在Microsoft Outlook 2003中,用户界面允许创建自定义的GroupBox组件。本文将介绍如何实现这样的组件,并且分享一个小技巧,即如何调整客户区域,以便在拖动控件到GroupBox内部时,可以利用边距指南进行定位而不重叠图标。
首先,需要在项目中添加一个新的组件类,并从标准的GroupBox继承。以下是使用C#语言实现的自定义GroupBox组件的代码示例:
public partial class CustomGroupBox : System.Windows.Forms.GroupBox
{
private Size _iconMargin;
private Image _image;
private Color _lineColorBottom;
private Color _lineColorTop;
public CustomGroupBox()
{
_iconMargin = new Size(0, 6);
_lineColorBottom = SystemColors.ButtonHighlight;
_lineColorTop = SystemColors.ButtonShadow;
this.SetStyle(ControlStyles.DoubleBuffer | ControlStyles.AllPaintingInWmPaint | ControlStyles.ResizeRedraw | ControlStyles.UserPaint | ControlStyles.SupportsTransparentBackColor, true);
this.CreateResources();
}
[Category("Appearance"), DefaultValue(typeof(Size), "0, 6")]
public Size IconMargin
{
get { return _iconMargin; }
set
{
_iconMargin = value;
this.Invalidate();
}
}
[Category("Appearance"), DefaultValue(typeof(Image), "")]
public Image Image
{
get { return _image; }
set
{
_image = value;
this.Invalidate();
}
}
[Category("Appearance"), DefaultValue(typeof(Color), "ButtonHighlight")]
public Color LineColorBottom
{
get { return _lineColorBottom; }
set
{
_lineColorBottom = value;
this.CreateResources();
this.Invalidate();
}
}
[Category("Appearance"), DefaultValue(typeof(Color), "ButtonShadow")]
public Color LineColorTop
{
get { return _lineColorTop; }
set
{
_lineColorTop = value;
this.CreateResources();
this.Invalidate();
}
}
protected override void OnPaint(PaintEventArgs e)
{
// 绘制GroupBox的文本和线条
e.Graphics.DrawString(this.Text, this.Font, _textBrush, 1, 1);
e.Graphics.DrawLine(_topPen, size.Width + 3, y, this.Width - 5, y);
e.Graphics.DrawLine(_bottomPen, size.Width + 3, y + 1, this.Width - 5, y + 1);
// 绘制图像
if (_image != null)
{
e.Graphics.DrawImage(_image, this.Padding.Left + _iconMargin.Width, this.Padding.Top + (int)size.Height + _iconMargin.Height, _image.Width, _image.Height);
}
// 设计时绘制轮廓
if (this.DesignMode)
{
Pen pen = new Pen(SystemColors.ButtonShadow);
pen.DashStyle = DashStyle.Dot;
e.Graphics.DrawRectangle(pen, 0, 0, Width - 1, Height - 1);
pen.Dispose();
}
}
protected override void OnSystemColorsChanged(EventArgs e)
{
base.OnSystemColorsChanged(e);
this.CreateResources();
this.Invalidate();
}
public override Rectangle DisplayRectangle
{
get
{
Size clientSize = base.ClientSize;
int fontHeight = this.Font.Height;
int imageSize = (_image != null) ? _iconMargin.Width + _image.Width + 3 : 0;
return new Rectangle(3 + imageSize, fontHeight + 3, Math.Max(clientSize.Width - (imageSize + 6), 0), Math.Max((clientSize.Height - fontHeight) - 6, 0));
}
}
private void CreateResources()
{
this.CleanUpResources();
_topPen = new Pen(_lineColorTop);
_bottomPen = new Pen(_lineColorBottom);
_textBrush = new SolidBrush(this.ForeColor);
}
private void CleanUpResources()
{
if (_topPen != null) _topPen.Dispose();
if (_bottomPen != null) _bottomPen.Dispose();
if (_textBrush != null) _textBrush.Dispose();
}
}
在上述代码中,定义了一个自定义的GroupBox组件,它具有图标边距、线条颜色和图像属性。还重写了OnPaint方法来自定义GroupBox的绘制过程,并在设计时添加了轮廓以便于布局。
此外,还重写了OnSystemColorsChanged方法,以确保当系统颜色发生变化时,组件能够重新创建资源并重绘。
最后,通过重写DisplayRectangle属性来调整客户区域,以便在放置控件时,边距指南能够正确地建议合适的左边距。