CODEWITHSUNDEEP
vb.netwinformslistbox
LimYX
LimYX

Reputation: 45

Changing color, highlight, background size of a ListBox?

https://i.imgur.com/2LTdcR2.png

So I've searched around and managed to highlight the values in my ListBox, but I'm trying to increase the font size for the text inside the ListBox but it results in the following image as attached:

enter image description here

This is my current code:

Private Sub ListBox1_DrawItem(sender As System.Object, e As System.Windows.Forms.DrawItemEventArgs) Handles ListBox1.DrawItem

    e.DrawBackground()

    If ListBox1.Items(e.Index).ToString().Contains("*") Then
        e.Graphics.FillRectangle(Brushes.Red, e.Bounds)
    End If

    e.Graphics.DrawString(ListBox1.Items(e.Index), e.Font, Brushes.Black, New System.Drawing.PointF(e.Bounds.X, e.Bounds.Y))
    e.DrawFocusRectangle()

I've tried messing with the "e.Bounds.X, e.Bounds.Y" to increase the rectangle/size of the highlighted value but nothing seemed to work.

How does one allow the highlighted rectangle increase according to the font size?

Upvotes: 2

Views: 935

Answers (1)

Jimi
Jimi

Reputation: 32248

When you set the DrawMode of a ListBox control to OwnerDrawVariable or you change the Font size after the control handle has been created (i.e. after it has already processed the WM_MEASUREITEM message), you need to manually set the ItemHeigh property to the new Font height.

The ItemHeight property is set subscribing the ListBox MeasureItem event and setting the MeasureItemEventArgs e.ItemHeight property.

Also, if you change the Font size on the fly, you also need to force the WM_MEASUREITEM message to be re-sent to the ListBox control, otherwise the Items Bounds will not be updated.
In other words, when the DrawItem event is raised, the DrawItemEventArgs e.Bounds property will report wrong measures.

A way to force the ListBox control to re-measure its Items bounds, is to set ListBox.DrawMode = DrawMode.Normal and immediatly resetting it back to OwnerDrawVariable. This causes the WM_MEASUREITEM message to be processed again.

listBox1.DrawMode = DrawMode.Normal
listBox1.DrawMode = DrawMode.OwnerDrawVariable
listBox1.Update()

Here I'm using the Font.Height to measure the current ItemHeight in the MeasureItem event, because it rounds up the measure. You could use TextRenderer.MeasureText or Font.GetHeight(); you'll end up with the same measure, but rounded down.

Private Sub ListBox1_DrawItem(sender As Object, e As DrawItemEventArgs) Handles ListBox1.DrawItem

    Dim ItemForeColor As Color
    Dim ItemBackColor As Color

    e.Graphics.TextRenderingHint = TextRenderingHint.ClearTypeGridFit

    If (e.State And DrawItemState.Selected) = DrawItemState.Selected Then
        ItemForeColor = Color.FromKnownColor(KnownColor.HighlightText)
        ItemBackColor = If(ListBox1.Items(e.Index).ToString().Contains("*"), Color.Red, Color.FromKnownColor(KnownColor.Highlight))
    Else
        ItemForeColor = ListBox1.ForeColor
        ItemBackColor = If(ListBox1.Items(e.Index).ToString().Contains("*"), Color.Red, ListBox1.BackColor)
    End If

    Using TextBrush As New SolidBrush(ItemForeColor)
        Using ItemBrush As New SolidBrush(ItemBackColor)
            e.Graphics.FillRectangle(ItemBrush, e.Bounds)
            e.Graphics.DrawString(ListBox1.Items(e.Index).ToString(), ListBox1.Font, TextBrush, e.Bounds, StringFormat.GenericTypographic)
        End Using
    End Using
    e.DrawFocusRectangle()
End Sub

Private Sub ListBox1_MeasureItem(sender As Object, e As MeasureItemEventArgs) Handles ListBox1.MeasureItem
    e.ItemHeight = ListBox1.Font.Height
End Sub

Test it resizing the Font:

ListBox1.Font = New Font(ListBox1.Font.FontFamily, ListBox1.Font.SizeInPoints + 2, ListBox1.Font.Style, GraphicsUnit.Point)
ListBox1.DrawMode = DrawMode.Normal
ListBox1.DrawMode = DrawMode.OwnerDrawVariable
ListBox1.Height = '[OriginalHeight]
ListBox1.Update()

enter image description here

Upvotes: 2

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