Display tool tip on drawn icon image of custom user control

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I have been working on my first custom user control. The custom control inherits UserControl. The user control contains a combination of drawn rectangles, circles and a icon image. I would like to display a tool tip when the user hovers the mouse over the image portion of the control. The image was created by using drawicon. I then have a mouse move event in my control that detects when the mouse is over the icon. That logic all works properly. What I am having a problem with is that after the tool tip disappears, it erases the part of the control is was hovering over. I am trying to figure out the proper way to repaint the control but I am not having any luck.

What I have tried:

Here is how I am painting the control:

Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)

        Dim rect As System.Drawing.Rectangle = e.ClipRectangle
        Dim g As Graphics = e.Graphics
        g.SmoothingMode = SmoothingMode.HighQuality

        'Draw the Machine Bed
        DrawBed(g, rect)

        'Draw and position the Machine Head
        DrawHead(g, rect, _HeadPosInInches)

    End Sub

    Private Sub DrawBed(ByVal g As Graphics, ByVal CtlRect As System.Drawing.Rectangle)

        'Draws the bed

        'Size the bed based on the control size
        _BedWidth = CInt(CtlRect.Width * _BedWidthFactor)
        _BedHeight = CInt(CtlRect.Height * _BedHeightFactor)

        'Center the bed within the control
        _BedYBorder = CInt((CtlRect.Height - _BedHeight) / 2)
        _BedXBorder = CInt(CtlRect.Width - _BedWidth)

        'Create a new rect for the bed
        Dim BedXLoc As Integer = 0

        If HeadTravelDir = 1 Then
            BedXLoc = _BedXBorder
        Else
            BedXLoc = 0
        End If

        Dim BedRect As New Rectangle(BedXLoc, _BedYBorder, _BedWidth, _BedHeight)

        'Fill the Bed
        Using Brush1 As New SolidBrush(_BedColor)
            g.FillRectangle(Brush1, BedRect)
        End Using

        'Create the Bed border
        Using Pen1 As New Pen(Color.Black, 1)
            g.DrawRectangle(Pen1, BedRect)
        End Using

    End Sub

Here is how I am drawing the icon image on the screen:

Dim TargetX As Integer = 0
Dim TargetY As Integer = 0
Dim TargetWidth As Integer = _BedYBorder
Dim TargetHeight As Integer = _BedYBorder

If _HeadTravelDir = 1 Then
   TargetX = HeadRect.X + HeadRect.Width + 5
Else
   TargetX = HeadRect.X - 5 - _BedYBorder
End If

Dim DashboardIcon As New Icon("U:\photos\DashboardIcons\Question.ico")
Dim TargetRect As New Rectangle(TargetX, TargetY, TargetWidth, TargetHeight)
IconRect = TargetRect
g.DrawIcon(DashboardIcon, TargetRect)

Here is how I am detecting when the mouse if over the icon image:

Private Sub ctlGantry_MouseMove(ByVal sender As Object, ByVal e As System.Windows.Forms.MouseEventArgs) Handles Me.MouseMove

        'Checks to see if the mouse if over the icon
        If IconRect.Contains(e.Location) Then
            Debug.WriteLine(e.Location.ToString & " is Over the Icon for " & Me.Name)
            _IconMouseOver = True
            'Me.ToolTip1.Show("test", Me)

        Else
            _IconMouseOver = False
            'Me.ToolTip1.Hide(Me)
            'Me.Invalidate()
        End If
    End Sub

I have tried displaying the tooltip in both the mousemove and the mousehover events but I get similar results. If I try to invalidate when the mouse is not over the icon, I get a lot of flickering. The background control also doesn't repaint when I move the mouse in a different position over the icon. I am not sure if this is related to the same issue but I also have a problem where the icon will no longer reappear after I hover on the control for a few seconds and then comeback and rehover. If I repaint the control and try it again, then the tooltip will reappear. I am very close to being able to wrap this control up but I need to figure this out first. Any ideas?

Posted 8-Aug-17 10:12am

theskiguy

Updated 9-Aug-17 2:56am

v2

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Comments

Graeme_Grant 9-Aug-17 2:12am

Are you rendering in the UserControl_Paint event [if the UserControl is your canvas] and calling UserControl.Invalidate() method to force repaint when updating the UI?

theskiguy 9-Aug-17 7:18am

You are correct. See improved question that now includes some code that show the control painting. As far as Invalidate, the problem I am having is determining the proper time to call it. If I only call invalidate when the mouse is not over the icon, the control will not repaint if I move the mouse to a different position on the icon. If I move the invalidate to the beginning of the mouse move event, my user control completely disappears even if I stop moving the mouse when it is over the icon.

Graeme_Grant 9-Aug-17 9:03am

I'm not seeing the problem with the code that you provided. So instead I've knocked up a little test and everything is working as expected. Hope it helps.

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Graeme_Grant · Accepted Answer · 2017-08-09T02:56:00

Here is a working sample for you:

VB

Public Class UserControl1

    Public Sub New()

        InitializeComponent()
        AddTootip()
        Recalc()

    End Sub

    Private Tooltip As ToolTip

    Private Sub AddTootip()

        Tooltip = New ToolTip() With
        {
            .AutoPopDelay = 5000,
            .InitialDelay = 1000,
            .ReshowDelay = 500,
            .ShowAlways = True
        }
        Tooltip.SetToolTip(Me, "Test tooltip 1 2 3...")

    End Sub

    Private boxes(9) As Rectangle

    Private Sub UserControl1_Paint(sender As Object, e As PaintEventArgs) Handles MyBase.Paint

        Dim gr = e.Graphics
        Dim br = New SolidBrush(Color.Red)

        For index = 0 To 9
            gr.FillRectangle(br, boxes(index))
        Next

    End Sub

    Private Sub UserControl1_MouseMove(sender As Object, e As MouseEventArgs) Handles MyBase.MouseMove

        For index = 0 To 9
            If boxes(index).Contains(e.Location) Then
                Tooltip.ToolTipTitle = "Box " + CStr(index + 1)
                Exit Sub
            End If
        Next
        Tooltip.ToolTipTitle = "UserControl background..."

    End Sub

    Private Sub UserControl1_Resize(sender As Object, e As EventArgs)
        Recalc()
    End Sub

    Private Sub Recalc()

        Dim hoffset = Height / 11
        Dim woffset = Width / 11
        Dim sz = New Size(woffset, hoffset)

        For index = 0 To 9
            Dim pt = New Point(index * woffset, index * hoffset)
            boxes(index) = New Rectangle(pt, sz)
        Next

        Invalidate()

    End Sub

End Class