这是一个自定义控件，源自Control，可以做成半透明的。
该界面是一个彩色圆圈，其中可以包含几个数字。
该控件公开这些自定义属性：
Opacity：控件的不透明度级别BackGround [0, 255]
InnerPadding：内部矩形之间的距离，定义圆边界和控件边界。
FontPadding：文本与内部矩形之间的距离。
透明度是压倒一切的创建参数 https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.createparams，然后设置ExStyle |= WS_EX_TRANSPARENT;
The Control.SetStyle() https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.control.setstyle方法用于修改控件行为，添加这些控件样式 https://learn.microsoft.com/en-us/dotnet/api/system.windows.forms.controlstyles:
▶ ControlStyles.Opaque：防止绘制控件的背景，因此它不受系统管理。结合CreateParams设置控件的扩展样式为WS_EX_TRANSPARENT，控件变得完全透明。
▶ ControlStyles.SupportsTransparentBackColor该控件接受 Alpha 值BackGround颜色。无需同时设置ControlStyles.UserPaint它不会用于模拟透明度。我们正在通过其他方式自己做到这一点。
要查看它的工作情况，请创建一个新的类文件，用此代码替换里面的所有代码保留命名空间并构建项目/解决方案。
新的自定义控件将出现在工具箱中。将其放在表格上。根据需要修改其自定义属性。
控件的直观表示：
注意事项和免责声明:
- 这是一个原型控件，缺少自定义设计器（无法在这里发布，代码太多，还连接到框架）。
正如这里所介绍的，它可用于完全地与表单或其他容器中的其他控件重叠。在这个简化的实现中不处理部分重叠。
- 字体被硬编码为
Segoe UI，因为此字体有一个基线，可以简化圆形区域中间文本的位置。
其他字体有不同的基线，这需要更复杂的处理。
See: 带虚线的文本框用于输入 https://stackoverflow.com/a/64673192/7444103用于基础数学。
using System;
using System.ComponentModel;
using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Text;
using System.Globalization;
using System.Runtime.CompilerServices;
using System.Windows.Forms;
[DesignerCategory("Code")]
public class RoundCenterLabel : Label, INotifyPropertyChanged, ISupportInitialize
{
private const int WS_EX_TRANSPARENT = 0x00000020;
private bool IsInitializing = false;
private Point MouseDownLocation = Point.Empty;
private readonly int fontPadding = 4;
private Font m_CustomFont = null;
private Color m_BackGroundColor;
private int m_InnerPadding = 0;
private int m_FontPadding = 25;
private int m_Opacity = 128;
public event PropertyChangedEventHandler PropertyChanged;
public RoundCenterLabel() => InitializeComponent();
private void InitializeComponent()
{
SetStyle(ControlStyles.Opaque |
ControlStyles.SupportsTransparentBackColor |
ControlStyles.ResizeRedraw, true);
SetStyle(ControlStyles.OptimizedDoubleBuffer, false);
m_CustomFont = new Font("Segoe UI", 50, FontStyle.Regular, GraphicsUnit.Pixel);
BackColor = Color.LimeGreen;
ForeColor = Color.White;
}
protected override CreateParams CreateParams {
get {
var cp = base.CreateParams;
cp.ExStyle |= WS_EX_TRANSPARENT;
return cp;
}
}
public new Font Font
{
get => m_CustomFont;
set {
m_CustomFont = value;
if (IsInitializing) return;
FontAdapter(value, DeviceDpi);
NotifyPropertyChanged();
}
}
public override string Text {
get => base.Text;
set { base.Text = value;
NotifyPropertyChanged();
}
}
public int InnerPadding {
get => m_InnerPadding;
set {
if (IsInitializing) return;
m_InnerPadding = ValidateRange(value, 0, ClientRectangle.Height - 10);
NotifyPropertyChanged(); }
}
public int FontPadding {
get => m_FontPadding;
set {
if (IsInitializing) return;
m_FontPadding = ValidateRange(value, 0, ClientRectangle.Height - 10);
NotifyPropertyChanged();
}
}
public int Opacity {
get => m_Opacity;
set { m_Opacity = ValidateRange(value, 0, 255);
UpdateBackColor(m_BackGroundColor);
NotifyPropertyChanged();
}
}
public override Color BackColor {
get => m_BackGroundColor;
set { UpdateBackColor(value);
NotifyPropertyChanged();
}
}
protected override void OnLayout(LayoutEventArgs e)
{
base.OnLayout(e);
base.AutoSize = false;
}
private void NotifyPropertyChanged([CallerMemberName] string PropertyName = null)
{
InvalidateParent();
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(PropertyName));
}
protected override void OnMouseDown(MouseEventArgs e)
{
base.OnMouseDown(e);
MouseDownLocation = e.Location;
}
protected override void OnMouseMove(MouseEventArgs e)
{
base.OnMouseMove(e);
if (e.Button == MouseButtons.Left) {
var loc = new Point(Left + (e.X - MouseDownLocation.X), Top + (e.Y - MouseDownLocation.Y));
InvalidateParent();
BeginInvoke(new Action(() => Location = loc));
}
}
private void InvalidateParent()
{
Parent?.Invalidate(Bounds, true);
Invalidate();
}
protected override void OnPaint(PaintEventArgs e)
{
using (var format = new StringFormat(StringFormatFlags.LineLimit | StringFormatFlags.NoWrap, CultureInfo.CurrentUICulture.LCID))
{
format.LineAlignment = StringAlignment.Center;
format.Alignment = StringAlignment.Center;
e.Graphics.SmoothingMode = SmoothingMode.AntiAlias;
e.Graphics.TextRenderingHint = TextRenderingHint.AntiAliasGridFit;
using (var circleBrush = new SolidBrush(m_BackGroundColor))
using (var foreBrush = new SolidBrush(ForeColor))
{
FontAdapter(m_CustomFont, e.Graphics.DpiY);
RectangleF rect = InnerRectangle();
e.Graphics.FillEllipse(circleBrush, rect);
e.Graphics.DrawString(Text, m_CustomFont, foreBrush, rect, format);
};
};
}
public void BeginInit() => IsInitializing = true;
public void EndInit()
{
IsInitializing = false;
Font = new Font("Segoe UI", 50, FontStyle.Regular, GraphicsUnit.Pixel);
FontPadding = m_FontPadding;
InnerPadding = m_InnerPadding;
}
private RectangleF InnerRectangle()
{
(float Min, _) = GetMinMax(ClientRectangle.Height, ClientRectangle.Width);
var size = new SizeF(Min - (m_InnerPadding / 2), Min - (m_InnerPadding / 2));
var position = new PointF((ClientRectangle.Width - size.Width) / 2,
(ClientRectangle.Height - size.Height) / 2);
return new RectangleF(position, size);
}
private void FontAdapter(Font font, float dpi)
{
RectangleF rect = InnerRectangle();
float fontSize = ValidateRange(
(int)(rect.Height - m_FontPadding), 6,
(int)(rect.Height - m_FontPadding)) / (dpi / 72.0F) - fontPadding;
m_CustomFont.Dispose();
m_CustomFont = new Font(font.FontFamily, fontSize, font.Style, GraphicsUnit.Pixel);
}
private void UpdateBackColor(Color color)
{
m_BackGroundColor = Color.FromArgb(m_Opacity, Color.FromArgb(color.R, color.G, color.B));
base.BackColor = m_BackGroundColor;
}
private int ValidateRange(int Value, int Min, int Max)
=> Math.Max(Math.Min(Value, Max), Min); // (Value < Min) ? Min : ((Value > Max) ? Max : Value);
private (float, float) GetMinMax(float Value1, float Value2)
=> (Math.Min(Value1, Value2), Math.Max(Value1, Value2));
}
