注：感谢Aleax博友提出的Bug（见#7楼），现已纠正，纠正的内容会在要点里说明，修改过的源码已附上，也谢谢各位博友提出的意见和方法，当然方法有很多种，这只是其中一种非常简单和直接的方法，给初学者一点参考，望大家多多提意。
效果图
一 准备工作
两张透明的png图片(尺寸73 x 81)，一张用于鼠标进入控件时显示，一张用于鼠标单击控件时显示。
新建自定义控件，在构造函数中添加代码
public GlassButton()
{
SetStyle(ControlStyles.DoubleBuffer, true); //双缓冲防止重绘时闪烁
SetStyle(ControlStyles.AllPaintingInWmPaint, true); //忽略 WM_ERASEBKGND 窗口消息减少闪烁
SetStyle(ControlStyles.UserPaint, true); //自定义绘制控件内容
SetStyle(ControlStyles.SupportsTransparentBackColor, true); //模拟透明
SetStyle(ControlStyles.Selectable, true); //接收焦点
Size = new Size(73, 81); //初始大小
Font = new Font("微软雅黑", 9); //控件字体
}
新建枚举，用来表示当前控件的状态
///<summary>
/// 控件状态
///</summary>
public enum State
{
///<summary>
/// 无
///</summary>
Normal = 0,
///<summary>
/// 获得焦点
///</summary>
Focused = 1,
///<summary>
/// 失去焦点
///</summary>
LostFocused = 2,
///<summary>
/// 鼠标指针进入控件
///</summary>
MouseEnter = 3
}
二 制作方法
比较简单，在这里只贴一下代码，大家一看就明白
属性
Property
///<summary>
/// 获取或设置控件显示的图片
///</summary>
[Description("获取或设置控件显示的图标")]
public Bitmap Bitmap
{
get { return _bmp; }
set {
_bmp = value;
Invalidate(false);
}
}
///<summary>
/// 重写控件焦点属性
///</summary>
[Description("重写控件焦点属性")]
public new bool Focused
{
get { return _focused; }
set
{
_focused = value;
if (_focused)
state = State.Focused;
else
state = State.LostFocused;
Invalidate(false);
}
}
重载事件
Override
//自定义绘制
protected override void OnPaint(PaintEventArgs e)
{
base.OnPaint(e);
Graphics g = e.Graphics;
g.SmoothingMode = SmoothingMode.HighQuality;
g.PixelOffsetMode = PixelOffsetMode.HighQuality;
switch (state)
{
case State.Focused: {
DrawSelected(g);
break;
}
case State.MouseEnter: {
if (!Focused)
g.DrawImage(Properties.Resources.enter, ClientRectangle);
else
DrawSelected(g);
break;
}
}
DrawImage(g);
DrawText(g);
}
//焦点进入
protected override void OnEnter(EventArgs e)
{
base.OnEnter(e);
Focused = true;
}
//失去焦点
protected override void OnLeave(EventArgs e)
{
base.OnLeave(e);
Focused = false;
}
//禁止调整大小
protected override void OnResize(EventArgs e)
{
Width = 73;
Height = 81;
}
protected override void OnMouseEnter(EventArgs e)
{
base.OnMouseEnter(e);
state = State.MouseEnter;
Invalidate(false);
}
protected override void OnMouseLeave(EventArgs e)
{
base.OnMouseLeave(e);
if (!Focused)
{
state = State.LostFocused;
Invalidate(false);
}
}
//只响应单击鼠标左键事件
protected override void OnClick(EventArgs e)
{
MouseEventArgs m = (MouseEventArgs)e;
if (m.Button == MouseButtons.Left)
{
base.OnClick(e);
Focus();
}
}
方法
Method
#region//Draw
void DrawSelected(Graphics g)
{
g.DrawImage(Properties.Resources.down, ClientRectangle);
}
void DrawImage(Graphics g)
{
if (_bmp != null)
{
Bitmap bmp = ScaleZoom(_bmp);
bmp_Left = (Width - bmp.Width) / 2;
g.DrawImage(bmp, new Rectangle(bmp_Left, bmp_Top, bmp.Width, bmp.Height));
}
}
void DrawText(Graphics g)
{
SizeF size = g.MeasureString(Text, Font);
g.DrawString(Text, Font, new SolidBrush(ForeColor), (Width - size.Width) / 2, 58);
}
#endregion
#region//按比例缩放图片
public Bitmap ScaleZoom(Bitmap bmp)
{
if (bmp != null)
{
double zoomScale;
if (bmp.Width > bmp_Size || bmp.Height > bmp_Size)
{
double imageScale = (double)bmp.Width / (double)bmp.Height;
double thisScale = 1;
if (imageScale > thisScale)
{
zoomScale = (double)bmp_Size / (double)bmp.Width;
return BitMapZoom(bmp, bmp_Size, (int)(bmp.Height * zoomScale));
}
else
{
zoomScale = (double)bmp_Size / (double)bmp.Height;
return BitMapZoom(bmp, (int)(bmp.Width * zoomScale), bmp_Size);
}
}
}
return bmp;
}
#endregion
#region//缩放BitMap
///<summary>
/// 图片缩放
///</summary>
///<param name="bmpSource">源图片</param>
///<param name="bmpSize">缩放图片的大小</param>
///<returns>缩放的图片</returns>
public Bitmap BitMapZoom(Bitmap bmpSource, int bmpWidth, int bmpHeight)
{
Bitmap bmp, zoomBmp;
try
{
bmp = new Bitmap(bmpSource);
zoomBmp = new Bitmap(bmpWidth, bmpHeight);
Graphics gh = Graphics.FromImage(zoomBmp);
gh.InterpolationMode = InterpolationMode.HighQualityBicubic;
gh.DrawImage(bmp, new Rectangle(0, 0, bmpWidth, bmpHeight), new Rectangle(0, 0, bmp.Width, bmp.Height), GraphicsUnit.Pixel);
gh.Dispose();
return zoomBmp;
}
catch
{ }
finally
{
bmp = null;
zoomBmp = null;
GC.Collect();
}
return null;
}
#endregion
三 要点
要点就在于各个按钮之间焦点切换的问题，就如效果图所示，当有一个按钮获取了焦点，其他按钮将显示为失去焦点的状态。
MSDN上建议当控件得到焦点时使用Enter事件，也就表示焦点进入当前所选择控件，当控件失去焦点时使用Leave事件。
所以要重载Control组件的OnEnter和OnLeave事件，在此控件中重写了Focused属性，当引发了控件的焦点事件后将触发OnPaint事件重新绘制，而引发Enter事件的发起者来自于控件的Focus()方法。
//焦点进入
protected override void OnEnter(EventArgs e)
{
base.OnEnter(e);
Focused = true;
}
//失去焦点
protected override void OnLeave(EventArgs e)
{
base.OnLeave(e);
Focused = false;
}
附