我有一个连接到远程服务器并在需要时轮询数据的应用程序。它有一个 TreeView，其中节点表示可用的对象，文本的颜色表示数据是否已加载；gray-italicized 表示未加载，黑色，常规文本已加载。
目前我已将 TreeView 设置为 OwnderDrawText 并让 TreeView.DrawNode 函数简单地绘制文本，如下所示：
private void TreeViewDrawNode(object sender, DrawTreeNodeEventArgs e)
{
if (!e.Node.IsVisible)
{
return;
}
bool bLoaded = false;
if (e.Bounds.Location.X >= 0 && e.Bounds.Location.Y >= 0)
{
if(e.Node.Tag != null)
{
//...
// code determining whether data has been loaded is done here
// setting bLoaded true or false
//...
}
else
{
e.DrawDefault = true;
return;
}
Font useFont = null;
Brush useBrush = null;
if (bLoaded)
{
useFont = e.Node.TreeView.Font;
useBrush = SystemBrushes.WindowText;
}
else
{
useFont = m_grayItallicFont;
useBrush = SystemBrushes.GrayText;
}
e.Graphics.DrawString(e.Node.Text, useFont, useBrush, e.Bounds.Location);
}
}
我认为这就足够了，但是，这引起了一些问题；
- When a node is selected, focused or not, it doesn't envelop all of the text, example (I hope imgur is ok).
- 当节点聚焦时，虚线轮廓也不显示。如果将其与此示例进行比较。文本中带有“日志”的节点使用的是 e.DefaultDraw = true
我尝试按照this question中给出的示例进行操作。它看起来像这样：
private void TreeViewDrawNode(object sender, DrawTreeNodeEventArgs e)
{
if (!e.Node.IsVisible)
{
return;
}
bool bLoaded = false;
if (e.Bounds.Location.X >= 0 && e.Bounds.Location.Y >= 0)
{
if(e.Node.Tag != null)
{
//...
// code determining whether data has been loaded is done here
// setting bLoaded true or false
//...
}
else
{
e.DrawDefault = true;
return;
}
//Select the font and brush depending on whether the property has been loaded
Font useFont = null;
Brush useBrush = null;
if (bLoaded)
{
useFont = e.Node.TreeView.Font;
useBrush = SystemBrushes.WindowText;
}
else
{
//member variable defined elsewhere
useFont = m_grayItallicFont;
useBrush = SystemBrushes.GrayText;
}
//Begin drawing of the text
//Get the rectangle that will be used to draw
Rectangle itemRect = e.Bounds;
//Move the rectangle over by 1 so it isn't on top of the check box
itemRect.X += 1;
//Figure out the text position
Point textStartPos = new Point(itemRect.Left, itemRect.Top);
Point textPos = new Point(textStartPos.X, textStartPos.Y);
//generate the text rectangle
Rectangle textRect = new Rectangle(textPos.X, textPos.Y, itemRect.Right - textPos.X, itemRect.Bottom - textPos.Y);
int textHeight = (int)e.Graphics.MeasureString(e.Node.Text, useFont).Height;
int textWidth = (int)e.Graphics.MeasureString(e.Node.Text, useFont).Width;
textRect.Height = textHeight;
//Draw the highlighted box
if ((e.State & TreeNodeStates.Selected) != 0)
{
//e.Graphics.FillRectangle(SystemBrushes.Highlight, textRect);
//use pink to see the difference
e.Graphics.FillRectangle(Brushes.Pink, textRect);
}
//widen the rectangle by 3 pixels, otherwise all of the text won't fit
textRect.Width = textWidth + 3;
//actually draw the text
e.Graphics.DrawString(e.Node.Text, useFont, useBrush, e.Bounds.Location);
//Draw the box around the focused node
if ((e.State & TreeNodeStates.Focused) != 0)
{
textRect.Width = textWidth;
Pen focusPen = new Pen(Color.Black);
focusPen.DashStyle = System.Drawing.Drawing2D.DashStyle.Dot;
e.Graphics.DrawRectangle(focusPen, textRect);
}
}
}
然而，结果是这样的。（注意，使用粉红色来区分颜色）。如您所见，突出显示的背景并没有一直延伸到焦点虚线所在的位置。并且还绘制了另一个框。
我对如何解决这个问题感到有些困惑。我想要的只是在加载某些内容时显示灰色斜体文本。第一种也是最简单的方法不太奏效，第二种方法感觉我做得太多了。
毕竟，是否有人对如何正确执行此操作有任何建议，因为必须有一种更简单的方法。
先感谢您。