WPF如何利用附加屬性修改ShowGridLines效果詳解

2019-10-29 21:05:59

字體：大中小

來源：轉載

供稿：網友

前言

附加屬性是說一個屬性本來不屬于某個對象，但由于某種需求而被后來附加上，也就是把對象放入一個特定環境后對象才具有的屬性就稱為附加屬性，附加屬性的作用就是將屬性與數據類型解耦，讓數據類型的設計更加靈活，舉例，一個TextBox被放在不同的布局容器中時就會有不同的布局屬性，這些屬性就是由布局容器為TextBox附加上的，附加屬性的本質就是依賴屬性，二者僅僅在注冊和包裝器上有一點區別

小技巧，在VS中輸入propa后，連按兩次tab鍵，可以添加好一個附加屬性的框架，繼續按tab鍵，可以繼續修改附加屬性的內容

本文主要介紹的是關于WPF用附加屬性修改ShowGridLines效果的相關內容，下面話不多說了，來一起看看詳細的介紹吧。

1.思路主要代碼

wpf的gridline原本效果是虛線類型的。有時候需要設計成表格形式的，因此有了用附加屬性來自動繪制邊框線的想法。

思路：繪制Line并添加到grid的children里，但效果并不理想，會出現鋸齒，像素對齊，模糊等問題。

UseLayoutRounding="False"
SnapsToDevicePixels="True"

RenderOptions.EdgeModeProperty 貌似都沒起作用。

于是想到了用border來實現，簡單又實用吧哈哈。

大致思路如下：

繪制border的左邊框和上邊框，在邊界的時候考慮邊界封閉。然后將border平移一半的距離。這樣邊框就居中并且包圍了所有的線。

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主要代碼如下：

using System.Windows;using System.Windows.Controls;using System.Windows.Media;namespace 用附加屬性修改Grid的邊框{ public class GridHelper {  private static void RefreshGrid(Grid grid, int lineWidth, Brush color)  {   for (var i = grid.Children.Count - 1; i > 0; i--)   {    var child = grid.Children[i];    var bd = child as Border;    if (bd != null && bd.Tag != null && bd.Tag.ToString() == "gridline")    {     grid.Children.Remove(bd);    }   }   var rows = grid.RowDefinitions.Count;   var cols = grid.ColumnDefinitions.Count;   //邊界考慮   if (rows == 0)   {    rows = 1;   }   if (cols == 0)   {    cols = 1;   }   //生成行列   for (var i = 0; i < rows; i++)   {    for (var j = 0; j < cols; j++)    {     var thick = new Thickness(lineWidth, lineWidth, 0, 0);     var margin = new Thickness(-lineWidth/2d, -lineWidth/2d, 0, 0);     //邊界考慮     if (i == 0)     {      margin.Top = 0;     }     if (i == rows - 1)     {      thick.Bottom = lineWidth;     }     if (j == 0)     {      margin.Left = 0;     }     if (j == cols - 1)     {      thick.Right = lineWidth;     }     var bd = new Border     {      BorderThickness = thick,      Margin = margin,      BorderBrush = color,      Tag = "gridline"     };     Grid.SetRow(bd, i);     Grid.SetColumn(bd, j);     grid.Children.Add(bd);    }   }   grid.InvalidateArrange();   grid.InvalidateVisual();  }   #region 線顏色  // Using a DependencyProperty as the backing store for LineColor. This enables animation, styling, binding, etc...  public static readonly DependencyProperty LineColorProperty =   DependencyProperty.RegisterAttached("LineColor", typeof (Brush), typeof (GridHelper),    new PropertyMetadata(Brushes.Black, LineColorPropertyChanged));   public static Brush GetLineColor(DependencyObject obj)  {   return (Brush) obj.GetValue(LineColorProperty);  }   public static void SetLineColor(DependencyObject obj, Brush value)  {   obj.SetValue(LineColorProperty, value);  }    private static void LineColorPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)  {   var grid = d as Grid;   if (grid == null)   {    return;   }   var showLines = GetShowGridLines(grid);   var color = GetLineColor(grid);   var lineWidth = GetLineWidth(grid);   if (showLines)   {    // grid.SnapsToDevicePixels = true;    grid.Loaded += delegate { RefreshGrid(grid, lineWidth, color); };   }  }   #endregion   #region 線寬度   // Using a DependencyProperty as the backing store for LineWidth. This enables animation, styling, binding, etc...  public static readonly DependencyProperty LineWidthProperty =   DependencyProperty.RegisterAttached("LineWidth", typeof (int), typeof (GridHelper),    new PropertyMetadata(1, LineWidthPropertyChanged));   public static int GetLineWidth(DependencyObject obj)  {   return (int) obj.GetValue(LineWidthProperty)    ;  }    public static void SetLineWidth(DependencyObject obj, int value)  {   obj.SetValue(LineWidthProperty, value);  }    private static void LineWidthPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)  {   var grid = d as Grid;   if (grid == null)   {    return;   }   var showLines = GetShowGridLines(grid);   var color = GetLineColor(grid);   var lineWidth = GetLineWidth(grid);   if (showLines)   {    // grid.SnapsToDevicePixels = true;    grid.Loaded += delegate { RefreshGrid(grid, lineWidth, color); };   }  }   #endregion  #region 是否顯示線  // Using a DependencyProperty as the backing store for ShowGridLines. This enables animation, styling, binding, etc...  public static readonly DependencyProperty ShowGridLinesProperty =   DependencyProperty.RegisterAttached("ShowGridLines", typeof (bool), typeof (GridHelper),    new PropertyMetadata(false, ShowGridLinesPropertyChanged));   public static bool GetShowGridLines(DependencyObject obj)  {   return (bool) obj.GetValue(ShowGridLinesProperty);  }   public static void SetShowGridLines(DependencyObject obj, bool value)  {   obj.SetValue(ShowGridLinesProperty, value);  }    private static void ShowGridLinesPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)  {   var grid = d as Grid;   if (grid == null)   {    return;   }   var showLines = GetShowGridLines(grid);   var color = GetLineColor(grid);   var lineWidth = GetLineWidth(grid);   if (showLines)   {    // grid.SnapsToDevicePixels = true;    grid.Loaded += delegate { RefreshGrid(grid, lineWidth, color); };   }  }  #endregion }}

2.效果圖

效果還可以，任何分辨率下，任何邊框大小，都沒有出現像素對齊或者模糊問題。圖中的虛線是grid的默認gridLine，紅色和綠色是自定義的gridline，跟虛線完美重合。

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