ScrollBarRenderer Classe
Definizione
Importante
Alcune informazioni sono relative alla release non definitiva del prodotto, che potrebbe subire modifiche significative prima della release definitiva. Microsoft non riconosce alcuna garanzia, espressa o implicita, in merito alle informazioni qui fornite.
Fornisce i metodi utilizzati per eseguire il rendering di un controllo barra di scorrimento con gli stili di visualizzazione. La classe non può essere ereditata.
public ref class ScrollBarRenderer sealedpublic ref class ScrollBarRenderer abstract sealedpublic sealed class ScrollBarRendererpublic static class ScrollBarRenderertype ScrollBarRenderer = classPublic NotInheritable Class ScrollBarRendererPublic Class ScrollBarRenderer- Ereditarietà
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ScrollBarRenderer
Esempio
Nell'esempio di codice seguente viene illustrato come creare un controllo personalizzato che usa i ScrollBarRenderer metodi per disegnare una barra di scorrimento che risponde ai clic del 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
Commenti
La ScrollBarRenderer classe fornisce un set di metodi che possono essere usati per eseguire il rendering di un controllo barra di static scorrimento con lo stile visivo corrente del sistema operativo. Il rendering di un controllo si riferisce alla grafica dell'interfaccia utente di un controllo. Questo è utile se si disegna un controllo personalizzato che deve avere l'aspetto dello stile di visualizzazione corrente. Per disegnare una barra di scorrimento, usare una combinazione dei metodi in questa classe per eseguire il rendering di ogni parte della barra di scorrimento.
Se gli stili di visualizzazione sono abilitati nel sistema operativo e gli stili di visualizzazione vengono applicati all'area client delle finestre dell'applicazione, i metodi di questa classe disegnano la barra di scorrimento con lo stile di visualizzazione corrente. In caso contrario, i metodi di questa classe genereranno un InvalidOperationExceptionoggetto . Per determinare se è possibile usare i membri di questa classe, è possibile controllare il valore della IsSupported proprietà.
Questa classe esegue il wrapping della funzionalità di un System.Windows.Forms.VisualStyles.VisualStyleRenderer oggetto impostato su uno degli elementi esposti dalla System.Windows.Forms.VisualStyles.VisualStyleElement.ScrollBar classe. Per altre informazioni, vedere Controlli di rendering con stili di visualizzazione.
Proprietà
| IsSupported |
Ottiene un valore che indica se la classe ScrollBarRenderer può essere utilizzata per disegnare una barra di scorrimento con stili di visualizzazione. |
Metodi
| DrawArrowButton(Graphics, Rectangle, ScrollBarArrowButtonState) |
Disegna una freccia di scorrimento con gli stili di visualizzazione. |
| DrawHorizontalThumb(Graphics, Rectangle, ScrollBarState) |
Disegna una casella di scorrimento orizzontale (anche nota come pulsante di scorrimento) con stili di visualizzazione. |
| DrawHorizontalThumbGrip(Graphics, Rectangle, ScrollBarState) |
Disegna un triangolo su una casella di scorrimento orizzontale (anche nota come pulsante di scorrimento) con stili di visualizzazione. |
| DrawLeftHorizontalTrack(Graphics, Rectangle, ScrollBarState) |
Disegna un indicatore della barra di scorrimento orizzontale con gli stili di visualizzazione. |
| DrawLowerVerticalTrack(Graphics, Rectangle, ScrollBarState) |
Disegna un indicatore della barra di scorrimento verticale con gli stili di visualizzazione. |
| DrawRightHorizontalTrack(Graphics, Rectangle, ScrollBarState) |
Disegna un indicatore della barra di scorrimento orizzontale con gli stili di visualizzazione. |
| DrawSizeBox(Graphics, Rectangle, ScrollBarSizeBoxState) |
Disegna un quadratino di ridimensionamento di una barra di scorrimento con gli stili di visualizzazione. |
| DrawUpperVerticalTrack(Graphics, Rectangle, ScrollBarState) |
Disegna un indicatore della barra di scorrimento verticale con gli stili di visualizzazione. |
| DrawVerticalThumb(Graphics, Rectangle, ScrollBarState) |
Disegna una casella di scorrimento verticale (anche nota come pulsante di scorrimento) con stili di visualizzazione. |
| DrawVerticalThumbGrip(Graphics, Rectangle, ScrollBarState) |
Disegna un triangolo su una casella di scorrimento verticale (anche nota come pulsante di scorrimento) con stili di visualizzazione. |
| GetSizeBoxSize(Graphics, ScrollBarState) |
Restituisce le dimensioni del quadratino di ridimensionamento. |
| GetThumbGripSize(Graphics, ScrollBarState) |
Restituisce le dimensioni del triangolo della casella di scorrimento. |