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WPF双滑块控件以及强制捕获鼠标事件焦点 - 普通的地球人
source link: https://www.cnblogs.com/tsliwei/p/16440364.html
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WPF双滑块控件以及强制捕获鼠标事件焦点
最近有个小需求要用双滑块表示一个取值范围,于是就简单做了个用户控件,在此记录下.
使用矩形Rectangle表示范围,椭圆Ellipse表示滑块,使用Canvas控制滑块的左右移动.
椭圆的鼠标按下事件里强制获取鼠标事件焦点,避免移动过快或移出控件范围时,滑块就不跟着跑了.椭圆的鼠标抬起事件释放强制获取鼠标事件焦点
需求比较简单,只定义了4个依赖属性,范围的最大值和最小值,取值的最大值和最小值.
接下来就是计算滑块和高亮矩形的位置,计算时注意减去椭圆Ellipse控件(圆)的半径,使圆心对准值,而不是左侧对准值.
鼠标移动的时候,计算当前位置对应的值,去改变依赖属性的值:
1 private void ell_MouseMove(object sender, MouseEventArgs e)
2 {
3 if (e.LeftButton == MouseButtonState.Pressed)
4 {
5 double percentage = e.GetPosition(rect).X / rect.ActualWidth;
6 double value = (Maximum - Minimum) * percentage + Minimum;
7 if (_ellFromPressed)
8 {
9 MinValue = (int)value;
10
11 }
12 if (_ellToPressed)
13 {
14 MaxValue = (int)value;
15 }
16 }
17 }
依赖属性的值变化,引起滑块的位置变化和高亮滑块宽度和位置的变化:
1 //最小值变化
2 private void MinValuePropertyChanged()
3 {
4 if (MinValue < Minimum)
5 {
6 MinValue = Minimum;
7 return;
8 }
9 if (MinValue > MaxValue)
10 {
11 MaxValue = MinValue;
12 }
13 //滑块位置变化
14 _offsetFrom = (MinValue - Minimum) * rect.ActualWidth / (Maximum - Minimum) - 8;
15 Canvas.SetLeft(ellFrom, _offsetFrom);
16 //高亮矩形长度和位置的变化
17 if (_offsetTo != -1)
18 {
19 double diff = _offsetTo - _offsetFrom;
20 if (diff >= 0)
21 {
22 rectHighLight.Width = diff;
23 Canvas.SetLeft(rectHighLight, _offsetFrom);
24 }
25 }
26 }
27
28 //最大值变化
29 private void MaxValuePropertyChanged()
30 {
31 if (MaxValue > Maximum)
32 {
33 MaxValue = Maximum;
34 return;
35 }
36 if (MaxValue < MinValue)
37 {
38 MinValue = MaxValue;
39 }
40 //滑块位置变化
41 _offsetTo = (MaxValue - Minimum) * rect.ActualWidth / (Maximum - Minimum) - 8;
42 Canvas.SetLeft(ellTo, _offsetTo);
43 //高亮矩形长度和位置的变化
44 if (_offsetFrom != -1)
45 {
46 double diff = _offsetTo - _offsetFrom;
47 if (diff >= 0)
48 {
49 rectHighLight.Width = diff;
50 Canvas.SetLeft(rectHighLight, _offsetFrom);
51 }
52 }
53 }
取值的TextBox没有封装在用户控件里,是单独的两个TextBox跟依赖属性双向绑定的.注意绑定的时候触发方式最好不要用PropertyChanged,没有防抖效果,不然体验不是很好.回车触发就可以了.
前台双向绑定:
1 <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
2 <local:DoubleThumbSlider x:Name="dts" Width="500" Minimum="100" Maximum="200"></local:DoubleThumbSlider>
3 <TextBox Name="tMin" Width="48" Text="{Binding ElementName=dts,Path=MinValue,UpdateSourceTrigger=Explicit,Mode=TwoWay}" PreviewKeyUp="tbox_PreviewKeyUp"></TextBox>
4 <TextBlock Margin="5,0" Text="-"></TextBlock>
5 <TextBox Name="tMax" Width="48" Text="{Binding ElementName=dts,Path=MaxValue,UpdateSourceTrigger=Explicit,Mode=TwoWay}" PreviewKeyUp="tbox_PreviewKeyUp"></TextBox>
6 </StackPanel>
后台回车触发:
1 private void tbox_PreviewKeyUp(object sender, KeyEventArgs e)
2 {
3 if (e.Key == Key.Enter)
4 {
5 TextBox tbox = (TextBox)sender;
6 var binding = tbox.GetBindingExpression(TextBox.TextProperty);
7 binding.UpdateSource();
8 }
9 }
参考连接:
1.https://docs.microsoft.com/zh-cn/dotnet/api/system.windows.uielement.capturemouse?view=windowsdesktop-6.0
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