定位椭圆以跟随鼠标 鼠标向上移动时,更改画布的颜色,以便可以清楚地看到正在拖动的画布 var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown"); var mouseUp = Observable.FromEvent<
var mouseDown = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonDown");
var mouseUp = Observable.FromEvent<MouseButtonEventArgs>(canvas, "MouseLeftButtonUp");
var mouseMove = Observable.FromEvent<MouseEventArgs>(canvas, "MouseMove");
Ellipse ellipse = null;
var q = from start in mouseDown.Do(x =>
{
// handle mousedown by creating a red ellipse,
// adding it to the canvas at the right position
ellipse = new Ellipse() { Width = 10, Height = 10, Fill = Brushes.Red };
Point position = x.EventArgs.GetPosition(canvas);
Canvas.SetLeft(ellipse, position.X);
Canvas.SetTop(ellipse, position.Y);
canvas.Children.Add(ellipse);
})
from delta in mouseMove.Until(mouseUp.Do(x =>
{
// handle mouse up by making the ellipse green
ellipse.Fill = Brushes.Green;
}))
select delta;
q.Subscribe(x =>
{
// handle mouse move by repositioning ellipse
Point position = x.EventArgs.GetPosition(canvas);
Canvas.SetLeft(ellipse, position.X);
Canvas.SetTop(ellipse, position.Y);
});
XAML非常简单
<Canvas x:Name="canvas"/>
这段代码有几点我不喜欢,我需要帮助重构它:
首先:mousedown和mouseup回调被指定为副作用。如果对q进行两次订阅,则会发生两次
其次,在mousemove回调之前指定mouseup回调。这使得阅读起来有点困难
第三,对椭圆的引用似乎是在一个愚蠢的地方。如果有两个订阅,该变量引用将很快被覆盖。我确信应该有某种方法可以利用let关键字向linq表达式引入一个变量,这意味着鼠标移动和鼠标向上处理程序都可以使用正确的椭圆引用
您将如何编写此代码?为了避免订阅的副作用,您应该发布您的observable。我认为像这样的事情可以:
public MainWindow()
{
InitializeComponent();
var mouseDown = Observable
.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonDown");
var mouseUp = Observable
.FromEvent<MouseButtonEventArgs>(this, "MouseLeftButtonUp");
var mouseMove = Observable
.FromEvent<MouseEventArgs>(this, "MouseMove");
var ellipses = mouseDown
.Select(args => new {
a = args,
el = new Ellipse
{
Width = 10, Height = 10, Fill = Brushes.Red
}})
.Publish();
ellipses
.Subscribe(elargs =>
{
var position = elargs.a.EventArgs.GetPosition(canvas);
Canvas.SetLeft(elargs.el, position.X);
Canvas.SetTop(elargs.el, position.Y);
canvas.Children.Add(elargs.el);
});
var elmove = from elargs in ellipses
from mm in mouseMove.TakeUntil(mouseUp)
select new { a = mm, el = elargs.el };
elmove.
Subscribe(elargs =>
{
var position = elargs.a.EventArgs.GetPosition(canvas);
Canvas.SetLeft(elargs.el, position.X);
Canvas.SetTop(elargs.el, position.Y);
});
var elmup = from elargs in ellipses
from mup in mouseUp
select elargs.el;
elmup.Subscribe(el => el.Fill = Brushes.Green);
ellipses.Connect();
}
我喜欢它的阅读方式。你/我可以在哪里读到更多关于订阅和Connect@rob-关于MSDN的丰塞卡传感器反应性扩展论坛是目前唯一的地方。。。我们需要看到更多这样的问题。