透明标签 .NET 控件

• 下载演示 - 208.96 KB
• 下载源代码 - 299.68 KB

引言

我认为很多人在创建具有渐变背景的控件上的透明标签时遇到困难。

本文档介绍了一种在基于 Windows 的应用程序中显示透明标签的方法。此库中的 uLabelX 控件旨在外观灵活且时尚。首先，它支持边框形状、图像以及具有渐变背景的父控件。与控件关联的图像可以以 Alpha 混合形式绘制。控件中的文本可以使用高级效果绘制。所有这些吸引人的特性还可以针对控件的不同状态进行个性化定制。

Using the Code

该项目包含以下文件

• BorderStyles.vb (指定控件的边框样式)
• ImageSizes.vb (指定控件的图像大小)
• uLabelXDesigner.vb (指定用于实现控件设计时服务的类)
• uLabelX.vb (指定自定义控件类)

控件类 uLabelX 继承自基类 Control。

Public Class uLabelX 
	Inherits Control 

构造函数

Public Sub New()
InitializeComponent()
	Me.SetStyle(ControlStyles.SupportsTransparentBackColor, True)
	Me.SetStyle(ControlStyles.ResizeRedraw, True)
	Me.SetStyle(ControlStyles.Opaque, False)
	Me.SetStyle(ControlStyles.OptimizedDoubleBuffer, False)
		AddHandler Me.PropertyChanged, AddressOf OnPropertyChanged
		RaiseEvent PropertyChanged(False)
End Sub

事件

事件声明

Protected Event PropertyChanged(ByVal _RecreateHandle As Boolean)

属性更改时调用的方法

Private Sub OnPropertyChanged(ByVal _RecreateHandle As Boolean) 
 	If (_RecreateHandle = True) Then Me.RecreateHandle() 
	Me.Invalidate() 
End Sub 

属性

' Gets or sets the Image of the control 
Public Property Image() As Image 
	Get 
		Return m_Image 
	End Get 
	Set(ByVal value As Image) 
		m_Image = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Gets or sets the ImageSize of the control 
Public ReadOnly Property ImageSize() As ImageSizes 
	Get 
		Return m_ImageSize 
	End Get 
End Property 

' Gets or sets the BorderStyle of the control 
Public Shadows Property BorderStyle() _
	As iGreen.Controls.uControls.uLabelX.Common.BorderStyles 
	Get 
		Return m_BorderStyle 
	End Get 
	Set(ByVal value As iGreen.Controls.uControls.uLabelX.Common.BorderStyles) 
		m_BorderStyle = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Gets or sets the BorderDashStyle of the control 
Public Property BorderDashStyle() As System.Drawing.Drawing2D.DashStyle 
	Get 
		Return m_BorderDashStyle 
	End Get 
	Set(ByVal value As System.Drawing.Drawing2D.DashStyle) 
		m_BorderDashStyle = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Gets or sets the BorderWidth of the control 
Public Property BorderWidth() As Single 
	Get 
		Return m_BorderWidth 
	End Get 
	Set(ByVal value As Single) 
		m_BorderWidth = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Gets or sets the BorderColor of the control 
Public Property BorderColor() As Color 
	Get 
		Return m_BorderColor 
	End Get 
	Set(ByVal value As Color)
	m_BorderColor = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Gets or sets the Text of the control. 
' Represents Text as a series of Unicode characters. 
Public Overrides Property Text() As String 
	Get 
		Return Replace(MyBase.Text, "ULabelX", "uLabelX") 
	End Get 
	Set(ByVal value As String) 
		MyBase.Text = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

' Specifies alignment of Text on the control. 
' Placement and direction of text in relation to the control border 
Public Property TextAlign() As ContentAlignment 
	Get 
		Return m_TextAlign 
	End Get 
	Set(ByVal value As ContentAlignment) 
		m_TextAlign = value 
		RaiseEvent PropertyChanged(True) 
	End Set 
End Property 

方法

在这里我们正在重写 OnPaintBackground()，否则背景绘制任务会破坏最近重新绘制的父控件内容，通过覆盖 OnPaintBackground() 方法来实现。

Protected Overrides Sub OnPaintBackground(ByVal e As PaintEventArgs) 
	' NOTHING TODO: 
End Sub 

重写以下内容以刷新控件

Protected Overrides Sub OnFontChanged(ByVal e As System.EventArgs)
	RaiseEvent PropertyChanged(True)
End Sub 

Protected Overrides Sub OnForeColorChanged(ByVal e As System.EventArgs)
	RaiseEvent PropertyChanged(True) 
End Sub

重写基类 OnPaint() 以绘制控件

Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)
MyBase.OnPaint(e) 
	e.Graphics.CompositingMode = CompositingMode.SourceOver 
	e.Graphics.CompositingQuality = CompositingQuality.GammaCorrected 
	e.Graphics.SmoothingMode = Drawing2D.SmoothingMode.AntiAlias 
		Call DrawControlBorder(e.Graphics, Me.ClientRectangle) 
		Call DrawControlText(e.Graphics, Me.ClientRectangle) 
		Call DrawControlImage(e.Graphics, Me.ClientRectangle) 
End Sub 

为了从设计时属性页中删除不必要的属性，我在这里使用 ControlDesigner 类的 PostFilterProperties。

Imports System.Windows.Forms.Design
Namespace Common
    Friend Class uLabelXDesigner
        Inherits ControlDesigner
        Protected Overrides Sub PostFilterProperties_
	(ByVal _Properties As System.Collections.IDictionary)
            _Properties.Remove("BackColor")
            _Properties.Remove("BackgroundImage")
            _Properties.Remove("BackgroundImageLayout")
            _Properties.Remove("RightToLeft")
            _Properties.Remove("TabStop")
            _Properties.Remove("TabIndex")
            _Properties.Remove("AutoSize")
            MyBase.PostFilterProperties(_Properties)
        End Sub
    End Class
End Namespace

希望这能有所帮助。
祝您编程愉快！！！