本文介绍了展开 ListBox 中的选定项高度的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着跟版网的小编来一起学习吧!
问题描述
有没有办法让 SelectedItem 的高度大于 ListBox 中的其他项目?这是我现在拥有的,但它只是作为一个普通的列表框:
Is there a way that I can have the SelectedItem's height larger than the rest of the items in a ListBox? This is what I have right now, yet it just acts as a normal listbox:
public class BuddyListBox : ListBox
{
public BuddyListBox()
{
this.ResizeRedraw = true;
this.DoubleBuffered = true;
this.BorderStyle = BorderStyle.None;
this.Dock = DockStyle.Fill;
this.DrawMode = DrawMode.OwnerDrawVariable;
this.ItemHeight = 16;
}
protected override void OnDrawItem(DrawItemEventArgs e)
{
if (e.Index == -1 || e.Index >= this.Items.Count)
return;
Buddy current = (Buddy)this.Items[e.Index];
//Bitmap icon = current.StatusImage;
//e.Graphics.DrawImage(icon, e.Bounds.Left, e.Bounds.Top, 16, 16);
e.DrawBackground();
e.Graphics.DrawString(current.Address, e.Font, new SolidBrush(current.Status != BuddyStatus.offline ? e.ForeColor : Color.DarkGray), 16 + e.Bounds.Left, e.Bounds.Top);
e.Graphics.DrawString(current.Status.ToString(), e.Font, new SolidBrush(Color.LightGray), e.Bounds.Right - (int)(e.Graphics.MeasureString(current.Status.ToString(), e.Font).Width) - this.Margin.Right, e.Bounds.Top);
e.DrawFocusRectangle();
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
this.Refresh();
}
protected override void OnMeasureItem(MeasureItemEventArgs e)
{
if (e.Index == this.SelectedIndex)
e.ItemHeight = this.ItemHeight * 2;
else
e.ItemHeight = this.ItemHeight;
}
}
推荐答案
当 DrawMode 为 OwnerDrawFixed 时,您的 OnMeasureItem 没有执行任何操作.将模式更改为 OwnerDrawVariable.
Your OnMeasureItem isn't doing anything while the DrawMode is OwnerDrawFixed. Change the mode to OwnerDrawVariable.
不幸的是,MeasureItem 事件仅在创建句柄时发生,所以这里有一个解决方法:
Unfortunately, the MeasureItem event only happens when the handle gets created, so here is a work-around:
public class BuddyListBox : ListBox
{
int thisIndex = -1;
public BuddyListBox()
{
this.DrawMode = DrawMode.OwnerDrawVariable;
}
protected override void OnDrawItem(DrawItemEventArgs e)
{
if (this.Items.Count > 0)
{
if ((e.State & DrawItemState.Selected) == DrawItemState.Selected)
e.Graphics.FillRectangle(SystemBrushes.Highlight, e.Bounds);
else
e.Graphics.FillRectangle(SystemBrushes.Window, e.Bounds);
e.Graphics.DrawString(this.Items[e.Index].ToString(), e.Font, Brushes.Black, e.Bounds.Left, e.Bounds.Top);
base.OnDrawItem(e);
}
}
protected override void OnSelectedIndexChanged(EventArgs e)
{
base.OnSelectedIndexChanged(e);
thisIndex = this.SelectedIndex;
this.RecreateHandle();
}
protected override void OnMeasureItem(MeasureItemEventArgs e)
{
if (e.Index > -1)
{
if (e.Index == thisIndex)
e.ItemHeight = 32;
else
e.ItemHeight = 16;
}
base.OnMeasureItem(e);
}
}
这篇关于展开 ListBox 中的选定项高度的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持跟版网!
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