Smartphon2003中没有RadioButton，但是RadioButton又是我们界面布局中常用的控件。虽然如今Smartphone2003已经很少了，但是总还有吧。我们不就碰到这样一个项目。
这里采用比较简单的方法，利用切换两张图片实现RadioButton选择与未选择时的效果，但是特别注意的是：Smartphone只有键盘没有触摸屏，因此控件之间的切换是通过导航键（上下左右）切换，因此一定要处理好这点。代码中注释很详细，参考如下：
public class RadioButton : Control
{
#region Fields
private string _groupKey = string.Empty;
private bool _checked = false;private const int CHeight = 24; //控件的高度
private const int CTextOffset = 2; //文字与RaidoButton之间的偏移距离;private Image _checkedImage = null;
private Image _unCheckedImage = null;//private ImageAttributes _imgAttr = null;
#endregion
public RadioButton()
{
/// <summary>
/// Windows.Forms 类撰写设计器支持所必需的
/// </summary>
InitializeComponent();
//
// TODO: 在 InitializeComponent 调用之后添加任何构造函数代码
////_imgAttr = new ImageAttributes();
//_imgAttr.SetColorKey(Color.White, Color.White);_checkedImage = RS.GetCheckedRadioButton();
_unCheckedImage = RS.GetDefaultRadioButton();
}#region Properties
/// <summary>
/// 分组
/// </summary>
public string GroupKey
{
get { return _groupKey; }
set { _groupKey = value; }
}/// <summary>
/// 是否选择;
/// </summary>
public bool Checked
{
get { return _checked; }
set
{
if (value != _checked)
{
_checked = value;
this.Invalidate();
}
}
}#endregion
#region Override
protected override void OnGotFocus(EventArgs e)
{
foreach (Control ctl in this.Parent.Controls)
{
if (ctl is RadioButton)
{
RadioButton btn = (RadioButton)ctl;
if (btn.GroupKey.Equals(this.GroupKey))
{
btn.Checked = false;
}
}
}
this.Checked = true;
base.OnGotFocus(e);}
/// <summary>
/// 限制控件的高度;
/// </summary>
/// <param name="e"></param>
protected override void OnResize(EventArgs e)
{
this.Height = CHeight;
}/// <summary>
/// 处理上下控件的焦点切换
/// </summary>
/// <param name="e"></param>
protected override void OnKeyDown(KeyEventArgs e)
{
int index = -1;
switch (e.KeyCode)
{
case Keys.Down:
index = this.Parent.Controls.GetChildIndex(this);
do
{
if ((index + 1) == this.Parent.Controls.Count)
index = -1; //roll over
index++;
} while (!IsFocusable(this.Parent.Controls[index]));
break;case Keys.Up:
index = this.Parent.Controls.GetChildIndex(this);
do
{
if (index == 0)
index = this.Parent.Controls.Count; //roll over
index--;
} while (!IsFocusable(this.Parent.Controls[index]));
break;
}
if (index > -1 && index < this.Parent.Controls.Count)
this.Parent.Controls[index].Focus();
base.OnKeyDown(e);
}protected override void Dispose(bool disposing)
{
if (_checkedImage != null)
{
_checkedImage.Dispose();
_checkedImage = null;
}
if (_unCheckedImage != null)
{
_unCheckedImage.Dispose();
_unCheckedImage = null;
}
base.Dispose(disposing);
}
#endregion#region 绘制RadioButton
/// <summary>
/// 绘制RadioButton
/// </summary>
/// <param name="e"></param>
protected override void OnPaint(PaintEventArgs e)
{
//e.Graphics.DrawString(this.Text, this.Font, new SolidBrush(Color.Black), 1f, 1f);
DrawButton(e.Graphics);
}private void DrawButton(Graphics g)
{
if (!Visible)
{
return;
}
//绘制Image && Text
int imgWidth = 0;
int imgHeight = 0;
float txtHeight = 0;
float txtWidth = 0;Image img;
if (Checked)
{
img = _checkedImage;
}
else
{
img = _unCheckedImage;
}imgWidth = img.Width;
imgHeight = img.Height;if (Text.Length > 0)
{
SizeF txtSizeF = g.MeasureString(Text, Font);
txtHeight = txtSizeF.Height;
txtWidth = txtSizeF.Width;
}int imgX = 2;
int imgY = (Size.Height - imgHeight) / 2;//Rectangle rect = new Rectangle();
//rect.X = imgX;
//rect.Y = imgY;
//rect.Width = imgWidth;
//rect.Height = imgHeight;//g.DrawImage(img, rect, 0, 0, imgWidth, imgHeight, GraphicsUnit.Pixel, _imgAttr);
g.DrawImage(img, imgX, imgY);float txtX = imgX + imgWidth + CTextOffset;
float txtY = (Size.Height - txtHeight) / 2F;
Color color = ForeColor;
if (!Enabled)
{
color = SystemColors.GrayText;
}
Brush cl = new SolidBrush(color);
try
{
g.DrawString(Text, Font, cl, txtX, txtY);
}
finally
{
cl.Dispose();
}
}private void DrawButton()
{
using (Graphics g = this.CreateGraphics())
{
DrawButton(g);
}
}
#endregion#region Methods
private bool IsFocusable(Control control)
{
if (control is Label)
return false;
else
return true;
}#endregion
#region 组件设计器生成的代码
/// <summary>
/// 设计器支持所需的方法 - 不要
/// 使用代码编辑器修改此方法的内容。
/// </summary>
private void InitializeComponent()
{
}
#endregion
}
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