1.思路主要代码
wpf的gridline原本效果是虚线类型的。有时候需要设计成表格形式的，因此有了用附加属性来自动绘制边框线的想法。
思路：绘制Line并添加到grid的children里，但效果并不理想，会出现锯齿，像素对齐，模糊等问题。
UseLayoutRounding="False"
SnapsToDevicePixels="True"
RenderOptions.EdgeModeProperty 貌似都没起作用。
于是想到了用border来实现，简单又实用吧 哈哈。
大致思路如下：绘制border的左边框和上边框，在边界的时候考虑边界封闭。然后将border平移一半的距离。这样边框就居中并且包围了所有的线。
主要代码如下：
using System.Windows; using System.Windows.Controls; using System.Windows.Media; namespace 用附加属性修改Grid的边框 { 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; //边界考虑 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); //边界考虑 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 线颜色 // 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 线宽度 // 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 是否显示线 // 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 } }