WPF ListBox的进阶使用(二)

项目中经常使用需要根据搜索条件查询数据,然后用卡片来展示数据。用卡片展示数据时,界面的宽度发生变化,希望显示的卡片数量也跟随变化。WrapPanel虽然也可以实现这个功能,但是将多余的部分都留在行尾,十分不美观,最好是能够将多余的宽度平分在每个ListBoxItem之间,比较美观,也符合项目需求。如下便是我自己实现的Panel:

  1 using System;
  2 using System.Collections.Generic;
  3 using System.Linq;
  4 using System.Text;
  5 using System.Threading.Tasks;
  6 using System.Windows;
  7 using System.Windows.Controls;
  8 
  9 namespace WpfDemo
 10 {
 11     public class MyWrapPanel : Panel
 12     {
 13         protected override System.Windows.Size MeasureOverride(System.Windows.Size availableSize)
 14         {
 15             Size currentLineSize = new Size();
 16             Size panelSize = new Size();
 17 
 18             foreach (UIElement element in base.InternalChildren)
 19             {
 20                 element.Measure(availableSize);
 21                 Size desiredSize = element.DesiredSize;
 22 
 23                 if (currentLineSize.Width + desiredSize.Width > availableSize.Width)
 24                 {
 25                     panelSize.Width = Math.Max(currentLineSize.Width, panelSize.Width);
 26                     panelSize.Height += currentLineSize.Height;
 27                     currentLineSize = desiredSize;
 28 
 29                     if (desiredSize.Width > availableSize.Width)
 30                     {
 31                         panelSize.Width = Math.Max(desiredSize.Width, panelSize.Width);
 32                         panelSize.Height += desiredSize.Height;
 33                         currentLineSize = new Size();
 34                     }
 35                 }
 36                 else
 37                 {
 38                     currentLineSize.Width += desiredSize.Width;
 39                     currentLineSize.Height = Math.Max(desiredSize.Height, currentLineSize.Height);
 40                 }
 41             }
 42 
 43             panelSize.Width = Math.Max(currentLineSize.Width, panelSize.Width);
 44             panelSize.Height += currentLineSize.Height;
 45 
 46             return panelSize;
 47         }
 48 
 49         protected override System.Windows.Size ArrangeOverride(System.Windows.Size finalSize)
 50         {
 51             int firstInLine = 0;
 52             int lineCount = 0;
 53 
 54             Size currentLineSize = new Size();
 55 
 56             double accumulatedHeight = 0;
 57 
 58             UIElementCollection elements = base.InternalChildren;
 59             double interval = 0.0;
 60             for (int i = 0; i < elements.Count; i++)
 61             {
 62 
 63                 Size desiredSize = elements[i].DesiredSize;
 64 
 65                 if (currentLineSize.Width + desiredSize.Width > finalSize.Width) //need to switch to another line
 66                 {
 67                     interval = (finalSize.Width - currentLineSize.Width) / (i - firstInLine + 2);
 68                     arrangeLine(accumulatedHeight, currentLineSize.Height, firstInLine, i, interval);
 69 
 70                     accumulatedHeight += currentLineSize.Height;
 71                     currentLineSize = desiredSize;
 72 
 73                     if (desiredSize.Width > finalSize.Width) //the element is wider then the constraint - give it a separate line                    
 74                     {
 75                         arrangeLine(accumulatedHeight, desiredSize.Height, i, ++i, 0);
 76                         accumulatedHeight += desiredSize.Height;
 77                         currentLineSize = new Size();
 78                     }
 79                     firstInLine = i;
 80                     lineCount++;
 81                 }
 82                 else //continue to accumulate a line
 83                 {
 84                     currentLineSize.Width += desiredSize.Width;
 85                     currentLineSize.Height = Math.Max(desiredSize.Height, currentLineSize.Height);
 86                 }
 87             }
 88 
 89             if (firstInLine < elements.Count)
 90             {
 91                 if (lineCount == 0)
 92                 {
 93                     interval = (finalSize.Width - currentLineSize.Width) / (elements.Count - firstInLine + 1);
 94                 }
 95                 arrangeLine(accumulatedHeight, currentLineSize.Height, firstInLine, elements.Count, interval);
 96             }
 97                 
 98 
 99             return finalSize;
100         }
101 
102         private void arrangeLine(double y, double lineHeight, int start, int end, double interval)
103         {
104             double x = 0;
105             UIElementCollection children = InternalChildren;
106             for (int i = start; i < end; i++)
107             {
108                 x += interval;
109                 UIElement child = children[i];
110                 child.Arrange(new Rect(x, y, child.DesiredSize.Width, lineHeight));
111                 x += child.DesiredSize.Width;
112             }
113         }
114     }
115 }

接下来,便是将这个MyWrapPanel作为ListBox的ItemsPanelTemplate即可:

 1 <Window x:Class="WpfDemo.MainWindow"
 2 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
 3         xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
 4         xmlns:comm="clr-namespace:WpfDemo.CommonControls;assembly=WpfDemo.CommonControls"
 5         xmlns:local="clr-namespace:WpfDemo"
 6         Title="MainWindow" Height="350" Width="525">
 7     
 8     <Grid>
 9         <ListBox ItemsSource="{Binding DataSource}" ScrollViewer.HorizontalScrollBarVisibility="Disabled"
10                  VerticalAlignment="Center" BorderThickness="0">
11             <ListBox.ItemsPanel>
12                 <ItemsPanelTemplate>
13                     <local:MyWrapPanel IsItemsHost="True"/>
14                 </ItemsPanelTemplate>
15             </ListBox.ItemsPanel>
16             <ListBox.ItemContainerStyle>
17                 <Style TargetType="{x:Type ListBoxItem}">
18                     <Setter Property="Template">
19                         <Setter.Value>
20                             <ControlTemplate TargetType="{x:Type ListBoxItem}">
21                                 <Border HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Background="Green" BorderBrush="Yellow" BorderThickness="1">
22                                     <TextBlock Text="{Binding CameraName}" Width="100" HorizontalAlignment="Center" VerticalAlignment="Center"/>
23                                 </Border>
24                             </ControlTemplate>
25                         </Setter.Value>
26                     </Setter>
27                 </Style>
28             </ListBox.ItemContainerStyle>
29             <ListBox.Style>
30                 <Style TargetType="{x:Type ListBox}">
31                     
32                 </Style>
33             </ListBox.Style>
34         </ListBox>
35     </Grid>
36 </Window>

界面对应的ViewModel:

 1 using System;
 2 using System.Collections.Generic;
 3 using System.Collections.ObjectModel;
 4 using System.Linq;
 5 using System.Text;
 6 using System.Threading.Tasks;
 7 using System.Windows.Threading;
 8 
 9 namespace WpfDemo
10 {
11     public class MainWindowVM : NotifyPropertyBase
12     {
13         private DispatcherTimer timer;
14         public MainWindowVM()
15         {
16             DataSource = new ObservableCollection<WndViewModel>();
17             Colums = 1;
18             for(int i =0; i < 60; ++i)
19             {
20                 var temp = new WndViewModel()
21                 {
22                     CameraName = string.Format("Camera {0}", ++count),
23                 };
24                 DataSource.Add(temp);
25             }
26             //timer = new DispatcherTimer();
27             //timer.Interval = new TimeSpan(0, 0, 1);
28             //timer.Tick += timer_Tick;
29             //timer.Start();
30         }
31 
32         private int count = 0;
33         void timer_Tick(object sender, EventArgs e)
34         {
35             var temp = new WndViewModel()
36             {
37                 CameraName = string.Format("Camera {0}", ++count),
38             };
39             DataSource.Add(temp);
40             Console.WriteLine(temp.CameraName);
41             if (count <= 6)
42             {
43                 Colums = count;
44             }
45             else if (count > 100)
46             {
47                 count = 0;
48                 DataSource.Clear();
49                 Colums = 1;
50             }
51         }
52 
53         private int colums;
54         public int Colums
55         {
56             get { return colums; }
57             set
58             {
59                 SetProperty(ref colums, value);
60             }
61         }
62 
63         private ObservableCollection<WndViewModel> dataSource;
64         public ObservableCollection<WndViewModel> DataSource
65         {
66             get { return dataSource; }
67             set
68             {
69                 SetProperty(ref dataSource, value);
70             }
71         }
72     }
73 }

运行结果:

拉伸后:

 

posted @ 2018-08-30 19:34 Johar 阅读(...) 评论(...) 编辑 收藏