ScrollBarRenderer Class

Definition

public ref class ScrollBarRenderer sealed

public ref class ScrollBarRenderer abstract sealed

public sealed class ScrollBarRenderer

public static class ScrollBarRenderer

type ScrollBarRenderer = class

Public NotInheritable Class ScrollBarRenderer

Public Class ScrollBarRenderer

Inheritance

Object

ScrollBarRenderer

Examples

The following code example demonstrates how to create a custom control that uses the ScrollBarRenderer methods to draw a scroll 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 ScrollBarRendererSample
{
 public ref class CustomScrollBar : public Control
 {
 private:
 Rectangle clickedBarRectangle;
 private:
 Rectangle thumbRectangle;
 private:
 Rectangle leftArrowRectangle;
 private:
 Rectangle rightArrowRectangle;
 private:
 bool leftArrowClicked;
 private:
 bool rightArrowClicked;
 private:
 bool leftBarClicked;
 private:
 bool rightBarClicked;
 private:
 bool thumbClicked;
 private:
 ScrollBarState thumbState;
 private:
 ScrollBarArrowButtonState leftButtonState;
 private:
 ScrollBarArrowButtonState rightButtonState;
 private:
 int thumbWidth;
 private:
 int arrowWidth;

 // The right limit of the thumb's right border.
 private:
 int thumbRightLimitRight;

 // The right limit of the thumb's left border.
 private:
 int thumbRightLimitLeft;

 // The left limit of thumb's left border.
 private:
 int thumbLeftLimit;

 // The distance from the left edge of the thumb to the
 // cursor tip.
 private:
 int thumbPosition;

 // The distance from the left edge of the scroll bar track
 // to the cursor tip.
 private:
 int trackPosition;

 // This timer draws the moving thumb while the scroll arrows or
 // track are pressed.
 private:
 Timer^ progressTimer;

 public:
 CustomScrollBar() : Control()
 {
 thumbState = ScrollBarState::Normal;
 leftButtonState = ScrollBarArrowButtonState::LeftNormal;
 rightButtonState = ScrollBarArrowButtonState::RightNormal;

 // This control does not allow these widths to be altered.
 thumbWidth = 15;
 arrowWidth = 17;

 progressTimer = gcnew Timer();
 this->Location = Point(10, 10);
 this->Width = 200;
 this->Height = 20;
 this->DoubleBuffered = true;

 SetUpScrollBar();
 progressTimer->Interval = 20;
 progressTimer->Tick += 
 gcnew EventHandler(this, &CustomScrollBar::progressTimer_Tick);
 }

 // Calculate the sizes of the scroll bar elements.
 private:
 void SetUpScrollBar()
 {
 clickedBarRectangle = ClientRectangle;
 thumbRectangle = Rectangle(
 ClientRectangle.X + ClientRectangle.Width / 2,
 ClientRectangle.Y, thumbWidth,
 ClientRectangle.Height);
 leftArrowRectangle = Rectangle(
 ClientRectangle.X, ClientRectangle.Y,
 arrowWidth, ClientRectangle.Height);
 rightArrowRectangle = Rectangle(
 ClientRectangle.Right - arrowWidth,
 ClientRectangle.Y, arrowWidth,
 ClientRectangle.Height);

 // Set the default starting thumb position.
 thumbPosition = thumbWidth / 2;

 // Set the right limit of the thumb's right border.
 thumbRightLimitRight = ClientRectangle.Right - arrowWidth;

 // Set the right limit of the thumb's left border.
 thumbRightLimitLeft = thumbRightLimitRight - thumbWidth;

 // Set the left limit of the thumb's left border.
 thumbLeftLimit = ClientRectangle.X + arrowWidth;
 }

 // Draw the scroll bar in its normal state.
 protected:
 virtual void OnPaint(PaintEventArgs^ e) override
 {
 __super::OnPaint(e);

 // Visual styles are not enabled.
 if (!ScrollBarRenderer::IsSupported)
 {
 this->Parent->Text = "CustomScrollBar Disabled";
 return;
 }

 this->Parent->Text = "CustomScrollBar Enabled";

 // Draw the scroll bar track.
 ScrollBarRenderer::DrawRightHorizontalTrack(e->Graphics,
 ClientRectangle, ScrollBarState::Normal);

 // Draw the thumb and thumb grip in the current state.
 ScrollBarRenderer::DrawHorizontalThumb(e->Graphics,
 thumbRectangle, thumbState);
 ScrollBarRenderer::DrawHorizontalThumbGrip(e->Graphics,
 thumbRectangle, thumbState);

 // Draw the scroll arrows in the current state.
 ScrollBarRenderer::DrawArrowButton(e->Graphics,
 leftArrowRectangle, leftButtonState);
 ScrollBarRenderer::DrawArrowButton(e->Graphics,
 rightArrowRectangle, rightButtonState);

 // Draw a highlighted rectangle in the left side of the scroll
 // bar track if the user has clicked between the left arrow
 // and thumb.
 if (leftBarClicked)
 {
 clickedBarRectangle.X = thumbLeftLimit;
 clickedBarRectangle.Width = thumbRectangle.X - thumbLeftLimit;
 ScrollBarRenderer::DrawLeftHorizontalTrack(e->Graphics,
 clickedBarRectangle, ScrollBarState::Pressed);
 }

 // Draw a highlighted rectangle in the right side of the scroll
 // bar track if the user has clicked between the right arrow
 // and thumb.
 else if (rightBarClicked)
 {
 clickedBarRectangle.X =
 thumbRectangle.X + thumbRectangle.Width;
 clickedBarRectangle.Width =
 thumbRightLimitRight - clickedBarRectangle.X;
 ScrollBarRenderer::DrawRightHorizontalTrack(e->Graphics,
 clickedBarRectangle, ScrollBarState::Pressed);
 }
 }

 // Handle a mouse click in the scroll bar.
 protected:
 virtual void OnMouseDown(MouseEventArgs^ e) override 
 {
 __super::OnMouseDown(e);

 if (!ScrollBarRenderer::IsSupported)
 {
 return;
 }

 // When the thumb is clicked, update the distance from the left
 // edge of the thumb to the cursor tip.
 if (thumbRectangle.Contains(e->Location))
 {
 thumbClicked = true;
 thumbPosition = e->Location.X - thumbRectangle.X;
 thumbState = ScrollBarState::Pressed;
 }

 // When the left arrow is clicked, start the timer to scroll
 // while the arrow is held down.
 else if (leftArrowRectangle.Contains(e->Location))
 {
 leftArrowClicked = true;
 leftButtonState = ScrollBarArrowButtonState::LeftPressed;
 progressTimer->Start();
 }

 // When the right arrow is clicked, start the timer to scroll
 // while the arrow is held down.
 else if (rightArrowRectangle.Contains(e->Location))
 {
 rightArrowClicked = true;
 rightButtonState = ScrollBarArrowButtonState::RightPressed;
 progressTimer->Start();
 }

 // When the scroll bar is clicked, start the timer to move the
 // thumb while the mouse is held down.
 else
 {
 trackPosition = e->Location.X;

 if (e->Location.X < this->thumbRectangle.X)
 {
 leftBarClicked = true;
 }
 else
 {
 rightBarClicked = true;
 }
 progressTimer->Start();
 }

 Invalidate();
 }

 // Draw the track.
 protected:
 virtual void OnMouseUp(MouseEventArgs^ e) override
 {
 __super::OnMouseUp(e);

 if (!ScrollBarRenderer::IsSupported)
 {
 return;
 }

 // Update the thumb position, if the new location is within
 // the bounds.
 if (thumbClicked)
 {
 thumbClicked = false;
 thumbState = ScrollBarState::Normal;

 if (e->Location.X > (thumbLeftLimit + thumbPosition) &&
 e->Location.X < (thumbRightLimitLeft + thumbPosition))
 {
 thumbRectangle.X = e->Location.X - thumbPosition;
 }
 }

 // If one of the four thumb movement areas was clicked,
 // stop the timer.
 else if (leftArrowClicked)
 {
 leftArrowClicked = false;
 leftButtonState = ScrollBarArrowButtonState::LeftNormal;
 progressTimer->Stop();
 }

 else if (rightArrowClicked)
 {
 rightArrowClicked = false;
 rightButtonState = ScrollBarArrowButtonState::RightNormal;
 progressTimer->Stop();
 }

 else if (leftBarClicked)
 {
 leftBarClicked = false;
 progressTimer->Stop();
 }

 else if (rightBarClicked)
 {
 rightBarClicked = false;
 progressTimer->Stop();
 }

 Invalidate();
 }

 // Track mouse movements if the user clicks on the scroll bar thumb.
 protected:
 virtual void OnMouseMove(MouseEventArgs^ e) override
 {
 __super::OnMouseMove(e);

 if (!ScrollBarRenderer::IsSupported)
 {
 return;
 }

 // Update the thumb position, if the new location is
 // within the bounds.
 if (thumbClicked)
 {
 // The thumb is all the way to the left.
 if (e->Location.X <= (thumbLeftLimit + thumbPosition))
 {
 thumbRectangle.X = thumbLeftLimit;
 }

 // The thumb is all the way to the right.
 else if (e->Location.X >= 
 (thumbRightLimitLeft + thumbPosition))
 {
 thumbRectangle.X = thumbRightLimitLeft;
 }

 // The thumb is between the ends of the track.
 else
 {
 thumbRectangle.X = e->Location.X - thumbPosition;
 }

 Invalidate();
 }
 }

 // Recalculate the sizes of the scroll bar elements.
 protected:
 virtual void OnSizeChanged(EventArgs^ e) override
 {
 __super::OnSizeChanged(e);
 SetUpScrollBar();
 }

 // Handle the timer tick by updating the thumb position.
 private:
 void progressTimer_Tick(Object^ sender, EventArgs^ myEventArgs)
 {
 if (!ScrollBarRenderer::IsSupported)
 {
 return;
 }

 // If an arrow is clicked, move the thumb in small increments.
 if (rightArrowClicked && thumbRectangle.X < thumbRightLimitLeft)
 {
 thumbRectangle.X++;
 }
 else if (leftArrowClicked && thumbRectangle.X > thumbLeftLimit)
 {
 thumbRectangle.X--;
 }

 // If the track bar to right of the thumb is clicked, move the
 // thumb to the right in larger increments until the right edge
 // of the thumb hits the cursor.
 else if (rightBarClicked &&
 thumbRectangle.X < thumbRightLimitLeft &&
 thumbRectangle.X + thumbRectangle.Width < trackPosition)
 {
 thumbRectangle.X += 3;
 }

 // If the track bar to left of the thumb is clicked, move the
 // thumb to the left in larger increments until the left edge
 // of the thumb hits the cursor.
 else if (leftBarClicked &&
 thumbRectangle.X > thumbLeftLimit &&
 thumbRectangle.X > trackPosition)
 {
 thumbRectangle.X -= 3;
 }

 Invalidate();
 }
 };


 public ref class Form1 : public Form
 {
 public:
 Form1() : Form()
 {
 this->Size = System::Drawing::Size(500, 500);

 CustomScrollBar^ sampleCustomScrollBar = gcnew CustomScrollBar();
 sampleCustomScrollBar->Location = Point(50, 100);
 sampleCustomScrollBar->Size = System::Drawing::Size(200, 20);

 Controls->Add(sampleCustomScrollBar);
 }
 };
}

[STAThread]
int main()
{
 // The call to EnableVisualStyles below does not affect whether
 // ScrollBarRenderer.IsSupported is true; as long as visual styles
 // are enabled by the operating system, IsSupported is true.
 Application::EnableVisualStyles();
 Application::Run(gcnew ScrollBarRendererSample::Form1());
}

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

namespace ScrollBarRendererSample
{
 class Form1 : Form
 {
 public Form1()
 : base()
 {
 this.Size = new Size(500, 500);

 CustomScrollBar Bar1 = new CustomScrollBar();
 Bar1.Location = new Point(50, 100);
 Bar1.Size = new Size(200, 20);

 Controls.Add(Bar1);
 }

 [STAThread]
 static void Main()
 {
 // The call to EnableVisualStyles below does not affect whether 
 // ScrollBarRenderer.IsSupported is true; as long as visual styles 
 // are enabled by the operating system, IsSupported is true.
 Application.EnableVisualStyles();
 Application.Run(new Form1());
 }
 }

 public class CustomScrollBar : Control
 {
 private Rectangle clickedBarRectangle;
 private Rectangle thumbRectangle;
 private Rectangle leftArrowRectangle;
 private Rectangle rightArrowRectangle;
 private bool leftArrowClicked = false;
 private bool rightArrowClicked = false;
 private bool leftBarClicked = false;
 private bool rightBarClicked = false;
 private bool thumbClicked = false;
 private ScrollBarState thumbState = ScrollBarState.Normal;
 private ScrollBarArrowButtonState leftButtonState =
 ScrollBarArrowButtonState.LeftNormal;
 private ScrollBarArrowButtonState rightButtonState =
 ScrollBarArrowButtonState.RightNormal;

 // This control does not allow these widths to be altered.
 private int thumbWidth = 15;
 private int arrowWidth = 17;

 // Set the right limit of the thumb's right border.
 private int thumbRightLimitRight = 0;

 // Set the right limit of the thumb's left border.
 private int thumbRightLimitLeft = 0;

 // Set the left limit of thumb's left border.
 private int thumbLeftLimit = 0;

 // Set the distance from the left edge of the thumb to the 
 // cursor tip.
 private int thumbPosition = 0;

 // Set the distance from the left edge of the scroll bar track 
 // to the cursor tip.
 private int trackPosition = 0;

 // This timer draws the moving thumb while the scroll arrows or 
 // track are pressed.
 private Timer progressTimer = new Timer();

 public CustomScrollBar()
 : base()
 {
 this.Location = new Point(10, 10);
 this.Width = 200;
 this.Height = 20;
 this.DoubleBuffered = true;

 SetUpScrollBar();
 progressTimer.Interval = 20;
 progressTimer.Tick += new EventHandler(progressTimer_Tick);
 }

 // Calculate the sizes of the scroll bar elements.
 private void SetUpScrollBar()
 {
 clickedBarRectangle = ClientRectangle;
 thumbRectangle = new Rectangle(
 ClientRectangle.X + ClientRectangle.Width / 2,
 ClientRectangle.Y, thumbWidth,
 ClientRectangle.Height);
 leftArrowRectangle = new Rectangle(
 ClientRectangle.X, ClientRectangle.Y,
 arrowWidth, ClientRectangle.Height);
 rightArrowRectangle = new Rectangle(
 ClientRectangle.Right - arrowWidth,
 ClientRectangle.Y, arrowWidth,
 ClientRectangle.Height);

 // Set the default starting thumb position.
 thumbPosition = thumbWidth / 2;

 // Set the right limit of the thumb's right border.
 thumbRightLimitRight = ClientRectangle.Right - arrowWidth;

 // Set the right limit of the thumb's left border.
 thumbRightLimitLeft = thumbRightLimitRight - thumbWidth;

 // Set the left limit of the thumb's left border.
 thumbLeftLimit = ClientRectangle.X + arrowWidth;
 }

 // Draw the scroll bar in its normal state.
 protected override void OnPaint(PaintEventArgs e)
 {
 base.OnPaint(e);

 // Visual styles are not enabled.
 if (!ScrollBarRenderer.IsSupported)
 {
 this.Parent.Text = "CustomScrollBar Disabled";
 return;
 }

 this.Parent.Text = "CustomScrollBar Enabled";

 // Draw the scroll bar track.
 ScrollBarRenderer.DrawRightHorizontalTrack(e.Graphics,
 ClientRectangle, ScrollBarState.Normal);

 // Draw the thumb and thumb grip in the current state.
 ScrollBarRenderer.DrawHorizontalThumb(e.Graphics,
 thumbRectangle, thumbState);
 ScrollBarRenderer.DrawHorizontalThumbGrip(e.Graphics,
 thumbRectangle, thumbState);

 // Draw the scroll arrows in the current state.
 ScrollBarRenderer.DrawArrowButton(e.Graphics,
 leftArrowRectangle, leftButtonState);
 ScrollBarRenderer.DrawArrowButton(e.Graphics,
 rightArrowRectangle, rightButtonState);

 // Draw a highlighted rectangle in the left side of the scroll 
 // bar track if the user has clicked between the left arrow 
 // and thumb.
 if (leftBarClicked)
 {
 clickedBarRectangle.X = thumbLeftLimit;
 clickedBarRectangle.Width = thumbRectangle.X - thumbLeftLimit;
 ScrollBarRenderer.DrawLeftHorizontalTrack(e.Graphics,
 clickedBarRectangle, ScrollBarState.Pressed);
 }

 // Draw a highlighted rectangle in the right side of the scroll 
 // bar track if the user has clicked between the right arrow 
 // and thumb.
 else if (rightBarClicked)
 {
 clickedBarRectangle.X =
 thumbRectangle.X + thumbRectangle.Width;
 clickedBarRectangle.Width =
 thumbRightLimitRight - clickedBarRectangle.X;
 ScrollBarRenderer.DrawRightHorizontalTrack(e.Graphics,
 clickedBarRectangle, ScrollBarState.Pressed);
 }
 }

 // Handle a mouse click in the scroll bar.
 protected override void OnMouseDown(MouseEventArgs e)
 {
 base.OnMouseDown(e);

 if (!ScrollBarRenderer.IsSupported)
 return;

 // When the thumb is clicked, update the distance from the left
 // edge of the thumb to the cursor tip.
 if (thumbRectangle.Contains(e.Location))
 {
 thumbClicked = true;
 thumbPosition = e.Location.X - thumbRectangle.X;
 thumbState = ScrollBarState.Pressed;
 }

 // When the left arrow is clicked, start the timer to scroll 
 // while the arrow is held down.
 else if (leftArrowRectangle.Contains(e.Location))
 {
 leftArrowClicked = true;
 leftButtonState = ScrollBarArrowButtonState.LeftPressed;
 progressTimer.Start();
 }

 // When the right arrow is clicked, start the timer to scroll 
 // while the arrow is held down.
 else if (rightArrowRectangle.Contains(e.Location))
 {
 rightArrowClicked = true;
 rightButtonState = ScrollBarArrowButtonState.RightPressed;
 progressTimer.Start();
 }

 // When the scroll bar is clicked, start the timer to move the
 // thumb while the mouse is held down.
 else
 {
 trackPosition = e.Location.X;

 if (e.Location.X < this.thumbRectangle.X)
 {
 leftBarClicked = true;
 }
 else
 {
 rightBarClicked = true;
 }
 progressTimer.Start();
 }

 Invalidate();
 }

 // Draw the track.
 protected override void OnMouseUp(MouseEventArgs e)
 {
 base.OnMouseUp(e);

 if (!ScrollBarRenderer.IsSupported)
 return;

 // Update the thumb position, if the new location is within 
 // the bounds.
 if (thumbClicked)
 {
 thumbClicked = false;
 thumbState = ScrollBarState.Normal;

 if (e.Location.X > (thumbLeftLimit + thumbPosition) &&
 e.Location.X < (thumbRightLimitLeft + thumbPosition))
 {
 thumbRectangle.X = e.Location.X - thumbPosition;
 thumbClicked = false;
 }
 }

 // If one of the four thumb movement areas was clicked, 
 // stop the timer.
 else if (leftArrowClicked)
 {
 leftArrowClicked = false;
 leftButtonState = ScrollBarArrowButtonState.LeftNormal;
 progressTimer.Stop();
 }

 else if (rightArrowClicked)
 {
 rightArrowClicked = false;
 rightButtonState = ScrollBarArrowButtonState.RightNormal;
 progressTimer.Stop();
 }

 else if (leftBarClicked)
 {
 leftBarClicked = false;
 progressTimer.Stop();
 }

 else if (rightBarClicked)
 {
 rightBarClicked = false;
 progressTimer.Stop();
 }

 Invalidate();
 }

 // Track mouse movements if the user clicks on the scroll bar thumb.
 protected override void OnMouseMove(MouseEventArgs e)
 {
 base.OnMouseMove(e);

 if (!ScrollBarRenderer.IsSupported)
 return;

 // Update the thumb position, if the new location is 
 // within the bounds.
 if (thumbClicked)
 {
 // The thumb is all the way to the left.
 if (e.Location.X <= (thumbLeftLimit + thumbPosition))
 {
 thumbRectangle.X = thumbLeftLimit;
 }

 // The thumb is all the way to the right.
 else if (e.Location.X >= (thumbRightLimitLeft + thumbPosition))
 {
 thumbRectangle.X = thumbRightLimitLeft;
 }

 // The thumb is between the ends of the track.
 else
 {
 thumbRectangle.X = e.Location.X - thumbPosition;
 }

 Invalidate();
 }
 }

 // Recalculate the sizes of the scroll bar elements.
 protected override void OnSizeChanged(EventArgs e)
 {
 base.OnSizeChanged(e);
 SetUpScrollBar();
 }

 // Handle the timer tick by updating the thumb position.
 private void progressTimer_Tick(object sender, EventArgs myEventArgs)
 {
 if (!ScrollBarRenderer.IsSupported)
 return;

 // If an arrow is clicked, move the thumb in small increments.
 if (rightArrowClicked && thumbRectangle.X < thumbRightLimitLeft)
 {
 thumbRectangle.X++;
 }
 else if (leftArrowClicked && thumbRectangle.X > thumbLeftLimit)
 {
 thumbRectangle.X--;
 }

 // If the track bar to right of the thumb is clicked, move the 
 // thumb to the right in larger increments until the right edge 
 // of the thumb hits the cursor.
 else if (rightBarClicked &&
 thumbRectangle.X < thumbRightLimitLeft &&
 thumbRectangle.X + thumbRectangle.Width < trackPosition)
 {
 thumbRectangle.X += 3;
 }

 // If the track bar to left of the thumb is clicked, move the 
 // thumb to the left in larger increments until the left edge 
 // of the thumb hits the cursor.
 else if (leftBarClicked &&
 thumbRectangle.X > thumbLeftLimit &&
 thumbRectangle.X > trackPosition)
 {
 thumbRectangle.X -= 3;
 }

 Invalidate();
 }
 }
}

Imports System.Drawing
Imports System.Windows.Forms
Imports System.Windows.Forms.VisualStyles

Namespace ScrollBarRendererSample

 Class Form1
 Inherits Form

 Public Sub New()
 Me.Size = New Size(500, 500)

 Dim Bar1 As New CustomScrollBar()
 Bar1.Location = New Point(50, 100)
 Bar1.Size = New Size(200, 20)

 Controls.Add(Bar1)
 End Sub

 <STAThread()> _
 Shared Sub Main()
 ' The call to EnableVisualStyles below does not affect whether 
 ' ScrollBarRenderer.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

 Public Class CustomScrollBar
 Inherits Control

 Private clickedBarRectangle As Rectangle
 Private thumbRectangle As Rectangle
 Private leftArrowRectangle As Rectangle
 Private rightArrowRectangle As Rectangle
 Private leftArrowClicked As Boolean = False
 Private rightArrowClicked As Boolean = False
 Private leftBarClicked As Boolean = False
 Private rightBarClicked As Boolean = False
 Private thumbClicked As Boolean = False
 Private thumbState As ScrollBarState = ScrollBarState.Normal
 Private leftButtonState As ScrollBarArrowButtonState = _
 ScrollBarArrowButtonState.LeftNormal
 Private rightButtonState As ScrollBarArrowButtonState = _
 ScrollBarArrowButtonState.RightNormal

 ' This control does not allow these widths to be altered.
 Private thumbWidth As Integer = 15
 Private arrowWidth As Integer = 17

 ' Set the right limit of the thumb's right border.
 Private thumbRightLimitRight As Integer = 0

 ' Set the right limit of the thumb's left border.
 Private thumbRightLimitLeft As Integer = 0

 ' Set the left limit of thumb's left border.
 Private thumbLeftLimit As Integer = 0

 ' Set the distance from the left edge of the thumb to the 
 ' cursor tip.
 Private thumbPosition As Integer = 0

 ' Set the distance from the left edge of the scroll bar track to 
 ' the cursor tip.
 Private trackPosition As Integer = 0

 ' This timer draws the moving thumb while the scroll arrows or 
 ' track are pressed.
 Private WithEvents progressTimer As New Timer()

 Public Sub New()
 With Me
 .Location = New Point(10, 10)
 .Width = 200
 .Height = 20
 .DoubleBuffered = True
 End With
 SetUpScrollBar()
 progressTimer.Interval = 20
 End Sub

 ' Calculate the sizes of the scroll bar elements.
 Private Sub SetUpScrollBar()

 clickedBarRectangle = Me.ClientRectangle
 thumbRectangle = New Rectangle(ClientRectangle.X + _
 Me.ClientRectangle.Width / 2, Me.ClientRectangle.Y, _
 thumbWidth, Me.ClientRectangle.Height)
 leftArrowRectangle = New Rectangle(Me.ClientRectangle.X, _
 Me.ClientRectangle.Y, arrowWidth, Me.ClientRectangle.Height)
 rightArrowRectangle = New Rectangle(Me.ClientRectangle.Right - _
 arrowWidth, Me.ClientRectangle.Y, arrowWidth, _
 Me.ClientRectangle.Height)

 ' Set the default starting thumb position.
 thumbPosition = thumbWidth / 2

 ' Set the right limit of the thumb's right border.
 thumbRightLimitRight = Me.ClientRectangle.Right - arrowWidth

 ' Set the right limit of the thumb's left border.
 thumbRightLimitLeft = thumbRightLimitRight - thumbWidth

 ' Set the left limit of the thumb's left border.
 thumbLeftLimit = Me.ClientRectangle.X + arrowWidth
 End Sub

 ' Draw the scroll bar in its normal state.
 Protected Overrides Sub OnPaint(ByVal e As PaintEventArgs)
 MyBase.OnPaint(e)

 ' Visual styles are not enabled.
 If Not ScrollBarRenderer.IsSupported Then
 Me.Parent.Text = "CustomScrollBar Disabled"
 Return
 End If

 Me.Parent.Text = "CustomScrollBar Enabled"

 ' Draw the scroll bar track.
 ScrollBarRenderer.DrawRightHorizontalTrack(e.Graphics, _
 Me.ClientRectangle, ScrollBarState.Normal)

 ' Draw the thumb and thumb grip in the current state.
 ScrollBarRenderer.DrawHorizontalThumb(e.Graphics, _
 thumbRectangle, thumbState)
 ScrollBarRenderer.DrawHorizontalThumbGrip(e.Graphics, _
 thumbRectangle, thumbState)

 ' Draw the scroll arrows in the current state.
 ScrollBarRenderer.DrawArrowButton(e.Graphics, _
 leftArrowRectangle, leftButtonState)
 ScrollBarRenderer.DrawArrowButton(e.Graphics, _
 rightArrowRectangle, rightButtonState)

 ' Draw a highlighted rectangle in the left side of the scroll 
 ' bar track if the user has clicked between the left arrow 
 ' and thumb.
 If leftBarClicked Then
 clickedBarRectangle.X = thumbLeftLimit
 clickedBarRectangle.Width = thumbRectangle.X - thumbLeftLimit
 ScrollBarRenderer.DrawLeftHorizontalTrack(e.Graphics, _
 clickedBarRectangle, ScrollBarState.Pressed)

 ' Draw a highlighted rectangle in the right side of the scroll 
 ' bar track if the user has clicked between the right arrow 
 ' and thumb.
 ElseIf rightBarClicked Then
 clickedBarRectangle.X = thumbRectangle.X + _
 thumbRectangle.Width
 clickedBarRectangle.Width = thumbRightLimitRight - _
 clickedBarRectangle.X
 ScrollBarRenderer.DrawRightHorizontalTrack(e.Graphics, _
 clickedBarRectangle, ScrollBarState.Pressed)
 End If
 End Sub

 ' Handle a mouse click in the scroll bar.
 Protected Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
 MyBase.OnMouseDown(e)

 If Not ScrollBarRenderer.IsSupported Then
 Return
 End If

 ' When the thumb is clicked, update the distance from the left
 ' edge of the thumb to the cursor tip.
 If thumbRectangle.Contains(e.Location) Then
 thumbClicked = True
 thumbPosition = e.Location.X - thumbRectangle.X
 thumbState = ScrollBarState.Pressed

 ' When the left arrow is clicked, start the timer to scroll 
 ' while the arrow is held down.
 ElseIf leftArrowRectangle.Contains(e.Location) Then
 leftArrowClicked = True
 leftButtonState = ScrollBarArrowButtonState.LeftPressed
 progressTimer.Start()

 ' When the right arrow is clicked, start the timer to scroll 
 ' while arrow is held down.
 ElseIf rightArrowRectangle.Contains(e.Location) Then
 rightArrowClicked = True
 rightButtonState = ScrollBarArrowButtonState.RightPressed
 progressTimer.Start()

 ' When the scroll bar is clicked, start the timer to move the
 ' thumb while the mouse is held down.
 Else
 trackPosition = e.Location.X
 If e.Location.X < Me.thumbRectangle.X Then
 leftBarClicked = True
 Else
 rightBarClicked = True
 End If
 progressTimer.Start()
 End If

 Invalidate()
 End Sub

 ' Draw the track.
 Protected Overrides Sub OnMouseUp(ByVal e As MouseEventArgs)
 MyBase.OnMouseUp(e)

 If Not ScrollBarRenderer.IsSupported Then
 Return
 End If

 ' Update the thumb position, if the new location is within 
 ' the bounds.
 If thumbClicked Then
 thumbClicked = False
 thumbState = ScrollBarState.Normal
 If e.Location.X > thumbLeftLimit + thumbPosition And _
 e.Location.X < thumbRightLimitLeft + thumbPosition Then
 thumbRectangle.X = e.Location.X - thumbPosition
 thumbClicked = False
 End If

 ' If one of the four thumb movement areas was clicked, 
 ' stop the timer.
 ElseIf leftArrowClicked Then
 leftArrowClicked = False
 leftButtonState = ScrollBarArrowButtonState.LeftNormal
 progressTimer.Stop()

 ElseIf rightArrowClicked Then
 rightArrowClicked = False
 rightButtonState = ScrollBarArrowButtonState.RightNormal
 progressTimer.Stop()

 ElseIf leftBarClicked Then
 leftBarClicked = False
 progressTimer.Stop()

 ElseIf rightBarClicked Then
 rightBarClicked = False
 progressTimer.Stop()
 End If

 Invalidate()
 End Sub

 ' Track mouse movements if the user clicks on the scroll bar thumb.
 Protected Overrides Sub OnMouseMove(ByVal e As MouseEventArgs)
 MyBase.OnMouseMove(e)

 If Not ScrollBarRenderer.IsSupported Then
 Return
 End If

 ' Update the thumb position, if the new location is 
 ' within the bounds.
 If thumbClicked Then

 ' The thumb is all the way to the left.
 If e.Location.X <= thumbLeftLimit + thumbPosition Then
 thumbRectangle.X = thumbLeftLimit

 ' The thumb is all the way to the right.
 ElseIf e.Location.X >= thumbRightLimitLeft + thumbPosition Then
 thumbRectangle.X = thumbRightLimitLeft

 ' The thumb is between the ends of the track.
 Else
 thumbRectangle.X = e.Location.X - thumbPosition
 End If

 Invalidate()

 End If
 End Sub

 ' Recalculate the sizes of the scroll bar elements.
 Protected Overrides Sub OnSizeChanged(ByVal e As EventArgs)
 MyBase.OnSizeChanged(e)
 SetUpScrollBar()
 End Sub

 ' Handle the timer tick by updating the thumb position.
 Private Sub progressTimer_Tick(ByVal sender As Object, _
 ByVal myEventArgs As EventArgs) Handles progressTimer.Tick

 If Not ScrollBarRenderer.IsSupported Then
 Return
 End If

 ' If an arrow is clicked, move the thumb in small increments.
 If rightArrowClicked And thumbRectangle.X < thumbRightLimitLeft Then
 thumbRectangle.X += 1

 ElseIf leftArrowClicked And thumbRectangle.X > thumbLeftLimit Then
 thumbRectangle.X -= 1

 ' If the track bar to right of the thumb is clicked, move the 
 ' thumb to the right in larger increments until the right edge 
 ' of the thumb hits the cursor.
 ElseIf rightBarClicked And thumbRectangle.X < thumbRightLimitLeft _
 And thumbRectangle.X + thumbRectangle.Width < trackPosition Then
 thumbRectangle.X += 3

 ' If the track bar to left of the thumb is clicked, move the 
 ' thumb to the left in larger increments until the left edge 
 ' of the thumb hits the cursor.
 ElseIf leftBarClicked And thumbRectangle.X > thumbLeftLimit And _
 thumbRectangle.X > trackPosition Then
 thumbRectangle.X -= 3
 End If

 Invalidate()
 End Sub

 End Class
End Namespace

Remarks

The ScrollBarRenderer class provides a set of static methods that can be used to render a scroll 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. To draw a scroll bar, use a combination of the methods in this class to render each part of the scroll bar.

If visual styles are enabled in the operating system and visual styles are applied to the client area of application windows, the methods of this class will draw the scroll bar with the current visual style. Otherwise, the methods of 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.ScrollBar class. For more information, see Rendering Controls with Visual Styles.

See also

• VisualStyleRenderer
• VisualStyleElement