ScrollBarRenderer Classe

Definição

Namespace:

System.Windows.Forms

Assembly:

System.Windows.Forms.dll

Fornece os métodos usados para renderizar um controle de barra de rolagem com estilos visuais. Essa classe não pode ser herdada.

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

Herança

Object

ScrollBarRenderer

Exemplos

O exemplo de código a seguir demonstra como criar um controle personalizado que usa os ScrollBarRenderer métodos para desenhar uma barra de rolagem que responde aos cliques do mouse.

#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

Comentários

A ScrollBarRenderer classe fornece um conjunto de static métodos que podem ser usados para renderizar um controle de barra de rolagem com o estilo visual atual do sistema operacional. Renderizar um controle refere-se a desenhar a interface do usuário de um controle. Isso será útil se você estiver desenhando um controle personalizado que deve ter a aparência do estilo visual atual. Para desenhar uma barra de rolagem, use uma combinação dos métodos nessa classe para renderizar cada parte da barra de rolagem.

Se os estilos visuais estiverem habilitados no sistema operacional e os estilos visuais forem aplicados à área do cliente das janelas do aplicativo, os métodos dessa classe desenharão a barra de rolagem com o estilo visual atual. Caso contrário, os métodos dessa classe lançarão um InvalidOperationException. Para determinar se os membros dessa classe podem ser usados, você pode verificar o valor da IsSupported propriedade.

Essa classe encapsula a funcionalidade de um System.Windows.Forms.VisualStyles.VisualStyleRenderer que é definido como um dos elementos expostos pela System.Windows.Forms.VisualStyles.VisualStyleElement.ScrollBar classe. Para obter mais informações, consulte Controles de renderização com estilos visuais.

Propriedades

IsSupported

Obtém um valor que indica se a classe ScrollBarRenderer pode ser usada para desenhar uma barra de rolagem com estilos visuais.

Métodos

DrawArrowButton(Graphics, Rectangle, ScrollBarArrowButtonState)	Desenha uma seta de rolagem com estilos visuais.
DrawHorizontalThumb(Graphics, Rectangle, ScrollBarState)	Desenha uma caixa de rolagem horizontal (também conhecida como thumb) com estilos visuais.
DrawHorizontalThumbGrip(Graphics, Rectangle, ScrollBarState)	Desenha uma alça em uma caixa de rolagem horizontal (também conhecida como thumb) com estilos visuais.
DrawLeftHorizontalTrack(Graphics, Rectangle, ScrollBarState)	Desenha uma faixa da barra de rolagem horizontal com estilos visuais.
DrawLowerVerticalTrack(Graphics, Rectangle, ScrollBarState)	Desenha uma faixa da barra de rolagem vertical com estilos visuais.
DrawRightHorizontalTrack(Graphics, Rectangle, ScrollBarState)	Desenha uma faixa da barra de rolagem horizontal com estilos visuais.
DrawSizeBox(Graphics, Rectangle, ScrollBarSizeBoxState)	Desenha uma alça de dimensionamento de barra de rolagem com estilos visuais.
DrawUpperVerticalTrack(Graphics, Rectangle, ScrollBarState)	Desenha uma faixa da barra de rolagem vertical com estilos visuais.
DrawVerticalThumb(Graphics, Rectangle, ScrollBarState)	Desenha uma caixa de rolagem vertical (também conhecida como thumb) com estilos visuais.
DrawVerticalThumbGrip(Graphics, Rectangle, ScrollBarState)	Desenha uma alça em uma caixa de rolagem vertical (também conhecida como thumb) com estilos visuais.
GetSizeBoxSize(Graphics, ScrollBarState)	Retorna o tamanho da alça de dimensionamento.
GetThumbGripSize(Graphics, ScrollBarState)	Retorna o tamanho da alça da caixa de rolagem.

Confira também

• VisualStyleRenderer
• VisualStyleElement