扩大ListBox中选定的项目高度 [英] Expanding Selected Item height in ListBox

问题描述

有没有我可以拥有的SelectedItem的身高比在ListBox中的项目的其余部分大的方法是什么？这就是我现在所拥有的，但它只是作为一个正常的列表框：

 公共类BuddyListBox：列表框
 {
 
公共BuddyListBox（）
 {
 this.ResizeRedraw = TRUE; 
 this.DoubleBuffered = TRUE; 
 this.BorderStyle = BorderStyle.None; 
 this.Dock = DockStyle.Fill; 
 this.DrawMode = DrawMode.OwnerDrawVariable; 
 this.ItemHeight = 16; 
} 
保护覆盖无效的OnDrawItem（DrawItemEventArgs E）
 {
如果（e.Index == -1 || e.Index> = this.Items.Count）
返回; 
 
好友电流=（好友）this.Items [e.Index] 
 //位图的图标= current.StatusImage; 
 
 //e.Graphics.DrawImage(icon，e.Bounds.Left，e.Bounds.Top，16，16）; 
 e.DrawBackground（）; 
 e.Graphics.DrawString（current.Address，e.Font，新SolidBrush（current.Status = BuddyStatus.offline e.ForeColor！？Color.DarkGray），16 + e.Bounds.Left，e.Bounds 。最佳）; 
 e.Graphics.DrawString（current.Status.ToString（），e.​​Font，新SolidBrush（Color.LightGray），e.Bounds.Right  - （INT）（e.Graphics.MeasureString（current.Status。 toString（）方法，e.Font）.WIDTH） -  this.Margin.Right，e.Bounds.Top）; 
 e.DrawFocusRectangle（）; 
} 
 
保护覆盖无效OnSelectedIndexChanged（EventArgs的发送）
 {
 this.Refresh（）; 
} 
 
保护覆盖无效OnMeasureItem的（MeasureItemEventArgs E）
 {
如果（e.Index == this.SelectedIndex）
 e.ItemHeight =这.ItemHeight * 2; 
，否则
 e.ItemHeight = this.ItemHeight; 
} 
} 
  

解决方案

您而DrawMode被OwnerDrawFixed OnMeasureItem的没有做任何事情。 。改变模式OwnerDrawVariable

不幸的是，手柄被创建的时候MeasureItem事件只发生，所以这里是一个变通：

 公共类BuddyListBox：列表框
 {
 INT thisIndex = -1; 
 
公共BuddyListBox（）
 {
 this.DrawMode = DrawMode.OwnerDrawVariable; 
} 
 
保护覆盖无效的OnDrawItem（DrawItemEventArgs E）
 {
如果（this.Items.Count大于0）
 {
如果（（e.State&安培; DrawItemState.Selected）== DrawItemState.Selected）
 e.Graphics.FillRectangle（SystemBrushes.Highlight，e.Bounds）; 
，否则
 e.Graphics.FillRectangle（SystemBrushes.Window，e.Bounds）; 
 e.Graphics.DrawString（this.Items [e.Index]的ToString（），e.​​Font，Brushes.Black，e.Bounds.Left，e.Bounds.Top）; 
 base.OnDrawItem（E）; 
} 
} 
 
保护覆盖无效OnSelectedIndexChanged（EventArgs的发送）
 {
 base.OnSelectedIndexChanged（E）; 
 thisIndex = this.SelectedIndex; 
 this.RecreateHandle（）; 
} 
 
保护覆盖无效OnMeasureItem的（MeasureItemEventArgs E）
 {
如果（e.Index -1个）
 {
如果（e.Index == thisIndex）
 e.ItemHeight = 32; 
，否则
 e.ItemHeight = 16; 
} 
 base.OnMeasureItem（E）; 
} 
} 
  

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;
    }
}

解决方案

Your OnMeasureItem isn't doing anything while the DrawMode is OwnerDrawFixed. Change the mode to OwnerDrawVariable.

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);
  }
}

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