Simple WPF: WPF 实现按钮的长按，短按功能
最新内容优先发布于个人博客：小虎技术分享站，随后逐步搬运到博客园。实现了一个支持长短按得按钮组件，单击可以触发Click事件，长按可以触发LongPressed事件，长按松开时触发LongClick事件。源码请自取：Github
长按阈值属性的建立
为了方便在xaml中使用，我们先配置一个DependencyProperty叫做LongPressTime来作为界定长按的阈值
public class LongPressButtonEx : Button
{
public static readonly DependencyProperty LongPressTimeProperty
= DependencyProperty.Register("LongPressTime", typeof(int),
typeof(LongPressButtonEx), new PropertyMetadata(500));
public int LongPressTime
{
set => SetValue(LongPressTimeProperty, value);
get => (int)GetValue(LongPressTimeProperty);
}
}定义完成后可以在Xaml设计器中使用LongPressTime这个拓展属性
<Window x:
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:LongPressButton"
mc:Ignorable="d"
Title="MainWindow" Height="450" Width="800">
<Grid>
<local:LongPressButtonEx Width="96" Height="48" LongPressTime="200">
Button
</local:LongPressButtonEx>
</Grid>
</Window>长按的定时器判定方法
C#中的4种定时器，在WPF中需要使用Dispater Timer
定义一个DispatcherTimer来监控是否按下达到了长按
private DispatcherTimer _pressDispatcherTimer;
private void OnDispatcherTimeOut(object sender, EventArgs e)
{
_pressDispatcherTimer?.Stop();
Debug.WriteLine($"Timeout {LongPressTime}");
}
protected override void OnMouseLeftButtonDown(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonDown(e);
Debug.WriteLine("Button: Mouse down.");
if (_pressDispatcherTimer == null)
{
_pressDispatcherTimer = new DispatcherTimer();
_pressDispatcherTimer.Tick += OnDispatcherTimeOut;
_pressDispatcherTimer.Interval = new TimeSpan(0, 0, 0, 0, LongPressTime);
_pressDispatcherTimer.Start();
Debug.WriteLine("Button: Timer started");
}
}
protected override void OnMouseLeftButtonUp(MouseButtonEventArgs e)
{
base.OnMouseLeftButtonUp(e);
Debug.WriteLine("Button: Mouse up.");
_pressDispatcherTimer?.Stop();
_pressDispatcherTimer = null;
}现在分别点击和长按按钮可以看到调试输出
...
# 点击
Button: Mouse down.
Button: Timer started
Button: Mouse up.
# 长按
Button: Mouse down.
Button: Timer started
Timeout 200
Button: Mouse up.实现长按事件的定义
现在作为一个自定义控件，我们需要在长按后发出一个RoutedEvent，并修改部分之前的代码抛出事件
/// <summary>
/// LongPress Routed Event
/// </summary>
public static readonly RoutedEvent LongPressEvent
= EventManager.RegisterRoutedEvent("LongPress",
RoutingStrategy.Bubble,
typeof(RoutedEventHandler),
typeof(LongPressButtonEx));
public event RoutedEventHandler LongPress
{
add => AddHandler(LongPressEvent, value);
remove => RemoveHandler(LongPressEvent, value);
}
private void OnDispatcherTimeOut(object sender, EventArgs e)
{
_pressDispatcherTimer?.Stop();
Debug.WriteLine($"Timeout {LongPressTime}");
RaiseEvent(new RoutedEventArgs(LongPressEvent)); // raise the long press event
}回到窗体的代码中，添加事件的响应
<local:LongPressButtonEx Height="48" Width="256" LongPressTime="200"
LongPress="LongPressButtonEx_LongPress"
Click="LongPressButtonEx_Click">
Click or Long Press Me!
</local:LongPressButtonEx>C#代码如下，长按按钮会显示Long Pressed，单击会是Click
private void LongPressButtonEx_LongPress(object sender, RoutedEventArgs e)
{
if (sender is LongPressButtonEx btn)
{
btn.Content = "Long Pressed";
}
}
private void LongPressButtonEx_Click(object sender, RoutedEventArgs e)
{
if (sender is LongPressButtonEx btn)
{
btn.Content = "Clicked";
}
}
发现Click和LongPress都可以响应，但是当松开按钮时又变成了Click，原因是鼠标松开时响应了默认的Click事件
现在对按钮控件默认的OnClick函数稍作修改，可以让Click也不出问题
/// <summary>
/// DependencyProperty for IsLongPress
/// </summary>
public static readonly DependencyProperty IsLongPressProperty
= DependencyProperty.Register("IsLongPress", typeof(bool),
typeof(LongPressButtonEx), new PropertyMetadata(false));
public bool IsLongPress
{
set => SetValue(IsLongPressProperty, value);
get => (bool)GetValue(IsLongPressProperty);
}
private void OnDispatcherTimeOut(object sender, EventArgs e)
{
IsLongPress = true;
_pressDispatcherTimer?.Stop();
Debug.WriteLine($"Timeout {LongPressTime}");
RaiseEvent(new RoutedEventArgs(LongPressEvent)); // raise the long press event
}
protected override void OnClick()
{
if (!IsLongPress)
{
base.OnClick();
}
else
{
RaiseEvent(new RoutedEventArgs(LongPressReleaseEvent)); // raise the long press event
IsLongPress = false;
}
}之后再进行点击操作，我们就可以看到符合预期的结果
长按+Style按钮的展示效果
外观Style自定义见这篇文章：WPF自定义按钮外形
参考链接
UIElement.MouseLeftButtonDown Event
用户控件自定义 DependencyProperty 属性使用教程
WPF 中 DispatcherTimer 计时器
如何：创建自定义路由事件
WPF 自定义带自定义参数路由事件
Use WPF Style in another assemble
来源:https://www.cnblogs.com/mrchip/p/18289007
免责声明：由于采集信息均来自互联网，如果侵犯了您的权益，请联系我们【E-Mail:cb@itdo.tech】 我们会及时删除侵权内容，谢谢合作！
页:
[1]