تطوير الكونترول Rendering Control الجزء الخامس

كود :
Imports System.Windows.Forms.VisualStyles



Public Class MsCustomScrollBar



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