TrackBarRenderer Class

Definition

public ref class TrackBarRenderer sealed

public ref class TrackBarRenderer abstract sealed

public sealed class TrackBarRenderer

public static class TrackBarRenderer

type TrackBarRenderer = class

Public NotInheritable Class TrackBarRenderer

Public Class TrackBarRenderer

Inheritance

Object

TrackBarRenderer

Examples

The following code example demonstrates how to create a custom control that uses the TrackBarRenderer methods to draw a horizontal track bar that responds to mouse clicks.

#using <System.Drawing.dll>
#using <System.Windows.Forms.dll>
#using <System.dll>

using namespace System;
using namespace System::Drawing;
using namespace System::Windows::Forms;
using namespace System::Windows::Forms::VisualStyles;

namespace TrackBarRendererSample
{
 ref class CustomTrackBar : public Control
 {
 private:
 int numberTicks;
 Rectangle trackRectangle;
 Rectangle ticksRectangle;
 Rectangle thumbRectangle;
 int currentTickPosition;
 float tickSpace;
 bool thumbClicked;
 TrackBarThumbState thumbState;

 public:
 CustomTrackBar(int ticks, System::Drawing::Size trackBarSize)
 {
 this->Location = Point(10, 10);
 this->Size = trackBarSize;
 this->numberTicks = ticks;
 this->BackColor = Color::DarkCyan;
 this->DoubleBuffered = true;
 numberTicks = 10;
 thumbState = TrackBarThumbState::Normal;

 // Calculate the initial sizes of the bar,
 // thumb and ticks.
 SetupTrackBar();
 }

 // Calculate the sizes of the bar, thumb, and ticks rectangle.
 private:
 void SetupTrackBar()
 {
 if (!TrackBarRenderer::IsSupported)
 {
 return;
 }

 Graphics^ g = this->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 = ((float)ticksRectangle.Width - 1) /
 ((float)numberTicks - 1);

 // Calculate the size of the thumb.
 thumbRectangle.Size =
 TrackBarRenderer::GetTopPointingThumbSize(g,
 TrackBarThumbState::Normal);

 thumbRectangle.X = CurrentTickXCoordinate();
 thumbRectangle.Y = trackRectangle.Y - 8;
 }

 private:
 int CurrentTickXCoordinate()
 {
 if (tickSpace == 0)
 {
 return 0;
 }
 else
 {
 return ((int)Math::Round(tickSpace) *
 currentTickPosition);
 }
 }

 // Draw the track bar.
 protected:
 virtual void OnPaint(PaintEventArgs^ e) override
 {
 if (!TrackBarRenderer::IsSupported)
 {
 this->Parent->Text = "CustomTrackBar Disabled";
 return;
 }

 this->Parent->Text = "CustomTrackBar Enabled";
 TrackBarRenderer::DrawHorizontalTrack(e->Graphics,
 trackRectangle);
 TrackBarRenderer::DrawTopPointingThumb(e->Graphics,
 thumbRectangle, thumbState);
 TrackBarRenderer::DrawHorizontalTicks(e->Graphics,
 ticksRectangle, numberTicks, EdgeStyle::Raised);
 }

 // Determine whether the user has clicked the track bar thumb.
 protected:
 virtual void OnMouseDown(MouseEventArgs^ e) override
 {
 if (!TrackBarRenderer::IsSupported)
 {
 return;
 }
 if (this->thumbRectangle.Contains(e->Location))
 {
 thumbClicked = true;
 thumbState = TrackBarThumbState::Pressed;
 }

 this->Invalidate();
 }

 // Redraw the track bar thumb if the user has moved it.
 protected:
 virtual void OnMouseUp(MouseEventArgs^ e) override
 {
 if (!TrackBarRenderer::IsSupported)
 {
 return;
 }
 if (thumbClicked)
 {
 if (e->Location.X > trackRectangle.X &&
 e->Location.X < (trackRectangle.X +
 trackRectangle.Width - thumbRectangle.Width))
 {
 thumbClicked = false;
 thumbState = TrackBarThumbState::Hot;
 this->Invalidate();
 }

 thumbClicked = false;
 }
 }

 // Track cursor movements.
 protected:
 virtual void OnMouseMove(MouseEventArgs^ e) override
 {
 if (!TrackBarRenderer::IsSupported)
 {
 return;
 }
 // The user is moving the thumb.
 if (thumbClicked)
 {
 // Track movements to the next tick to the right, if
 // the cursor has moved halfway to the next tick.
 if (currentTickPosition < numberTicks - 1 &&
 e->Location.X > CurrentTickXCoordinate() +
 (int)(tickSpace))
 {
 currentTickPosition++;
 }

 // Track movements to the next tick to the left, if
 // cursor has moved halfway to the next tick.
 else if (currentTickPosition > 0 &&
 e->Location.X < CurrentTickXCoordinate() -
 (int)(tickSpace / 2))
 {
 currentTickPosition--;
 }

 thumbRectangle.X = CurrentTickXCoordinate();
 }

 // The cursor is passing over the track.
 else
 {
 if (thumbRectangle.Contains(e->Location))
 {
 thumbState = TrackBarThumbState::Hot;
 }
 else
 {
 thumbState = TrackBarThumbState::Normal;
 }
 }

 Invalidate();
 }
 };

 ref class Form1 : public Form
 {
 public:
 Form1()
 {
 CustomTrackBar^ TrackBar1 = gcnew CustomTrackBar(19,
 System::Drawing::Size(300, 50));
 this->Width = 500;
 this->Controls->Add(TrackBar1);
 }
 };
}

[STAThread]
int 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(gcnew TrackBarRendererSample::Form1());
 return 0;
}

using System;
using System.Drawing;
using System.Windows.Forms;
using System.Windows.Forms.VisualStyles;

namespace TrackBarRendererSample
{
 class Form1 : Form
 {
 public Form1()
 {
 CustomTrackBar TrackBar1 = new CustomTrackBar(19,
 new Size(300, 50));
 this.Width = 500;
 this.Controls.Add(TrackBar1);
 }

 [STAThread]
 static void 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());
 }
 }

 class CustomTrackBar : Control
 {
 private int numberTicks = 10;
 private Rectangle trackRectangle = new Rectangle();
 private Rectangle ticksRectangle = new Rectangle();
 private Rectangle thumbRectangle = new Rectangle();
 private int currentTickPosition = 0;
 private float tickSpace = 0;
 private bool thumbClicked = false;
 private TrackBarThumbState thumbState =
 TrackBarThumbState.Normal;

 public CustomTrackBar(int ticks, Size trackBarSize)
 {
 this.Location = new Point(10, 10);
 this.Size = trackBarSize;
 this.numberTicks = ticks;
 this.BackColor = Color.DarkCyan;
 this.DoubleBuffered = true;

 // Calculate the initial sizes of the bar, 
 // thumb and ticks.
 SetupTrackBar();
 }

 // Calculate the sizes of the bar, thumb, and ticks rectangle.
 private void SetupTrackBar()
 {
 if (!TrackBarRenderer.IsSupported)
 return;

 using (Graphics g = this.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 = ((float)ticksRectangle.Width - 1) /
 ((float)numberTicks - 1);

 // Calculate the size of the thumb.
 thumbRectangle.Size =
 TrackBarRenderer.GetTopPointingThumbSize(g,
 TrackBarThumbState.Normal);

 thumbRectangle.X = CurrentTickXCoordinate();
 thumbRectangle.Y = trackRectangle.Y - 8;
 }
 }

 private int CurrentTickXCoordinate()
 {
 if (tickSpace == 0)
 {
 return 0;
 }
 else
 {
 return ((int)Math.Round(tickSpace) *
 currentTickPosition);
 }
 }

 // Draw the track bar.
 protected override void OnPaint(PaintEventArgs e)
 {
 if (!TrackBarRenderer.IsSupported)
 {
 this.Parent.Text = "CustomTrackBar Disabled";
 return;
 }

 this.Parent.Text = "CustomTrackBar Enabled";
 TrackBarRenderer.DrawHorizontalTrack(e.Graphics,
 trackRectangle);
 TrackBarRenderer.DrawTopPointingThumb(e.Graphics,
 thumbRectangle, thumbState);
 TrackBarRenderer.DrawHorizontalTicks(e.Graphics,
 ticksRectangle, numberTicks, EdgeStyle.Raised);
 }

 // Determine whether the user has clicked the track bar thumb.
 protected override void OnMouseDown(MouseEventArgs e)
 {
 if (!TrackBarRenderer.IsSupported)
 return;

 if (this.thumbRectangle.Contains(e.Location))
 {
 thumbClicked = true;
 thumbState = TrackBarThumbState.Pressed;
 }

 this.Invalidate();
 }

 // Redraw the track bar thumb if the user has moved it.
 protected override void OnMouseUp(MouseEventArgs e)
 {
 if (!TrackBarRenderer.IsSupported)
 return;

 if (thumbClicked)
 {
 if (e.Location.X > trackRectangle.X &&
 e.Location.X < (trackRectangle.X +
 trackRectangle.Width - thumbRectangle.Width))
 {
 thumbClicked = false;
 thumbState = TrackBarThumbState.Hot;
 this.Invalidate();
 }

 thumbClicked = false;
 }
 }

 // Track cursor movements.
 protected override void OnMouseMove(MouseEventArgs e)
 {
 if (!TrackBarRenderer.IsSupported)
 return;

 // The user is moving the thumb.
 if (thumbClicked)
 {
 // Track movements to the next tick to the right, if 
 // the cursor has moved halfway to the next tick.
 if (currentTickPosition < numberTicks - 1 &&
 e.Location.X > CurrentTickXCoordinate() +
 (int)(tickSpace))
 {
 currentTickPosition++;
 }

 // Track movements to the next tick to the left, if 
 // cursor has moved halfway to the next tick.
 else if (currentTickPosition > 0 &&
 e.Location.X < CurrentTickXCoordinate() -
 (int)(tickSpace / 2))
 {
 currentTickPosition--;
 }

 thumbRectangle.X = CurrentTickXCoordinate();
 }

 // The cursor is passing over the track.
 else
 {
 thumbState = thumbRectangle.Contains(e.Location) ?
 TrackBarThumbState.Hot : TrackBarThumbState.Normal;
 }

 Invalidate();
 }
 }
}

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

Remarks

The TrackBarRenderer 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.

See also

• VisualStyleRenderer
• VisualStyleElement