Provides methods used to render a track bar control with visual styles. This class cannot be inherited.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
Thetype exposes the following members.
|DrawBottomPointingThumb||Draws a downward-pointing track bar slider (also known as the thumb) with visual styles.|
|DrawHorizontalThumb||Draws a horizontal track bar slider (also known as the thumb) with visual styles.|
|DrawHorizontalTicks||Draws the specified number of horizontal track bar ticks with visual styles.|
|DrawHorizontalTrack||Draws the track for a horizontal track bar with visual styles.|
|DrawLeftPointingThumb||Draws a left-pointing track bar slider (also known as the thumb) with visual styles.|
|DrawRightPointingThumb||Draws a right-pointing track bar slider (also known as the thumb) with visual styles.|
|DrawTopPointingThumb||Draws an upward-pointing track bar slider (also known as the thumb) with visual styles.|
|DrawVerticalThumb||Draws a vertical track bar slider (also known as the thumb) with visual styles.|
|DrawVerticalTicks||Draws the specified number of vertical track bar ticks with visual styles.|
|DrawVerticalTrack||Draws the track for a vertical track bar with visual styles.|
|Equals(Object)||Determines whether the specified object is equal to the current object. (Inherited from Object.)|
|GetBottomPointingThumbSize||Returns the size, in pixels, of the track bar slider (also known as the thumb) that points down.|
|GetHashCode||Serves as the default hash function. (Inherited from Object.)|
|GetLeftPointingThumbSize||Returns the size, in pixels, of the track bar slider (also known as the thumb) that points to the left.|
|GetRightPointingThumbSize||Returns the size, in pixels, of the track bar slider (also known as the thumb) that points to the right.|
|GetTopPointingThumbSize||Returns the size, in pixels, of the track bar slider (also known as the thumb) that points up.|
|GetType||Gets the Type of the current instance. (Inherited from Object.)|
|ToString||Returns a string that represents the current object. (Inherited from Object.)|
The class provides a set of static methods that can be used to render each part of a track bar control with the current visual style of the operating system. Rendering a control refers to drawing the user interface of a control. This is useful if you are drawing a custom control that should have the appearance of the current visual style.
If visual styles are enabled in the operating system and visual styles are applied to the client area of application windows, the methods in this class will draw the track bar with the current visual style. Otherwise, the methods in this class will throw an InvalidOperationException. To determine whether the members of this class can be used, you can check the value of the IsSupported property.
This class wraps the functionality of a System.Windows.Forms.VisualStyles.VisualStyleRenderer that is set to one of the elements exposed by the System.Windows.Forms.VisualStyles.VisualStyleElement.TrackBar class. For more information, see Rendering Controls with Visual Styles.
Windows XP Home Edition, Windows XP Professional x64 Edition, Windows Server 2003 Platform Note: Visual styles are supported only on these platforms.
The following code example demonstrates how to create a custom control that uses the methods to draw a horizontal track bar that responds to mouse clicks.
Imports System Imports System.Drawing Imports System.Windows.Forms Imports System.Windows.Forms.VisualStyles Namespace TrackBarRendererSample Class Form1 Inherits Form Public Sub New() Dim TrackBar1 As New CustomTrackBar(19, New Size(300, 50)) Me.Width = 500 Me.Controls.Add(TrackBar1) End Sub <STAThread()> _ Shared Sub Main() ' Note that the call to EnableVisualStyles below does ' not affect whether TrackBarRenderer.IsSupported is true; ' as long as visual styles are enabled by the operating system, ' IsSupported is true. Application.EnableVisualStyles() Application.Run(New Form1()) End Sub End Class Class CustomTrackBar Inherits Control Private numberTicks As Integer = 10 Private trackRectangle As New Rectangle() Private ticksRectangle As New Rectangle() Private thumbRectangle As New Rectangle() Private currentTickPosition As Integer = 0 Private tickSpace As Single = 0 Private thumbClicked As Boolean = False Private thumbState As TrackBarThumbState = TrackBarThumbState.Normal Public Sub New(ByVal ticks As Integer, ByVal trackBarSize As Size) With Me .Location = New Point(10, 10) .Size = trackBarSize .numberTicks = ticks .BackColor = Color.DarkCyan .DoubleBuffered = True End With ' Calculate the initial sizes of the bar, ' thumb and ticks. SetupTrackBar() End Sub ' Calculate the sizes of the bar, thumb, and ticks rectangle. Private Sub SetupTrackBar() If Not TrackBarRenderer.IsSupported Then Return End If Using g As Graphics = Me.CreateGraphics() ' Calculate the size of the track bar. trackRectangle.X = ClientRectangle.X + 2 trackRectangle.Y = ClientRectangle.Y + 28 trackRectangle.Width = ClientRectangle.Width - 4 trackRectangle.Height = 4 ' Calculate the size of the rectangle in which to ' draw the ticks. ticksRectangle.X = trackRectangle.X + 4 ticksRectangle.Y = trackRectangle.Y - 8 ticksRectangle.Width = trackRectangle.Width - 8 ticksRectangle.Height = 4 tickSpace = (CSng(ticksRectangle.Width) - 1) / _ (CSng(numberTicks) - 1) ' Calculate the size of the thumb. thumbRectangle.Size = _ TrackBarRenderer.GetTopPointingThumbSize( _ g, TrackBarThumbState.Normal) thumbRectangle.X = CurrentTickXCoordinate() thumbRectangle.Y = trackRectangle.Y - 8 End Using End Sub Private Function CurrentTickXCoordinate() As Integer If tickSpace = 0 Then Return 0 Else Return CInt(Math.Round(tickSpace)) * currentTickPosition End If End Function ' Draw the track bar. Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs) If Not TrackBarRenderer.IsSupported Then Me.Parent.Text = "CustomTrackBar Disabled" Return End If Me.Parent.Text = "CustomTrackBar Enabled" TrackBarRenderer.DrawHorizontalTrack(e.Graphics, _ trackRectangle) TrackBarRenderer.DrawTopPointingThumb(e.Graphics, _ thumbRectangle, thumbState) TrackBarRenderer.DrawHorizontalTicks(e.Graphics, _ ticksRectangle, numberTicks, EdgeStyle.Raised) End Sub ' Determine whether the user has clicked the track bar thumb. Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs) If Not TrackBarRenderer.IsSupported Then Return End If If Me.thumbRectangle.Contains(e.Location) Then thumbClicked = True thumbState = TrackBarThumbState.Pressed End If Me.Invalidate() End Sub ' Redraw the track bar thumb if the user has moved it. Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs) If Not TrackBarRenderer.IsSupported Then Return End If If thumbClicked = True Then If e.Location.X > trackRectangle.X And _ e.Location.X < trackRectangle.X + _ trackRectangle.Width - thumbRectangle.Width Then thumbClicked = False thumbState = TrackBarThumbState.Hot Me.Invalidate() End If thumbClicked = False End If End Sub ' Track cursor movements. Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs) If Not TrackBarRenderer.IsSupported Then Return End If ' The user is moving the thumb. If thumbClicked = True Then ' Track movements to the next tick to the right, if the ' cursor has moved halfway to the next tick. If currentTickPosition < numberTicks - 1 And _ e.Location.X > CurrentTickXCoordinate() + _ CInt(tickSpace) Then currentTickPosition += 1 ' Track movements to the next tick to the left, if ' the cursor has moved halfway to the next tick. Else If currentTickPosition > 0 And _ e.Location.X < CurrentTickXCoordinate() - _ CInt(tickSpace / 2) Then currentTickPosition -= 1 End If End If thumbRectangle.X = CurrentTickXCoordinate() ' The cursor is passing over the track. Else If thumbRectangle.Contains(e.Location) Then thumbState = TrackBarThumbState.Hot Else thumbState = TrackBarThumbState.Normal End If End If Invalidate() End Sub End Class End Namespace